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

Abstract

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.

Keywords: Psoriasis; Psoriatic arthritis; Review; Skin manifestations.

Fig. 1

Flowchart. A literature search was conducted to identify original articles that reported psoriasis severity in patients with psoriasis and PsA. PubMed and Embase were searched on 11 February 2021. A combination of synonym terms in title/abstract and MesH/Emtree terms for “psoriasis,” “psoriatic arthritis,” “severity,” “PASI,” and “BSA” was used (online suppl. Table S1). In total, 3,032 articles were identified. Duplicates were removed and 2,000 articles were screened on title and abstract based on predefined eligibility criteria. Consequently, 90 selected articles were screened full-text for relevancy to be included in the analysis. The search was supplemented with 13 articles by Rouzaud et al. [9] and 2 articles via related citations in PubMed and reference citations of the identified articles in the initial search. In total, 29 studies were included in the qualitative analyses. These studies reported the following outcome measures for skin disease severity: PASI (n = 17), PASI and BSA (n = 2), BSA (n = 8) and number of affected sites (n = 2). We included 13, 4, and 0 of these studies in the quantitative analyses, respectively.

Fig. 2

Meta-analysis: psoriasis severity in PsO-PsA and PsA patients Forrest plots of studies that measure psoriasis severity as PASI (a) or BSA (b) and compare mean values between PsO-PsA and PsA patients. BSA, body surface area; CI, confidence interval; PASI, psoriasis area and severity index; PsA, psoriatic arthritis; Pso-PsA, psoriasis without psoriatic arthritis; SD, standard deviation.