Recommended methods for determining responsiveness and minimally important differences for patient-reported outcomes.
To evaluate the responsiveness of EQ-5D 3L in patients undergoing intracranial glioma surgery and estimate the minimal clinically important difference (MCID). EQ-5D 3L index values from 164 patients who underwent glioma surgery in the period 2007–2012 were analysed. Responsiveness and MCID were estimated using a combination of distribution-based and anchor-based methods. Karnofsky performance status served as an anchor. Patients who improved functionally did not report significantly higher EQ-5D 3L scores post operatively with a standardized response mean (SRM) of 0.04 (p = 0.13). Patients who deteriorated functionally reported significantly lower EQ-5D 3L scores post operatively with a SRM of 0.72 (p < 0.001). With different approaches, we determined a range of MCID values from 0.13 to 0.15. EQ-5D 3L is responsive to changes when glioma patients are deteriorating functionally after surgery but not responsive when the patients are improving. The MCID values for EQ-5D 3L in glioma surgery seem higher than reported MCID values for other types of cancers.