Supplementary Material for: Distinct Mortality Risks in Generalized Pustular Psoriasis and Palmoplantar Pustulosis: A Nationwide, Population-based, Cohort Study

Introduction: The differences in all-cause and cause-specific mortality among patients with generalized pustular psoriasis (GPP), palmoplantar pustulosis (PPP), and psoriasis vulgaris (PV) are not well understood. The aim of our study was to compare all-cause and cause-specific mortality in patients with GPP, PPP, and PV.
Methods: We conducted a nationwide, retrospective cohort study using data from the Korean National Health Insurance Service and National Death Registry between 2002 and 2022. Patients with GPP, PPP, and PV aged ≥18 years were identified based on ≥3 visits with principal diagnosis codes. Baseline characteristics, including demographics, general health data, socioeconomic status, and comorbidity profiles, were balanced using inverse probability weighting. Participants were followed-up from the index date until the occurrence of death, emigration, or the end of the observation period to investigate all-cause and cause-specific mortality.
Results: Multivariate regression analysis showed that patients with GPP had significantly higher all-cause mortality than those with PV (adjusted hazard ratio [aHR], 1.23; 95% confidence interval [CI], 1.20–1.25), while patients with PPP had lower all-cause mortality (aHR, 0.89; 95% CI, 0.87–0.91). GPP was associated with higher cause-specific mortality, particularly from hematologic (aHR, 1.76; 95% CI, 1.27–2.44) and respiratory diseases (aHR, 1.37; 95% CI, 1.30–1.46), whereas PPP patients had lower mortality from gastrointestinal (aHR, 0.57; 95% CI, 0.52–0.63) and infectious diseases (aHR, 0.71; 95% CI, 0.63–0.80). Subgroup and sensitivity analyses confirmed these findings.
Conclusions: GPP is associated with higher all-cause and cause-specific mortality than PV, while PPP is linked to lower mortality, indicating potential epidemiological and biological differences among these subtypes.