Just over half (55%) of all joint replacement trials report on pre-specified primary outcome measures and even when they do, there is a wide heterogeneity in the type of outcome measures, a review of literature reveals.
The problem makes it difficult to compare findings between clinical trials and reliably answer important research questions.
The systematic review examining trials published in 2008 and 2013 showed there has been some improvement over time – outcome measures were specified in only 17% of trials in 2008 – but clearly, there was still further to go.
Coauthor of the review Dr Bethan Richards, from the University of Sydney, told the limbic the findings justified the introduction of international efforts such as OMERACT and CONSORT.
“Not more than two trials reported the same outcome measure. This is not a rigorous or defendable way to do research.”
The review found 17 different primary outcome measures specified in just 15 knee trials despite the fact they were ostensibly evaluating similar questions.
“We need a core set of outcome measures including patient reported outcome measures. Hopefully then we will see another big swing in improvement,” Dr Richards said.
The review found the majority of outcome measures (71%) focused on technical aspects of the surgery rather than patient-focussed outcomes.
For example, primary outcome measures used in hip trials included component migration and deviation of planned stem shaft angle rather than measures such as death, adverse events and function.
Trials in other surgical fields had similarly inadequate reporting of outcome measures.
More than half of studies also failed to address potential bias such as participant blinding, incomplete data and selective reporting.
Dr Richards said an additional problem was that the trials continued to be published.
“The system is falling down in multiple places,” she said.
She added that work on a core set of outcome measures was underway and included input from patients. The set may be approved at OMERACT 2018, which is being held in May in Australia.