Background: Multiple comorbidities, including rheumatoid arthritis (RA), have been reported to be associated with psoriasis. Objective: This study aimed to determine the prevalence and the clinical features of RA among patients with psoriasis in a tertiary referral center. Methods: Between January 2000 and December 2013, all patients coded with psoriatic disease (ICD-9 CM 696.0 OR ICD-9 CM696.1) and RA (ICD-9 CM 714.0) in a tertiary medical center were enrolled. Results: There were 10,844 patients and 9073 patients with psoriatic disease and RA identified by diagnostic codes, respectively. Among patients with psoriasis, 111 patients had claim-based diagnosis of RA (1.02%). By reviewing medical records and telephone interview or clinic visits, 25 of the 111 patients (0.23%) was identified unequivocally as having concurrent RA. Among them, 17 (68%) were female and 16 (64%) patients developed arthritis prior to the onset of psoriasis with a mean lag of 6.3 years (1–19 years); 8 (32%) had psoriasis skin lesions prior to the onset of arthritis with a mean lag of 6.9 years (3–20 years); 1 (4%) had skin lesions and arthritis in the same time; 17 (68%) patients also fulfilled the CASPAR classification criteria for psoriatic arthritis. The mean age of onset for arthritis was 49.6 years old. Conclusions: The prevalence of RA in psoriasis might be overestimated in some previous studies using claimed database. Patients with concurrent RA and psoriasis showed a comparable age of onset and male to female ratio, but had more axial involvements compared to patients without psoriasis.
Prevalence, clinical features and treatment pattern of patients with concurrent diagnoses of rheumatoid arthritis and psoriatic disease: results of a 14-year retrospective study in a tertiary referral center
