The primary endpoint was evaluated between each risankizumab dose and placebo using the Cochran–Mantel–Haenszel test, adjusting for stratification factors (prior exposure to anti-TNF therapies and baseline worst Hurley stage). Missing efficacy values during the double-blind period were handled using nonresponder imputation incorporating multiple imputation to handle missing data due to COVID-19 as the primary approach for categorical endpoints and mixed-effect model repeat measures for continuous endpoints. All safety analyses were performed on the safety populations, defined as all patients who received at least one dose of study drug in the respective study period. The number and percentage of patients experiencing TEAEs were tabulated using the Medical Dictionary For Regulatory Activities (version 24.0) system organ class and preferred terms; severity and relationship to the study drug were assessed by the investigator.