Reduction in psoriasis related pruritus during biologic therapy *

Dear Editor According to a recent multinational population based study, itch is the most common and bothersome symptom in psoriasis (Lebwohl, Kavanaugh, Armstrong, & Van Voorhees, 2015), and it is reported by 64%– 97% of psoriatic patients (Prignano, Ricceri, Pescitelli, & Lotti, 2009; Roblin, Wickramasinghe, & Yosipovitch, 2014). Despite its prevalence and importance, there is paucity of data regarding pruritus associated with plaque psoriasis and effective antipruritic treatment. However a significant reduction in psoriasis related pruritus during therapy with some biological agents has been observed recently (Mrowietz et al., 2015; Revicki et al., 2007; Zhu et al., 2014). The objectives of our study were to characterize the extent of pruritus in patients with moderate-to-severe psoriasis, and to evaluate and compare the effect of four different biological therapies on itch. We enrolled 103 consecutive patients, attending the Florence University Psoriasis Service between June 2014 and September 2015, who were candidate for biological treatment with etanercept (ETN), adalimumab (ADA), infliximab (IFX), or ustekinumab (UST) (dosage schemes recommended by German S3 Guidelines) (Nast et al., 2012). Inclusion criteria required being 18 years old, having a diagnosis of moderate-to-severe plaque psoriasis (body surface area 10% and PASI 10), and either failing, being intolerant to or contra-indicated for at least two conventional systemic psoriasis treatments. Presence of other dermatological or systemic conditions causing pruritus was considered as exclusion criteria. Validated instruments to study pruritus are few. We used a 6-point Likerttype scale (05no itch and 55most severe itch), which has proved to have good test–retest reliability and responsiveness in psoriatic patients (Gottlieb, Feng, Harrison, & Globe, 2010). Pruritus levels were categorized as follows: 05no itch, 1–35mild-to-moderate itch, 45 severe itch. Patients which reported no pruritus at baseline were excluded from further statistical analysis. Pruritus assessment was repeated after 24 weeks of biological treatment. Topical medications were not allowed during this period. Patients’ demographics and clinical characteristics for each treatment group are listed in Table 1. Pruritus was reported by 92 patients (89%) at baseline, 52% of whom reported severe itching (level 4). Mean pruritus score in the total patient population at baseline was 3.53 (6 1.16 STD). Mean BMI and PASI scores were similar between patients belonging to different treatment arms. At the end of the 24th week overall pruritus score was significantly reduced (0.8861.09); 51% of patients reported no itching (score50), and 30.5% showed a decrease in pruritus level of 1. Pruritus intensity was unchanged in 17 patients; among them 6 were treated with ADA, 6 with ETN, 2 with IFX, and 3 with UST. None showed increased pruritus. The efficacy of each treatment on pruritus intensity was assessed by paired t-test, which revealed a significant score reduction in every treatment arm (p< .001, Figure 1). One-way analysis of variance (ANOVA) was performed to compare the change in pruritus during therapy among the four different treatment groups (ADA, IFX, ETN, UST). No significant difference in reducing pruritus was found among all biological agents tested. Analysis of variance was also performed in order to evaluate the relationship between itch improvement and baseline itch category. According to our data, patients who reported greater itch at baseline had greater improvement at week 24 (p< .0001), and this result is congruent with those observed by Mrowietz et al. (2015). A further analysis of variance was performed in order to assess a potential correlation between PASI and pruritus at week 24. However, we did not find any statistically significant association between PASI percentage decrease and pruritus score reduction (Figure 2). In conclusion, all biological agents considered in the study (ADA, IFX, ETN, UST) proved to be effective in reducing pruritus, particularly in patients with severe baseline itch. Moreover, lack of pruritus improvement seems to be independent of PASI reduction.