Diagnostic utility of erythrocyte sedimentation rate and anti-Scl-70 positivity for interstitial lung disease in diffuse systemic sclerosis.

BackgroundInterstitial lung disease (ILD) is a major cause of mortality in patients with diffuse cutaneous systemic sclerosis (dcSSc). Although high-resolution computed tomography (HRCT) is recommended for diagnosis, it is costly, time-consuming, and prone to subjective interpretation.ObjectivesThis study aimed to investigate the utility of hematological biomarkers, specifically routine blood parameters and their derived indices in discriminating dcSSc-ILD to support clinical decision-making.DesignRetrospective, cross-sectional study.MethodsPatients monitored with dcSSc who underwent HRCT evaluation were analyzed. The cohort was divided into two groups based on the presence of ILD to evaluate routine blood parameters and derived indices. Significant parameters from univariate analysis were further evaluated using two separate multivariable logistic regression models adjusted for age, gender, erythrocyte sedimentation rate (ESR), anti-Scl-70, immunosuppressive use, newly diagnosed status and monocyte-to-lymphocyte ratio (MLR).ResultsOut of 117 patients (mean age: 49.03 ± 13.48 years, 90.6% female), dcSSc-ILD was detected in 53% (n=62). Within the cohort, 42.7% (n=50) were receiving immunosuppressive therapy, and 35.0% (n=41) were newly diagnosed with dcSSc. Patients with dcSSc-ILD demonstrated significantly higher ESR (p=0.002), ESR-to-C-reactive protein ratio (ECR) (p=0.042), and ESR-to-lymphocyte ratio (SLR) (p=0.003) levels compared to those without ILD. Anti-Scl-70 positivity was observed in 39.3% of the cohort and was significantly more prevalent in the ILD group (50.0% vs. 27.3%, p=0.012). ROC curve analysis revealed an optimal ESR cut-off value of >23.5 mm/hour for identifying ILD, yielding a high specificity of 90.9% and a sensitivity of 43.5% (AUC: 0.667, 95% CI: 0.569-0.766, p=0.002). In multivariable regression analyses, the diagnostic value of ESR and anti-Scl-70 remained significant and independent after adjusting for age, gender, MLR and immunosuppressive therapy (Model 1), as well as new diagnosis status (Model 2). Each 1 mm/hour increase in ESR was associated with an approximately 7% increase in the probability of dcSSc-ILD.ConclusionESR and Anti-Scl-70 positivity serve as modest but highly specific independent indicators of lung involvement in dcSSc. While Anti-Scl-70 provides significant etiological stratification, ESR's high specificity makes it a valuable, cost-effective preliminary triage tool for identifying patients at higher risk for ILD.