Do Patients with Psoriatic Arthritis Have More Severe Skin Disease than Patients with Psoriasis Only? A Systematic Review and Meta-Analysis

BACKGROUND: Early identification of patients at risk of psoriatic arthritis (PsA) is essential to facilitate early diagnosis and improve clinical outcomes. Severe cutaneous psoriasis has been proposed to be associated with PsA, but a recent assessment of the evidence is lacking. Therefore, in this systematic review, we address the association of psoriasis skin severity with the presence and development of PsA. SUMMARY: We included articles from a review published in 2014 and supplemented these with recent literature by performing an additional systematic search to identify studies published between 1 January 2013 and 11 February 2021. A meta-analysis was performed when sufficient comparable evidence was available. Of 2,000 screened articles, we included 29 in the analysis, of which 16 were identified by our updated search. Nineteen studies reported psoriasis severity as psoriasis area and severity index (PASI), ten studies as body surface area (BSA), and two studies as “number of affected sites.” Most studies show that more extensive skin disease is associated with the presence of PsA. The quantitative pooled analyses demonstrate higher PASI (mean difference [Δ] 1.59; 95% confidence interval [CI] 0.29–2.89) and higher BSA (Δ 5.31; 95% CI 1.78–8.83) in patients with PsA as compared to psoriasis patients without PsA. Results from prospective studies − that assess the risk of future development of PsA in psoriasis patients − were inconclusive. KEY MESSAGES: In patients with psoriasis, more severe skin involvement is associated with the presence of PsA, underpinning the importance of optimal dermatology-rheumatology collaboration in clinical care. There are insufficient data to support the use of psoriasis skin severity to predict the future development of PsA in psoriasis patients.