Musculoskeletal ultrasound in monitoring response to apremilast in psoriatic arthritis patients: results from a longitudinal study

Introduction/objective Apremilast, PDE4 competitive inhibitor, has been recently introduced in the treatment of adult psoriatic arthritis (PsA) patients, but only preliminary data are available on imaging evaluation. Thus, we evaluated the response to apremilast in PsA patients by ultrasonographic (US) assessment. Methods Thirty-four patients (M/F 7/27; median age 61 years, IQR 15; median disease duration 10 years, IQR 13) treated for polyarticular involvement were longitudinally evaluated. All the patients were assessed at baseline (T0), and after 6 (T1), 12 (T2), and 24 weeks (T3) by DAS28, CDAI, SDAI, and DAPSA. At the same time-points, US assessment was performed in 22 sites (wrists, MCPs, PIPs): synovial effusion/hypertrophy and power Doppler were scored with a semi-quantitative scale (0-3). A total score, corresponding to patient's inflammatory status, was obtained by their sum (0-198). We assessed also the presence of tenosynovitis of flexor (tendons) of hands' fingers bilaterally, registering the number of involved tendons (US-tenosynovitis score 0-10). Results We found a significant reduction in the US inflammatory score values after 6 weeks (T0, median 15 (IQR 11.2); T1, 6 (10.0); P = 0.0002), confirmed at T2 (4.0 (4.0), P = 0.0002) and T3 (4.0 (6.0); P = 0.0003). Finally, US-detected tenosynovitis was observed in 44.1% of patients: a significant improvement in tenosynovitis score was identified at 6 weeks (T0, median 4 (IQR 4); T1, 1 (2); P < 0.0001) and maintained at T2 (0 (IQR 1); P < 0.0001) and T3 ((IQR 1.25); P < 0.0001). Conclusions Apremilast is able to induce an early and sustained improvement of ultrasonographic inflammatory status at articular and peri-articular level.