Published Clinical Trial Reports Lack Patient-Relevant Data

Published trial reports contain less than half of the patient-outcomes data contained in company-controlled documents, according to an analysis published online October 8 in PLoS Medicine.

A comparison of patient-relevant clinical trial outcomes in unpublished clinical study reports (CSRs) provided to German regulatory authorities by drug companies showed that publicly available data on the same trials from journal articles and registry reports included only about half of the clinically important information, researchers from the Institute for Quality and Efficiency in Health Care (IQWiG), Cologne, Germany, report in an article .

"In contrast to CSRs, publicly available sources provide insufficient information on patient-relevant outcomes of clinical trials. CSRs should therefore be made publicly available," led by Beate Wieseler, PhD, head of IQWiG's Drug Assessment Department, and colleagues conclude.

The researchers analyzed information in CSRs for 101 trials for which the IAWiG had requested and received full CSRs from pharmaceutical companies during the drug regulatory review process. CSRs are detailed but usually unpublished accounts of clinical trials. The researchers then compared the completeness of information on patient-relevant benefits (such as symptom relief) and harms (such as adverse effects) in the CSRs with the completeness of information in publicly available sources, including journal publications, presentations, and registry reports, for the same studies.

They found CSRs included complete information for 86% of the patient-relevant outcomes, but the publicly available sources provided complete information for only 39% of the outcomes. This included CSR data for 78% to 100% of the benefit outcomes compared with data for 20% to 53% of benefit outcomes in the publicly available sources. For harm outcomes, CSRs provided complete information on 84% to 92% of outcomes, whereas the publicly available sources provided complete information on 27% to 72% of outcomes.

"Overall, each of these analyses confirmed that a substantial amount of additional information on patient-relevant outcomes is gained from CSRs compared to journal publications or registry reports (or a combination of both), even for published trials," the authors write.

The analysis also confirmed both publication bias and outcome reporting bias: 36% of the trials for which CSRs were available had not been published in journals, 15% had no publicly available reports of any kind, and even those that were publicly available lacked information on "outcomes of major clinical relevance," according to the authors. They also note that information from CSRs was used to challenge efficacy and safety conclusions for the antiviral drug oseltamivir and the antidepressant reboxetine after approval based on published evidence.

This study is expected to add to growing demands for public access to all data from clinical study reports and to recent efforts such as the AllTrials initiative, which aim to make clinical trial outcome data publicly available.

This work was supported by the IQWiG. All authors are employees of the institute.

PLoS Med. Published online October 8, 2013.

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