Nail involvement as a negative prognostic factor in biological therapy for psoriasis: a retrospective study

Background Psoriasis (Pso) has a strong impact on quality of life and a positive association has been reported between nail psoriasis (NP) and more severe disease, together with a longer duration of skin lesions. The treatment of NP represents a challenge and biological therapy can be recommended for severe disease. Objective The first end point of this retrospective study was to evaluate the time to achieve Psoriasis Area Severity Index (PASI) 75 in patients with and without NP treated with biological therapy. The second end point was to evaluate the efficacy of biological therapy to improve NP. Methods A total of 127 patients (88 men and 39 women) with moderate to severe Pso referring to our Service between 2007 and 2014 were included. Inclusion criteria were age ≥18 years and a 24 week treatment. The outcome variable was achievement of PASI 75 at 24 weeks with and without NP. All patients were treated with topical therapy and one of four different biological treatments: adalimumab (44.09%), etanercept (18.11%), infliximab (13.39%) and ustekinumab (24.41%). Physical examinations were performed every 4 weeks, and at each visit, the clinician assessed the PASI and Nail Psoriasis Severity Index (NAPSI). Results At multivariate Cox regression analysis, a smaller proportion of patients with NP achieved PASI 75 at 24 weeks than patients without NP when adjusted for the epidemiological, clinical features and biological treatment received. With all biological drugs, the NAPSI score began to improve already after 8 weeks (from 18.53 at week 0–2.83 at week 24). Conclusion Patients with NP reach PASI 75 more slowly than patients without NP. Clinicians should therefore consider that treatment with a biological agent may require a longer period before reaching a satisfying therapeutical goal. Nevertheless, adalimumab, infliximab, ustekinumab and etanercept demonstrated their equal effectiveness in reducing the NAPSI score.