Musculoskeletal decline and mortality: prospective data from the Geelong Osteoporosis Study.

BACKGROUND

We aimed to examine the relationship between musculoskeletal deterioration and all-cause mortality in a cohort of women studied prospectively over a decade.

METHODS

A cohort of 750 women aged 50-94 years was followed for a decade after femoral neck bone mineral density (BMD) and appendicular lean mass (ALM) were measured using dual energy X-ray absorptiometry, in conjunction with comorbidities, health behaviour data, and other clinical measures. The outcome was all-cause mortality identified from the Australian National Deaths Index. Using Cox proportional hazards models and age as the time variable, mortality risks were estimated according to BMD groups (ideal-BMD, osteopenia, and osteoporosis) and ALM groups (T-scores > -1.0 high, -2.0 to -1.0 medium, <-2.0 low).

RESULTS

During 6712 person years of follow-up, there were 190 deaths, the proportions increasing with diminishing BMD: 10.7% (23/215) ideal-BMD, 23.5% (89/378) osteopenia, 49.7% (78/157) osteoporosis; and with diminishing ALM: 17.0% (59/345) high, 26.2% (79/301) medium, 50.0% (52/104) low. In multivariable models adjusted for smoking, polypharmacy, and mobility, compared with those with ideal BMD, mortality risk was greater for those with osteopenia [hazard ratio (HR) 1.77, 95% confidence interval (CI) 1.11-2.81] and osteoporosis (HR 2.61, 95%CI 1.60-4.24). Similarly, compared with those with high ALM, adjusted mortality risk was greater for medium ALM (HR 1.36, 95%CI 0.97-1.91) and low ALM (HR 1.65, 95%CI 1.11-2.45). When BMD and ALM groups were tested together in the model, BMD remained a predictor of mortality (HR 1.74, 95%CI 1.09-2.78; HR 2.82, 95%CI 1.70-4.70; respectively), and low ALM had borderline significance (HR 1.52, 95%CI 1.00-2.31), which was further attenuated after adjusting for smoking, polypharmacy, and mobility.

CONCLUSIONS

Poor musculoskeletal health increased the risk for mortality independent of age. This appears to be driven mainly by a decline in bone mass. Low lean mass independently exacerbated mortality risk, and this appeared to operate through poor health exposures.