Key Risk Factors Identified for Psoriasis Transforming Into Psoriatic Arthritis

Individuals with psoriasis (PsO) are at greater risk for psoriatic arthritis (PsA) if they report nail involvement, are aged ≥40 years, have high-sensitivity C-reactive protein (hs-CRP), or have an elevated erythrocyte sedimentation rate (ESR), according to new findings on independent risk factors.¹

These findings resulted from research led by Amin Yao, from the department of dermatology at the Third Affiliated Hospital of Sun Yat-sen University in Guangzhou, China. Yao and colleagues commented on the recent implementation of non-invasive magnetic resonance imaging (MRI) for evaluating inflammatory arthritis, noting that the European League Against Rheumatism (EULAR) also recommends the use of MRI for other joint issues.²

“MRI is increasingly employed to evaluate and detect rheumatoid arthritis (RA) and other inflammatory joint diseases,” Yao and colleagues wrote. “This study attempted to identify the possible risk factors for the transformation of PsO into clinical PsA and explore the clinical value of MRI in detecting PsA early.”

Background and Methods

The investigators used a retrospective, longitudinal case–control study design in which they separated their participants into a case group and a control group. These individuals had been patients in the period between January 2017 - December 2021 at the department of dermatology at Beijing Chaoyang Hospital.

Those who met the research team’s specified criteria for inclusion had been given a first clinical diagnosis of psoriasis. The team’s case cohort was made up of 75 subjects who had been diagnosed with psoriatic arthritis, and the remaining 345 individuals with psoriasis made up the control arm. The team reviewed both cohorts retrospectively from their initial psoriasis vulgaris diagnosis.

The CASPAR criteria were implemented for diagnosis of psoriatic arthritis, with a score ≥3 in 5 categories being necessary for qualification: psoriatic nail dystrophy, evidence of psoriasis (current or familial), a negative rheumatoid factor (RF) test, dactylitis, and radiographic juxta-articular new bone formation. The investigators used a diagnosis by experienced dermatologists as their standard, having any contentious cases assessed by a panel of 3 experts.

Criteria for inclusion in the study were being within the age range of 18-65, having a confirmed PsO/PsA diagnosis, informed consent having been signed, and a peripheral joint MRI. The team had several criteria for trial exclusion, some of which included having related arthritic issues, having erythrodermic or pustular psoriasis, malignancies, and others.

The investigators would collect baseline covariates from the subjects’ data. Their analyses—including univariate, multivariate, receiver operating characteristic curves—were carried out to better understand the associated risk factors and evaluate the necessity of psoriasis patient imaging.

Findings

The research team’s multivariate logistic regression analysis showed that there were major links between various factors connecting psoriasis to PsA. Some of these were found by the team to be nail involvement (odds ratio (OR): 1.17, 95% confidence interval (CI): 1.09–1.32, P < .01), increased hs-CRP levels (OR: 1.31, 95% CI: 1.13–1.53, P < .01), being aged ≥40 years (OR: 1.04, 95% CI: 1.02–1.06, P < .01), and ESR (OR: 1.03, 95% CI: 1.01–1.06, P < .05).

Additionally, the investigators reported that the combination of MRI-detected enthesitis with tenosynovitis as predictive elements indicated strong diagnostic accuracy, with specificity being particularly high (94.3% versus 69%, respectively). There was also a notably similar sensitivity (89% versus 84.6%, respectively).

The research team also noted that the areas under the ROC curve (AUCs) had been substantially high at 0.925 (95% CI: 0.882–0.967, P < .01) as well as 0.858 (95% CI: 0.814–0.903, P < .01). This suggested there was robust predictive capability.

“First, this retrospective study has inherent limitations, such as underlying selection and information biases,” they wrote. “Second, this study only examined patients' peripheral joints. Thus, these findings may not be applicable to PsO patients with exclusively axial involvement. Third, the conclusions from this single-center study still require external validation.”

References

1. ^{Yao, A., Wang, L., Qi, F., Li, J., Meng, J., Jiang, T., He, Y. and Lai, W. (2024), Risk factors and early detection of joint damage in patients with psoriasis: a case–control study. Int J Dermatol. https://doi.org/10.1111/ijd.17212.}
2. ^{Mandl P, Navarro-Compán V, Terslev L, Aegerter P, van der Heijde D, D'Agostino MA, et al. EULAR recommendations for the use of imaging in the diagnosis and management of spondyloarthritis in clinical practice. Ann Rheum Dis. 2015; 74(7): 1327–1339.}