People with cutaneous psoriasis who have arthralgia and signs of subclinical inflammation on MRI are at an increased risk of progressing to psoriatic arthritis, according to findings from a cross-sectional, longitudinal study.
First author Dr. Francesca Faustini of the University of Erlangen-Nuremberg, Erlangen, Germany, and her colleagues said the fact that psoriatic skin disease has a higher prevalence than arthritis raises the question whether patients with psoriasis without psoriatic arthritis (PsA) are spared from joint inflammation or whether mild changes, which escape physical examination, can be found in some patients (Ann Rheum Dis. 2016 Feb. 25. doi: 10.1136/annrheumdis-2015-208821).
Research published last year by the researchers shed some light on this by showing that psoriasis patients without PsA exhibit enthesiophytes as the result of pathological bone formation in the joint (Ann Rheum Dis. 2015 Feb 4. doi: 10.1136/annrheumdis-2014-206347).
“The presence of similar changes in patients with psoriasis strongly supports the hypothesis of subclinical joint pathology that antedates the clinical onset of PsA,” they said. The current study help to build on that finding by examining the extent to which inflammatory changes in the joints precede the onset of PsA, how such changes are related to structural pathology, and whether they influence the progression of psoriasis to PsA.
Dr. Faustini and her colleagues studied 55 patients with psoriasis who were attending a dermatology clinic and 30 healthy controls who underwent MRI of the hand and were scored for synovitis, osteitis, tenosynovitis, and periarticular inflammation. Patients with psoriasis also received a clinical investigation, high-resolution CT for detecting erosions and enthesiophytes, and were followed up for at least 1 year for the development of PsA.
Results showed that almost half of the patients with psoriasis (47%) had a least one inflammatory lesion shown on MRI.
Synovitis was the most prevalent inflammatory lesion (38%), while osteitis (11%), tenosynovitis (4%) and periarticular inflammation (4%) were less frequent.
Based on the PsA MRI scoring (PsAMRIS) system in patients with MRI lesions, the extent of inflammation was scored 3.0 units for synovitis, 1.8 for osteitis, 10.5 for tenosynovitis, and 3.0 for periarticular inflammation. Synovitis was deemed moderate (PsAMRIS of 2) in five joints and mild (score of 1) in all others where it was present; none of the joints scored 3 (severe).
Enthesiophytes and bone erosions were not different between patients with psoriasis with or without inflammatory MRI changes.
Among 41 patients who completed a follow-up examination a mean of about 14 months after the first, the risk for developing PsA at 1 year was as high as 56% if patients had subclinical synovitis and symptoms related to arthralgia (at least one tender joint), but was as low as 15% if patients had normal MRIs and did not report arthralgia. A total of 12 (30%) developed PsA according to CASPAR criteria.
“Subclinical inflammation appears to substantially influence the risk of patients with psoriasis to progress to PsA ... these findings indicate the possibility to define patients with psoriasis, in which preventive treatment for the development of PsA may be feasible,” they concluded.
However, they noted that it was important to consider that the presence of inflammatory lesions does not necessarily indicate that cutaneous psoriasis is causally linked to such lesions, particularly because neither disease activity and duration nor scalp and nail involvement was associated with MRI lesions.
“These findings suggest that skin and joint inflammation occur uncoupled and that skin disease may not represent the key pacemaker for joint inflammation,” they said.
The study received funding from the German Research Foundation, the Marie Curie project OSTEOIMMUNE, the German Ministry of Science and Education, the Innovative Medicines Initiative, and the Pfizer Competitive Grant Award Germany. The authors declared no conflicts of interest.