Quality of life assessed with EQ-5D 3L in patients undergoing glioma surgery; What is the responsiveness and minimal clinically important difference?
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Background: There are few studies on the impact of glioma surgery on health-related quality of life (HRQoL). The generic instrument EQ-5D 3L has been utilized in this context, but several questions concerning use and interpretation are unanswered. Objective: To evaluate the responsiveness of EQ-5D 3L in patients undergoing glioma surgery and estimate the minimal clinically important difference (MID). Materials and methods: EQ-5D 3L index values from 164 patients who underwent glioma surgery in the period 2007-2012 were analysed. Responsiveness and MID were estimated by using a combination of distribution-based and anchor-based methods. Karnofsky Performance Status (KPS) served as an anchor. Results: Patients who improved functionally did not report significantly higher EQ-5D 3L scores postoperatively with a Standardized Response Mean (SRM) of 0.04 (p=0.13). Patients who deteriorated functionally reported significantly lower EQ-5D 3L scores postoperative with a SRM of 0.72 (p <0.001). With different approaches we determined a range of MID-values from 0.07 to 0.15. Conclusions: EQ-5D 3L is responsive to changes when glioma patients are deteriorating functionally after surgery but not responsive when the patients are improving. The MID-values for EQ-5D 3L in glioma surgery are in the upper range of reported MID-values for other conditions.