[Study on the baseline physical activity and the risk of ischemic cardiovascular diseases].

Objective: To examine the associations between physical activity measures [metabolic equivalents of energy expenditure (MET) per hour per day] and ischemic cardiovascular diseases (ICVD) in Chinese population.

Methods: A survey on cardiovascular risk factors was conducted in different areas of China in fall 1998. People aged 35 to 59 but without a history of coronary heart and stroke at baseline were prospectively followed and 11 849 subjects whose information were complete at the end of second follow-up were valid. Cox regression was used to estimate the hazard ratios (HRs) for incident ischemic cardiovascular diseases and the different measures of physical activity.

Results: During a mean follow-up period of 5.9 years, 84 incident ischemic cardiovascular events were ascertained. We examined the HRs of ischemic cardiovascular events for a 1-unit change in METs value, which were included in the models as continuous variable. There were negative association of METs values found with ischemic cardiovascular events in total, urban, rural, male and female subjects, and statistical significance in the urban (HRs = 0.22, 95% CI: 0.05-0.95) but the association was weakened after adjustment for demographic factors. When further adjustment for other intermediate factors, the significance in the urban was again attenuated. When the urban males and females, rural males and females were divided into 3 groups according to their respective tertiles and the combination of different population groups, the factors of male/female and urban/ rural were equally distributed in different groups, and no more adjustment in the Cox model. The multivariate - adjusted (age and education attainment) HRs associated with the tertiles, from lowest to highest, were: 1, 1.03 and 0.65 (P(trend) = 0.170) for the total, 1, 0.72 and 0.64 for the urban, 1, 1.49 and 0.72 for the rural, 1, 1.05 and 0.59 for men, 1, 0.90 and 0.84 for women.

Conclusion: The totality of our findings pointed to METs per hour per day seemed to be weakly associated with a reduction in ischemic cardiovascular events incidence among urban middle-aged adults.