Comparison of directly elicited preferences to preferences derived from the SF-36 in adults with asthma.
BACKGROUND
Algorithms have been developed that estimate preferences from the Short Form 36 (SF-36). The objective of this study was to compare SF-36-derived preferences to directly elicited preferences.


METHODS
The authors used data from a clinical trial of adult asthmatics to derive preferences from the SF36 and compare those to visual analog scale (VAS) values and the Asthma Quality-of-Life Questionnaire (AQLQ).


RESULTS
The differences between VAS and derived preferences ranged from -0.066 to 0.024 at baseline and 0.006 to 0.107 at the end of follow-up. All measures improved from baseline (P < 0.001); however, derived preferences underestimated change (0.066 to 0.131) compared to the VAS (0.173) (P < 0.001), which could affect economic evaluations. Correlations between preferences and the AQLQ ranged from 0.56 to 0.70 at baseline (P < 0.001) and 0.53 to 0.70 for changes from baseline (P < 0.001).


CONCLUSIONS
The derivation methods produce valid and responsive measures of patient preference. However, derived preferences differ from one another and directly elicited VAS preferences.
Lee
Todd A
TA
Midwest Center for Health Services and Policy Research, Hines VA Hospital, P.O. Box 5000 (151-H), Hines, IL 60141, USA. lee@research.hines.med.va.gov
Hollingworth
William
W
Sullivan
Sean D
SD
D000305:Adrenal Cortex Hormones / Q000627:therapeutic use; D000328:Adult; D000465:Algorithms; D001249:Asthma / Q000188:drug therapy / Q000503:physiopathology / Q000523:psychology*; D005260:Female; D006801:Humans; D008297:Male; D017060:Patient Satisfaction; D011788:Quality of Life; D016032:Randomized Controlled Trials as Topic; D018434:Sickness Impact Profile; D012923:Social Class; D011795:Surveys and Questionnaires
D000305:Adrenal Cortex Hormones