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 m2) 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.