Comorbidities in patients with palmoplantar plaque psoriasis

Background Psoriasis has been shown to be associated with several comorbidities. Whether the palmoplantar subtype of plaque psoriasis carries similar risks for comorbidities as generalized plaque psoriasis remains to be defined. Objective To examine the association between palmoplantar plaque psoriasis and comorbidities known to be associated with generalized plaque psoriasis. Methods We retrospectively compared the prevalence of comorbidities previously found to be associated with generalized plaque psoriasis among 163 patients with palmoplantar plaque psoriasis who had been treated with topical psoralen and ultraviolet A from 2009 to 2017 and a cohort of 781 control individuals. Each patient with psoriasis was matched according to sex and age (±1 year) with up to 5 control individuals. Conditional logistic regression was used to evaluate the associations after matching. Results Diabetes mellitus (odds ratio [OR], 2.296), cardiovascular disease (OR, 1.797), and most remarkably, mood disorders (OR, 6.232) were significantly associated with palmoplantar plaque psoriasis. Dyslipidemia, hypertension, and psoriatic arthritis were more frequent among patients with palmoplantar plaque psoriasis, but those associations did not reach statistical significance. Limitations The retrospective nature of this study, the fact that some data were collected through a survey questionnaire, and the relatively small sample size suggest the need to validate the present data in a prospective manner. Additionally, within the psoriasis group, patients were assessed for the presence of comorbidities during the whole follow-up period, whereas the comorbidities of individuals in the control group were assessed during a baseline visit. Conclusions Several comorbidities known to be associated with psoriasis vulgaris were also found to be prevalent in a series of patients with plaque palmoplantar psoriasis. Individuals affected with plaque palmoplantar psoriasis showed a particularly high risk for mood disorders.