Lifestyle factors and incident metabolic syndrome. The Tromsø Study 1979-2001

Objectives: To assess the relationship between lifestyle characteristics and incident metabolic syndrome. Methods: A total of 17,014 men and women without the metabolic syndrome at baseline who participated in at least two of four surveys between 1979-1980 and 2001 were included in this population based longitudinal study in the municipality of Tromsø, Norway. At each survey the participants went through a physical examination, completed two questionnaires, and blood samples were taken. The metabolic syndrome was defined according to the Adult Treatment Panel III criteria with modifications. Results: The age-adjusted incidence rates of the metabolic syndrome per 1000 person-years for people age 20-56 years were 10.0 in men and 8.7 in women. The metabolic syndrome risk significantly increased with age in women, but not in men. Leisure-time physical activity was inversely related to the metabolic syndrome. Smoking more than 20 cigarettes per day was associated with an increased risk compared to non-smokers. The hazard ratios (95% confidence intervals) were 1.27 (1.04-1.54) and 1.40 (1.02-1.92) in men and women, respectively. Alcohol intake and education were inversely associated with metabolic syndrome in women but not in men. Conclusions: Physical inactivity and heavy smoking increased the metabolic syndrome incidence in men and women. Low or no intake of alcohol was also associated with increased risk, but in women only.