Psoriasis: Joint Inflammation, Pain May Predict PsA

Janis C. Kelly

March 02, 2016

Subtle signs of joint involvement detectable using magnetic resonance imaging (MRI) of the hand helped identify a subset of patients with psoriasis who were at high risk of developing psoriatic arthritis (PsA), researchers report in an article published online February 25 in the Annals of the Rheumatic Diseases.

"These findings suggest that subclinical musculoskeletal disease affects a substantial proportion of patients with psoriasis. Together with arthralgia these changes predict the risk for the onset of PsA," write Francesca Faustini, MD, from the Department of Internal Medicine, University of Erlangen-Nuremberg, Erlangen, Germany, and colleagues.

The results also "indicate the possibility to define patients with psoriasis, in which preventive treatment for the development of PsA may be feasible," the researchers add.

Dr Faustini and colleagues examined 55 patients with psoriasis and 30 healthy control patients, using high-field MRI of the dominant hand for synovitis, osteitis, tenosynovitis, and periarticular inflammation, scored using the PsA MRI scoring system. Patients with psoriasis were also examined for erosions and enthesiophytes by high-resolution peripheral quantitative computed tomography.

None of the patients with psoriasis or the healthy controls had arthritis at study entry. Patients with psoriasis were monitored for at least 1 year for development of PsA, defined using the Classification of Psoriatic Arthritis criteria.

The researchers found that 47.3% of the patients with psoriasis had at least one subclinical inflammatory lesion vs 13.3% of the healthy control patients (P = .002). The patients with psoriasis most commonly had synovitis (21 patients; 38.2%), osteitis (6 patients; 10.9%), flexor tendon tenosynovitis (2 patients; 3.6%), or periarticular inflammation (2 patients; 3.6%).

One-year follow-up data were available for 41 of the patients with psoriasis, 12 (29.6%) of whom had developed PsA. The two strongest predictive factors for progression to PsA were MRI synovitis and joint pain.

Patients with psoriasis who later developed PsA also had more pain, more joint tenderness, a higher visual analogue scale global health disease burden, and more compromised physical function at baseline than patients with psoriasis who did not develop PsA.

Notably, MRI differences alone were not sufficient to differentiate between patients with psoriasis who would or would not develop PsA. That required combining MRI with clinical symptoms. The authors write, "Patients with psoriasis with MRI synovitis and symptoms related to arthralgia had 55.5% likelihood to develop PSA within 1 year. In contrast, only 15.3% of patients with psoriasis without signs of synovitis or arthralgia progressed to PsA." Active smoking and older age were also associated with greater risk for PsA.

The researchers acknowledge being surprised that one third of patients with cutaneous psoriasis had subclinical inflammatory changes in the hand, as patients with clinical signs of inflammatory joint disease were excluded from the study at baseline. They also emphasize that the presence of inflammatory lesions on MRI does not prove that the cutaneous psoriasis caused those lesions, and that neither the duration nor the severity of cutaneous psoriasis was associated with the presence of MRI lesions.

Despite the assumption that scalp or nail involvement are predictors of PsA risk, neither was associated with greater MRI inflammation, suggesting that skin and joint inflammation might not be tightly linked.

"Our longitudinal analysis showed that subclinical inflammation appears to substantially influence the risk of patients with psoriasis to progress to PsA. This transition to PsA is considered being a critical step in defining the onset of musculoskeletal disease in patients with psoriasis and to shape early interventions," the study authors conclude.

The study was supported by the Deutsche Forschungsgemeinschaft, the Marie Curie project OSTEOIMMUNE, the Metarthros project of the German Ministry of Science and Education, the IMI-funded project BTCure, and the Pfizer Competitive Grant Award Germany. The authors have disclosed no relevant financial relationships.

Ann Rheum Dis. Published online 25 February 2016. Abstract

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