Association between serum β2-microglobulin levels and frailty in an elderly Chinese population: results from RuLAS

OBJECTIVE: To examine the association between serum β2-microglobulin (B2M) levels and frailty in an elderly Chinese population. DESIGN: A population-based cohort study. SETTING AND PARTICIPANTS: We used data on 1,663 elderly participants (aged 70–84 years) from the aging arm of the Rugao Longevity and Ageing study, a population-based observational two-arm cohort study conducted in Rugao, China. MEASUREMENTS: The serum B2M was measured with chemiluminescence immunoassay by a technician in the biochemistry laboratory of the Rugao People’s Hospital. Information on the frailty index and phenotype was collected. RESULTS: The mean B2M levels and frailty index were 1.8 mg/L and 0.16, respectively; 188 (11.3%) participants were classified as frail (frailty phenotype). For a standard deviation increase in B2M, the adjusted odds ratio for frailty phenotype was 1.20 (95% CI: 1.05, 1.39; P=0.009) and the standardized coefficient for frailty index was 0.07 (95% CI: 0.02, 0.11; P=0.004). Relative to the lowest quartile, the highest B2M quartile had a greater risk of prevalent frailty with adjusted odds ratios of 1.68 (95% CI: 1.04, 2.71; P=0.034) for frailty phenotype and 1.51 (95% CI: 1.01, 2.27; P=0.044) for frailty index (≥0.25). In addition, estimated glomerular filtration rate (based on B2M) or chronic kidney disease (estimated glomerular filtration rate <60 mL/min/1.73 m(2)) was significantly associated with frailty phenotype and index. CONCLUSION: B2M was significantly associated with both frailty phenotype and index in elderly Chinese population. The findings underscore the promising kidney relevant biomarkers for identifying vulnerable elderly Chinese population.