Background: The X‐ACT study aimed to examine the effect of omalizumab treatment on quality of life (QoL) in chronic spontaneous urticaria (CSU) patients with angioedema refractory to high doses of H1‐antihistamines. Methods: In X‐ACT, a phase III, double‐blind, placebo‐controlled study, CSU patients (18‐75 years) with ≥4 angioedema episodes during the 6 months before inclusion were randomized (1:1) to receive omalizumab 300 mg or placebo every 4 weeks for 28 weeks. Angioedema‐related QoL, skin‐related QoL impairment, and psychological well‐being were assessed. Results: Ninety‐one patients were randomized and 68 (omalizumab, n = 35; placebo, n = 33) completed the 28‐week treatment period. At baseline, the mean (SD) total Angioedema QoL (AE‐QoL; 56.2 [18.7] and 59.9 [19.2]) and Dermatology Life Quality Index (DLQI; 14.6 [5.7] and 16.6 [7.3]) score were high in the omalizumab and placebo group, respectively. At Week 4 (after the first treatment), the least squares mean difference in the AE‐QoL and DLQI score between groups was −17.6 (P < .001) and −7.2 (P < .001), respectively. Significant QoL improvements in the omalizumab vs placebo groups continued until Week 28, but returned to placebo levels at the follow‐up visit. The mean (SD) baseline 5‐item World Health Organization Well‐being Index was 10.0 (5.5, omalizumab) and 7.7 (5.3, placebo), which increased above the depression threshold (<13) from Week 4 and throughout with omalizumab but not placebo treatment. Compared to placebo, omalizumab was also associated with decreased fear of suffocation due to angioedema. Conclusions: Our findings support omalizumab treatment in patients with severe H1‐antihistamine‐refractory CSU with angioedema.
