Psoriasis severity matters when dealing with all-cause mortality in psoriasis patients: a record linkage analysis in Northern Italy

Psoriasis has been linked with several comorbidities and increased all-cause mortality compared with the general population. Data are still limited concerning mortality especially from Southern European countries. Between January 2012 and December 2018, we conducted a retrospective cohort study on psoriasis patients and population controls in Northern Italy. Through record linkage of health-care databases, psoriasis cases were identified, and their morbidity and mortality were compared with the general population. The Charlson index was used as an index of comorbidities. Standardized mortality ratios (SMR) were estimated for overall psoriasis cases and for patients with mild vs moderate-to-severe disease, separately. We identified 12,693 psoriasis patients (mean age: 60.8 ± 16.3 years). They had a significantly higher Charlson index compared with the general population (p < 0.001). In spite of the higher rate of comorbidities, age-specific SMR was not increased in the psoriasis population as a whole (1.04 (95% CI 0.89–1.20)) or in people with mild psoriasis. However, a 40% higher than the expected risk of all-cause mortality was documented in individuals with moderate-to-severe psoriasis (SMR: 1.41; 95% CI 1.12–1.75). Notably, an excess mortality in these patients occurred as early as age 40-49 years. The proportion of deaths from malignancies and cardiovascular diseases was remarkably high. Our results support the notion that psoriasis severity influences mortality and indicate that patients with psoriasis, especially those with severe disease, should receive appropriate screening and health education.