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ACR was a key indicator of risk for mortality in RA with chronic renal insufficiency, predicting all-cause mortality better than eGFR.

Urine albumin-to-creatine ratio (ACR) is a sensitive indicator for early assessment of renal function in patients with rheumatoid arthritis (RA) experiencing chronic renal insufficiency.

Recent findings published in Frontiers in Immunology showed that ACR is also an important independent risk factor affecting the prognosis of this patient population.

“Elucidating the association of ACR with all-cause and cardiovascular mortality among RA participants facilitates the investigation of novel, sensitive markers that predict poor prognosis and the evaluation of the effect of urine albumin excretion on RA prognosis,” said Zexuan Bin and colleagues.

Using 2009-2018 data from the National Health and Nutrition Examination Survey, the researchers compared the cumulative survival probability of patients with RA with different urinary albumin excretion. A total of 1,282 patients were enrolled.

A Cox regression model adjusted for covariates revealed that patients with RA with modestly elevated albuminuria (30-300 mg/g) had a 53% increase in all-cause mortality (HR, 1.63; 95% CI, 1.06-2.21) and a statistically nonsignificant increase in cardiovascular disease (CVD) mortality. In addition, ACR 300 mg/g or greater was associated with an increase in all-cause mortality (HR, 2.62; 95% CI, 1.55-4.45) and CVD mortality (HR, 5.67; 95% CI, 1.96-16.39).

The researchers observed a nonlinear correlation between ACR and all-cause mortality in patients with RA using restricted cubic spline analysis, with an upward trend of CVD mortality as ACR exceeded 152.44 mg/g.

Subgroup analysis indicated that CVD mortality was higher in patients with RA with microalbuminuria who were female, had an estimated glomerular filtration rate (eGFR) of 60 mL/min/1.73 m² or greater, and had hypertension or hyperlipidemia. Compared with eGFR, ACR offered better prognostic efficacy than eGFR, with higher values of the area under the curve for all-cause mortality (0.683; 95% CI, 0.613-0.754) and CVD mortality (0.681; 95% CI, 0.541-0.820).

“Overall, ACR was closely related to the prognosis of RA patients and could be considered as a sensitive and independent indicator for physicians to predict the mortality, especially CVD mortality, in the process of diagnosis and treatment,” the researchers concluded.