Completeness of Reporting of Patient-Relevant Clinical Trial Outcomes: Comparison of Unpublished Clinical Study Reports with Publicly Available Data

Abstract

Access to unpublished clinical study reports (CSRs) is currently being discussed as a means to allow unbiased evaluation of clinical research. The Institute for Quality and Efficiency in Health Care (IQWiG) routinely requests CSRs from manufacturers for its drug assessments. Our objective was to determine the information gain from CSRs compared to publicly available sources (journal publications and registry reports) for patient-relevant outcomes included in IQWiG health technology assessments (HTAs) of drugs. We used a sample of 101 trials with full CSRs received for 16 HTAs of drugs completed by IQWiG between 15 January 2006 and 14 February 2011, and analyzed the CSRs and the publicly available sources of these trials. For each document type we assessed the completeness of information on all patient-relevant outcomes included in the HTAs (benefit outcomes, e.g., mortality, symptoms, and health-related quality of life; harm outcomes, e.g., adverse events). We dichotomized the outcomes as “completely reported” or “incompletely reported.” For each document type, we calculated the proportion of outcomes with complete information per outcome category and overall. We analyzed 101 trials with CSRs; 86 had at least one publicly available source, 65 at least one journal publication, and 50 a registry report. The trials included 1,080 patient-relevant outcomes. The CSRs provided complete information on a considerably higher proportion of outcomes (86%) than the combined publicly available sources (39%). With the exception of health-related quality of life (57%), CSRs provided complete information on 78% to 100% of the various benefit outcomes (combined publicly available sources: 20% to 53%). CSRs also provided considerably more information on harms. The differences in completeness of information for patient-relevant outcomes between CSRs and journal publications or registry reports (or a combination of both) were statistically significant for all types of outcomes. The main limitation of our study is that our sample is not representative because only CSRs provided voluntarily by pharmaceutical companies upon request could be assessed. In addition, the sample covered only a limited number of therapeutic areas and was restricted to randomized controlled trials investigating drugs. In contrast to CSRs, publicly available sources provide insufficient information on patient-relevant outcomes of clinical trials. CSRs should therefore be made publicly available. Please see later in the article for the Editors' Summary People assume that, when they are ill, health care professionals will ensure that they get the best available treatment. In the past, clinicians used their own experience to make decisions about which treatments to offer their patients, but nowadays, they rely on evidence-based medicine—the systematic review and appraisal of clinical trials, studies that investigate the benefits and harms of drugs and other medical interventions in patients. Evidence-based medicine can guide clinicians, however, only if all the results of clinical research are available for evaluation. Unfortunately, the results of trials in which a new drug performs better than existing drugs are more likely to be published than those in which the new drug performs badly or has unwanted side effects (publication bias). Moreover, trial outcomes that support the use of a new treatment are more likely to be published than those that do not support its use (outcome reporting bias). Both types of bias pose a substantial threat to informed medical decision-making. Recent initiatives, such as making registration of clinical trials in a trial registry (for example, ClinicalTrials.gov) a precondition for publication in medical journals, aim to prevent these biases but are imperfect. Another way to facilitate the unbiased evaluation of clinical research might be to increase access to clinical study reports (CSRs)—detailed but generally unpublished accounts of clinical trials. Notably, information from CSRs was recently used to challenge conclusions based on published evidence about the efficacy and safety of the antiviral drug oseltamivir and the antidepressant reboxetine. In this study, the researchers compare the information available in CSRs and in publicly available sources (journal publications and registry reports) for the patient-relevant outcomes included in 16 health technology assessments (HTAs; analyses of the medical implications of the use of specific medical technologies) for drugs; the HTAs were prepared by the Institute for Quality and Efficiency in Health Care (IQWiG), Germany's main HTA agency. The researchers searched for published journal articles and registry reports for each of 101 trials for which the IQWiG had requested and received full CSRs from drug manufacturers during HTA preparation. They then assessed the completeness of information on the patient-relevant benefit and harm outcomes (for example symptom relief and adverse effects, respectively) included in each document type. Eighty-six of the included trials had at least one publicly available data source; the results of 15% of the trials were not available in either journals or registry reports. Overall, the CSRs provided complete information on 86% of the patient-related outcomes, whereas the combined publicly available sources provided complete information on only 39% of the outcomes. For individual outcomes, the CSRs provided complete information on 78%–100% of the benefit outcomes, with the exception of health-related quality of life (57%); combined publicly available sources provided complete information on 20%–53% of these outcomes. The CSRs also provided more information on patient-relevant harm outcomes than the publicly available sources. These findings show that, for the clinical trials considered here, publicly available sources provide much less information on patient-relevant outcomes than CSRs. The generalizability of these findings may be limited, however, because the trials included in this study are not representative of all trials. Specifically, only CSRs that were voluntarily provided by drug companies were assessed, a limited number of therapeutic areas were covered by the trials, and the trials investigated only drugs. Nevertheless, these findings suggest that access to CSRs is important for the unbiased evaluation of clinical trials and for informed decision-making in health care. Notably, in June 2013, the European Medicines Agency released a draft policy calling for the proactive publication of complete clinical trial data (possibly including CSRs). In addition, the European Union and the European Commission are considering legal measures to improve the transparency of clinical trial data. Both these initiatives will probably only apply to drugs that are approved after January 2014, however, and not to drugs already in use. The researchers therefore call for CSRs to be made publicly available for both past and future trials, a recommendation also supported by the AllTrials initiative, which is campaigning for all clinical trials to be registered and fully reported. Please access these websites via the online version of this summary at http://dx.doi.org/10.1371/journal.pmed.1001526.