Assessing the validity of the RAND negative impact of asthma on quality of life short forms

Abstract

Background: In response to recommendations from the 2010 National Institutes of Health Asthma Outcomes Workshop, we developed a system for measuring the negative impact of asthma on quality of life (QoL), which was referred to as the RAND Negative Impact of Asthma on Quality of Life (RAND-IAQL) item bank. The bank contains 65 items that focus on the patient's perception of the impact or bother of asthma on his or her life.

Objective: Evidence for the validity of 2 short forms, the RAND-IAQL 4-item and 12-item Short Forms, from the bank is presented.

Methods: Using a sample of 2032 adults with asthma, we validated our short forms against the Asthma Quality of Life Questionnaire-Marks (AQLQ-M), the Asthma Control Test, and generic measures of QoL developed by the Patient-reported Outcomes Measurement Information System (PROMIS). Discriminant validity was examined by comparing scores of respondents who differed according to multiple health indicators.

Results: Our sample ranged in age from 18 to 99 years (mean, 43 years), with 14% Hispanic, 11% Asian, 19% African American, and 56% non-Hispanic white race/ethnicity. Men had a significantly worse impact of asthma on QoL than women. The impact of asthma on QoL was greatest in African American and Hispanic subjects compared with that seen in non-Hispanic white subjects. Our measures correlated highly with the AQLQ-M and more strongly with the PROMIS global physical than mental scales. They differentiated between adults with asthma according to their perceived severity, level of control, presence or absence of exacerbations, and physical comorbidity.

Conclusion: The RAND-IAQL item bank, measuring the impact of asthma on QoL, will complement other patient-reported outcomes, such as measures of asthma symptoms, functioning, and control.

Keywords: Validity; asthma; quality of life; short forms.