Data on smoking in Turkey: Systematic review, meta-analysis and meta-regression of epidemiological studies on cardiovascular risk factors

OBJECTIVE
Smoking is one of the most important public health problems and preventable causes of mortality in Turkey. Major healthcare policies have been implemented to combat this problem over the past 10 years. The aim of this study was to conduct a systematic review and meta-analysis of epidemiological studies performed in the country in the last 15 years to determine the prevalence of smoking in Turkey.

METHODS
Ovid Medline, the Web of Science Core Collection, and the Turkish Academic Network and Information Center (ULAKBIM), as well as the websites of the Ministry of Health and the Turkish Statistical Institute were searched for the appropriate epidemiological studies. Studies included in the analysis were evaluated by a self-developed bias score regarding their potential to represent Turkey and standardization of measurements. The meta-analysis and meta-regression analysis were performed using a random effects model.

RESULTS
Ten epidemiological studies (n=122383) that included data about smoking were found. Eight of them (all with low bias score) included separate data about the smoking habit of women (n=49524) and men (n=37684). The smoking prevalence was determined to be 30.5% for the whole group, 15.7% for women, and 46.1% for men, when occasional smokers were included. Although the change observed in crude prevalence values over time was not statistically significant, when the data of the 3 studies that gave prevalence values according to age categories were standardized according to age, the incidence of smoking between 2003 and 2012 decreased 6.8% (20.2%) when occasional smokers were included and 8.4% (26.3%) when they are excluded.

CONCLUSION
Despite implementation of major healthcare policies and some success in decreasing rate of smoking, one-third of the Turkish population aged over 15 years and nearly half of the men are smokers. It is essential to continue and to strengthen measures to combat smoking.