Corrected arm muscle area: an independent predictor of long-term mortality in community-dwelling older adults?

OBJECTIVES: Older people are at risk of undernutrition because of a number of physiological conditions and lifestyle factors. The purpose of this study was to explore the predictive relationship of corrected arm muscle area (CAMA) with 8-year mortality in a representative sample of older Australians.

DESIGN: Prospective cohort study: The Australian Longitudinal Study of Ageing.

SETTING: Community.

PARTICIPANTS: One thousand three hundred ninety-six participants aged 70 and older.

MEASUREMENTS: Trained observers measured baseline weight, height, mid upper arm circumference, and triceps skinfold thickness using standard techniques. Body mass index (BMI) and CAMA were calculated. Baseline BMI and CAMA measurements were categorized according to cutoff values proposed by Garrow et al. and Friedman et al., respectively. Subsequent analyses were undertaken using Cox proportional hazards regression.

RESULTS: After adjustment for potential confounders (baseline age, gender, marital status, smoking, self-rated health, ability to conduct activities of daily living, comorbidity, cognition performance, and presence of depression), those older Australians with a low CAMA (<or=21.4 cm2 for men and <or=21.6 cm2 for women) had an increased risk of mortality at 8-year follow-up (hazard ratio=1.94, 95% confidence interval=1.25-3.00, P=.003). There was no increased risk in 8-year mortality identified for those with a high or low BMI.

CONCLUSION: CAMA is a useful assessment of undernutrition in older adults that has better prognostic value than BMI in predicting death in older, community-living Australians.