OBJECTIVES: To document the incidence, economic burden and all-cause mortality associated with generalized pustular psoriasis (GPP) management in Canadian hospitals, emergency departments (ED) and hospital-/community-based outpatient clinics, and to compare with plaque psoriasis (PP)

METHODS: Adult Canadians (excluding Quebec) hospitalized or visiting an ED or hospital-/community-based outpatient clinic with a most responsible diagnosis (MRD) code indicating GPP (i.e., ICD-10-CA L40.1) or PP (ICD10-CA L40.9 or L40.0) were included. Incident cases were defined as having a GPP/PP MRD code for the 5 fiscal years (April 1, 2012 to March 31, 2017) without any GPP/PPP MRD code in the 5 previous years (April 1, 2007 to March 31, 2012) allowing every case to have 3-year follow-up data (up to March 31, 2020). Patient characteristics and 3-year MRD costs as well as inpatient all-cause mortality were documented. Multivariable regressions were used for comparing costs and all-cause inpatient mortality between GPP and PP. Sensitivity analyses were conducted considering all inpatient resource use associated independent of the presence of a GPP/PP diagnostic code in the administrative records (i.e., all-cause costs).

RESULTS: Over the 5-year period, 212 incident cases of GPP (5-year incidence rate: 1.95/1,000,000) and 5,979 incident cases of PP (5-year incidence rate: 54.93/1,000,000) were identified. Compared with PP patients, GPP patients were older (mean age [standard deviation] of 52.3 [15.6] years versus 48.3 [17.3years, p<0.01) and mostly female (57.5% versus 45.3%; p<0.01). Over the 3-year period following the incident index date, MRD mean (SD) costs were $3,477 ($14,979) for GPP and $503 ($2,267) for PP (p<0.01). Three-year inpatient all-cause mortality rates were 5.2% for GPP and 2.1% for PP (p=0.03). Three-year all-cause mean (SD) costs were $17,665 ($49,219) for GPP and $10,109 ($30,212) for PP (p<0.01).

CONCLUSIONS: The burden of GPP is significant. GPP patients incurred significantly higher costs and mortality than PP patients.