PRM10 - Assessing the Relationship Between Treatment Effect and Baseline Risk in Network Meta-Analsysis of Moderate to Severe Chornic Plaque Psoriasis Trials

Abstract

To investigate differences across randomized controlled trials (RCTs) evaluating biological therapies for the treatment of moderate to severe chronic plaque psoriasis in terms of baseline risk in psoriasis area severity index score (PASI) and the association with treatment effects by means of network meta-analysis (NMA). 25 RCTs reporting the proportion of patients experiencing a 75% improvement from baseline in PASI (PASI 75) at the end of the trial were identified from two recently published NMAs focused on the efficacy of biologics in the treatment of moderate to severe psoriasis based on a systematic literature review. Differences in baseline risk of PASI 75 were explored graphically. The association between the treatment effect of 19 different biologics and baseline risk of PASI 75 with placebo was assessed by conducting a Bayesian NMA with baseline risk covariate adjustment using a model assuming a constant treatment by covariate interaction, and a normal distribution for baseline risk. The model also allowed for the baseline risk adjustment of RCTs that did not include a placebo arm. Across the RCTs, PASI 75 at the end of the trial period for patients in the placebo arm ranged from 2% to 19%. The coefficient for baseline risk was a median of -0.33 (95% credible intervals: -0.79,0. 21) which suggested baseline risk was not significantly associated with the proportion achieving PASI 75 across the RCTs. Based on a NMA of RCTs regarding the efficacy of biologics in terms of PASI 75, it is unclear if baseline risk of PASI 75 acts as a treatment effect modifier. Further analyses are required to assess whether baseline risk may explain differences in the classes of biological therapies used to treatment moderate to severe psoriasis.