Self-reported prevalence of psoriasis and evaluation of the impact on the natural history of hip osteoarthritis: results of a 10 years follow-up study of 507 patients (ECHODIAH study).

Objective: The objective of the present study was to assess the frequency of self-reported psoriasis in a hip osteoarthritis (OA) cohort, and a secondary objective was to assess the course of hip OA with psoriasis.

Methods: ECHODIAH was a 3-year, randomised double-blind controlled trial evaluating diacerein vs. placebo in hip OA. During the 36 months of the trial, the Lequesne algofunctional index and pain visual analog scale (VAS) and joint space width (JSW) were assessed every 3 months. From month 36 to 120, the requirement for total hip replacement (THR) was collected annually via a phone call. At the end of 10 years of follow-up, the prevalence of self-reported psoriasis, family psoriasis was assessed by letter, retrospectively--(retrolective design).

Results: Of the 507 ECHODIAH patients, 279 were followed-up 10 years; 192 (68.8%) answered the psoriasis questionnaire. Twenty-two (11.4%) of 192 patients had self-reported psoriasis. Eighteen patients (9.4%) had family history of psoriasis. Eleven (50%) of 22 patients were diagnosed by a dermatologist. Baseline characteristics were similar between responders and non-responders, and between psoriasis and no psoriasis patients. The disease course was not different according to the presence of psoriasis, though total hip replacement was more frequent with psoriasis (77.2% after 10 years) than without (58.8%), no statistical difference (p=0.10).

Conclusion: The prevalence of self-reported psoriasis was high in this cohort, almost twice the frequency reported in the general population. The disease course was not modified by the presence of psoriasis. These data should be further confirmed.