Ca. Mancuso et al., Comparing discriminative validity between a disease-specific and a generalhealth scale in patients with moderate asthma, J CLIN EPID, 54(3), 2001, pp. 263-274
Citations number
45
Categorie Soggetti
Envirnomentale Medicine & Public Health","Medical Research General Topics
Health-related quality of life scales such as the Asthma Quality of Life Qu
estionnaire and the Medical Outcomes Study Short-form General Health Survey
SF-36 have become important measures of health status in clinical asthma t
rials. The discriminative properties of these scales, however, have not bee
n extensively evaluated and compared. The purposes of this study were to as
sess and compare scale and discriminative properties of the Asthma Quality
of Life Questionnaire (AQLQ) and the SF-36 in a group of patients with mode
rate asthma using a patient-rated global measure of disease activity as the
criterion variable. Patients were interviewed in-person with a series of q
uestionnaires including the AQLQ and the SF-36, and were also asked the glo
bal question "How active is your asthma now?" with possible responses of "e
xtremely," "very," "moderately," "mildly" or "not active." Discriminative p
roperties were determined using receiver operating characteristic (ROC) cur
ves with responses to the global question as the criterion variable and mea
n domain scale scores as the independent variables. Relative validities for
the AQLQ and SF-36 domains were also compared. A total of 230 patients, me
an age of 41 years, were enrolled. Scores were lower and ranges were narrow
er for the AQLQ compared to the SF-36. In general, the AQLQ and the SF-36 w
ere highly correlated, with r = 0.69 for the AQLQ overall score and the SF-
36 Physical Component Summary (PCS) score. According to ROC analyses, both
scales had excellent discriminative properties; however the area under the
ROC curve was higher for the AQLQ overall score (0.81) than for the PCS (0.
75). When ranked according to ROC area, the symptoms domain (0.83) had the
greatest area under the ROC curve, followed by the emotional (0.76) and act
ivities (0.76) domains of the AQLQ. However, in some cases, the area under
the curve was less for an AQLQ domain (for example, 0.71 for the environmen
tal domain) than for SF-36 domains (for example, 0.75 for the role physicia
l, and 0.75 for the social domain). Similarly, the AQLQ overall had a highe
r relative validity (5.2) compared to the PCS (2.2), and the symptoms domai
n of the AQLQ had the highest relative validity (6.0). Thus, both the Asthm
a Quality of Life Questionnaire and the SF-36 were able to characterize pat
ients with moderate asthma in our cross-sectional study. In addition, both
scales had strong discriminative properties when assessed with a global pat
ient rating of current disease activity. (C) 2001 Elsevier Science Inc. All
rights reserved.