Participants and assessment
We conducted a cross-sectional study, subjects were enrolled into five groups based on cigarette and e-cigarette use, demographic information and medical history were collected and followed by pulmonary function testing (PFT), a six-minute walk test (6MWT) and a completed Health-Related Quality of Life (HRQoL) questionnaire. Participants were recruited via the college website and social media platforms (www.bmc.edu.sa). The study was conducted over a period of one year and seven months from February 2023 to August 2023 at the PFT lab, Respiratory Therapy department, Batterjee Medical College (BMC), Jeddah, Saudi Arabia.
Study protocol.
The recruitment process for participants in our research on adult users (≥18 years old) incorporated a multi-faceted approach that utilized a variety of channels to reach potential participants. This included the use of online platforms such as Twitter, Facebook, and Snapchat, where visual advertisements and tailored messages were employed to highlight the study's objectives, eligibility criteria, and contact information. Moreover, flyers and visually appealing advertisements were strategically placed in vape shops to target regular customers outlining the study's purpose and providing clear instructions for participation. The participants were allocated into five groups. 1- Control, 2-Individuals who use cigarettes only, 3-Individuals who only use e-cigarettes, 4-Individuals who previously smoked and currently use only e-cigarettes and 5-Individuals who use both cigarettes and e-cigarettes. 1-The control group included participants who had never smoked or vaped. 2-Individuals who use cigarettes only had a history of smoking for at least 3.5 pack years or above and smoked only cigarettes based on previously conducted study (17). 3- E-cigarette use-only group participants were required to have a history of vaping for at least 3.5 years and above. 4- The previously smoked and currently uses e-cigarette group includes participants who report no smoking for the past year and a history of vaping for at least 3.5 years and above. 5- Use of both cigarette and e-cigarette group, participants had smoked for 3.5 years and had vaped for at least 3.5 years. Subjects with a history of unstable cardiopulmonary status, neuromuscular disorders, and diagnosed with any acute or chronic respiratory conditions, use of any respiratory medications such as corticosteroids were excluded.The tests were conducted in the same building and a 30-minute rest period was given between the tests. The BMC college clinic doctor was readily available for any emergencies during conducting the study.
Pulmonary function test
All participants performed spirometry. The measurements included forced vital capacity (FVC), forced expiratory volume in the first second (FEV1), and FEV1 / FVC were recorded. Absolute values and a percentage of expected normal values (% predicted) were used to express all PFT measurements. The test was carried out by the recommendations of the European Respiratory Society (ERS) and the American Thoracic Society (ATS) (18). The PFT machine was performed using Master Screen PFT powered by Sentry Suite (SentrySuite™ Software Solution | Vyaire Medical)
Six-minute walk test
For assessing the cardiopulmonary capacity, 6MWT was performed over a 30-meter indoor corridor with pre-and post-test measurements of oxygen saturation, blood pressure, fatigue, and dyspnea score assessed using a Borg Scale. The test was performed per ATS guidelines (19).
Health-related quality of life
The HRQoL domain was assessed using the RAND SF-36 questionnaire (20). It includes 36 items covering eight domains. Physical functioning (10 items), social functioning (2 items), role limitation due to physical health problems (4 items), role limitation due to emotional problems (4 items), bodily pain (2 items), emotional well-being (5 items), general health perceptions (5 items), and energy/fatigue (4 items). A higher score indicated a healthier state, with scores for each domain ranging from zero (worst) to 100 (best).
Sample size:
A priori power analysis was conducted using G*Power version 3.1.9.7 (21). To achieve 80% power for detecting a medium effect, at a significance criterion of α=0.05, the estimated sample size was n = 200 (one-way ANOVA test). Our post hoc G*Power analysis based on our study mean and SD of FEV1 with an effect size of 0.24, sample size of n=175, type-I errors (alpha) of 0.05 (5%), produced a power of 74%.
Ethical approval
The study was approved by the institutional ethical committee at BMC (RES 2023-0036). The purpose of the study was explained to all participants and informed consent was taken.
Statistical analysis
The test of normality was performed using the Shapiro–Wilkins test. Normally distributed data were represented as mean (± standard deviation (SD)) and non-normally distributed data as median (and interquartile range (IQR)). Categorical variables were expressed in number (and percentage (%)). One-way ANOVA and Kruskal-Wallis tests were used to compare the differences in continuous variables across the groups. A post-hoc Fisher’s least significant difference was applied to each significant ANOVA to determine the difference between the groups. The level of significance assumed was a p-value of ≤0.05. The results were analyzed using the Statistical Package for Social Sciences (SPSS version 25.0 for Windows, Chicago, IL USA)