STUDY DESIGN: This was a case-control study including 1604 Malays, 1654 Chinese and 1728 Indians from the Malaysian Cohort Project.
METHODS: The proportion of T2D risk variance explained by known genetic and environmental factors was assessed by fitting multivariable logistic regression models and evaluating McFadden's pseudo R(2) and the area under the receiver-operating characteristic curve (AUC). Models with and without the genetic risk score (GRS) were compared using the log likelihood ratio Chi-squared test and AUCs. Multiplicative interaction between genetic and environmental risk factors was assessed via logistic regression within and across ancestral groups. Interactions were assessed for the GRS and its 62 constituent variants.
RESULTS: The models including environmental risk factors only had pseudo R(2) values of 16.5-28.3% and AUC of 0.75-0.83. Incorporating a genetic score aggregating 62 T2D-associated risk variants significantly increased the model fit (likelihood ratio P-value of 2.50 × 10(-4)-4.83 × 10(-12)) and increased the pseudo R(2) by about 1-2% and AUC by 1-3%. None of the gene-environment interactions reached significance after multiple testing adjustment, either for the GRS or individual variants. For individual variants, 33 out of 310 tested associations showed nominal statistical significance with 0.001
MATERIALS AND METHODS: A cross-sectional study was conducted at the Management and Science University from December 2011 until March 2012. The questionnaire consisted of five sections including socio-demographic, social environment, knowledge about shisha, psychosocial factors, and personal shisha smoking behavior. Obtained data were analyzed using Statistical Package for the Social Sciences (SPSS 13). T-test was used to determine the relationships between shisha smoking and socio-demographic characteristic.
RESULTS: A total number of 300 medical students participated in this study. Mean age was 22.5±2.5 years. The majority were female, Malay, single, from urban areas (67%, 54%, 97%, 73%; respectively). The prevalence of shisha smoking among medical students was found to be 20%. The study revealed that many students believed that shisha does not contains nicotine, carbon monoxide, does not lead to lung cancer, dental problems and does not lead to cardiovascular diseases (25%, 20.7%, 22.3%, 29%, 26.7%; respectively). Age and sex were found to be significantly associated with smoking shisha status among medical students (p=0.029, p<0.001; respectively). Furthermore, having parents, siblings and friends smokers of shisha were found to be significantly associated with shisha smoking status (p<0.001, p<0.001, p<0.001; respectively). Furthermore, family problems, problems with friends, financial problems and university life were found to significantly associated with shisha smoking status among medical students (p<0.001, p=0.002, p<0.001, p=0.002; respectively).
CONCLUSIONS: There is a high prevalence of shisha smoking and a poor knowledge about its impact on health among medical students. More attention is needed to focus on medical education in this regard. The policies that are currently employed in order to reduce the cigarettes smoking should be applied to shisha smoking and shisha products.