A large-scale retrospective study in China explores risk factors for disease severity in plaque psoriasis

Severe psoriasis has a long course and poor outcome, and it has long been a problem for patients. Understanding the independent risk factors that contribute to patients with severe psoriasis is critical for the development of effective treatment strategies. This large, multicenter study recruited 2,109 plaque psoriasis patients from 12 hospitals across China (October 31, 2019 – May 31, 2022). The logistic regression model underwent internal validation and external validation using two independent cohorts over future time periods (June 1, 2022 – January 31, 2023). The discriminative power of our model was substantiated by a C-index of 0.863 (95% CI: 0.848–0.879) in internal validation, further affirmed through 1,000 bootstrap validation (C-index: 0.860, 95% CI: 0.836–0.885) and external validation cohorts, where the C-index reached up to 0.910 (95% CI: 0.868–0.953) and 0.951 (95% CI: 0.924–0.977) in 2 external validation cohorts. To enhance accessibility for clinicians, the model has been made available as a dynamic nomogram and QR code. Our study identified 10 risk factors (the "DELPHI" consensus dichotomy, the DLQI index, the extent of skin involvement as measured by body surface area, the age of the patient at the time of clinical visit, sex, body weight in kilograms, career, the presence of scalp involvement, facial involvement, and arthropathy) for the overall severity of psoriasis (PASI ≥ 10). "Nomogram-10" provides clinicians with a practical tool to develop personalized intervention strategies based on an individual's risk profile. Trial registration: Chinese Clinical Trial Registry: ChiCTR1900024852.