Association of hematological inflammatory indices with disease activity and interstitial lung disease in systemic sclerosis.

introductionThe current study evaluates the association of hematological inflammatory indices with disease activity and interstitial lung disease (ILD) in patients with systemic sclerosis (SSc), with particular emphasis on their potential independent predictive value for pulmonary involvement.

methodsThis cross-sectional study included 51 patients diagnosed with SSc and 106 healthy controls. Hematological parameters, including neutrophil-to-lymphocyte ratio (NLR), platelet-to-lymphocyte ratio (PLR), systemic immune-inflammation index (SII), red cell distribution width (RDW), and mean platelet volume (MPV), were compared between groups. Disease activity was assessed using the European Scleroderma Trials and Research (EUSTAR) activity index, and patients were further evaluated according to the presence of ILD. Multivariable logistic regression analyses were performed to identify independent predictors of ILD. Receiver operating characteristic (ROC) analysis was used to assess the discriminatory performance of hematological inflammatory indices.

resultsCompared with healthy controls, patients with SSc had significantly higher levels of NLR, PLR, SII, RDW, C-reactive protein (CRP), and erythrocyte sedimentation rate (ESR), while MPV was significantly lower (p < 0.05 for all). Patients with active disease (EUSTAR ≥ 2.5) demonstrated significantly higher modified Rodnan skin score (mRSS), NLR, and SII levels compared with patients with inactive disease (p < 0.05). In analyses according to ILD status, both NLR and SII were significantly elevated in patients with ILD, whereas PLR, RDW, MPV, CRP, and ESR did not differ significantly between groups (p > 0.05). Anti-Scl-70 positivity was significantly more frequent in patients with ILD, while anti-centromere positivity was more common in patients without ILD. ROC analysis demonstrated moderate discriminatory performance for SII (AUC = 0.72) and NLR (AUC = 0.68). In multivariable logistic regression analysis, anti-Scl-70 positivity emerged as the strongest independent predictor of ILD, while NLR remained independently associated with ILD (OR 2.63, 95% CI 1.01-6.85, p = 0.047). SII did not retain statistical significance in the multivariable model.

conclusionHematological inflammatory indices are associated with disease activity and pulmonary involvement in SSc. Among these indices, NLR appears to be a more robust independent marker of ILD compared to SII. These findings suggest that simple hematological indices may provide additional value in the clinical assessment of patients with SSc. Key Points • Patients with SSc-associated ILD exhibited significantly higher NLR and SII levels than those without ILD. • NLR remained independently associated with ILD after adjustment for established clinical and serological factors. • NLR and SII were associated with both pulmonary involvement and disease activity, supporting their potential utility as readily available inflammatory biomarkers in SSc.