Validation and prognostic utility of SLERPI in a single-centre retrospective Central European cohort

Objectives To evaluate the diagnostic performance of the SLE Risk Probability Index (SLERPI) in a European cohort and explore its potential prognostic utility for early flare risk stratification. Methods This retrospective study included 280 patients with physician-diagnosed SLE and 156 non-SLE controls from a tertiary centre. Diagnostic performance (sensitivity, specificity, and area under the curve [AUC]) of the SLERPI and the 2019 European League Against Rheumatism (EULAR)/American College of Rheumatology (ACR) classification criteria were assessed against physician diagnosis as the reference standard. Severe flares within 3 years of diagnosis were defined using the SELENA-SLEDAI Flare Index. Multivariable logistic regression was used to identify predictors of severe flare. Results SLERPI demonstrated a higher AUC than the 2019 EULAR/ACR criteria (0.967, 95% CI 0.950–0.984 vs 0.932, 95% CI 0.908–0.957; DeLong p = 0.0004) and greater specificity (97.4% vs 94.9%), whereas sensitivity (85.7% vs 87.1%) and negative predictive value (79.2% vs 80.4%) were slightly lower. Analysis of discordant classifications revealed that the SLERPI captured cutaneous-predominant presentations more effectively, while the EULAR/ACR criteria showed greater sensitivity for serositis-driven disease. Patients who developed a severe flare within 3 years had significantly higher baseline SLERPI scores ( p = 0.047). Youden’s J statistic identified a threshold of ≥10.2 points as potentially informative for severe flare risk stratification. In multivariable analysis, a model incorporating SLERPI constituent items identified proteinuria and serositis at diagnosis as independent predictors of severe flare (AUC 0.708, 95% CI 0.641-0.775); bootstrap internal validation yielded a lower, optimism-corrected AUC of 0.635 (95% CI 0.574-0.695). Conclusion SLERPI demonstrates high diagnostic accuracy in a single-centre retrospective Central European cohort. Exploratory analyses suggest that higher baseline SLERPI scores may be associated with an increased risk of early severe flares; however, these findings require external validation before prognostic use can be recommended.