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

Jammbe Z Musoro; Corneel Coens; Frederic Fiteni; Pogoda Katarzyna; Fatima Cardoso; Nicola S Russell; Madeleine T King; Kim Cocks; Mirjam Ag Sprangers; Mogens Groenvold; Galina Velikova; Hans-Henning Flechtner; Andrew Bottomley; EORTC Breast and Quality of Life Groups

doi:10.1093/jncics/pkz037

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

JNCI Cancer Spectr. 2019 Jun 4;3(3):pkz037. doi: 10.1093/jncics/pkz037. eCollection 2019 Sep.

Authors

Jammbe Z Musoro¹, Corneel Coens¹, Frederic Fiteni^{1

2

3

4}, Pogoda Katarzyna^{1

5}, Fatima Cardoso^{1

6}, Nicola S Russell^{1

7}, Madeleine T King^{1

8}, Kim Cocks^{1

9

10}, Mirjam Ag Sprangers^{1

11}, Mogens Groenvold^{1

12}, Galina Velikova^{1

13}, Hans-Henning Flechtner^{1

14}, Andrew Bottomley¹; EORTC Breast and Quality of Life Groups

Affiliations

¹ European Organisation for Research and Treatment of Cancer, Brussels, Belgium.
² Department of Medical Oncology, University Hospital of Nîmes, France.
³ Institut de Recherche en Cancérologie de Montpellier, France.
⁴ University of Montpellier, France.
⁵ Maria Sklodowska-Curie Institute-Oncology Center, Warsaw, Poland.
⁶ Breast Unit, Champalimaud Clinical Centre, Champalimaud Foundation, Lisbon, Portugal.
⁷ Netherlands Cancer Institute, Amsterdam, The Netherlands.
⁸ University of Sydney, Faculty of Science, School of Psychology, Sydney, NSW, Australia.
⁹ Department of Health Sciences, University of York, York, UK.
¹⁰ Adelphi Values, Bollington, Cheshire, UK.
¹¹ Department of Medical Psychology, Amsterdam University Medical Centers, Academic Medical Center, University of Amsterdam, Cancer Center Amsterdam, The Netherlands.
¹² Department of Public Health, University of Copenhagen, and Bispebjerg Hospital, Copenhagen, Denmark.
¹³ Leeds Institute of Cancer and Pathology, University of Leeds, St James's Hospital, Leeds, UK.
¹⁴ Clinic for Child and Adolescent Psychiatry and Psychotherapy, University of Magdeburg, Magdeburg, Germany.

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.