Is there a response shift in generic health-related quality of life 6 months after glioma surgery?

BACKGROUND: Patients may recalibrate internal standards when faced with a serious diagnosis or neurological deficits. This so-called response shift is important to understand in longitudinal health-related quality of life (HRQoL) data, but this is not quantitatively assessed in glioma patients. METHODS: Patients with gliomas were eligible for this HRQoL study. We used EuroQol-5D 3 L to assess generic HRQoL with assessment preoperatively and at 6 months postoperatively. At time of follow-up, patients scored how they considered their baseline HRQoL in retrospect using the same questionnaire (“then-test”). RESULTS: Seventy-three patients were enrolled between January 2013 and September 2015. With the then-test approach, the mean EQ-5D 3 L index was similar compared to baseline (0.77, mean difference 0.01, 95% CI −0.57 to 0.07, p = 0.82). Also, then-test and baseline VAS score were similar (mean difference 0, 95% CI −7 to 7, p = 0.97). However, a 0.10–0.13 difference from baseline was observed in patients that improved or deteriorated in HRQoL at follow-up according to the then-test EQ-5D 3 L index value. The direction of change as observed from the then-test was similar to the direction of clinical change, reducing the impact of any HRQoL change from baseline to follow-up. CONCLUSIONS: On average, we observed no response shift using EQ-5D 3 L in the selection of glioma patients able to participate at 6 months after surgery. However, following change in HRQoL at follow-up, response shift seems to reduce the effects of HRQoL changes by lowering of internal standards in patients that deteriorate and raising the standards in patients that improve.