Usefulness of clock-drawing test in Indian older adults with diabetes mellitus.

BACKGROUND: Clock-drawing test (CDT) is a simple, quick, and bedside cognitive screening test which measures different cognitive domains but has some limitations. The aim of this study was to examine the usefulness of CDT for Indian older adult based on a part of an ICMR-funded research project, New Delhi, India.
MATERIALS AND METHODS: Sample comprised seventy participants (38 controls and 32 cases) aged 60 years and above included according to the inclusion/exclusion criteria in a consecutive series. Participants, who gave written informed consent, residing permanently in the area of Chowk, Lucknow, constituted the study sample. Semistructured sociodemographic details and medical history pro forma, socioeconomic status scale, General Health Questionnaire-12 (GHQ-12), CDT, and Hindi cognitive screening test (HCST) were administered. Biochemical investigations were carried out, and blood glucose level (fasting ≤100 mg/dl and postprandial ≤140 mg/dl) was considered for having diabetes mellitus (DM). The participants were categorized into two groups: (1) case: participants with DM only and (2) control: participants without discernible abnormality of physical illness and GHQ negative. Data were analyzed using percentages, t-test, the Chi-square test, sensitivity, and specificity.
RESULTS: About 71.05% participants in control and 81.25% in the case group have cognitive impairment on CDT. Significantly higher illiterates (P < 0.05) were found to be significantly more cognitively impaired on HCST. CDT has a high level of sensitivity (0.71) and low specificity (0.23) when compared with HCST.
CONCLUSION: CDT had screening bias to Indian older adults as a higher number of literates (almost double) and illiterates (four times) were found to be cognitively impaired compared to on HCST. Usefulness of CDT to screen Indian older adults for cognitive impairment is debatable. Copyright:

INTRODUCTION

The clock-drawing test (CDT) is used for screening for cognitive impairment and dementia and as a measure of spatial dysfunction and neglect.[1] CDT quickly assesses the visuospatial and praxis abilities and may determine the presence of both attention and executive dysfunctions[23] but has some limitations also related with education and screening mild cognitive impairment.[45] The CDT is a simple tool that is used to screen people for the signs of neurological problems, such as Alzheimer's and other dementias. It is often used in combination with other, more thorough screening tests, but even when used by itself, it can provide helpful insight into a person's cognitive ability. There are several scoring systems that exist for the CDT each differing slightly and reporting varying levels of sensitivity and specificity.[467] Very few validation studies are found in the Asian population. A review of 16 different CDT methods reported variations in the instructions such as time setting, copying, and time reading commands, as well as the use of predrawn circle.[7]

There is strong evidence that Type 2 diabetes increases the risk of dementia in the form of multi-infarct dementia, Alzheimer 's disease, and mixed type of dementia.[8] A national survey of diabetes conducted in six major cities in India in 2000 has shown that the prevalence of diabetes in urban Indian adults 12.1% and[9]8.3% in other study,[10] and a recent study reported 16.9% prevalence of diabetes in elderlies aged 60 years and above in a community-based study.[11] In a current study, the prevalence of diabetes mellitus (DM) alone is found to be 7.5%.[12] Older adult patients with DM have been found to have cognitive impairment (9.6%)[11] that can be attributed to their disease. The CDT is a simple validated measure of cognitive functions and found to be effective in DM as well. There is a study which shows higher sensitivity and low specificity of CDT in patients with Alzheimer's dementia and mild cognitive impairment.[13]

Patients with diabetes need to be evaluated for barriers to safe and effective diabetes control. Screening for subtle cognitive dysfunction is important when complicated treatment regimens are used. CDT can help in the early diagnosis of such illnesses. The rising prevalence of early detection of cognitive function of the participants with DM with less time will provide directions to the health-care professionals for the effective management of DM and cognitive impairment. Therefore, we studied the applicability of CDT to the Indian older adults, which is handy and quick to screen and in the early detection of cognitive function of the participants.

MATERIALS AND METHODS

Sample

The study was a part of the 1st-year report of an ICMR-funded case–control study entitled, “A study to evaluate the effect of DM, hypertension (HT), and lipid profile on cognitive function.”[12] The study protocol was approved by the Institutional Ethics Committee. Relevant detail and procedure related to this article only are given here. The older adults aged 60 years and above, residing permanently in the central (nearby) catchment areas (Chowk, Raja Bazar, and Nakhas) of the KG Medical University, Lucknow, formed the study universe. Participants aged 60 years and above with documentary proof given written informed consent fulfilling inclusion/exclusion criteria (given below) were included in the study. Of 333 consecutively included older adults in the parent study, only seventy participants in two groups, namely DM (case 32 participants) and control group (38 participants) were taken for this article. Participants, who gave written informed consent, residing permanently in the central catchment area of Chowk, Lucknow, constituted the study sample. Semistructured sociodemographic details and medical history pro forma, socioeconomic status (SES) scale, General Health Questionnaire-12 (GHQ-12),[14] CDT,[15] and Hindi cognitive screening test (HCST)[16] were administered. Biochemical investigations were carried out, and a blood glucose level (fasting ≤100 mg/dl and PP ≤140 mg/dl) was considered for not having DM. The participants were categorized into two groups: (1) case: participants with DM only and (2) control: participants without discernible abnormality of physical illness and GHQ negative. Data were analyzed using the Chi-square test, sensitivity, and specificity.

Inclusion criteria

The inclusion criteria were as follows:

Participants aged 60 years and above with documentary proof, i.e., age certificate/ration card/voter card/any identity card/passport, etc.

Actual age at the time of marriage can be calculated by marriage year + age of elder son/daughter + gap when there is no documentary proof

The diagnosis of DM was established on the basis of available records/medical prescriptions/investigations, etc., and baseline investigation reports on the basis of biochemical parameters

Permanently residing in the study area

Informed consent for participating in the study either by the participant or first-degree relative.

Exclusion criteria

The exclusion criteria were as follows:

Uncooperative participants

Having any other problem which may impede with conducting the interview or assessments

The presence of any major physical illness or medication causing significant cognitive impairment, for example, HT, dyslipidemia (DL), renal failure, hepatic problems, anemia, thyroid problems, electrolyte imbalance, head injury, seizure disorders use of corticosteroids, cholinesterase inhibitors, hypnotics, and sedatives

Participants having any other neuropsychiatric illness which can contribute to a cognitive impairment such as mental retardation, depression, anxiety disorders, bipolar affective disorders, and schizophrenia other than cognitive impairment and dementia.

Tools used

Semistructured pro forma for sociodemographic details, personal history details, information about diabetes, HT, and DL pertaining to age of onset, treatment history, reports, prescriptions, etc., was used to collect exhaustive information about the above-mentioned personal details of older adult's individuals

SES scale[1718] was administered to measure the SES of the included participants. The urban domicile subscale was used comprising broad seven heads, namely house profile, material possession, education profile, occupational profile, economic profile, land/house profile, and social profile. The scores range on five categories which are, upper class, upper middle, middle class, lower middle, and lower class

GHQ:[14] GHQ with 12 items was included as a selection criteria using a cut–off score of more than 2 to rule out and having any psychiatric symptoms

CDT:[15] The CDT ranges from 1 to 6 scores in which higher scores reflect a greater number of errors and more impairment. Scoring has been done in the increasing order of severity. A score of ≥3 represents a cognitive deficit, whereas a score of 1 or 2 is considered as normal.

Scores on CDT and their errors

1 = Perfect

2 = Minor visuospatial errors

3 = Inaccurate representation of 10 after 11 when the visuospatial organization is perfect or shows only minor deviations

4 = Moderate visuospatial disorganization of times such that accurate denotation of 10 after 11 is impossible

5 = Several levels of disorganization

6 = No reasonable representation of a clock, exclude severe depression or other psychotic states.

HCST:[16] HCST is an education and culture bias cognitive screening test in which items suited to both literate and illiterate participants and could be interchanged depending on the literacy level. It assesses orientation to time (culture fair scoring) and place, registration (culture fair items), attention and concentration (calculation depending on literacy), recall, naming, repetition, follow commands (verbal and cued depending on literacy), writing or telling a sentence (depending on literacy), and copying (depending upon literacy). HCST has a high level of sensitivity (0.93), specificity (0.96), and high positive (0.96) and negative (0.94) predictive value against a brief cognitive rating scale (BCRS).[19] A significant (P < 0.01) negative correlation (r = −0.87) with BCRS total scores and different axes of BCRS was found for concentration (r = −0.79), recent memory (r = −0.83), past memory (r = −0.79), orientation (r = −0.73), and functioning/self-care (r = −0.77). HCST total score was found to be negatively correlated with education (r = −0.15) also.

Procedure

Semistructured pro forma for sociodemographic, personal history details, information about diabetes, HT, and DL pertaining the age of onset, treatment history, reports, prescriptions, etc., was administered. The information sheet was read individually to the screened population, and written informed consent was obtained before including participants. SES scale[1718] and GHQ-12 items[14] were administered by the Research Assistant (Medical); HCST,[16] Saint Louis University Mental State Examination,[20] and CDT[15] were administered by the psychologist. Biochemical investigations of all included older adults were done.

After the data collection, the participants were categorized into the following groups:

Control group

A: Normal: Participant without discernible abnormality of physical illness

Case groups

B: DM: Participants with DM only

C: HT: Participants with HT only

D: DL: Participants with DL only

E: B + C Group: Participants with DM and HT

F: B + D Group: Participants with DM and DL

G: C + D Group: Participants with HT and DL

H: B + C + D Group: Participants with DM, HT, and DL.

Blood glucose level: fasting <100 mg/dl and postprandial <140 mg/dl (the American Diabetes Association Diabetes Guidelines, 2016); blood pressure: systolic <140 mmHg and diastolic <90 mmHg (Institute for Clinical Systems Improvement 2014); lipid profile: serum cholesterol <200 mg/dl, low-density lipoprotein <100 mg/dl, and triglycerides <150 mg/dl (AACE Guidelines for the management of DL and prevention of atherosclerosis); creatinine: 1.5 mg/dl; serum urea <40 mg/dl; and glycosylated hemoglobin 4.2% to <7% (Harrison's Principles of Internal Medicine Vol. II Edition 16, 2005) were considered as normal. On the basis of the blood reports, the participants were assigned in the following groups of study: Control Group A – participants without discernible abnormality or physical illness and Case Group B – participants with DM only. In this article, only these two groups are presented. Data were analyzed using the statistical methods of percentages, mean, Chi-square, sensitivity, and specificity.

RESULTS

Sociodemographic details of the examined participants are given in Table 1. Sociodemographic detail-wise, there was an insignificant difference between the control (normal) and case (DM) group. Most of the participants were in the age range of 60–69 years, in which the mean age in diabetes and healthy control group was found to be 67.84 ± 6.72 and 67.62 ± 5.70, respectively. Participants were of middle and lower-middle SES. Most of the participants were literate, living in joint families, and were nonworking.

Table 1

Sociodemographic details of the study sample (n=70)

Category	Variables	Normal (n=38), n (%)	Diabetes (n=32), n (%)	Df	t-test/χ2	P
Age (years)	Mean±SD	67.84±6.72	67.62±5.70	68	0.1461	0.8843
Gender	Male	22 (57.89)	19 (59.37)	1	0.1199	0.7291
	Female	16 (42.10)	13 (40.62)
SES	Middle	15 (39.47)	13 (40.62)	1	0.010	0.922
	Lower	23 (60.52)	19 (59.37)
Education	Literate	31 (81.57)	26 (81.85)	1	0.0023	0.95
	Illiterate	7 (18.42)	6 (18.75)
Type of family	Joint	22 (57.89)	24 (75)	1	2.2559	0.133105
	Nuclear	16 (42.10)	8 (25)
Occupation	Working	11 (28.94)	9 (28.12)	1	0.0058	0.939521
	Nonworking	27 (71.05)	23 (71.87)

SD – Standard deviation; SES – Socioeconomic status

Table 2 shows the cognitive status of normal participants and participants with DM on CDT and HCST. P (0.321) of CDT and P (0.1089) of HCST are not statistically significant for both the groups. About 81.25% of the participants with DM were found to be cognitively impaired as compared to the normal participants 71.05% on CDT, whereas only 12.5% of the participants with DM were found to be cognitively impaired as compared to the normal participants 31.58% on HCST.

Table 2

Cognitive status of normal (control) participants and participants with diabetes mellitus (case) on clock-drawing test and Hindi cognitive screening test

Tools	Groups	With cognitive impairment, n (%)	Without cognitive impairment, n (%)	χ2	Df	P
CDT	Normal (n=38)	27 (71.05)	11 (28.94)	0.98	1	0.321
	Diabetes (n=32)	26 (81.25)	6 (18.75)
HCST	Normal (n=38)	12 (31.58)	26 (68.42)	2.57	1	0.1089
	Diabetes (n=32)	4 (12.5)	28 (87.5)

CDT – Clock-drawing test; HCST – Hindi cognitive screening test

Table 3 shows that CDT has a high level of sensitivity (0.71) and low specificity (0.23) with high positive (0.23) and negative (0.71) predictive values.

Table 3

Sensitivity and specificity of clock drawing test (CDT) with Hindi cognitive screening test (HCST)

		Hindi cognitive screening test (HCST)		Total
		Yes	No
CDT	Yes	12	41	53
	No	5	12	17
Total		17	53	70

Sensitivity – 0.71; Specificity – 0.23; Positive predictive value – 0.23; Negative predictive value – 0.71

Table 4 reveals comparatively more illiterates were found to be cognitively impaired on CDT (84.61%) than on HCST (46.15%).

Table 4

Cognitive status of literate and illiterate group of older adults aged 60 years and above on clock-drawing test and Hindi cognitive screening test

	HCST					CDT
	With cognitive impairment, n (%)	Without cognitive impairment, n (%)	χ2	df	P	With cognitive impairment, n (%)	Without cognitive impairment, n (%)	χ2	df	P
Illiterate (n=13)	6 (46.15)	7 (53.85)	4.91	1	0.0266	11 (84.61)	2 (15.38)	0.0938	1	0.7593
Literate (n=57)	10 (17.55)	47 (82.45)				44 (77.19)	13 (22.80)

CDT – Clock-drawing test; HCST – Hindi cognitive screening test

DISCUSSION

The objective of the present study was to examine the usefulness of CDT on Indian older adults with DM only and the control group. In this study, CDT found to have good cognitive screening utility, particularly with the comprehensive scoring methods. The development of screening tests that are easily applied by generalists and have adequate accuracy, even in populations with low educational level, should be included in the objectives of programs for the investigation of cognitive disturbances in elderly people. “Variables such as language and education were also found to influence the performance on CDT. Literacy could be a problem and could particularly affect the elderly participants in areas with a high illiteracy rate.“[7] A study showed that CDT is useful as a screening test for cognitive impairment, especially in populations with higher educational levels.[721] It also has various application methods,[5222324] each with its own scoring system, but no consensus as to which is the best has been obtained.

Table 1 showed that most of the participants were in the age range of 60–69 years; males, from lower SES and literates. Illiterates were lesser in both the groups because mostly there were businessman families residing in the study area, and they have privileged to have educational facilities. Most of them were nonworking also because they hand over their business to offspring and now they are not actively involved in this. Why businessman families found to be in lower SES is a further point of discussion. SES scale not only includes money and land property but also educational, occupational, social participation, and understanding also.[1718] If scores fall short in any of the area, SES status becomes lower on this scale.

Although there were insignificant differences in the cognitive status between both the groups on CDT and HCST, CDT screened more positive than HCST in both the groups. Thus, the percentages of cognitive impairment in both the groups found to be on the higher side than reported in other studies.[101125] P (0.321) of CDT and P (0.1089) of HCST are not statistically significant for both the groups. It suggests both tests screened Indian older adults for cognitive impairment on a similar pattern, but CDT screened more positives than HCST. Nearly 81.25% of the participants with DM were found to be cognitively impaired as compared to the normal participants – 71.05% on CDT, whereas 12.5% participants with DM were found to be cognitively impaired compared to the normal participants (31.58%) on HCST. Cognitive impairment was found to be higher when assessed with CDT and less in DM group and higher in the control group when assessed with HCST in this study compared to reported by Tiwari et al.[11] where cognitive functions were assessed in detail. Although the results on HCST were found to be nearer to the study reported previously,[11] the highest number of participants (more than 70%) with DM and normal group was found to screen positive for cognitive impairment on CDT, which is not even nearer to the report of other Indian studies.[101125] It is indicating that CDT screened more Indian older adults positive for cognitive impairment.

Less number of participants with DM group found to have cognitive impairment compared to the normal group on HCST. We took participants having DM only and excluded those who had comorbid other physical illnesses such as HT and dyslipidemia. Another concern is that more participants of normal group found to be cognitively impaired on HCST compared to DM group which is contrary to other research reports. Is this decline in cognition of normal group is a part of the normal aging process? Studies reported the higher prevalence of Alzheimer's dementia than vascular dementia in India.[2627] Vascular events such as stroke, cardiac disease, DM, HT, and abnormality in lipid profile are causal factors for vascular dementia. Our study finding that lesser older adults with DM (only diabetes) had cognitive impairment than normal (who had not diabetes) may produce a hypothesis, “Does DM protect cognitive impairment?” This may be an important area of research in the future.

As observed in Table 3, the sensitivity of CDT was found to be 0.71 and specificity 0.23 which shows that CDT is highly sensitive and is low in specificity similar to the studies[721] where the author states that CDT is sensitive enough to detect mild cognitive impairment in participants with more than 5 years of education.

Table 4 shows that there was a significant difference between literates and illiterates on HCST, it means HCST is able to differentiate literates and illiterates for their cognitive status. Although there was an insignificant difference on CDT between literates and illiterates, a higher number of participants found to be cognitively impaired on CDT (84.61%) compared to 46.15% on HCST. This was found to be much higher on CDT than reported in other studies.[28293031] The prevalence of cognitive impairment varies from 3.35% to 25%[28293031] among older adults in India. HCST screened nearer to it than CDT. Hence, it can be said that CDT is more biased in cognitive screening than HCST for Indian older adults.

Table 4 shows that cognitive status of illiterates was found to be more impaired on CDT (84.61%) when compared to HCST (46.15%). Literacy is defined as the ability to read and write with understanding in any language. A person who can merely read but cannot write is not classified as literate;[32] according to this definition, we have classified the literate Indian older adults with education from class fifth and above. Ardila et al.[33] compared the performance of illiterates and educated professionals in a wide variety of neuropsychological tests and found that almost all of the abilities tested were strongly influenced by education. It is not necessary to be able to draw a clock face to understand and manipulate the concepts related to the passage of time.[15] This can explain, in part, a large number of people who, although not demented, are unable to produce “normal” clock drawings. However, these same people may be capable of telling time on a clock or even by placing the pointers on a clock's partially drawn face. This can also explain the low accuracy of the CDT in individuals with very low formal educational attainment. It indicates that CDT is an education bias test and screened literates well for cognitive impairment.

To summarize our results that showed a higher percentage of participants with DM only (81.2%) were found to have more cognitive impairment as compared to the control group (71.05%) on CDT. More illiterates were found to have cognitive impairment than literates on CDT and HCST. CDT has a high level of sensitivity (0.71) and low specificity (0.23) when compared with HCST to screen the Indian older adults for cognitive impairment but had education bias.

CONCLUSION

It has been observed that CDT is sensitive enough to screen Indian older adults when compared with HCST, but specificity is very low. More illiterates were found to have cognitive impairment than literates on CDT and HCST. However, it had some screening bias as high number of literates (almost double) and illiterates (four times) were found to be cognitively impaired on CDT compared to HCST. Higher percentages of participants with DM only were found to be cognitively impaired when compared with the control group. Applicability of CDT to screen urban Indian older adults for cognitive impairment was found to be debatable.

Limitations

One of the most important limitations of CDT is that of the different clock-drawing protocols and scoring systems. Diagnostic criteria to diagnose dementia are not used in this study. Activities of daily living of the cognitively impaired participants were not assessed. Duration of having DM was not considered; hence, results may be biased. Although sociodemographic detail-wise, there were insignificant differences, a proper representation of illiterate and upper SES participants in both groups is lacking. The results of the study cannot be generalized due to small sample size and considering limitations, but providing clues and opens the opportunity to study those variables which affect cognitive status of older adults using sound methodology.

Financial support and sponsorship

Funded by Indian Council of Medical Research through Department of Health Research, New Delhi, India.

Conflicts of interest

There are no conflicts of interest.