Clinical characteristics and heterogeneity of generalized pustular psoriasis: A comparative study in a large retrospective cohort.

Generalized pustular psoriasis (GPP) is a rare and potentially life-threatening skin disease and the clinical heterogeneity of which is largely unknown. Retrospective cohort analysis was conducted on hospitalized GPP patients between January 2010 and November 2022. A total of 416 patients with GPP and psoriasis vulgaris (PV) respectively were included, matched 1:1 by sex and age. The heterogeneity of GPP was stratified by PV history and age. Compared with PV, GPP was significantly associated with prolonged hospitalization (11.7 vs. 10.3 day, p < 0.001), elevated neutrophil lymphocyte ratio (NLR) (5.93 vs. 2.44, p < 0.001) and anemia (13.9% vs. 1.2%, p < 0.001). Moreover, GPP alone (without PV history) was a relatively severer subtype with higher temperature (37.6°C vs. 38.0°C, p = 0.002) and skin infections (5.2% vs. 11.4%, p = 0.019) than GPP with PV. For patients across different age, compared with juvenile patients, clinical features support a severer phenotype in middle-aged, including higher incidence of anaemia (7.5% vs. 16.0%, p = 0.023) and NLR score (3.83 vs. 6.88, p < 0.001). Interleukin-6 (r = 0.59), high density lipoprotein cholesterol (r = -0.56), albumin (r = -0.53) and C-reactive protein-to-albumin ratio (r = 0.49) were the most relevant markers of severity in GPP alone, GPP with PV, juvenile and middle-aged GPP, respectively. This retrospective cohort suggests that GPP is highly heterogeneous and GPP alone and middle-aged GPP exhibit severe disease phenotypes. More attention on the heterogeneity of this severe disease is warranted to meet the unmet needs and promote the individualized management of GPP.