Objective  To explore the relevance between neutrophil-to-lymphocyte ratio (NLR) and renal injury in patients with primary Sjogren's syndrome (pSS) and evaluate the clinical application value of NLR in renal injury of pSS.

Methods  From January 2017 to June 2022, the relevant clinical data were retrospectively reviewed for 134 hospitalized pSS patients. Based upon the presence or absence of renal injury, they were assigned into two groups of pSS with renal injury and pSS without renal injury. NLR and other laboratory parameters were compared between two groups. Through Spearman's rank correlation analysis, the correlations were examined between NLR and renal injury parameters (creatinine, urea nitrogen, uric acid, cystatin C & glomerular filtration rate) and inflammation-related parameters (erythrocyte sedimentation rate & C-reactive protein). The risk factors of renal injury were explored by multivariate Logistic regression. Receiver operating characteristic (ROC) curve was utilized for comparing the diagnostic efficacy of NLR, renal injury parameters and inflammation-related parameters for renal injury in pSS.

Results  NLR was markedly elevated in renal injury group than that in renal non-injury group (P<0.05). According to Spearman’s correlation analysis, positive correlation existed between NLR and creatinine, uric acid, cystatin C, erythrocyte sedimentation rate, C-reactive protein (all P<0.05). And negative correlation existed between NLR and glomerular filtration rate (P<0.05). According to multivariate Logistic regression, NLR (OR=7.036, P<0.001) was a risk factor for renal injury in pSS. ROC curve revealed that area under curve (AUC) of NLR in the diagnosis of pSS renal injury was 0.713 with an optimal cut-off value of 2.30. With the highest diagnostic efficiency, there was a sensitivity of 80% and a specificity of 91.3%. It was higher than that of renal injury and inflammation-related parameters.

Conclusions  NLR may be utilized as a biochemical indicator for predicting renal injury in pSS.