Sensitivity to change and minimal clinically important difference of the angioedema control test

Abstract

Background The Angioedema Control Test (AECT) is a patient-reported outcome measure developed and validated for the assessment of disease control in patients with recurrent angioedema. Its sensitivity to change and minimal clinically important difference (MCID) have hitherto not been established.

Methods Patients with recurrent angioedema due to chronic spontaneous urticaria, hereditary angioedema, or acquired C1-inhibitor deficiency were repeatedly asked to complete the AECT along with the Angioedema Quality of Life Questionnaire (AE-QoL), Dermatology Life Quality Index (DLQI), and anchors for disease control and whether treatment was sufficient during routine care visits. The sensitivity to the change of the AECT was determined by correlating changes in its scores over time with changes in the applied anchors. The MCID was determined using anchor-based and distributional criterion-based approaches.

Results Eighty-six cases were used for this analysis. Changes in AECT scores correlated well with AE-QoL changes (but less with changes in the DLQI) as well as other applied anchors, demonstrating its sensitivity to change. The MCID was found to be three points for improvement of angioedema control. The available number of cases with meaningful deterioration in our dataset was too low to reach a definite conclusion on the MCID for deterioration of angioedema control.

Conclusion The AECT is a valuable tool to assess changes in disease control in patients with recurrent angioedema over time. The lowest AECT score change that reflects a meaningful improvement of disease control to patients (MCID) is three points.