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

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

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.

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.

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.