Sex Differences in the Associations of Creatinine to Cystatin C Ratio with Incident Symptomatic Knee Osteoarthritis-Evidence From the CHARLS

Abstract

Background Little was known about whether Creatinine to Cystatin C Ratio (CCR) can predict the occurrence of symptomatic knee osteoarthritis (KOA). We examined the association between CCR and incident KOA and sex differences among Chinese middle-aged and older adults. Methods We included 4,155 participants aged ≥ 45 years in the 2011 and 2015 wave of the China Health and Retirement Longitudinal Study (CHARLS). The incident of symptomatic KOA was defined as participants who were free of symptomatic KOA at baseline and diagnosed with symptomatic KOA at the 4-year follow-up. Logistic regression models were used to explore the relationship between CCR and incidence KOA in both sexes. Restricted cubic analysis was employed to analyze non-linear relationship. Results 420 participants (10.1%) developed KOA during 4-year follow-up. The multivariable-adjusted odds ratio (OR) for KOA was 0.85 (95% confidence interval (CI), 0.74 to 0.98) per 1 standard deviation (SD) higher of CCR. The significant effect modification by sex was observed (P-interaction = 0.013). The highest tertile of CCR was significantly correlated with a lower incidence of symptomatic KOA in males (OR = 0.50, 95% CI = 0.29–0.88, P = 0.015), but not in females (OR = 0.88, 95% CI = 0.61–1.29, P = 0.522) compared with the lowest tertile. Significant non-linear relationship was identified for male with 75.0 of CCR being an inflection point. Conclusions Our findings provided new insights that CCR could serve as a promising biomarker for early KOA screening among Chinese males.