Psoriasis and hidradenitis suppurativa: A large-scale population-based study.

Background: The coexistence of psoriasis and hidradenitis suppurativa (HS) has been described, but the association between these conditions is yet to be firmly established.

Objective: To study the association between psoriasis and HS by using a large-scale real-life computerized database.

Methods: A cross-sectional study was conducted to compare the prevalence of HS among patients with psoriasis with that among age-, sex- and ethnicity-matched control subjects.

Results: A total of 68,836 patients with psoriasis and 68,836 controls were included in the study. The prevalence of HS was increased in patients with psoriasis versus in those in the control group (0.3% vs 0.2%, respectively; odds ratio, 1.8; 95% confidence interval, 1.5-2.3; P < .001). In a multivariate analysis adjusting for smoking, obesity, and other comorbidities, psoriasis was still associated with HS (odds ratio, 1.8; 95% confidence interval, 1.4-2.2; P < .001). Patients with coexistent psoriasis and HS were significantly younger (39.0 ± 15.7 vs 42.6 ± 21.2 years [P = .015]) and had a higher prevalence of obesity (35.1% vs 25.3% [P = .001]) and smoking (58.5% vs 37.3% [P < .001]) compared with patients with psoriasis alone.

Limitations: Retrospective data collection.

Conclusions: A positive association was observed between HS and psoriasis. Further longitudinal observational studies are necessary to establish these findings in other study populations.