Urinary albumin-to-creatinine ratio for predicting risk of all-cause mortality and specific-cause mortality in patients with rheumatoid arthritis: evidence from NHANES 1999-2018.

OBJECTIVE

To explore the relationship between urinary albumin-to-creatinine ratio (uACR) and all-cause/specific-cause mortality among patients with rheumatoid arthritis (RA).

METHODS

This study included 1354 RA patients in the National Health and Nutritional Examination Surveys (NHANESs) during 1999-2018. The mortality status was assessed by linkage to death certificate data reported in the National Death Index (NDI) until December 31, 2019. Cox proportional hazards models and Kaplan-Meier (K-M) analysis were used to elucidate the relationship between uACR and all-cause/specific-cause mortality. Restricted cubic spline (RCS) was used to visualize the association of uACR with all-cause mortality risk. Stratified analyses were employed to identify patients with higher mortality risk.

RESULTS

Over a median of 115 months of follow-up, 298 deaths occurred. Cox proportional hazards models indicated that RA patients with higher uACR had an increased risk of all-cause mortality, but not cardiovascular disease, kidney disease, and cancer mortality. K-M survival curves showed a significant difference (log-rank, p < 0.001) in all-cause mortality among uACR tertiles. RCS analysis revealed an L-shaped association between uACR and all-cause mortality, and patients with uACR above the threshold points (5.96 mg/g) had a 13.2% increased risk of all-cause mortality (HRs 1.132; 95% CI 1.011, 1.267) for each ln unit increase in uACR. The stratified analysis revealed consistent patterns for correlations between uACR and all-cause mortality.

CONCLUSIONS

High uACR, even in the normal range, was associated with an increased risk of all-cause mortality (not specific-cause mortality) in individuals with RA. Identifying high-risk populations using uACR assessment may contribute to target risk interventions among RA patients in the future. Key points • uACR, even within the normal range, significantly increased the hazard for all-cause mortality among RA patients. • uACR has good performance in identifying populations with different mortality risk levels in RA patients. • uACR, independent of varied well-recognized cardiovascular risk factors, is a predictor of mortality in RA patients.