Minimally Important Differences for Interpreting EORTC QLQ-C30 Scores in Patients With Advanced Breast Cancer

Abstract

Background We aimed to estimate the minimally important difference (MID) for interpreting group-level change over time, both within a group and between groups, for the European Organisation for Research and Treatment of Cancer Quality of Life Questionnaire core 30 (EORTC QLQ-C30) scores in patients with advanced breast cancer. Methods Data were derived from two published EORTC trials. Clinical anchors (eg, performance status [PS]) were selected using correlation strength and clinical plausibility of their association with a particular QLQ-C30 scale. Three change status groups were formed: deteriorated by one anchor category, improved by one anchor category, and no change. Patients with greater anchor changes were excluded. The mean change method was used to estimate MIDs for within-group change, and linear regression was used to estimate MIDs for between-group differences in change over time. For a given QLQ-C30 scale, MID estimates from multiple anchors were triangulated to a single value via a correlation-based weighted average. Results MIDs varied by QLQ-C30 scale, direction (improvement vs deterioration), and anchor. MIDs for within-group change ranged from 5 to 14 points (improvement) and −14 to −4 points (deterioration), and MIDs for between-group change over time ranged from 4 to 11 points and from −18 to −4 points. Correlation-weighted MIDs for most QLQ-C30 scales ranged from 4 to 10 points in absolute values. Conclusions Our findings aid interpretation of changes in EORTC QLQ-C30 scores over time, both within and between groups, and for performing more accurate sample size calculations for clinical trials in advanced breast cancer.

Minimally important differences for interpreting the EORTC QLQ‐C30 in patients with advanced colorectal cancer treated with chemotherapy

“…A similar MID range has been previously reported in patients with breast cancer [8,20], small-cell lung cancer [8], brain cancer [14] and lung cancer [13] and in pooled data across multiple cancer sites [9,10]. Also in line with previous findings [12,13,14,20], it is important to note that our MIDs varied according to the EORTC QLQ-C30 scale and direction of change (improvement versus deterioration). Furthermore, as highlighted by Cocks et al [9,10], the 5-10 point threshold is not always achievable in all settings.…”

“…Based on their overlapping results, mean differences ≥ 10 points have been commonly considered as clinically meaningful when interpreting EORTC QLQ‐C30 scale scores [19]. Nevertheless, there is increasing empirical evidence that MIDs can depend on the HRQOL scale, direction of change scores (improvement versus deterioration) and disease setting [9,10,12–14,20], implying that a global rule for MIDs applicable to all contexts is highly unlikely [21]. Therefore, there is a need to gather more empirical evidence on MID patterns across scales of the EORTC QLQ‐C30 and across disease sites [22].…”

Breast cancer surgery in older women: outcomes of the Bridging Age Gap in Breast Cancer study

“…It is worth noting that some of the differences in mean scores were small when taken in context of the 0-100 scale, so may be of little clinical or practical importance. For example, for EORTC QLQ-C30 global health status, it has been suggested that a difference of 8 points or more is important 39 .…”

The Impact of the Timing of Health-Related Quality of Life Assessments on the Actual Results in Glioma Patients: A Randomized Prospective Study

“…The choice of a clinically relevant difference, i.e., ≥10 points on a scale, may also have impacted our results. Although this value is universally accepted as a clinically meaningful change and used in cancer clinical trials, recent research has shown that this value may be different for different cancers and may not be applicable to changes on the individual patient level [ 25 , 26 , 27 ]. More appropriately defined clinically relevant differences may therefore be useful in both clinical trials and practice, when evaluating the impact of treatment over time.…”