Validity of Quality of Life Measurement in Economic Evaluations in Total Joint Replacement: Agreement between Western Ontario and McMasters' Osteoarthritis Index (WOMAC) and the EuroQOL 5D (EQ-5D) Utility scores
Abstract
Health economic evaluations are commonly conducted through a cost-utility analysis, where health benefits are measured using utility scores. A common utility measure is the European Quality of Life (EQ-5D). Osteoarthritis (OA) research studies commonly use disease-specific quality of life tools such as the Western Ontario and McMaster’s Universities Osteoarthritis Index (WOMAC) to derive utility scores, but the validity of this method is unknown. This research aims to determine the agreement between utility scores derived from WOMAC and the EQ-5D surveys among patients who have undergone Total Joint Replacement (TJR). To estimate the agreement, we calculated an intraclass correlation coefficient (ICC) and its 95% confidence interval (CI) and produced Bland Altman plots. Our results indicate good agreement between the two scores, as seen with the ICC value of 0.85, 95% CI (0.82 - 0.87).