Statistical analysis
The primary outcome of this study was the change in the endoscopic nasal polyp score at 20 weeks treatment compared to baseline for both placebo and benralizumab treatment groups. This was analyzed using a two-tailed paired t-test and with 0.05 determined to be significant a priori . Lund-Mackay score as determined by CT scan, nasal blockage score (NBS), SNOT-22 and UPSIT smell test were evaluated by the same statistical methods. Baseline characteristics and laboratory values were compared by either an unpaired two-tailed t-test or Fisher’s exact test when required. Among the benralizumab treated subjects, blood eosinophil count and skin prick test sensitivity were also compared against endoscopic NP score reduction or CT scan by using a one-tailed Spearman rank correlation and then plotted with a four-parameter logistic curve interpolation.
An a priori power analysis was performed based on prior studies using anti-IL5 monoclonal antibody therapy where there was an average of 32% reduction in nasal polyp score yielding an effect size of 0.535 and standard deviation of 1.5. To achieve 80% power (alpha 0.05) using the same effect size, a total sample size of 22 was determined to be adequate for our study (11 per arm). To accommodate for potential dropout, we randomized 24 total subjects. An intention to treat analysis was performed.
Randomization and data monitoring was performed by an independent team. An independent and blinded group was also responsible for data monitoring and receipt of locked study data prior to unblinding. Two separate groups then analyzed the data. Data analysis was performed using Prism version 8.4.1 for Mac (GraphPad Software, San Diego, CA).