Background Knee osteoarthritis is one of the most prevalent diseases in developed countries. When symptoms are severe and affect the quality of life, total knee replacement (TKR) is often recommended. Economic evaluation (EE)of treatments used in order to promote more efficient use of resources is advised. In processes such as TKR, where quality of life is the most important clinical outcome to assess, cost-utility analysis, which allows comparison of two treatment alternatives in terms of costs and benefits and which uses quality-adjusted life years (QALYs), is the preferred type of EE. In Spain, an incremental cost of between € 8,400 and € 44,200 per QALY gained is generally accepted (Abellan JM et al).
Objectives To estimate the cost-utility of TKR in patientsdiagnosedwith knee osteoarthritis and obesity, compared with non-intervention.
Methods Cost-utility evaluation from the social perspective, with all relative costs was taken into account, regardless of the financer. 71 patients undergoing TKR were prospectively studied for 12months. Variables: Sociodemographicand clinical. Health-related quality of life (HRQOL) was assessed using the WOMAC and SF-36 and QALYs by the Short Form6D (SF-6D) index. The baseline total cost of the economic resources used due to the knee process included direct medical and non-medical and indirect costs. The total post-TKR cost included the cost of surgery (operating room, hospital stay, technicalprocedures and physiotherapy). Resources used were collected during the six months before and 6-12 months after TKR.
Results 71 patients, mean age 67.48 years (SD 8.6), 66 female, BMI 38.71 (SD 4.5) were included. Mean difference between scores at baseline and at 12 months was 33.14 points (95% CI 28.56 to 37.72, in the WOMAC total index (p <0.001) and 10.38 points (95% CI 7.97 to 12.80) in the physical component SF-36, (p <0.001) and 1.57 (95% CI -5.2 to 2.04) in the mental component SF-36 (p = 0.388). 12 months after TKR, patients gained a mean of 0.11 QALYS, compared with non-intervened patients.
Mean direct non-medical costswere € 3,329 (SD 4,079) at baseline vs. € 2,901 (SD 4,885) at 12 months (p = 0.371), mean indirect costs were € 335 (SD 1,750) vs. € 90 (SD 322), p = 0.299, and mean direct medical costs were € 375 (SD 174) vs. € 173 (SD 78)without the cost of surgery, p <0.001. The mean incremental cost-utility was € 32,358 per QALY gained (P25: € -16,470; P50: €13,049: P75: € 44,706) when TKR was carried out.
Conclusions Quality of life improved significantly after TKR. The costs, borne by patients and their families were similar at baseline and at 12 months after TKR. The analysis shows TKR has an acceptable cost-utility ratio from the accepted Spanish perspective in the first 12 months after surgery.
References Abellán JM et al. La medición de la calidad de los estudios de evaluación económica. Propuesta de ‘checklist’ y guía de uso para la toma de decisiones. Rev Esp Salud Pública 2009;83:71-84
Acknowledgements This study was funded by Spanish Ministry of Health grant FIS PS09/01148
Disclosure of Interest None Declared