Real-world evidence on palmoplantar pustulosis: Patient characteristics, diagnostic challenges and predictive factors for treatment survival – a retrospective registry study

Introduction Little is known about the clinical characteristics, delay in diagnosis and treatment survival in patients with palmoplantar pustulosis (PPP). Methods This is a retrospective study using data from the Psoriasis Registry Austria (PsoRA). Results This study included data from 190 patients, who underwent 397 treatments. A substantial proportion of patients (53.6%) were initially misdiagnosed as having eczema with a mean (standard deviation) diagnostic delay of 2.8 years (4.8). Patients were predominantly female (74.2%) and smokers (77.6%). Patients were treated with biologics (49.9%), phototherapy (25.2) and conventional systemic therapies (24.9%). The median survival time (95% confidence interval) for all treatments was 0.6 years (0.5–0.8), with ustekinumab having the longest median survival time of 2.7 years (2.3 – upper limit not reached), surpassing all other therapies. However, this superiority disappeared after IL-23p19 inhibitors were introduced in Austria. Compared to biologics, conventional systemic treatments (hazard ratio [HR] 2.17, p < 0.001) and phototherapy (HR 4.43, p < 0.001) were associated with a significantly higher risk of treatment discontinuation. In the overall cohort, disease duration of ≥ 2 to < 10 years (HR 0.66, p = 0.049) and ≥ 10 years (HR 0.59, p = 0.004) significantly reduced the risk of treatment discontinuation, while concomitant plaque psoriasis significantly increased the risk for treatment discontinuation (HR 1.43, p = 0.049). In the biologic cohort, concomitant arthritis (HR 2.11, p = 0.002) and the presence of one comorbid disease (HR 2.34, p = 0.026) increased the risk for treatment discontinuation. Furthermore, gender, age at disease onset and smoking did not influence the risk of treatment discontinuation. Conclusion The findings of this cohort suggest that more than half of patients experienced a diagnostic delay of several years due to an initial misdiagnosis. Among all therapies, the IL-12/23p40 inhibitor ustekinumab showed the longest treatment survival. However, its superiority diminished with the introduction of IL-23p19 inhibitors. Finally, shorter disease duration and concomitant plaque psoriasis was identified as a general risk factor for treatment discontinuation, while the presence of comorbidity and presence of concomitant psoriatic arthritis were identified as risk factors for discontinuation of biologic treatment.