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Outcome measures

Last updated on 13 Feb 2019

If you are an investigator designing a clinical trial you will need to make early decisions as to which outcome measures to include. 

This in turn may influence decisions about sample size. In turning research into evidence, systematic reviewers often encompass problems in making valid comparison between trials which superficially are about the same intervention but which use different outcome measures. This problem is exacerbated in meta-analysis.

Careful section of outcome measures is crucial in the design of randomised controlled trials (RCTs) and investigators should consider the inclusion of patient reported outcome measures alongside primary outcome measures. 

COMET – Core Outcome Measures in Effectiveness Trials

The COMET Initiative supports investigators in developing and applying agreed standardised sets of outcomes, known as a ‘core outcome set’. These sets represent the minimum that should be measured and reported in all clinical trials, audits of practice or other forms of research for a specific condition.

They do not imply that outcomes in a particular study should be restricted to those in the core outcome set. Rather, there is an expectation that the core outcomes will be collected and reported to allow the results of trials and other studies to be compared, contrasted and combined as appropriate; and that researchers will continue to collect and explore other outcomes as well. The COMET website links to a database of outcome measures searchable by disease area and study type.


Patient-reported outcomes (PROs)

Patient reported outcome (PRO) data, such as quality of life and symptoms, if collected, analysed and reported appropriately can be used to inform shared-decision making, clinical guidelines and health policy.

Key considerations for researchers designing studies involving PROs, patient advocates and reviewers can be found on the Centre for Patient Reported Outcomes Research web based information resource.

International Consensus Guidance on the Inclusion of PROs in Clinical Trial Protocols: The SPIRIT-PRO Extension

University of Birmingham research has found that the patient-reported outcome (PRO) content of clinical trial protocols is often suboptimal. This may hinder trial implementation and reporting, limiting the extent to which PRO data informs shared-decision making, labelling claims, clinical guidelines and health policy. The SPIRIT (Standard Protocol Items: Recommendations for Interventional Trials) Statement was published in 2013 and aims to improve the completeness of trial protocols by providing evidence-based recommendations for a minimum set of items to be addressed. SPIRIT 2013, however, does not provide PRO-specific guidance. The Centre for Patient Reported Outcomes Research at the University of Birmingham and the Quality of Life Office at the University of Sydney, working with a range of international partners, including the HRA, and with funding from Macmillan Cancer Support have recently led the development of a SPIRIT-PRO Extension: a minimum checklist of PRO specific items for inclusion in clinical trial protocols.  The results will be published in the coming months and further details can be found on the CPROR website.
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