The RAND Negative Impact of Asthma on Quality of Life item bank (RAND-IAQL-Bank) and short forms (RAND-IAQL-12 and RAND-IAQL-4) can help assess health-related quality of life in adult patients with asthma. Quality of life is defined in terms of how much asthma symptoms and impairments bother or matter to the patient. The item bank's 65 items cover a more comprehensive range of content areas than is typically assessed by asthma-specific quality-of-life measures.
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To develop these items, RAND
Psychometric evaluation of the field test data suggested that the concept of asthma impact on quality of life can be measured as a single underlying construct. A real-data simulated computer adaptive test suggests that highly precise scores can be obtained with as few as four to five items from the bank. From the item bank, we developed two short forms consisting of four and 12 items (reliability = .86 and .93, respectively).
Our methodological approach was informed by the standards for measure development set forth by PROMIS (Patient-Reported Outcomes Measurement Information System Collaborative), but deviated in our emphasis on developing items based on focus group content rather than prioritizing items in the existent research literature.
Items do not appear to confound quality of life with asthma symptomatology, control, or functional impairment.
Preliminary evidence supports the construct and discriminant validity of the two short-form measures. Our measures correlate highly with Marks' Asthma Quality of Life Questionnaire (AQLQ-M) and more strongly with the PROMIS global physical than mental scale. The impact of asthma on quality of life is greater in people with indicators of more severe asthma, less asthma control, and in people with greater asthma-related hospitalizations and emergency room visits.
The 65-items, item parameters, and short forms are public documents, available for free. Interested parties can develop their own short forms based on data from the full item bank or use the item parameters to create their own computer adaptive test (CAT).
This research was supported by NHLBI Grant R01HL107312. The content is solely the responsibility of the authors and does not necessarily represent the official views of the National Institutes of Health.
