Obesity and muscle strength as long-term determinants of all-cause mortality--a 33-year follow-up of the Mini-Finland Health Examination Survey.

OBJECTIVE: To examine the independent and combined associations of obesity and muscle strength with mortality in adult men and women.

DESIGN: Follow-up study with 33 years of mortality follow-up.

SUBJECTS: A total of 3594 men and women aged 50-91 years at baseline with 3043 deaths during the follow-up.

MEASUREMENT: Body mass index (BMI) and handgrip strength were measured at baseline.

RESULTS: Based on Cox models adjusted for age, sex, education, smoking, alcohol use, physical activity and chronic conditions, baseline obesity (BMI ≥30 kg m(-2)) was associated with mortality among participants aged 50-69 years (hazard ratio (HR) 1.14, 95% confidence interval (CI), 1.01-1.28). Among participants aged 70 years and older, overweight and obesity were protective (HR 0.77, 95% CI, 0.66-0.89 and HR 0.76, 95% CI, 0.62-0.92). High handgrip strength was inversely associated with mortality among participants aged 50-69 (HR 0.89, 95% CI, 0.80-1.00) and 70 years and older (HR 0.78, 95% CI, 0.66-0.93). Compared to normal-weight participants with high handgrip strength, the highest mortality risk was observed among obese participants with low handgrip strength (HR 1.23, 95% CI, 1.04-1.46) in the 50-69 age group and among normal-weight participants with low handgrip strength (HR 1.30, 95% CI, 1.09-1.54) among participants aged 70+ years. In addition, in the old age group, overweight and obese participants with high handgrip strength had significantly lower mortality than normal-weight participants with high handgrip strength (HR 0.79, 95% CI, 0.67-0.92 and HR 0.77, 95% CI, 0.63-0.94).

CONCLUSION: Both obesity and low handgrip strength, independent of each other, predict the risk of death in adult men and women with additive pattern. The predictive value of obesity varies by age, whereas low muscle strength predicts mortality in all age groups aged>50 years and across all BMI categories. When promoting health among older adults, more attention should be paid to physical fitness in addition to body weight and adiposity.