Waist circumference provides improved cardiometabolic discrimination compared with body mass index in psoriatic disease: discrimination and reclassification analyses

Background Patients with psoriatic disease present a distinctive metabolic phenotype, yet the optimal anthropometric marker to capture cardiometabolic risk remains unclear. We evaluated whether waist circumference provides superior cardiometabolic discrimination and reclassification compared with BMI in psoriatic disease.Methods In this cross-sectional study, we assessed consecutive patients with psoriasis and/or psoriatic arthritis (n = 572). The primary outcome was clustered cardiometabolic burden (≥2 predefined cardiometabolic abnormalities). Waist circumference and BMI were compared using principal component analysis (PCA), ROC curves, Youden-derived sex-specific thresholds, and both categorical and continuous reclassification metrics (NRI and IDI), overall and stratified by sex. Additional sensitivity analyses used standard metabolic cutoffs (ATP III/IDF).Results Waist circumference and BMI showed the highest loadings on the first principal component representing the cardiometabolic axis, with a slightly higher contribution from waist circumference (loading 0.864 vs 0.826). Waist circumference showed modest but statistically significant improvement in discrimination compared with BMI for clustered cardiometabolic abnormalities (AUC 0.78 vs 0.73 for ≥2 factors, DeLong p = 0.003; AUC 0.78 vs 0.71 for ≥3 factors, DeLong p < 0.001). Waist circumference-derived thresholds provided incremental risk stratification beyond BMI, with consistent improvements in reclassification metrics across cardiometabolic burden definitions. Youden-derived thresholds (100 cm in men and 99 cm in women) showed better balance between sensitivity and specificity than ATP III and IDF criteria, while maintaining clinically relevant likelihood ratios. Sensitivity analyses incorporating waist-to-height ratio showed similar findings without additional benefit over waist circumference alone.Conclusion Waist circumference provided consistently better overall cardiometabolic discrimination than BMI and may represent a more informative anthropometric marker for cardiometabolic risk assessment in psoriatic disease.