QoL measure gives the asthma patient’s perspective
medwireNews: Researchers have devised a new measure for assessing the effect of asthma on quality of life (QoL) from the patient’s perspective.
The Asthma Impact on Quality of Life Scale (A-IQOLS) asks respondents to rate the negative effect of their asthma and its treatment over the preceding 4 weeks on 16 QoL items developed from the National Institutes of Health’s Patient-Reported Outcome Measurement Information System.
This patient perspective provides “unique information,” say the researchers, noting: “Many of those measures that have long been included in the asthma outcome measurement toolbox continue to be useful but are not adequate proxies for a measure of the patient’s perception of how his or her asthma and its treatment are affecting their QoL.”
The A-IQOLS is based on the 15 dimensions included in the generic Flanagan Quality of Life Scale (QOLS), with the addition of one dimension – independence in doing day-to-day activities. And rather than asking patients how well their needs and wants are satisfied, it asks them to rate the negative effect of asthma on each dimension, from 1 for no negative effect to 5 for extremely negative effect.
A total of 147 participants aged an average of 49 years, of whom 76% were White and 65% female, completed the A-IQOLS and QOLS twice with a 3- to 5-week interval between each test. The majority of the patients were taking medium- or high-dose inhaled corticosteroids plus a long-acting inhaled beta-agonist.
The baseline and re-test A-IQOLS scores were consistent, at an average 1.35 and 1.25 points, respectively, indicating relatively low negative effect of asthma on QoL. The test demonstrated an appropriately sized standard error of measurement of 0.27, implying that a minimal within-person score change of plus or minus 0.73 would constitute a true change.
Scores on the A-IQOLS correlated significantly with other measures of patients’ symptoms or functional status, including the Asthma Control Test, the Asthma Symptom Utility Index, and the Marks and Juniper Mini Asthma Quality of Life Questionnaires. Forced expiratory volume in 1 second (FEV1) was the only exception, which the team says “would be expected for an objective but effort-dependent and labile clinical measure.”
The common variance with these other measures was relatively low, however, at less than 40% in nearly all cases, validating that the A-IQOLS also offers unique information, note the researchers.
The findings were similar for the QOLS, although correlations with other measures were not as strong as those seen with the A-IQOLS. Also, the A-IQOLS, unlike the QOLS, was sensitive to changes in asthma status, correlating significantly and in the expected directions with scores on other measures.
“It appears that a measure, such as the A-IQOLS, which asks the patients to evaluate the effect of a specific disease on his or her QoL is a more direct, sensitive, and appropriate approach than inferring effect from changes or differences in a generic measure such as the QOLS,” say Sandra Wilson (Palo Alto Medical Foundation Research Institute, California, USA) and colleagues in The Journal of Allergy and Clinical Immunology.
They believe that the A-IQOLS could be useful in clinical research and potentially in the clinic, helping to ensure “a more complete evaluation of therapeutic benefits than is provided by physiologic, symptom, or functional status measures,” particularly in patients with moderately severe or severe asthma for whom both asthma and its treatment might have negative effects.
The team adds that the generic QOLS, which could be used alongside the A-IQOLS, might play an additional unique role in patients with multiple chronic conditions, a severe or life-limiting disease, or both.
By Lucy Piper
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