Platelet-to-lymphocyte ratio: a predictive biomarker for exocrine gland involvement in Sjögren disease

To investigate the relationship between the platelet-to-lymphocyte ratio (PLR) and ocular surface damage as well as labial gland pathology in patients with Sjögren disease (SjD).

This retrospective study included 181 newly diagnosed SjD patients. Blood tests were used to calculate PLR, systemic immune-inflammation index (SII), neutrophil-to-lymphocyte ratio (NLR), and fibrinogen-to-albumin ratio (FAR). All patients underwent comprehensive ocular surface examinations and labial gland biopsies. Spearman correlation analysis was used to evaluate the relationships between variables, and receiver operating characteristic (ROC) curves determined optimal cutoff values for PLR in predicting tear meniscus height (TMH) abnormality and labial gland pathology positivity. Mann-Whitney U tests identified potential risk factors for labial gland pathology positivity. The significant factors (P < 0.05) from the univariate analysis were incorporated into a binary logistic regression model to determine independent risk factors.

(1) Correlation analysis showed that PLR was positively correlated with SII (r = 0.680, P < 0.001), NLR (r = 0.488, P < 0.001), FAR (r = 0.162, P = 0.031), and labial gland pathology (r = 0.159, P = 0.035), while PLR was negatively correlated with TMH (r=-0.202, P = 0.008). (2) ROC analysis revealed that PLR had an area under the curve (AUC) of 0.609 (95%CI: 0.522-0.695, p = 0.015) for predicting abnormal TMH, with a sensitivity of 48.6% and specificity of 74% at a cutoff of 151.34. For predicting labial gland pathology positivity, PLR had an AUC of 0.616 (95% CI: 0.503-0.730, p = 0.035), with a sensitivity of 65.7% and specificity of 58.8% at a cutoff of 122.92. (3) Binary logistic regression analysis showed that the high PLR group(PLR > 122.92) had 2.8 times the risk of labial gland pathology positivity compared to the low PLR group (OR = 2.842, 95%CI: 1.271-5.358, p = 0.011).

PLR is a useful inflammatory marker for evaluating exocrine gland involvement in SjD patients.