OBJECTIVES: To develop and validate approaches for mapping Oswestry Disability Index (ODI) responses to EQ-5D-3L utility values and to evaluate the impact of using mapped utility values on cost-utility results compared to published regression models.
METHODS: Three response mapping approaches were developed in a random sample of 70% of 18,692 patients with low back pain: non-parametric approach (Non-p), non-parametric approach excluding logical inconsistencies (Non-peLI), and ordinal logistic regression (OLR). Performance was assessed in the remaining 30% using R-square (R2), Root Mean Square Error (RMSE), and Mean Absolute Error (MAE). To evaluate whether MAEs and their 95% limits of agreement (95%LA) were clinically relevant, a minimally clinically important difference (MCID) of 0.074 was used. Probabilities of cost-effectiveness estimated using observed and mapped utility values were compared in two economic evaluations.
RESULTS: The Non-p performed best (R2=0.43; RMSE=0.22; MAE=0.03; 95%LA=-0.40;0.47) compared to the Non-peLI (R2=0.07; RMSE=0.29; MAE=-0.15; 95%LA=-0.63;0.34), and ORL (R2=0.22; RMSE=0.26; MAE=0.02; 95%LA=-0.49;0.53). MAEs were lower than the MCID for the Non-p and OLR, but not for the Non-peLI. Differences in probabilities of cost-effectiveness ranged from 1-4% (Non-p), 0.1-9% (Non-peLI), and 0.1-20% (OLR).
CONCLUSIONS: Results suggest that the developed response mapping approaches are not valid for estimating individual patients' EQ-5D-3L utility values, and - depending on the approach - may considerably impact cost-utility results. The developed approaches did not perform better than previously published regression-based models and are therefore not recommended for use in economic evaluations.
|Number of pages||10|
|Journal||Value in health : the journal of the International Society for Pharmacoeconomics and Outcomes Research|
|Early online date||9 Feb 2023|
|Publication status||Published - Jun 2023|
- Oswestry Disability Index
- low back pain
- response mapping