Pattern of bone erosion and bone proliferation in psoriatic arthritis hands: a high-resolution computed tomography and radiography follow-up study during adalimumab therapy.

OBJECTIVES: To investigate the pattern and development of bone erosion and proliferation in patients with psoriatic arthritis (PsA) during treatment with adalimumab, using high-resolution computed tomography (CT) and conventional radiography. METHOD: Forty-one biologic-naïve PsA patients were initiated with adalimumab 40 mg subcutaneously every other week. CT and radiography of the 2nd-5th metacarpophalangeal (MCP), proximal interphalangeal (PIP), and distal interphalangeal (DIP) joints were conducted at baseline (n = 41) and after 24 weeks (n = 32). Changes in bone erosion and proliferation are described and the imaging modalities compared. RESULTS: Ninety percent of bone erosions detected by CT were located in the metacarpal heads, and most frequently in the 2nd-3rd MCP joints. Radial (37%) and ulnar (31%) surfaces were more frequently eroded than dorsal (10%) and palmar (22%) sites. Using CT, bone proliferations were located primarily on the sides of the distal part of the DIP joints (43% of all proliferations), but also proximally in DIP (17%) and MCP joints (27%). For bone erosions and proliferations, respectively, radiography showed a low sensitivity (17% and 26%), but a high specificity (98% and 95%) and accuracy (93% and 87%), with CT as the gold standard reference. Neither CT nor radiography revealed statistically significant changes in bone erosion or proliferation scores between baseline and follow-up. CONCLUSIONS: Patterns of bone erosion and proliferation in PsA hands were revealed in more detail by CT than by radiography. No overall progression or repair could be detected during adalimumab treatment with either of the methods.

Plasma YKL-40: a potential biomarker for psoriatic arthritis?

BACKGROUND: Plasma YKL-40 is an inflammatory biomarker. No useful biomarker exists in patients with psoriasis or psoriatic arthritis. OBJECTIVE: To measure YKL-40 and high-sensitivity C-reactive protein (hs-CRP) in patients with psoriasis or psoriatic arthritis before and during treatment. METHODS: In 48 patients with psoriasis, we measured YKL-40, hs-CRP and Psoriasis Area and Severity Index (PASI) at inclusion and in a subgroup of 14 patients, we repeated the measurements after four to six weeks of methotrexate treatment. In 42 patients with psoriatic arthritis, we measured YKL-40 and hs-CRP at inclusion and during 48 weeks of adalimumab treatment. The patients with psoriatic arthritis were divided into responders and non-responders. RESULTS: In patients with psoriasis, the baseline median PASI score was 10.8 and baseline YKL-40 was 45 µg/L. Seventeen per cent had elevated plasma YKL-40 compared with healthy subjects. Baseline PASI and YKL-40 were not correlated (rho = 0.14, P = 0.347) and YKL-40 and hs-CRP remained unchanged after treatment. In patients with psoriatic arthritis, the median pretreatment YKL-40 was 112 µg/L and 43% had elevated YKL-40. YKL-40 decreased in 33 patients who responded to adalimumab (from 112 µg/L to 68 at 48 weeks, P = 0.007). Hs-CRP decreased (from 4.65 mg/L to 0.91, P = 0.013) in the responders. In the non-responders (n = 9), YKL-40 and hs-CRP remained unchanged. CONCLUSIONS: YKL-40 is elevated in many patients with psoriatic arthritis, but not in patients with psoriasis. YKL-40 decreased in patients with psoriatic arthritis who responded to treatment. YKL-40 may be a useful biomarker to monitor the effect of treatment with tumour necrosis factor-α inhibitors in patients with psoriatic arthritis.