A systematic review of core outcome set development studies demonstrates difficulties in defining unique outcomes

Amber E Young; Sara T Brookes; Kerry N L Avery; Anna Davies; Chris Metcalfe; Jane M Blazeby

doi:10.1016/j.jclinepi.2019.06.016

A systematic review of core outcome set development studies demonstrates difficulties in defining unique outcomes

J Clin Epidemiol. 2019 Nov:115:14-24. doi: 10.1016/j.jclinepi.2019.06.016. Epub 2019 Jul 2.

Authors

Amber E Young¹, Sara T Brookes², Kerry N L Avery³, Anna Davies⁴, Chris Metcalfe⁵, Jane M Blazeby³

Affiliations

¹ Bristol Centre for Surgical Research, Population Health Sciences, Bristol Medical School, University of Bristol, Canynge Hall, 39 Whatley Road, Bristol, UK, BS8 2PS. Electronic address: amber.young1@nhs.net.
² Cancer Research UK Clinical Trials Unit (CRCTU), Institute of Cancer and Genomic Sciences, University of Birmingham, Edgbaston, Birmingham, B15 2TT, UK.
³ Medical Research Council ConDuCT-II Hub for Trials Methodology Research, National Institute for Health Research Bristol Biomedical Research Centre, Bristol Centre for Surgical Research, Bristol Medical School: Population Health Sciences, University of Bristol, 39 Whatley Road, Bristol, BS8 2PS, UK.
⁴ Centre for Academic Child Health, University of Bristol, 1-5 Whiteladies Road, Bristol BS8 1NU, UK.
⁵ Population Health Sciences, Bristol Medical School, University of Bristol, Canynge Hall, 39 Whatley Road, Bristol, UK, BS8 2PS.

PMID: 31276780
DOI: 10.1016/j.jclinepi.2019.06.016

Abstract

Objectives: Core outcome set (COS) development often begins with a systematic review to identify outcomes. Reviews frequently show heterogeneity in numbers of outcomes reported across trials. Contributing to this is a lack of a uniform definition for an outcome. This study proposes a first working definition for a unique trial outcome to support reporting a quantitative assessment of outcome reporting heterogeneity (ORH).

Study design and setting: Eligible COS literature (development papers, protocols, and reviews) were identified using the COMET database, Ovid MEDLINE, and PubMed. Outcome numbers, definitions, timing, and grouping methodology were examined.

Results: One hundred and thirty two studies were included. 82 (88.1%) studies (excluding protocols) reported a total number of unique outcomes (median, 82; range, 12-5776; IQR, 261). Timing of assessment was reported in 32 (31.4%) studies. Methods to group similar outcomes were reported in 8 (7.8%) articles. No study defined how outcomes were agreed as different and how final numbers of unique outcomes were determined. It is proposed that a unique outcome requires original meaning and context. Thus ORH is suggested to be the reporting of multiple unique outcomes across trials related to one health care condition.

Conclusion: This review identified inconsistencies in how authors define, extract, group, and count trial outcomes. Further work is needed to refine our proposed definitions to optimize COS development and allow a quantifiable measure of ORH.

Keywords: COMET; Clinical trials; Core outcome set; Outcomes; Research methodology; Systematic review.

Publication types

Research Support, Non-U.S. Gov't
Systematic Review

MeSH terms

Clinical Trials as Topic / standards*
Databases, Factual
Evidence-Based Medicine
Humans
Outcome Assessment, Health Care / standards*
Research Design / standards

Grants and funding

MR/K025643/1/MRC_/Medical Research Council/United Kingdom