Association between lifestyle and metabolic syndrome incidence of workers in northern Okinawa, Japan: A cohort study.

In Japan, specific health checkups were implemented to prevent metabolic syndrome (MetS) and cardiovascular diseases in April 2008. This study aimed to clarify the relationship between lifestyle factors and the MetS incidence to understand how the disease can be prevented and to improve the public health policy. A retrospective cohort study was conducted using the specific health checkup data of 2,781 workers. Lifestyle factors were assessed using lifestyle-related items in the general health questionnaire included in the specific health checkups. The hazard ratio values for the incidence of MetS according to lifestyle-related items were determined from the data of the specific health checkup for 12 years. The Cox proportional hazard survival model was used to evaluate hazard ratio values after adjusting for confounding factors. The limitations of this research method are discussed using a target trial emulation framework which investigates problems such as biases in observational studies. The crude incidence rates per 1,000 person-years of MetS in women and men were 15.25 and 47.58, respectively. Three dietary lifestyle-related factors, namely "Eating snacks and sweet beverages other than breakfast, lunch, and dinner," "Eating faster than others," and "Skipping breakfast at least three times a week," were identified, with the hazard ratio values 1.262 (95 % confidence interval [CI] 1.032-1.542, p = 0.023), 1.220 (95 % CI 1.032-1.442, p = 0.020) and 1.189 (95 % CI 1.012-1.397, p = 0.036), respectively. These results suggest that lifestyle improvements related to extracted lifestyle-related items contribute to the prevention of MetS.