Deriving utility scores from the SF-36 health instrument using Rasch analysis

被引:24
作者
Hawthorne, Graeme [1 ,2 ]
Densley, Konstancja [2 ]
Pallant, Julie F. [3 ]
Mortimer, Duncan [4 ]
Segal, Leonie [5 ]
机构
[1] Royal Melbourne Hosp, Dept Psychiat, Parkville, Vic 3050, Australia
[2] Univ Melbourne, Dept Psychiat, Fac Med Dent & Hlth Sci, Melbourne, Vic, Australia
[3] Univ Melbourne, Sch Rural Hlth, Fac Med Dent & Hlth Sci, Shepparton, Australia
[4] Monash Univ, Ctr Hlth Econ, Fac Business & Econ, Melbourne, Vic 3004, Australia
[5] Univ S Australia, Div Hlth Sci, Adelaide, SA 5001, Australia
基金
英国医学研究理事会;
关键词
AQoL; Cost-utility analysis; Health services research; SF-36; Item response theory; Quality of life; Rasch analysis;
D O I
10.1007/s11136-008-9395-5
中图分类号
R19 [保健组织与事业(卫生事业管理)];
学科分类号
摘要
Background Utility scores for use in cost-utility analysis may be imputed from the SF-36 health instrument using various techniques, typically regression analysis. This paper explored imputation using partial credit Rasch analysis. Method Data from the Assessment of Quality of Life (AQoL) instrument validation study were re-analysed (n = 996 inpatients, outpatients and a community sample). For each AQoL item, factor analysis identified those SF-36 items forming a unidimensional scale. Rasch analysis located scale logit scores for these SF-36 items. The logit scores were used to assign AQoL item scores. The standard AQoL scoring algorithm was then applied to obtain the utility scores. Results Many SF-36 items were limited predictors of AQoL items; some items from both instruments obtained disordered thresholds. All imputed scores were consistent with the AQoL model and fell within AQoL score boundaries. The explained variance between imputed and true AQoL scores was 61%. Discussion Rasch-imputed mapping, unlike many regression-based algorithms, produced results consistent with the axioms of utility measurement, while the proportion of explained variance was similar to regression-based modelling. Item properties on both instruments implied that some items should be revised using Rasch analysis. The methods and results may be used by researchers needing to impute utility scores from SF-36 health scores.
引用
收藏
页码:1183 / 1193
页数:11
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