People with COPD have greater participation restrictions than age-matched older adults without respiratory conditions assessed during the COVID-19 pandemic.

BACKGROUND: Participation restriction has detrimental effects for older adults but it is unknown how participation differs for people with chronic obstructive pulmonary disease (COPD) compared to older adults of the same age without respiratory conditions. We compared scores on the Late Life Disability Instrument (LLDI) between people with COPD (study group) and a random sample of older adults (control group).
METHODS: Participants with COPD (study group) were recruited from two hospitals in Ontario and age- and sex-matched with a ratio of 1:2 with participants from a random sample of community-dwelling older adults who did not report having respiratory conditions (control group). The study group completed the LLDI prior to the COVID-19 pandemic and the control group completed the LLDI at the end of the first wave of the pandemic. LLDI frequency and limitation scores were compared between groups using Wilcoxon rank-sum tests.
RESULTS: Forty-six study group participants (mean age 74.2 (SD 5.5) years) and 92 control group participants (mean age 74.4 (SD 5.4) years) were included. Fifty-four percent of the participants were female. The majority of the study group had severe COPD (median forced expiratory volume in one second of 34.5 (25th-75th percentile 27.0-56.0) % predicted). LLDI sores were lower for the study group compared to the control group for both the frequency (median difference -5.4 points, p<0.001) and limitation (median difference -7.6 points, p<0.001) domains. The personal subscale demonstrated the largest magnitude of difference between groups (median difference -13.4 points) and the social subscale demonstrated the smallest magnitude of difference (-5.2 points).
CONCLUSION: People with COPD had greater participation restrictions than a random sample of older adults without ongoing respiratory conditions. The differences seen in participation between the two groups may have been reduced due to temporal confounding from the COVID-19 pandemic. While participation is relevant to all older adults, our results suggest that it is especially important that it be assessed in those with COPD.

Introduction

Chronic obstructive pulmonary disease (COPD) is a highly prevalent condition worldwide [1,2] that is characterized by airborne particulate exposure causing irreversible damage to the lungs. The most common cause is tobacco smoke often in combination with other environmental exposures and/or genetic susceptibility [2,3]. The primary signs and symptoms associated with COPD are breathlessness, cough and increased secretions or sputum production [2]. In addition, people with COPD often present with extra-pulmonary manifestations of their condition, including skeletal muscle dysfunction, reduced exercise tolerance, physical inactivity, functional impairment, reduced quality of life, and social isolation [4]. However, there is little information regarding the impact of COPD on participation.

Participation, as it is conceptualized in the World Health Organization’s International Classification of Functioning, Disability and Health [5], is involvement in a life situation, congruent with the concept of disability in both Nagi’s disablement model [6] and Verbrugge and Jette’s disablement process model [7]. In these models or frameworks, ‘participation restriction’ or ‘disability’ arises from the interaction between functional limitations caused by health conditions such as COPD and intrinsic or personal factors such as age and sex, and the environment. It reflects limitations in the ability to perform tasks that are expected given one’s role in a specific sociocultural context and physical environment [6].

The prevalence of participation restriction for community-dwelling adults ≥ 50 years has been estimated to be 52% with the most affected area on the Keele Assessment of Participation being mobility outside the home [8]. In a report assessing basic and instrumental activities of daily living and social participation in 6903 adults ≥ 65 years with chronic conditions such as arthritis, ischaemic heart disease and diabetes, up to 68% of the cases of disability would not have occurred if it were not for the presence of these chronic conditions [9]. Given the mediating effect of social participation restrictions on psychological distress [10] and the protective effect of social relationships against mortality [11], there is a clear need to better understand this construct in older adults with chronic conditions.

COPD may present important challenges to participation that are not seen in other chronic conditions because of its progressive symptoms such as breathlessness and cough, the nature of its episodic exacerbations, and devices employed in its management such as mobility aids and supplemental oxygen [2]. However, to our knowledge, there are no studies that have compared scores on a validated measure of participation between people with and without chronic lung disease, limiting our knowledge of the impact of COPD on participation. Such information will assist healthcare professionals in formulating a care plan that addresses this important aspect of health. Therefore, the objective of this study was to compare participation scores in people with COPD to scores from a random sample of older adults using a widely-used, validated measure of participation, the Late Life Disability Instrument (LLDI) [12]. The LLDI is based on Nagi’s disablement model [6], and is consistent with the concept of participation in the international classification of functioning, disability and health [5]. We hypothesized that the study group (those with COPD) would have lower scores than the control group on both domains, meaning greater restriction in the frequency of participation as well as greater perceived limitations in their ability to participate.

Materials and methods

This was a secondary analysis of data from two studies, the first a cross-sectional study in patients with COPD (conducted from February 2018 to March 2020), and the second, baseline data from a longitudinal study of older adults conducted during the coronavirus disease 2019 (COVID-19) pandemic (May to August 2020). Ethics approval for the primary studies was obtained from the Joint West Park Healthcare Centre—Toronto Central Community Care Access Centre—Toronto Grace Health Centre Research Ethics Board (17-013WP) and the Hamilton Integrated Research Ethics Board (HiREB #3878 and #10814). All participants provided informed consent prior to data collection for the primary studies; written consent was obtained from the study group and verbal consent was obtained from the control group.

Study group participants

We recruited study group participants during routine clinical visits at two respiratory centres in Ontario- West Park Healthcare Centre in Toronto and the Firestone Institute for Respiratory Health in Hamilton. They were recruited for a cross-sectional validation study of the primary outcome measure, the LLDI. Details of recruitment, eligibility, and data collection have been reported previously [13]. Briefly, participants living in the community had to have a physician diagnosis of COPD as well as a 10-pack-year smoking history.

Control group participants

A random sample of older adults was identified using 2016 census data and a sampling company that provides representative samples of publically available phone numbers [14]. These participants had been recruited for a longitudinal tele-survey looking at the impact of the COVID-19 pandemic on the mobility and participation of community-dwelling older adults who were not suffering from COVID-19 [15]. Postal codes were selected based on the distance from McMaster University in Hamilton and the ratio of older adults (≥ 65 years) within the dissemination area. Participants had to be living independently within the Greater Hamilton Area, aged 65 or older, and able to provide consent. Potential participants were excluded if they had severe and uncorrectable cognitive, visual or hearing impairments that would prevent their completing the questionnaires. The baseline data was used for this analysis.

Outcome measure

The disability component of the Late Life Function and Disability Instrument (LLDI) was administered via one-on-one interview to both groups. Respondents were asked how often they participated in 16 various life tasks (frequency scale) and how limited they were in participating in those same tasks (limitation scale) [12]. The frequency scale is comprised of a social role subscale (9 items related to going out with others) and a personal role subscale (7 items related to personal care and local errands). The limitation scale is comprised of an instrumental role subscale (12 items related to moving around the home and community) and a management role subscale (4 items related to communication and planning) [12]. We used the scaled summary scores with possible scores from 0–100% and higher scores indicating greater frequency of and fewer limitations in participation [12]. The minimal detectable change score (MDC90) for the LLDI is 7.4 points for the frequency scale and 11.6 points for the limitation scale in mobility-limited older adults [16] and the MDC95 is 6.7 points for the frequency scale and 9.9 points for the limitation scale in people with COPD [13]. This measure has been used extensively in older adults [17] and has shown good construct validity and test-retest reliability in people with COPD [13].

Data analysis

We performed statistical analyses using Stata 14.2 (StataCorp LLC, College Station, Texas). We explored raw data for normality visually using histograms and numerically using the Shapiro–Wilk test. Based on the distribution of the data, we used either independent students t-tests or Wilcoxon rank-sum tests to compare the study group and the control group. If the F-test for equal variances was significant, unequal t-tests were performed and Satterthwaite’s approximation of degrees of freedom reported. We used one-sided tests and applied the Bonferroni correction for multiple comparisons. Raw data is available in S1 File. As a sensitivity analysis, we also compared LLDI scores between the full samples of people with and without respiratory disease, without age- and sex-matching using quantile regression with age and sex as covariates. We accepted an alpha value of ≤ 0.05 as indicating statistical significance.

Results

From the primary studies, LLDI scores were collected in 96 people with COPD and 272 older adults. For this analysis, we excluded participants from the control group if they had a physician-diagnosed respiratory condition such as COPD or asthma. Participants were then age- and sex-matched for the study and control groups at a ratio of 1:2, matching age within 2 years. This resulted in 46 study group participants and 92 control group participants (Fig 1).

Fig 1

Flow diagram of recruitment for primary studies and inclusion in current analysis.

SG = study group; CG = control group.

Participants had a mean age of 74 years and 54% of them were female. The study group participants had a median forced expiratory volume in 1 second of 34.5% predicted, corresponding to a global initiative for chronic obstructive lung disease airflow stage of 3 (severe) [2]. See Table 1 for additional participant characteristics. The groups differed in baseline characteristics in terms of use of gait aid (p < 0.001) with more study group participants using one, self-reported general health (p < 0.001) with study group participants reporting worse health, and comorbidities with more study group participants having anxiety (p < 0.001) and depression (p = 0.047) and more control group participants having cataracts (p = 0.046).

Table 1

Participant characteristics.

	Study Group, n (%)a, n = 46	Control Group, n (%)a, n = 92	p-value of between-group difference
Age, y, mean (SD)	74.2 (5.5)	74.4 (5.4)	0.84
Sex, female	25 (54.4)	50 (54.4)	1.00
BMI, kg/m2, median (25th-75th percentile)b	27.9 (24.1–33.3)	26.7 (24.4–29.6)	0.40
Self-reported general health:			<0.001
Excellent	0 (0.0)	17 (18.5)
Very good	1 (2.2)	35 (38.0)
Good	16 (34.8)	32 (34.8)
Fair	18 (39.1)	7 (7.6)
Poor	11 (23.9)	1 (1.1)
Uses Gait Aid	26 (56.5)	10 (10.9)	<0.001
Uses Supplemental Oxygen	29 (63.0)	Not collected	N/A
Modified medical research council dyspnea scale, mean (SD) c	2.2 (0.9)	N/A	N/A
COPD assessment test, mean (SD) d	21.6 (6.4)	N/A	N/A
Most common comorbidities (reported in >20% of total sample):
Hypertension	28 (60.9)	41 (44.6)	0.07
Anxiety	13 (28.3)	4 (4.4)	<0.001
Back pain	10 (21.7)	18 (19.6)	0.77
Cancer	10 (21.7)	16 (17.4)	0.54
Cataracts	8 (17.4)	31 (33.7)	0.046
Diabetes	8 (17.4)	20 (21.7)	0.55
Osteoarthritis	8 (17.4)	17 (18.5)	0.88
Depression	8 (17.4)	6 (6.5)	0.047
Osteoporosis	7 (15.2)	10 (10.9)	0.47

BMI = body mass index; N/A = not applicable; COPD = chronic obstructive pulmonary disease.

aUnless stated otherwise.

bn = 86 for control group (6 participants did not know their weight).

c0-4 points, higher = worse dyspnea.

d0-40 points, higher = greater impact of COPD.

Other than the social subscale, the LLDI scores were not normally distributed for at least one of the groups. Therefore, non-parametric tests were conducted. We calculated the probability of an observation in the control group having a true value higher than an observation in the study group [18]. Both LLDI domain scores and all four subscale scores were significantly higher for the control group than the study group with probabilities ranging from 0.63 to 0.74 (Table 2).

Table 2

Between-group comparison of LLDI scores.

	Study group, median (25th-75th percentile)	Control group, median (25th-75th percentile)	Between-group comparison,z (p)	Probability (95% CI) that control group score > study group score
Frequency domain	47.2 (44.5–51.5)	52.6 (46.9–58.0)	-4.18 (<0.001)	0.72 (0.63–0.80)
Personal subscale	51.7 (47.9–62.8)	65.1 (56.3–84.0)	-4.53 (<0.001)	0.74 (0.64–0.83)
Social subscale	41.1 (37.3–46.3)	46.3 (40.5–53.3)	-3.13 (0.011)	0.66 (0.57–0.76)
Limitation domain	59.7 (51.8–64.8)	67.3 (58.1–83.4)	-4.34 (<0.001)	0.73 (0.64–0.81)
Instrumental subscale	55.4 (48.5–64.4)	65.5 (55.8–88.9)	-4.46 (<0.001)	0.73 (0.65–0.82)
Management subscale	78.3 (71.0–100.0)	89.5 (74.5–100.0)	-2.64 (0.05)	0.63 (0.54–0.73)

LLDI = late life disability instrument.

These results were similar when the LLDI scores of the full sample of 96 people with COPD and 202 people without respiratory disease were compared (see S1 and S2 Tables in S2 File).

The difference in median scores for the frequency and limitation domains for the two groups was lower than the MDC95 established in people with COPD (5.4 points compared to 6.7 points, and 7.6 points compared to 9.9 points, respectively) and the MDC90 established in mobility-limited older adults for the frequency and limitation domains (7.4 and 11.6 points, respectively) [13,16]. The largest magnitude of difference between groups was seen for the personal subscale of the frequency domain (median difference 13.4 points), followed by the management and instrumental subscales of the limitation domain (11.2 and 10.1 points, respectively), with the smallest magnitude of difference being for the social subscale of the frequency domain (median difference 5.2 points). Figs 2 and 3 show the distribution of the frequency and limitation domain scores for both groups.

Fig 2

Late-life disability instrument frequency domain scores for the study group and control group.

The box represents the 25th to 75th percentiles with the horizontal line inside the box representing the median score. The horizontal lines above and below the box represent the maximum (75th percentile plus 1.5*IQR) and minimum (25th percentile minus 1.5*IQR) scores. IQR = interquartile range.

Fig 3

Late-life disability instrument limitation domain scores for the study group and control group.

The box represents the 25th to 75th percentiles with the horizontal line inside the box representing the median score. The horizontal lines above and below the box represent the maximum (75th percentile plus 1.5*IQR) and minimum (25th percentile minus 1.5*IQR) scores. IQR = interquartile range.

Discussion

This is the first study to compare scores on a validated measure of participation between people with COPD and an age- and sex-matched sample of older adults without respiratory disease. The results showed, as hypothesized, that people with COPD have greater participation restrictions than age-matched adults. They participated in tasks less frequently and had greater limitations in their ability to participate in life situations, particularly in those that involved some level of mobility or physical function such as taking care of the home and active recreation.

The greatest magnitude of difference between the median scores for the study group and the control group were seen for the personal role subscale of the frequency domain and the management role subscale of the limitation domain. Life tasks represented in both of these subscales are taking care of household business and finances and taking care of one’s own health (i.e., how often do you take care of your own health and how limited do you feel in taking care of your own health). There was also a large magnitude of difference in limitations related to the instrumental role which includes tasks such as taking part in a regular fitness program, taking care of one’s own personal care needs, taking care of local errands, and preparing meals for oneself, all tasks that require some level of mobility or physical activity [12] which is a recognized limitation in people with COPD [2].

A smaller difference, and potentially a less clinically meaningful difference, in scores between groups was seen for the social subscale of the frequency domain, suggesting that the two groups experienced similar reductions in social activities. This subscale, comprised of tasks such as visiting friends and family, volunteering, travelling, going out with others to public places, and participating in organized social activities, was the lowest scoring subscale (below 50%) for both groups. The control group completed the questionnaire at the end of the first wave of the COVID-19 pandemic when social and public health restrictions were in place whereas all of the people from the study group participated prior to the pandemic. Accordingly, the control groups’ frequency of participating in these life tasks was likely impacted, highlighting the extent to which participation is restricted for older adults during a pandemic and potentially explaining the smaller difference between groups in this subscale. Normative scores have not been established for the LLDI but two previous studies of community-dwelling adults aged 65 and over reported mean scores of 41.4 [19] and 45.5 [20] points on the social subscale, similar to the mean score of 47.2 points seen in our control group. While the magnitude of difference on the social subscale between the study group and control group was less than that of the other subscales, these tasks should remain a focus of intervention for all older adults, given that both groups scored < 50%.

Some additional variability and between-group differences may have been missed as the limitation domain showed a ceiling effect [21] for the control group with 21% scoring 100%. In the initial study of the development of the measure, only 6.7% of the respondents (adults ≥ 60 years with a range of functional limitations) scored 100% on the limitation domain [22]. Subsequent studies in general populations of older adults have varied from no ceiling effect for the limitation domain [23,24], to > 30% of participants scoring 100% [25]. These inconsistent findings are likely due to differences in age (mean age ≥ 79 [23,24] vs 69 years [25]) and physical activity levels of the participants, but they are worthy of further exploration. In particular, we noted a ceiling effect on the management subscale of the limitation domain, with 26% of the study group participants and 43% of the control group participants scoring 100%. It is therefore likely that this measure has not captured the full range of limitations related to communication and planning (or non-mobility-related life tasks) in people with COPD.

The wide distribution of scores, particularly in the control group, is important to note. The control group was a random sample of older adults who were only excluded from the tele-survey if they were unable to complete the questionnaires. Therefore, as is expected in the general population of older adults [26], the majority of participants had multimorbidity. For the purpose of this analysis, we excluded those with respiratory diagnoses, but there were people with arthritis, diabetes and vision impairment, all diagnoses that have a potential impact on participation [9]. We likely would have seen a greater magnitude of difference in median scores had the control group been a healthy group without any chronic conditions. In addition, the spread of the scores in the control group likely reflected the within-group heterogeneity associated with differences in intrinsic factors (e.g., health conditions and functional impairments) and extrinsic factors (e.g., medications, clinical treatments, assistive devices, and barriers in the built environment) [27] less likely in the more homogenous group with COPD.

The decreased frequency of and increased limitations in participation found in people with COPD highlights the importance of assessing this important aspect of health in this population and addressing participation restrictions as part of pulmonary rehabilitation in order to mitigate negative sequalae such as psychological distress and mortality.

Limitations

The LLDI scores demonstrated by the study group reflect those with severe COPD and therefore cannot be generalized to those with mild disease. This was a secondary analysis with data retrieved from two independent studies in which the LLDI was measured. As the primary studies differed in design, we did not consistently have other baseline data or outcome measures, such as physical function or quality of life, that might have more completely characterized the participants. In addition, we did not have pulmonary function test results from the control group participants and it is possible that some of them had undiagnosed respiratory disease. And finally, the control group completed the study at the end of the first wave of the COVID-19 pandemic at which time there were social and public health restrictions in place. This difference in social circumstances might have impacted the frequency of participation in life tasks, making the control group results non-generalizable to non-pandemic times. The frequency of social activities was low in both groups and it is likely that the control group would have shown even higher scores on this subscale had public health restrictions not been in place at the time. As such, the differences seen in the participation scores between the two groups may have been attenuated due to temporal confounding.

Conclusion

People with COPD have greater restrictions in both their frequency of participation and their limitations in participation, than their peers without respiratory disease, especially in life tasks related to personal, management, and instrumental roles. Clinicians have a unique opportunity to address the extra-pulmonary effects of COPD in pulmonary rehabilitation programs. Valid measures of participation are not generally included in such programs that address the longer-term impact of COPD on patients and their families. However, an assessment of participation restrictions could be a valuable addition to the management of chronic lung disease so that targeted interventions can be considered for these patients.

Raw data for study group and control group.

Group 1 = study group; Group 2 = control group.

(XLSX)

Click here for additional data file.

Participant characteristics and between-group comparison of LLDI scores for 96 study group participants and 202 control group participants who were not age- or sex-matched.

(DOCX)

Click here for additional data file.

14 Jun 2022

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5. Review Comments to the Author

Reviewer #1: This is an interesting study that compares limitations to participation in a cohort of subjects with advanced COPD against age and sex matched control subjects. I would recommend the following revisions be undertaken:

Major comments:

1) One of the major limitations of this study is that it is temporally confounded. The control group completed the questionnaire during the first wave of the COVID-19 pandemic when social and public health restrictions were in place, whereas all of the people from the study group participated prior to the pandemic. Accordingly, the control groups’ frequency of participating in these life tasks was likely impacted, highlighting the extent to

which participation is restricted for older adults during a pandemic. The overall effect of this confounding would have been to reduce inter-group differences seen on the LLDI scores. I think that this major limitation has to be mentioned and explained within the abstract of the paper, and the abstract has to conclude that 'People with COPD had greater participation restrictions than a random sample of older adults without ongoing respiratory conditions, but differences in participation restriction seen in this study may have been reduced due to temporal confounding.

2) The authors state on page 6 that "The minimal detectable change score (MDC90) for the

LLDI is 7.4 points for the frequency scale and 11.6 points for the limitation scale in mobility limited older adults." Since the between-group differences in this study were less than these MDC90 scores does this mean that the differences are not clinically significant between groups? Please clarify.

3) Did the control group undergo lung function testing? If not, how can we be sure they did not have COPD?

4) A Figure 1 flow diagram needs to be added which shows how the study subjects were recruited and included/excluded and which subjects were ultimately included in the final study analysis.

5) I note that from the primary studies, LLDI scores were collected in 96 people with COPD and 272

older adults. For this paper, only 46 study group participants and 92 control group participants were retained. This means that a lot of interesting collected data has not been analyzed. I think it would be interesting to see the LLDI scores for the entire COPD cohort and the entire 272 control cohort. This analysis could be added to the paper, and the between-group differences could be adjusted for age and sex. This additional age and sex adjusted analysis would be complementary to the case-control analysis.

6) Minor comment- please delete the dots showing outliers from figs 1 and 2- they are distracting and not needed.

Reviewer #2: This is a well-written manuscript, an interesting and relevant work on participation in people with chronic obstructive pulmonary disease (COPD). The authors have compared the level of participation between people with COPD and community-dwelling older adults without lung disease. People with COPD presented with greater participation restrictions compared to their peers without chronic respiratory conditions. Please find below some major and minor concerns the authors should address before publication.

Abstract

Minor

The LLDI abbreviation should be indicated at its first appearance in the text.

Results

Minor

In Table 1, the presentation of statistical differences between groups should be revised to support the manuscript text. Some symbols used should be moved to the first column for a description of the variables, and only statistical differences should be indicated in the middle and left data columns. It is not clear to the reader which frequencies of self-reported general health differences are between groups.

Major

In the study group, is there any subanalysis available on differences in LLDI Participation scores between people with COPD on Long-term home oxygen therapy (LTOT) compared to those who are not? This would bring new information to the COPD literature. The authors should also provide in Table 1 the number of study group participants on LTOT, as it could impact Participation due to the use of non-portable oxygen delivery devices.

Discussion

Page 13, line 225: please consider the replacement of 'pathologies' for 'diseases' or 'illnesses'.

Page 14, lines 244-247: the authors should consider rewriting the sentences as it is difficult for the reader knows who they are referring to in 'We have a unique opportunity...' Are the authors referring to themselves, physiotherapists or healthcare professionals in general involved in COPD rehabilitation? Also, the study sample comprised patients who were not exclusively on admission to pulmonary rehabilitation programs.

Reviewer #3: Sachi O’Hoski et al s aimed to compare participation scores in people with COPD to scores from a random sample of older adults using a validated measure of participation, the LLDI which is consistent with the concept of participation in the international classification of functioning, disability and health. LLDI sores were lower for the COPD group compared to controls for both the frequency and limitation domains of the LLDI. The paper is generally written in an excellent way, the description of methods used is clear, results are nicely presented and discussion is focused. However, the study is limited by its design.

I have the following concerns.

1. The authors used a secondary analysis of existing data to compare COPD patients and controls in terms of quality-of-life outcomes. Data are derived from two different time periods, one of the them during the COVID-19 pandemic. This type of design may have introduced biases in the accuracy of the results of this study.

2. During the pandemic many things occurred in terms of our living that may have affected subjects’ decisions and activities. In this respect activities and participation may have been different compared to the previous period- where COPD patients were recruited. How the authors treated this source of potential bias in their analysis? Has LLDI been validated during these circumstances? Or, do we know that this instrument is accurate even during periods with such different social conditions? It would be useful to know that LLDI provides similar results in similar populations but in different time periods/social conditions (or not).

3. In addition, COPD patients experience relatively severe disease based on the FEV1 reported. Is there a similar assessment of the respiratory function for controls?

4. Introduction could be shorter. I would highlight more -being more specific- the clinical value of the results of this study in the discussion section

12 Jul 2022

Editor:

1. The title about comparing the limitations between elderly with COPD and their peers is inaccurate. The control group is the elderly assessed during the COVID-19 pandemic. Covid-19 pandemic per se is a cofounding factor. Please make corrections as per suggestion.

Response (R): The title has been changed to “People with COPD have greater participation restrictions than age-matched older adults without respiratory conditions assessed during the COVID-19 pandemic” and we have removed ‘peers’ throughout the manuscript and instead referred to the control group as “older adults of the same age without respiratory conditions” (Page 2 Line 26) or “age-matched adults” (Page 13 Line 204). We have also acknowledged that the age-matched group was assessed during the COVID-19 pandemic in the abstract on Page 2 Lines 31-33: “The study group completed the LLDI prior to the COVID-19 pandemic and the control group completed the LLDI during the first wave of the pandemic.” and Pages 2-3 Lines 44-45: “The differences seen in participation between the two groups may have been reduced due to temporal confounding from the COVID-19 pandemic.” We have also expanded on this limitation in the discussion on Pages 15-16 Lines 268-276: “And finally, the control group completed the study during the first wave of the COVID-19 pandemic at which time there were social and public health restrictions in place. This difference in social circumstances might have impacted the frequency of participation in life tasks, making the control group results non-generalizable to non-pandemic times. The frequency of social activities was low in both groups and it is likely that the control group would have shown even higher scores on this subscale had public health restrictions not been in place at the time. As such, the differences seen in the participation scores between the two groups may have been attenuated due to temporal confounding.”

2. The baseline demographic even match, is not identical, and not every characteristic matches. Therefore, the comparison must be made and corrections/adjustments in the statistical analysis of study outcomes should be made if any significant difference is noted.

R: We included a narrative summary of the differences between groups on Page 8 Lines 159-163: “The groups differed in baseline characteristics in terms of use of gait aid (p < 0.001) with more study group participants using one, self-reported general health (p < 0.001) with study group participants reporting worse health, and comorbidities with more study group participants having anxiety (p < 0.001) and depression (p = 0.047) and more control group participants having cataracts (p = 0.046).” We have now added a column to Table 1 with the statistical comparison of baselines characteristics between groups. We did not adjust for these differences between groups in our analyses because these differences in the characteristics of people with COPD are likely related to their increased participation restrictions. We were not solely interested in the impact of a diagnosis of COPD on participation, but in the impact of having COPD and all that goes along with it, including use of a gait aid, lower self-reported health, and comorbidities such as anxiety and depression.

3. The sample size is small, therefore, abnormal distribution is expected. Authors also declare the distribution of primary outcomes is abnormal. Thus, the continuous variables have to be reported in the median, even the result of reporting the mean is also no different. Same as the statistic methods.

R: We have adjusted the reporting of all variables and outcomes to account for the non-normal distribution of the LLDI scores. Changes to the manuscript can be found in the following sections:

Abstract methods and results on Page 2 Lines 34 and 37-42, respectively.

Page 8 Line 157: Results reported as median (25th-75th percentile)

Page 9 (Table 1): Results reported as median (25th-75th percentile)

Pages 10-11 Lines 170-174: “Other than the social subscale, the LLDI scores were not normally distributed for at least one of the groups. Therefore, non-parametric tests were conducted. We calculated the probability of an observation in the control group having a true value higher than an observation in the study group [18]. Both LLDI domain scores and all four subscale scores were significantly higher for the control group than the study group with probabilities ranging from 0.63 to 0.74 (Table 2).”

Page 11 (Table 2): Median (25th-75th percentile) and probabilities added to the table.

Page 12 Lines 184-188: “The largest magnitude of difference between groups was seen for the personal subscale of the frequency domain (median difference 13.4 points), followed by the management and instrumental subscales of the limitation domain (11.2 and 10.1 points, respectively), with the smallest magnitude of difference being for the social subscale of the frequency domain (median difference 5.2 points).”

Page 13 Lines 207-212: We have adjusted this part of the discussion since the subscales with the largest mean difference and the largest median difference were different.

4. The fact that the study was conducted at different time frames is a major limitation. Please justify that.

R: Given that this was a secondary analysis, we were unable to control when the data were collected. However, this has been included as a limitation on Pages 15-16 Lines 268-276: “And finally, the control group completed the study during the first wave of the COVID-19 pandemic at which time there were social and public health restrictions in place. This difference in social circumstances might have impacted the frequency of participation in life tasks, making the control group results non-generalizable to non-pandemic times. The frequency of social activities was low in both groups and it is likely that the control group would have shown even higher scores on this subscale had public health restrictions not been in place at the time. As such, the differences seen in the participation scores between the two groups may have been attenuated due to temporal confounding.”

5. Do your sample size adequate?

R: Because this was a secondary analysis, we did not calculate a sample size a priori. For the frequency domain, assuming a pooled standard deviation of 10, power of 80% and alpha of 5%, we would need 38 participants in the study group and 76 participants in the control group to detect a difference of 5 points. For the limitation domain, assuming a pooled standard deviation of 15, power of 80% and alpha of 5%, we would need 44 participants in the study group and 88 participants in the control group to detect a difference of 9 points. With 46 study group participants and 92 control group participants, we were powered to detect clinically important differences.

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R: We have made adjustments to the formatting to ensure the manuscript meets the style requirements.

7. We note that the grant information you provided in the ‘Funding Information’ and ‘Financial Disclosure’ sections do not match.

When you resubmit, please ensure that you provide the correct grant numbers for the awards you received for your study in the ‘Funding Information’ section.

R: We have corrected the financial disclosure section so that it matches the funding information.

8. Please include captions for your Supporting Information files at the end of your manuscript, and update any in-text citations to match accordingly. Please see our Supporting Information guidelines for more information: http://journals.plos.org/plosone/s/supporting-information.

We have added captions for the S1 Full Sample Analysis and S2 Data File at the end of the manuscript and referred to them in the text where appropriate.

Reviewer #1:

This is an interesting study that compares limitations to participation in a cohort of subjects with advanced COPD against age and sex matched control subjects. I would recommend the following revisions be undertaken:

Major comments:

1) One of the major limitations of this study is that it is temporally confounded. The control group completed the questionnaire during the first wave of the COVID-19 pandemic when social and public health restrictions were in place, whereas all of the people from the study group participated prior to the pandemic. Accordingly, the control groups’ frequency of participating in these life tasks was likely impacted, highlighting the extent to

which participation is restricted for older adults during a pandemic. The overall effect of this confounding would have been to reduce inter-group differences seen on the LLDI scores. I think that this major limitation has to be mentioned and explained within the abstract of the paper, and the abstract has to conclude that 'People with COPD had greater participation restrictions than a random sample of older adults without ongoing respiratory conditions, but differences in participation restriction seen in this study may have been reduced due to temporal confounding.

R: As suggested, we have added to the methods section of the abstract on Page 2 Lines 31-33: “The study group completed the LLDI prior to the COVID-19 pandemic and the control group completed the LLDI during the first wave of the pandemic.” as well as to the abstract conclusion on Pages 2-3 Lines 44-45: “The differences seen in participation between the two groups may have been reduced due to temporal confounding from the COVID-19 pandemic.”

2) The authors state on page 6 that "The minimal detectable change score (MDC90) for the

LLDI is 7.4 points for the frequency scale and 11.6 points for the limitation scale in mobility limited older adults." Since the between-group differences in this study were less than these MDC90 scores does this mean that the differences are not clinically significant between groups? Please clarify.

R: The reviewer is correct that the MDC90 values reported in a study of mobility limited older adults were 7.4 and 11.6 points for frequency and limitation, respectively. However, it is also important to note that MDC values are population-specific. We have previously established MDC95 values in people with COPD that were lower than what was reported in the study of older adults (4.82 and 7.21 points for frequency and limitation, respectively) (O’Hoski S, et al. A tool to assess participation in people with COPD. Chest. 2021;159(1):138-146.). We have added reference to these values into the manuscript on Page 7 Lines 132-133: “…and the MDC95 is 4.8 points for the frequency scale and 7.2 points for the limitation scale in people with COPD [13].” We have updated the results on Pages 12 Lines 180-184 to reflect both sets of previously established MDC values: “The difference in median scores for the frequency and limitation domains for the two groups was higher than the MDC95 established in people with COPD (5.4 points compared to 4.8 points, and 7.6 points compared to 7.2 points, respectively) but lower than the MDC90 established in mobility-limited older adults for the frequency and limitation domains (7.4 and 11.6 points, respectively) [13,16].” The magnitude of differences seen in participation between the groups may have been reduced due to temporal confounding as previously mentioned.

3) Did the control group undergo lung function testing? If not, how can we be sure they did not have COPD?

R: Unfortunately, we do not have pulmonary function test data for the control group participants. We have updated the manuscript to indicate that control group participants were those who did not “report having respiratory conditions” (Page 2 Lines 30-31) and that we excluded participants if they had “physician-diagnosed respiratory condition” (Page 8 Line 151). We have also added this as a limitation on Pages 15-16 Lines 267-268: “In addition, we did not have pulmonary function test results from the control group participants and it is possible that some of them had undiagnosed respiratory disease.”

4) A Figure 1 flow diagram needs to be added which shows how the study subjects were recruited and included/excluded and which subjects were ultimately included in the final study analysis.

R: A flow diagram (now Figure 1) has been added to show recruitment, inclusion and exclusion.

5) I note that from the primary studies, LLDI scores were collected in 96 people with COPD and 272 older adults. For this paper, only 46 study group participants and 92 control group participants were retained. This means that a lot of interesting collected data has not been analyzed. I think it would be interesting to see the LLDI scores for the entire COPD cohort and the entire 272 control cohort. This analysis could be added to the paper, and the between-group differences could be adjusted for age and sex. This additional age and sex adjusted analysis would be complementary to the case-control analysis.

R: Of the 272 participants in the general sample of older adults, there were 202 who had complete scores for the LLDI and did not have a respiratory condition. The full sample (96 study group participants and 202 control group participants) was compared using quantile regression including age and sex as covariates and having COPD was a significant predictor of both frequency of and limitations in participation. We have added to the methods on Page 8 Lines 144-146: "As a sensitivity analysis, we also compared LLDI scores between the full samples of people with and without respiratory disease, without age- and sex-matching using quantile regression with age and sex as covariates." We have also added to the results on Page 12 Lines 177-179: "These results were similar when the LLDI scores of the full sample of 96 people with COPD and 202 people without respiratory disease were compared (see Supplementary Tables 1 and 2 in S2 Full sample analysis)."

6) Minor comment- please delete the dots showing outliers from figs 1 and 2- they are distracting and not needed.

R: Figures 2 and 3 (previously figures 1 and 2) have been revised as requested.

Reviewer #2:

This is a well-written manuscript, an interesting and relevant work on participation in people with chronic obstructive pulmonary disease (COPD). The authors have compared the level of participation between people with COPD and community-dwelling older adults without lung disease. People with COPD presented with greater participation restrictions compared to their peers without chronic respiratory conditions. Please find below some major and minor concerns the authors should address before publication.

Abstract, Minor

1. The LLDI abbreviation should be indicated at its first appearance in the text.

R: This has been added (Page 2 Line 27).

Results, Minor

2. In Table 1, the presentation of statistical differences between groups should be revised to support the manuscript text. Some symbols used should be moved to the first column for a description of the variables, and only statistical differences should be indicated in the middle and left data columns. It is not clear to the reader which frequencies of self-reported general health differences are between groups.

R: Table 1 on Pages 9-10 has been revised to include statistical comparisons between the two groups so that column 2 presents the study group data, column 3 present the control group data and column 4 presents the between-group p-values.

Results, Major

3. In the study group, is there any subanalysis available on differences in LLDI Participation scores between people with COPD on Long-term home oxygen therapy (LTOT) compared to those who are not? This would bring new information to the COPD literature. The authors should also provide in Table 1 the number of study group participants on LTOT, as it could impact Participation due to the use of non-portable oxygen delivery devices.

R: We have added supplemental oxygen use for the study group to Table 1 on Page 9. While the use of supplemental oxygen may impact participation frequency and limitations, we chose not to explore it in the current paper as it has been previously investigated in another secondary analysis involving this data (D’Amore C, O’Hoski S, Griffith LE, Richardson J, Goldstein RS, Beauchamp MK. Factors associated with participation in life situations in people with COPD. Chron Respir Dis. 2022;19:1–8. DOI: 10.1177/14799731221079305.)

Discussion, Minor

4. Page 13, line 225: please consider the replacement of 'pathologies' for 'diseases' or 'illnesses'.

R: This has been changed to “health conditions” (Page 15 Line 254).

5. Page 14, lines 244-247: the authors should consider rewriting the sentences as it is difficult for the reader knows who they are referring to in 'We have a unique opportunity...' Are the authors referring to themselves, physiotherapists or healthcare professionals in general involved in COPD rehabilitation? Also, the study sample comprised patients who were not exclusively on admission to pulmonary rehabilitation programs.

R: We have changed this sentence on Page 16 Lines 280-282 to, “Clinicians have a unique opportunity…” The reviewer is correct that our sample was not exclusively PR participants. Our intended meaning here is that measurement of participation may be a valuable addition to these programs because of the lower scores seen among people with COPD. There is a need to assess participation in people with COPD and to treat restrictions and PR programs might be the place to do that since patients are followed for an extended period of time. Clinicians in PR have a unique opportunity to address the longer-term consequences of the disease.

Reviewer #3:

Sachi O’Hoski et al aimed to compare participation scores in people with COPD to scores from a random sample of older adults using a validated measure of participation, the LLDI which is consistent with the concept of participation in the international classification of functioning, disability and health. LLDI sores were lower for the COPD group compared to controls for both the frequency and limitation domains of the LLDI. The paper is generally written in an excellent way, the description of methods used is clear, results are nicely presented and discussion is focused. However, the study is limited by its design.

I have the following concerns.

1. The authors used a secondary analysis of existing data to compare COPD patients and controls in terms of quality-of-life outcomes. Data are derived from two different time periods, one of the them during the COVID-19 pandemic. This type of design may have introduced biases in the accuracy of the results of this study.

R: We have added that the control group’s social participation was likely impacted by the pandemic, “potentially explaining the smaller difference between groups in this subscale” (Page 14 Lines 226-227). We have also indicated this as a limitation on Page 16 Lines 268-276: “And finally, the control group completed the study during the first wave of the COVID-19 pandemic at which time there were social and public health restrictions in place. This difference in social circumstances might have impacted the frequency of participation in life tasks, making the control group results non-generalizable to non-pandemic times. The frequency of social activities was low in both groups and it is likely that the control group would have shown even higher scores on this subscale had public health restrictions not been in place at the time. As such, the differences seen in the participation scores between the two groups may have been attenuated due to temporal confounding.”

2. During the pandemic many things occurred in terms of our living that may have affected subjects’ decisions and activities. In this respect activities and participation may have been different compared to the previous period- where COPD patients were recruited. How the authors treated this source of potential bias in their analysis? Has LLDI been validated during these circumstances? Or, do we know that this instrument is accurate even during periods with such different social conditions? It would be useful to know that LLDI provides similar results in similar populations but in different time periods/social conditions (or not).

R: We have acknowledged that participation scores for the control group may have been higher had it not been for the pandemic and public health restrictions and indicated that this was a potential limitation. We have not adjusted our analyses for this temporal difference as our aim was to simply investigate the difference in scores between the groups. The LLDI has strong evidence for its psychometric properties in various populations and contexts (Beauchamp MK, Schmidt CT, Pedersen MM, Bean JF, Jette AM. Psychometric properties of the Late-Life Function and Disability Instrument: A systematic review. BMC Geriatr 2014;14:12. doi: 10.1186/1471-2318-14-12) and while scores may differ based on a variety of factors such as external barriers to participation and participant choice, these factors are individual and are taken into account when one is answering the questions on the LLDI. While we have assumed that scores on some of the subscales would have been impacted by social restrictions, this should not impact the validity of the measure. In terms of comparison of scores in different social conditions, we have provided some information about scores found in the literature pre-pandemic on Pages 14 Lines 227-230: “Normative scores have not been established for the LLDI but two previous studies of community-dwelling adults aged 65 and over reported mean scores of 41.4 [19] and 45.5 [20] points on the social subscale, similar to the mean score of 47.2 points seen in our control group.”

3. In addition, COPD patients experience relatively severe disease based on the FEV1 reported. Is there a similar assessment of the respiratory function for controls?

R: We do not have data on respiratory function for the control group. This was a secondary analysis of data so we were limited by what information was collected for the primary study. We have added this as a limitation on Pages 15-16 Lines 267-268: “In addition, we did not have pulmonary function test results from the control group participants and it is possible that some of them had undiagnosed respiratory disease.”

4. Introduction could be shorter. I would highlight more -being more specific- the clinical value of the results of this study in the discussion section

R: We have added to the discussion on Page 15 Lines 257-260: “The decreased frequency of and increased limitations in participation found in people with COPD highlights the importance of assessing this important aspect of health in this population and addressing participation restrictions as part of pulmonary rehabilitation in order mitigate negative sequalae such as psychological distress and mortality.”

Submitted filename: Response to Reviewers.docx

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13 Sep 2022

People with COPD have greater participation restrictions than age-matched older adults without respiratory conditions assessed during the COVID-19 pandemic

PONE-D-22-03462R1

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Congratulations for successful amendments!

26 Sep 2022

PONE-D-22-03462R1

People with COPD have greater participation restrictions than age-matched older adults without respiratory conditions assessed during the COVID-19 pandemic

Dear Dr. Beauchamp:

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