Serum creatinine and cystatin C-derived indices suggesting future deterioration in muscular function, physical performance and frailty status among community dwelling older adults.

Objectives: Serum biomarkers, particularly serum creatinine and cystatin C, have garnered increased attention as a potential method for predicting future declines in muscle strength. Nevertheless, there is currently a dearth of research in this area. We evaluated the association of serum creatinine and cystatin C-derived indices with the subsequent decline in lower-extremity muscle strength among community-dwelling older adults.

Design: Prospective observational study.

Setting and subjects: Community-dwelling older individuals (age ≥65 years) residing in the Sasayama-Tamba area of Japan.

Predictor: Five indices based on serum creatinine and cystatin C, including the total body muscle mass index (TBMM), were computed.

Main outcome: Changes in muscular function including isometric knee extensor strength and handgrip strength, physical performance, and frailty status, underwent assessments at baseline and two years.

Results: The final dataset comprised 528 community-dwelling older adults (72 [68, 76] years, 65.7% women). The median change and the proportion of individuals experiencing a significant decline in isometric knee extensor strength over a 2-year period were -37.4N and 40.2%, respectively. TBMM showed significant associations with the subsequent decline in isometric knee extensor strength, handgrip strength, and frailty status.

Conclusions: This study demonstrates the association between serum creatinine and cystatin C-derived index, TBMM, and the subsequent decline in lower-extremity muscle strength among older adults. Utilizing markers derived from serum creatinine and cystatin C enables prompt assessment of the need for proactive measures and may facilitate initiating these interventions at a suitable juncture for older individuals.