Data on prevalence of obesity and waist circumference in Turkey: Systematic review, meta-analysis and meta-regression of epidemiological studies on cardiovascular risk factors

OBJECTIVE
Obesity is the most important epidemic of the 21st century and its incidence is increasing steadily in Turkey. The aim of this study was to assess the current status and temporal change in the prevalence of obesity in Turkey with a systematic review and meta-analysis of epidemiological studies conducted in the last 15 years.

METHODS
Ovid Medline, the Web of Science Core Collection and the Turkish Academic Network and Information Center (ULAKBIM) databases, as well as the web pages of the Turkish Ministry of Health, the Turkish Statistical Institute, and cardiology, nephrology and endocrinology associations were searched for epidemiological studies conducted within Turkey the last 15 years. Research focusing on local data was excluded. Studies included in the analysis were assessed with a special bias score and categorized as having low or high risk of bias. Body mass index (BMI), waist circumference, obesity and prevalence of abdominal obesity were calculated as crude values. Meta-regression analysis was performed to assess heterogeneity and change over time.

RESULTS
The agreement between the two investigators on the selection and bias scoring of the studies was excellent (kappa=0.95), but the heterogeneity between the studies was high. BMI (10 studies, n=93.554) was calculated as 28.2 kg/m2 for women and 26.5 kg/m2 for men. The prevalence of obesity (12 trials, n=106.553) was 33.2% in females and 18.2% in males. In 6 studies (n=66.591) that included a measurement of waist circumference, the values were 89.72 cm in women and 93.57 cm in men. Especially in women, the prevalence of abdominal obesity (5 studies, n=62331) was greater than that of general obesity (50.8% in women vs 20.8% in men). Meta-regression analysis revealed that the variance of the obesity prevalence between the studies could partly be explained by the age differences, but there was no temporal change in the prevalence of obesity during the years the studies were conducted.

CONCLUSION
The prevalence of obesity, especially abdominal obesity, is considerably high in Turkish women and increases with advancing age. This finding points out that nationwide action plans against obesity, especially for women, should be designed and implemented by health policy makers.