There is controversy about the severity of peripheral psoriatic arthritis (PsA) compared to rheumatoid arthritis (RA). Early reports found PsA to be a milder disorder, excepting the mutilans form. Recent reports suggest that PsA can be as severe as RA. We compared severity, disability, and quality of life in patients with PsA and RA matched primarily for disease duration.
Data relating to the extent and severity of disease were recorded in a hospital clinic setting. Recent radiographs of hands and feet were read blinded to diagnosis, and information on function and quality of life was collected with the Health Assessment Questionnaire (HAQ) and EuroQol-5D, respectively.
Forty-seven patients were matched for disease duration (median PsA 5 yrs, RA 7 yrs). The male/female ratio was 24/23 for PsA, 16/31 for RA, and median ages were 45 and 51 years, respectively. Patients with RA had significantly more joint involvement of metacarpophalangeal joints and wrists, whereas distal interphalangeal joints, spine, sternoclavicular joints, and sacroiliac joints were significantly more involved in PsA. No difference was found regarding Ritchie Articular Index, inflammatory markers, HAQ score, or EuroQol-5D. Patients with RA had significantly more damage on radiographs of hands and feet: median (range) Larsen score hands PsA 8 (0-91), RA 38 (0-125); feet PsA 4 (0-34), RA 11(0-56). Patients with RA were taking significantly more disease modifying drugs.
Peripheral joint damage is significantly greater in RA than in PsA after equivalent disease duration, but function and quality of life scores are the same for both groups. The additional burden of skin disease in PsA may account for this.