Association between the serum creatine kinase level and all-cause mortality in centenarians: a prospective cohort study in China

BACKGROUND: Muscle mass (MM) has a strong correlation with all-cause mortality. However, its assessment is not easily accessible and expensive. Serum creatine kinase (CK) has been proposed as a solution, but its association with mortality remains unclear. This study aimed to investigate the association between the serum CK level and all-causes mortality among centenarians in China. METHODS: This prospective cohort study included Chinese centenarians residing in the community between June 2014 and December 2016. All-cause mortality was analyzed according to serum CK level using restricted cubic spline (RCS) analysis, Cox regression analysis, Kaplan-Meier curves, the log-rank test, and subgroup analysis. RESULTS: In total, 949 centenarians were eligible for participation and were followed up for a median of 29.4 months (IQR 14.5, 51.7). During the study period, 92.9% of the study participants died. RCS analysis revealed an inverse J-shaped relationship between the serum CK level and the risk of death. Mortality was 34.3% higher when the serum CK level was in the range of 8-66 U/L (Q1-Q2) than in the range of 66-192 U/L (Q3-Q4) (HR = 1.343 in multivariable analysis; 95%CI: 1.173-1.538; P<0.001). Kaplan-Meier analysis showed a significantly shorter median survival in the low-CK group (Q1-Q2) compared to the high-CK group (Q3-Q4). (26 months vs 36 months; P<0.001, log-rank test). CONCLUSIONS: Among community-dwelling centenarians, serum CK level was independently and inversely associated with all-cause mortality in an inverse J-shaped manner and may serve as a practical biomarker for physiological status and survival.