Serum C-reactive Protein Levels in Japanese Patients with Psoriasis and Psoriatic Arthritis: Long-term Differential Effects of Biologics

Psoriasis has been shown to accompany systemic inflammation. We aimed to examine serum C-reactive protein (CRP) levels in Japanese psoriatic patients, and to elucidate their long-term as well as short-term changes by treatment with different biologics. A retrospective study was conducted in those who initiated and successfully continued the treatment for up to 24 months with either infliximab, adalimumab or ustekinumab, at the psoriasis special clinic of Jikei University School of Medicine. A total of 212 patients were included, 171 with plaque-type psoriasis (PsV) and 41 with psoriatic arthritis (PsA). A statistically significant elevation of CRP values was found in the group with a Psoriasis Area and Severity Index (PASI) of 12 or more compared with the PASI of less than 12 for both PsV and PsA. The CRP-positive patients had a higher proportion of PsA compared with the CRP-negative patients, and they had significantly higher PASI scores. Serum CRP values declined as early as at 3 months after systemic treatment with biologics. Tumor necrosis factor (TNF)-α antagonists did lead to a notable and sustained CRP decline up to 24 months. Infliximab showed rapid decline, while CRP decline by adalimumab treatment was time-dependent. The interleukin-12/23 p40 antagonist, ustekinumab, appeared to be less potent than TNF-α antagonists in stabilizing CRP values at low levels despite good control of cutaneous lesions. In conclusion, serum CRP levels can be used to assess disease severity in Japanese psoriatic patients as a marker of systemic inflammation. TNF-α antagonists may be more beneficial than ustekinumab in this regard.