Although there has been a push toward making data from clinical trials more widely available, a study published online Oct. 8 in PLOS Medicine found that unpublished clinical study reports (CSRs) provide more complete information related to patient outcomes than publicly available information.
“Publication bias and outcome reporting bias pose a substantial threat to the validity of clinical research findings and thus to informed decision-making in health care,” wrote the authors, led by Beate Wieseler, PhD, of the Institute for Quality and Efficiency in Health Care (IQWiG).
A group of German researchers from the IOWiG, an independent group that assesses the benefits and harms of medical treatments, requested CSRs from drug manufacturers for 101 separate studies. With those reports, they analyzed how comprehensive the information in each CSR was on patient-related benefit and harm outcomes. Public information from at least one source was available for 86 of these studies.
Looking at information such as mortality, adverse effects and clinical events, the authors found that CSRs provided complete information on 86 percent of outcomes compared with 39 percent of outcomes from publicly available sources. Looking at specific outcomes, the CSRs offered complete information on 78 to 100 percent of beneficial outcomes, excluding health-related quality of life. Public sources provided complete information on 20 to 53 percent of these outcomes. There was also significantly more information on adverse outcomes in CSRs than in publicly available sources.
The authors acknowledged that their sample of studies was not representative of all clinical trials since they only had access to CSRs voluntarily provided by pharmaceutical companies. Additionally, the trials encompassed only a few medical conditions.
Despite the limitations, they argued that their findings highlight the need to make CSRs publicly available. They noted there is an initiative underway in Europe to make them public documents as well as other measures to better inform the public about clinical trials.