The association of grip strength from midlife onwards with all-cause and cause-specific mortality over 17 years of follow-up in the Tromsø Study

Abstract

Background: Grip strength has consistently been found to predict all-cause mortality rates. However, few studies have examined cause-specific mortality or tested age differences in these associations.

Methods: In 1994, grip strength was measured in the population-based Tromsø Study, covering the ages 50-80 years (N=6850). Grip strength was categorised into fifths, and as z-scores. In this cohort study, models with all-cause mortality and deaths from specific causes as the outcome were performed, stratified by sex and age using Cox regression, adjusting for lifestyle-related and health-related factors.

Results: During 17 years of follow-up, 2338 participants died. A 1 SD reduction in grip strength was associated with HR=1.17 (95% CI 1.12 to 1.22) for all-cause mortality in a model adjusted for age, gender and body size. This association was similar across all age groups, in men and women, and robust to adjustment for a range of lifestyle-related and health-related factors. Results for deaths due to cardiovascular disease (CVD), respiratory diseases and external causes resembled those for all-cause mortality, while for cancer, the association was much weaker and not significant after adjustment for lifestyle-related and health-related factors.

Conclusions: Weaker grip strength was associated with increased all-cause mortality rates, with similar effects on deaths due to CVD, respiratory disease and external causes, while a much weaker association was observed for cancer-related deaths. These associations were similar in both genders and across age groups, which supports the hypothesis that grip strength might be a biomarker of ageing over the lifespan.

Keywords: Epidemiology of ageing; LONGITUDINAL STUDIES; MORTALITY; PHYSICAL FUNCTION.

Figure 1

Grip z-scores and mortality HRs with 95% CIs (shaded areas) for men (blue solid lines) and women (red dashed lines). Estimated in Cox regression with grip z-scores modelled as natural cubic splines with three knots. Z-score 0 is reference. *A is minimally adjusted for age and body size (BMI and height); *B is fully adjusted for age and body size (BMI and height)+systolic blood pressure, total cholesterol, triglycerides, self-reported general health status, self-reported history of heart attack, stroke, angina, asthma and diabetes, self-reported blood pressure treatment, smoking, leisure-time physical activity and education. BMI, body mass index; CVD, cardiovascular disease.