Minimally important differences for the EORTC QLQ-C30 in prostate cancer clinical trials

BMC Cancer. 2021 Oct 7;21(1):1083. doi: 10.1186/s12885-021-08609-7.

Abstract

Background: The aim of the study was 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 prostate cancer.

Methods: We used data from two published EORTC trials. Clinical anchors were selected by strength of correlations with QLQ-C30 scales. In addition, clinicians' input was obtained with regard to plausibility of the selected anchors. The mean change method was applied for interpreting change over time within a group of patients and linear regression models were fitted to estimate MIDs for between-group differences in change over time. Distribution-based estimates were also evaluated.

Results: Two clinical anchors were eligible for MID estimation; performance status and the CTCAE diarrhoea domain. MIDs were developed for 7 scales (physical functioning, role functioning, social functioning, pain, fatigue, global quality of life, diarrhoea) and varied by scale and direction (improvement vs deterioration). Within-group MIDs ranged from 4 to 14 points for improvement and - 13 to - 5 points for deterioration and MIDs for between-group differences in change scores ranged from 3 to 13 for improvement and - 10 to - 5 for deterioration.

Conclusions: Our findings aid the meaningful interpretation of changes on a set of EORTC QLQ-C30 scale scores over time, both within and between groups, and for performing more accurate sample size calculations for clinical trials in prostate cancer.

Keywords: European Organisation for Research and Treatment of Cancer; HRQL; HRQOL; Health-related quality of life; Interpretation of scores; MIDs; PROs; Patient-reported outcomes.

MeSH terms

  • Aged
  • Cancer Pain
  • Clinical Deterioration*
  • Clinical Trials, Phase III as Topic / statistics & numerical data
  • Denture Liners
  • Diarrhea*
  • Europe
  • Fatigue
  • Health Surveys*
  • Humans
  • Male
  • Middle Aged
  • Patient Reported Outcome Measures
  • Physical Functional Performance
  • Prostatic Neoplasms*
  • Quality of Life*
  • Severity of Illness Index*
  • Social Interaction
  • Time Factors