Change in lifestyle factors and their influence on health status and all-cause mortality.

BACKGROUND: The purpose of this study was to analyse both cross-sectional associations and how longitudinal changes in lifestyle factors from one state in 1980-1981 to another in 1988-1989 influence self-reported health status. Another aim was to estimate the hazard ratios for all-cause mortality for the changes in lifestyle factors and self-reported hypertension during the same period of time.
METHOD: The cross-sectional and the longitudinal analyses are based on the same simple random sample of 3,843 adults, aged 25-74, interviewed in 1980-1981 and 1988-1989 and is part of the Swedish Annual Level-of-Living Survey. About 85% of the respondents in the first interview participated in a second interview in 1988-1989. Cross-sectional odds ratios, based on a marginal model, were estimated using the generalized estimating equations. The transitional models were analysed using unconditional logistic regression. A proportional hazard model was applied to investigate the influence of lifestyle transitions on mortality.
RESULTS: Physical inactivity, being a current or former smoker and obesity (women only) were strong risk factors for poor health either as main effects and/or combined (interactions). There was a strong interaction between physical activity and smoking, and for women, also between body mass index (BMI) and physical activity. Smoking, physically inactive and obese women had about a ten times higher risk of poor health status than non-smoking, physically active, and normal-weight women. The corresponding risk for men was about five times higher. Physically active, but smoking and obese individuals showed only moderately increased risks for poor health status. The transitional model showed that those who were physically inactive in 1980-1981, but did exercise in 1988-1989, improved their health after adjustments for sociodemographic and other lifestyle factors. Continuing to smoke or being physically inactive or having hypertension at both points in time were all associated with higher hazard ratios for all-cause mortality (1.6, 1.9 and 1.8, respectively) than those who reported that they were in good status at both points in time.
CONCLUSIONS: We found that physical activity protects against poor health irrespective of an increased BMI and smoking. The major clinical implications are the long-standing benefits of physical activity and not smoking.