Impact of Cigarettes Smoking on Undergraduates' Lung Health and Functional Performance: Observational Cross-Sectional Study.

Background: Cigarettes Smoking is a major social and global health problem. Cigarette smoking continues to be a major contributor to deteriorated health status across different age categories. Clarifying the impact of the cigarette smoking on young adults' lungs health and functional aspects can serve eliminating further deterioration in health status and establishing proper management regimens. This study aimed to investigate the impact of cigarette smoking on lung health (age and functions) and functional performance in the university smoker students.
Methods: One hundred and Thirty eligible volunteer, current smoker students participated in this study to objectively evaluate their pulmonary functions (including forced vital capacity "FVC", forced expiratory volume in one second "FEV1", FEV1/FVC, peak expiratory flow rate "PEFr"), lung age and functional performance (via the 6-minutes' walk test "6MWT") and compare "the observed" with "the predicted normal" mean values. Data were analyzed via SPSS program using the student t-test.
Results: There were significant differences (P < 0.05) between the "observed" and the "predicted normal" FVC, FEV1, FEV1/FVC, PEFr, lung age, and the 6MWT mean values. The "observed" and the "predicted normal" FVC, FEV1, FEV1/FVC, PEFr, lung age and the 6MWT mean values were [(4.47 ± 0.53, 4.77 ± 0.5 liter), (3.95 ± 0.42, 4.08 ± 0.4 liter), (88.74 ± 7.17, 85.59 ± 4.91%), (550.75 ± 114.96, 572.72 ± 53.02 liter/minute), (32.77 ± 9.44, 21.55 ± 1.37 year), (387.06 ± 56.47, 466.82 ± 18.45 meter)], respectively. Conclusions: Cigarette smoking negatively impacts the lung age, functions, and functional performance of the university smoker students; the concept that can be used to encourage prevention and early smoking cessation. Copyright:

Introduction

Tobacco smoking is a global public health deteriorus agent that is associated with abnormally elevated death percentage worldwide.[1] Cigarette smoking is a leading cause of preventable death and usually begins at the adolescence phase.[2] Early smoking cessation and prevention is a public health priority.[3]

Cigarette smoking is predicted to cause about ten million deaths per year by 2030 worldwide.[4] Furthermore; cigarette smoking is a strong contributing factor for many health problems[5] especially in areas with high smoking prevalence as the Eastern Mediterranean region.[6]

The smoking-related health risks are strongly associated with the number of smoked cigarettes.[7] Almost all organs in the body are negatively affected by smoking, with majority of cancer deaths and chronic obstructive pulmonary disease (COPD) are caused by cigarette smoking.[1] Youth smoking in particular is associated with deteriorated lung function and other serious systemic pathologies.[8]

The prevalence of cigarette smoking varies according to demographic regions and gender. Algabbani et al. reported that the overall prevalence of cigarette smoking among subjects aged 18 years and above was 21.4%; with a 32.5% prevalence among men and 3.9% among women.[9] Cigarette smoking became an increasingly propagating phenomenon among the university students; with the smoking prevalence is higher in men compared to women across many geographic regions.[101112]

Spirometry is a simple, non-invasive procedure to screen the pulmonary health status,[13] with normal predicted spirometric values depends on the subject's age, gender, height, and body size.[14] The pulmonary function (PF) test can clarify respiratory function variations over time, so further deterioration can be prevented.[15] The forced vital capacity (FVC) and forced expiratory volume in one second (FEV1) are the most commonly utilized measurements of the PF.[13] Lung age is a FEV1-dependent variable that is considered a strong motivator for smoking cessation. The critically altered PF in cigarette smokers is usually manifested in form of abnormally reduced FVC and FEV1.[16]

Knowledge of the cigarette smoking hazards is essential to control smoking.[17] Cigarette smoking accelerates the age-related decline in the PF,[18] so adult or adolescent cigarette smokers are usually characterized by reduced PF compared to their counter partner non-smokers.[1920]

The cigarette smoking epidemic spreads in a fast manner among university students. Extra-efforts are required to protect young adults from smoking-related hazards, so a smoking prevention and cessation supporting strategies are urgently needed.[21] Although smoking control is a pivot health concern, unfortunately; There is limited understanding of the impact of cigarette smoking on pulmonary health as well as functional performance (FP) among the university students, this is in part due to the limited number of studies conducted to evaluate the PF and FP among smokers youth and university smoker students.[22]

The continuously alarming concept is that the majority of smokers are still underestimating the smoking-related health hazards[23] and even the acknowledgment of the cigarette smoking-adverse effects are not commonly translated into avoidance or stoppage of the smoking habit. There is still a shortage in the health message regarding the smoking hazards on the youth health and physical performance and there is still a shortage in the utilization of the smoking-related health hazards as a motive for smoking cessation.[24] Accurate data about the cigarette smoking-related health risks and the PF alternations are mandatory[22] to correct the alteration in risk perception[25] and motivate younger adult smokers to quit smoking.[26]

Despite the incorporation of the many practical strategies to fight cigarette smoking among young adults; only modest achievements were obtained,[27] more efforts are still needed to alleviate the smoking impact in students’ health and more health warnings are required to encourage the process of cigarette smoking control and cessation among youth.[28] Increasing awareness about smoking impacts on health through implementing effective interventions that provides information about the hazards of smoking can augment the intention to stop smoking among the university smoker students.[29]

Providing information about smokers’ lung function and lung age can help in increasing motivation to stop smoking,[30] so the aim of this study was to objectively investigate the impact of cigarette smoking on lung age, PF and FP in the university smoker students.

Methods

Research design

Observational cross-sectional study.

Participants

Smoker students from the Saudi Arabia Western region Universities were invited to participate in the study.

Recruitment and sampling

Non-probability, purposive sampling technique was utilized to recruit the smoker students to voluntarily participate in this study. Participants were recruited through face-to-face interviews and web-based announcements. One Hundred and Forty-Two sedentary volunteer, current smoker students were recruited. One Hundred and Thirty participants (105 men and 25 women) fulfilled the inclusion criteria, had no exclusion criteria and were eligible for participation in this study.

This study was conducted in accordance with the principles of the World Medical Association Declaration of Helsinki 1975, revised in Hong Kong 1989 and was approved by the ethics committee of the Faculty of Applied Medical Sciences, Umm Al-Qura University, Saudi Arabia and was conducted between September 2017 and July 2019.

Inclusion and exclusion criteria

Participants were current cigarette smoker university students, from both genders, age ranged from 16-24 years old, 30> body mass index “BMI” > 18.5. Participants were excluded if they refused to sign the written informed consent, had diabetes mellitus, with high resting blood pressure (more than 140/90 mmHg), were underweight or obese subjects (30 ≤ BMI ≤ 18.5), had unstable cardiopulmonary, neuromuscular or musculoskeletal insults that can affect the accuracy of the study outcomes, participated in any regular exercise training within the last four weeks, were unable to perform the six minutes’ walk test (6MWT).

The study objectives and procedures were fully explained to each participant who signed a written informed consent form, agreeing for participation and publication of the study results.

Evaluation

All participants underwent similar evaluations that were conducted at the same time of the day (between 8 and 11 am). Outcomes were PF (including FVC, FEV1, FEV1/FVC%, peak expiratory flow rate “PEFr”), lung age and the FP (through the 6MWT).

The pulmonary function and lung age evaluations

Evaluations of the FVC, FEV1, FEV1/FVC, PEFr, and lung age were carried according to previously published guidelines,[31] using (Spiro Analyzer ST 250; Fukuda, Sangyo, Japan) a portable PF testing unit that measures “the observed” PF and estimates “the predicted normal” values. After 10-minutes rest and sufficient explanation about how to perform the test, each participant was directed to perform forced maximal expiration after full inspiration and the procedure was repeated three times for each participant, and the best trial was considered in data analysis.

Functional performance evaluation

Each participant performed the 6MWT according to a previously published protocol.[32] Each participant walked at his/her own maximal steady pace without running between the two ends of a 40-meter straight, flat corridor and the total distance covered in the 6 minutes was then recorded. The “predicted normal” 6MWT values were estimated using the following formula:

6MWT = (2.81×Height) + (0.79× Age – 28.5 [33]

Statistical analysis

All data were examined using SPSS version 16.0 (SPSS Inc., Chicago). Descriptive statistics and the student t-test were used to test hypothesis and compare between the “observed” and the “predicted normal” mean values of the evaluated variables. Correlation analysis was done to test the association between the considered variables. Results were reported as means and standard deviations. For all procedures, significance was accepted at the alpha level of <0.05.

Results

One Hundred and forty-two sedentary volunteer smoker students were identified as eligible for enrolment in this study; twelve of them were excluded (three had diabetes, seven were included in an exercise training program at the time of the study, and two refused to sign the written informed consent). Thus, 130 participants were included and completed the study.

Participants’ characteristics

Participants’ age was 21.55 ± 1.37 years, weight = 72.30 ± 10.72 kg, height = 1.70 ± 0.07 meter, body mass index = 24.90 ± 3.25 Kg/m2, resting heart rate = 74.98 ± 5.42 beats/minute, blood pressure = 130.65 ± 7.88/76.30 ± 6.92 mmHg, cigarette number/day = 10.06 ± 3.38 cigarette/day, smoking duration = 5.75 ± 2.36 years [Table 1].

Table 1

Demographic data of all participants (mean±standard deviation); (n=130)

Variable	(Men; n=104)	(Women; n=26)	Total	t, P
Age (year)	21.55±1.32	21.5±1.5	21.55±1.37	-0.16, 0.87**
Weight (kg)	75.91±8.42	57.56±4.48	72.3±10.72	-10.72, 00*
Height (meter)	1.71±0.06	1.67±0.07	1.7±0.07	-3.06, 0.003*
Body mass index (Kg/m2)	25.95±2.68	20.72±1.44	24.9±3.25	-9.6, 0.00*
Resting heart rate (beat/minute)	74.84±4.98	75.58±6.7	74.98±5.42	0.62, 0.54**
Systolic blood pressure (mmHg)	130.57±7.75	131.00±8.47	130.65±7.88	0.25, 0.8**
Diastolic blood pressure (mmHg)	76.43±6.89	75.77±7.16	76.3±6.92	-0.44, 0.66**
Cigarette number/day	9.98±3.25	10.39±3.91	10.06±3.38	0.54, 0.59**
Smoking Duration (year)	5.69±2.36	5.96±2.38	5.75±2.36	0.52, 0.6**

**Non-Significant, *Significant, P<0.05

Pulmonary functions

The overall “observed” and the “predicted normal” mean values of FVC, FEV1, FEV1/FVC, PEFr were [(4.47 ± 0.53, 4.77 ± 0.5 liter), (3.95 ± 0.42, 4.08 ± 0.4 liter), (88.74 ± 7.17, 85.59 ± 4.91%), (550.75 ± 114.96, 576.72 ± 53.02 liter/minute)] respectively. The results revealed that overall “observed values” were significantly lower than the “predicted normal” values for the FVC (P < 0.001), FEV1 (P = 0.01) and PEFr (P = 0.02). Results also revealed that the FVC, FEV1, PEFr “observed values” were significantly lower than the “predicted normal” values in men (P < 0.05), while the “observed values” were non-significantly lower than the “predicted normal” values for the same variables in women. (P ≥ 0.05) [Table 2].

Table 2

Comparison between the observed and predicted smokers’ undergraduates FVC, EFV1, FEV1/FVC and PEFr (mean±standard deviation); (n=130)

Variable		Men (n=104)	Women (n=26)	Total (Overall)
FVC (liter)	Observed	4.49±0.48	4.39±0.73	4.47±0.53
	Predicted	4.83±0.46	4.57±0.59	4.77±0.5
	t, P	6.7, 0.00*	1.26, 0.22**	6.18, 0.00*
FEV1 (liter)	Observed	3.67±0.40	3.87±0.52	3.95±0.42
	Predicted	4.12±0.39	3.92±0.44	4.08±0.4
	t, P	3.91, <0.001*	0.59, 0.56**	3.69, 0.00*
FEV1/FVC (%)	Observed	88.74±7.39	88.77±6.39	88.74±7.17
	Predicted	85.47±5.20	86.11±3.53	85.59±4.91
	t, P	-4.71, <0.001*	-2.12, 0.05**	-5.18, 0.00*
PEFr (liter/min)	Observed	549.24±115.13	556.8±116.35	550.75±114.96
	Predicted	581.17±51.92	558.89±54.67	576.72±53.02
	t, P	3.17, 0.002*	0.95, 0.93**	2.83, 0.02*

FVC: Forced vital capacity, FEV1=forced expiratory volume in one second, FEV1/FVC%, PEFr=peak expiratory flow rate, **Non-significant, *Significant, P<0.05

Lung age

The results revealed that the overall “observed/measured” mean value of the lung age (32.77 ± 9.44 year) was significantly higher than the overall “predicted actual chronological” mean value (21.55 ± 1.37 year) (P = 0.00). The results also revealed that the lung age “observed” mean values were significantly higher than the “predicted actual chronological” mean values in both men and women (P < 0.05) [Table 3].

Table 3

Comparison between the observed and predicted smokers’ undergraduates lung age and Physical Functional performance (mean±standard deviation); (n=130)

Variable		Men (n=104)	Women (n=26)	Total (Overall)
Lung age (year)	Observed	33.00±9.20	31.81±10.49	32.77±9.44
	Predicted “Chronological”	24.18±2.17	23.68±2.38	21.55±1.37
	t, P	9.71, 0.00*	4.36, <0.001*	10.67, 0.00*
6MWT (meter)	Observed	386.89±56.64	387.73±56.85	387.06±56.47
	Predicted	469.22±17.28	457.2±20.17	466.82±18.45
	t, P	-14.4, 0.00*	-6.6, <0.001*	-15.83, 0.00*

6MWT=6-min walk test, **Non-significant, *Significant, P<0.05

Physical functional performance

The results revealed that the overall “observed value” of the 6MWT (387.06 ± 56.47 meter) were significantly lower than the “predicted normal” value (466.82 ± 18.45 meter). The results also revealed that the 6MWT “observed values” were significantly lower than the “predicted normal” values in both men and women (P < 0.05) [Table 3].

The results also revealed that there were significant inverse correlations between smoking duration and the observed values of FVC (r = -0.31, P < 0.001), FEV1 (r = -0.14, P < 0.01), FEV1/FVC (r = -0.24, P = 0.01). Also there were significant inverse correlations between the lung age observed values and the observed values of FVC (r = -0.48, P = 0.00), FEV1 (r = -0.78, P = 0.00), FEV1/FVC (r = -0.34, P < 0.001) [Table 4]. The results revealed that the smoking duration and “observed lung age” had significant inverse correlations with the “observed” FVC, FEV1 and FEV1/FVC in both men and women [Table 4].

Table 4

Correlations between smokers’ undergraduates smoking duration, lung age and evaluated pulmonary function variables (correlation coeffecient “r” & P)

Variable	Smoking duration			Lung age (Observed)
	Men (n=104)	Women (n=26)	Total	Men (n=104)	Women (n=26)	Total
FVC (Observed)	-0.23, 0.02*	-0.56, 0.03*	-0.31, <0.001*	-0.5, 0.00*	-0.5, 0.01*	-0.48, 0.00*
FEV1 (Observed)	-0.07, 0.02*	-0.4, 0.04*	-0.14, <0.01*	-0.81, 0.00*	-0.76, 0.00*	-0.78, 0.00*
FEV1/FVC (Observed)	-0.2, 0.04*	-0.41, 0.04*	-0.24, 0.01*	-0.34, 0.00*	-0.32, 0.01*	-0.34, <0.001*

r=correlation coeffecient, FVC=Forced vital capacity, FEV1=forced expiratory volume in one second, FEV1/FVC%, *Significant, P<0.05

Discussion

The current study was conducted to evaluate the impact of cigarette smoking on the lung age, function, and functional performance in sedentary university smokers’ students. This study aimed to give a conclusion about the harmful effects of smoking on pulmonary system and subject's performance during daily living activities so as to give an encouragement for smokers to stop smoking. This aim was achieved through comparing the “observed” mean values of the PF, lung age, and FP with the “predicted normal” mean values of the same participants.

This study targeted the university students because adolescence and early adulthood are important stages since it is usually the starting point for initiation of smoking consumption or nicotine addiction[34] Furthermore; youth are more susceptible to smoking-related consequences that can alter both lung functions as well as lung growth.[4] Unfortunately; adolescents and young adult smokers’ usually underestimate the obscenity[35] and the harm of the smoking on their health and consider the smoking to be less risky.[26]

Cigarette smoking has a direct deteriorus effect on the lung, producing multiple respiratory disorders, including COPD, pneumonia, and lung cancer.[36] The smoking-related deterioration in PF can be evaluated through the pulmonary function testing (PFT).[37]

The results of the current study showed that cigarette smoking negatively impacts lung functions of the smokers’ undergraduates of both genders (men more than women). This came in accordance with previous studies stated that the FVC and FEV1 are abnormally reduced in smokers adolescent girls and boys[2038] this can be in part because girls smoke as frequently as boy.[39]

Regarding the smokers’ PF; cigarette smoking harms the pulmonary system, both on short and long-term basis. The results of this study came in accordance with that of Bano et al. Who reported that PF are usually impaired in smokers.[40] Even the early stages of cigarette smoking can produce obvious respiratory system abnormalities[41] and abnormal deteriorations in the lung functions among youth.[3841] Cigarette smoking produces acute airways irritation and increases the airways resistance.[42] Cigarette smoking is the most causative agent in the ventilatory impairments.[40] Smoking impairs the normal age-related increase in the FEV1 in children[43] and causes an accelerated FEV1 deterioration in adults.[44]

The results of the current study regarding the correlation between the smoking duration and the PF came in accordance with the results reported by Hariri and Wan Mansor who found significant correlation between the number of cigarettes and smoking duration with the reduction in the smoker's FVC and FEV1,[22] this correlation follows a dose-dependent relationship[20] and the cigarettes smoking dose was the significant predictor of the level of decrease in the FVC and FEV1.[22] Additionally; previous studies reported reduced FVC, FEV1, FEV1/FVC and Forced Expiratory Flow rate among adult smokers[4546] that indicate affection of the small airways and airways obstruction,[47] with the severity of affection directly depends on the intensity of cigarette smoking.[48]

The observed reduction in smokers’ students’ PF can be explained on the basis that smoking is negatively impacting the lung growth and thereby lung functions and is usually associated with a variety of pulmonary pathologies.[49] The abnormalities in the lung age and functions are secondary to the harmful, diffuse pathological changes affecting the airways epithelium, lining, and bronchial tree structure[50] since smoking causes a pre-mature lung function deterioration especially when the cigarette smoking starts earlier in the youth's life.[51]

Ambrose and Barua previously reported that the cigarette smoking affects the lung function through reducing the respiratory muscles strength secondary to increasing the free radicals within the smoker's vascular system, that in turn can restrict the blood flow to the respiratory muscles and so impairing its function.[52] This oxidative stress can fragment the cell nuclei, harms its DNA and even destroy its chromosomes.[53] Impaired respiratory muscles’ function and altered PF are negatively impacting the subject's functional performance.[54]

Despite the confirmed harmful effects of cigarette smoking on PF and general health; current study results did not show severe impairments in PF of the smokers’ students. This conflict can be clarified when considering the relatively short time and low intensity of smoking that were unlikely to develop intense respiratory or health-related disturbances as those usually encountered in elderly smokers.[41] Despite non-significant differences in cigarette number/day and smoking duration (year) between men and women; but surprisingly there was non-significant difference “reduction” between observed and predicted women's PF compared with significant difference “reduction” between observed and predicted men's PF. This can be resolved when considering that the deterioration and the accelerated rate of the PF loss are greater in smokers’ men than smokers’ women.[5556]

Some points should be mentioned as limitation in this study. This study included a limited age and educational level group. Differences in the demographic and anthropometric characteristics between various geographic areas may limit the generalizability of this study results. The relatively small sample number is another limitation that should be considered when using this study results.

Conclusions

Cigarette smoking proved to have deteriorations impacts on the lung age, functions and the functional performance of the university smokers’ students. Such information can be used to encourage youth and university students to avoid and quit cigarette smoking through implementation of this study results in the health education programs targeting the undergraduate smokers to help them stop smoking.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.