Researchers define clinically meaningful score change in angioedema test
AECT questionnaire scoring refined to better assess treatment response
A 3-point score increase is the minimum change on the widely used Angioedema Control Test (AECT) to reflect meaningful improvement in disease control for people with recurrent angioedema, a study showed.
The AECT was developed to help patients keep score of disease control over a recall period, but the minimal clinically important difference (MCID), or the least change they would identify as meaningful, has been unclear until now.
Knowing the MCID for improvement offers both patients and doctors a way to check how well angioedema is responding to treatment over time, which ultimately can help improve angioedema care.
Still, more studies are needed to determine the MCID for disease control worsening, the researchers noted.
The study, “Sensitivity to change and minimal clinically important difference of the angioedema control test,” was published in Clinical and Translational Allergy by researchers in Germany and the Netherlands.
Angioedema occurs when fluids leak out of blood vessels into tissues in the deeper layers of the skin, causing them to swell. Symptoms of angioedema can be chronic (long-lasting), recurring over weeks or even months.
“Given the unpredictability and day-to-day fluctuation of symptoms, it is difficult to establish disease activity, disease burden, and treatment response based on clinical signs and symptoms during routine care visits,” the researchers wrote.
Designed to capture a patient’s actual disease status, the AECT comprises four questions about how often and how severe symptoms were in the past four weeks or three months, depending on the test version used.
For each of the four questions there are five possible answers, scored from 0 to 4 points, meaning that total score ranges from 0 to 16. Scoring 10 or more points indicates well-controlled disease, whereas less than 10 indicates poorly controlled disease.
The AECT “is available in many languages and widely used in clinical trials and routine practice as recommended by current international guidelines,” the researchers wrote.
A closer look at responses to angioedema treatment
While “it is imperative to know the ability of the AECT to determine changes over time, for example, before and after treatment adjustment,” the team wrote, “this property of the AECT has not been investigated” and its MCID “is unknown.”
To calculate AECT’s minimal clinically important difference, the researchers asked 66 people with recurrent angioedema, mean age 50.5 years, to complete the four-week recall version of the questionnaire at study’s start (baseline) and at a follow-up visit.
Most patients (72.7%) were women and the most common diagnosis was hereditary angioedema type 1 or 2 (40.9%). Other diagnoses included isolated angioedema, acquired angioedema, and chronic urticaria with angioedema.
Angioedema control during the past four weeks also was self-rated at baseline on a 5-point scale from “completely controlled” to “not controlled at all,” and at follow-up on a 7-point scale from “improvement to complete control” to “deterioration to complete lack of control.” Patients also indicated if their angioedema treatment in that period was “sufficient” or “not sufficient.”
The treating physicians also were asked to fill out these questions from their perspectives.
Results showed that the median AECT total score was 10 points (range, 6-13) at baseline and 13 points (7-16) at follow-up.
Greater AECT score increases linked to better disease control
Greater AECT score increases were significantly associated with better disease control, reported by either the patient or the physician, and with a treatment classification change from insufficient to sufficient. Notably, this treatment change was reported by 18 patients (27.2%), and was linked to a 6-point increase in the AECT total score.
A 6-point score change in the opposite direction was associated with a treatment change from sufficient to insufficient, which was reported by three patients (4.5%). For most patients (56.1%), treatment was classified as sufficient and remained sufficient at follow-up, being linked to a 1-point increase in the AECT total score.
In general, greater increases in the AECT total score also were significantly associated with lower scores in the Angioedema Quality of Life (AE-QoL) questionnaire and the Dermatology Life Quality Index, indicating better quality of life.
“We found that changes in the AECT correlate well with anchor instruments that measure changes in angioedema control, health-related [quality of life], and treatment sufficiency,” the researchers wrote.
For patients who reported a one-step improvement in global angioedema control, the mean increase in the AECT score was 4.5 points. Those who reported a reduction of 6-11 points in the AE-QoL — corresponding to a one-step improvement — had a mean increase of 2.9 points in the AECT.
In addition, statistical models supported a 3-point score increase as the cut-off to more accurately identify patients reporting improvements in angioedema control or in quality of life.
Recommendation of 3 points as the MCID of the AECT
“We found the MCID of the AECT to be between 2.5 and 4.5 points,” the researchers wrote, adding that they “recommend three points to be used as the MCID … for improvement in angioedema control.”
The team noted, however, that the low number of patients experiencing worsening disease control did not allow the determination of the MCID for deterioration.
“The MCID for improvement (three points) cannot simply be applied to deterioration, since it is known that these often differ,” they wrote.
Still, “the knowledge of the MCID of three points for improvement increases the interpretability of AECT results and further recommends its use in clinical trials and routine patient care,” the researchers concluded.