Objectives
To investigate the relationship between involuntary weight loss with low muscle mass and health-related quality of life in a large representative sample of older adults.

Methods
A nationwide cross-sectional study based on data from the Korea National Health and Nutritional Examination Survey, 2008 to 2011. Study participants included 2249 individuals aged ≥70 years. The participants reported an unintentional weight loss >3 kg in the past year. Appendicular lean mass was measured using dual-energy X-ray absorptiometry and calculated with the appendicular lean mass index. Health-related quality of life was measured using the EuroQol-5 dimension (EQ-5D) instrument. Univariate and multivariate survey logistic regression models were used to calculate odds ratios (OR) with 95% confidence intervals (95% CI) for the lowest quintile of the EQ-5D index.

Results
In total, 39.1% of participants were male and 60.9% were female. The weighted mean age was 75.6 years (95% CI; 75.3–75.9). Clinically significant weight loss is typically 5% of one's body weight; average, 2.8 kg (3.1 kg for men; 2.7 kg, women) for our participants. Compared with the normal reference group and after adjusting for potential confounders, the ORs for the lowest quintile of the EQ-5D indices were 1.39 (95% CI, 0.92–2.10), 2.56 (95% CI, 1.56–4.18), and 3.40 (95% CI, 2.05 to 5.63) for the low muscle mass, involuntary weight loss, involuntary weight loss with low muscle mass groups, respectively.

Conclusion
Involuntary weight loss combined with low muscle mass was more closely associated with poor quality of life than involuntary weight loss alone in community-dwelling older adults.