Association between neutrophils and renal impairment of rheumatoid arthritis: A retrospective cross-sectional study

Previous studies have shown that increased neutrophils, as a manifestation of oxidative stress, may be involved in the progression of kidney disease. To our knowledge, little is known about the relationship between neutrophils and renal impairment in rheumatoid arthritis (RA). Therefore, we aim to investigate whether neutrophil is associated with renal impairment in RA patients.

We retrospectively investigated the renal function of 602 RA patients in the First Affiliated Hospital of Guangzhou University of Traditional Chinese Medicine by estimated glomerular filtration rate (eGFR) from September 2018 and September 2019. The exposure variable was neutrophils, and the main outcome was eGFR. General data (gender, age, duration, hypertension, diabetes, hobbies, and medication history), whole blood markers, lipid indexes, and inflammatory indexes were collected as much as possible. We used multivariable logistic regression analysis to evaluate the association between neutrophils and renal impairment in RA participants.

A total of 89 cases (14.8%) had renal impairment with eGFR < 60 ml/min/1.73 m² , and 75 cases (84.3%) were female. Subgroup analysis showed that female (odds ratio [OR] = 0.523, 95% confidence interval [CI]: 0.318-0.867, p = .011), neutrophils greater thsn 7.5 × 10⁹ /L (OR = 2.314, 95% CI: 1.310-4.087, p = .004), NLR > 3.53 (OR = 1.757, 95% CI: 1.104-2.799, p = .018), hemoglobin less than 120 g/L (OR = 2.413, 95% CI: 1.418-4.118, p = .001), and UA > 360 μmol/L (OR = 6.052, 95% CI: 3.708-9.878, p < .001) was related to renal damage in RA. Adjusted for several confounders, the multivariable analysis indicated that neutrophils greater than 7.5 × 10⁹ /L (OR = 1.784, 95% CI: 1.164-3.288, p = .031) was independently associated with an increased risk of renal impairment in RA.

Our study demonstrated that neutrophils greater than 7.5 × 10⁹ /L was associated with a high risk of renal impairment in RA, suggesting that neutrophil may be a biomarker for renal impairment in RA.