Given that many supplements may be ineffective and/or associated with adverse events, compliance of registered trials to the European Medicines Agency (EMA) rule for prompt reporting of the results is of crucial importance for consumers’ health.
Yet, according to a new study in the newly created open access journal 'Dietetics', selective reporting bias remains an issue of concern, especially among commercially funded research.
The study from Aristotle University of Thessaloniki, Greece, pulls together a wealth of previous research which it states "appears unanimous" on the fact that trials with positive findings are more likely to be published than those with negative findings.
According to the report, Lesser et al. were the first to report (back in 2007) that the type of funding source is significantly related to the conclusions drawn, with commercial funding being associated with more positive results. Since then, this industry effect has been reported in drug and device studies concerning direct and indirect funding.
The recent report states: "Trial quality appears to be a constantly moving target and the lack of adherence to good clinical practices is apparent in both the USA and the European Union (EU). Within the EU, registration of all RCTs is required on the European Union Clinical Trials Database (EudraCT) platform. The completion of the study must be followed by the prompt (within a year) publication of the results. Through this rule, the European Medicines Agency (EMA) aims to increase transparency and availability of the results, irrespectively of their publication in scientific journals.
"However, a review of the EudraCT entries revealed that only half (49.4%) of the completed trials reported their results promptly. The same trend was identified in the clinicaltrials.gov registry. Given that vitamin supplements are over-the-counter medications (i.e., available without a prescription) and consumed by most adults while often entailing various adverse events, compliance of the registered trials to the EMA rule for prompt results reporting is crucial for consumers’ health."
The authors conducted their own evaluation of vitamin supplement trials’ compliance with the EU requirement to post the results of the trials to the EudraCT, and assess the trial characteristics associated with this compliance.
The EudraCT was searched for completed trials on vitamin supplements by three independent researchers (M.L., S.K., D.B.). Trials were considered eligible when (1) performed on humans of any age and health status, (2) were completed, (3) involved an intervention with any vitamin supplement without concomitant medication, and (4) did not include vitamin supplements in the placebo comparator.
Out of the 360 trials identified, 95 consisted of duplicate entries and were removed. Of the remaining, 144 involved completed trials, including 40,464 participants. For 45.7% of identified registered trials, results were due.
Results analysis revealed that trial results were more likely to be reported when assessing vitamin safety and being sponsored by the industry. Trials funded by the industry had approximately quadrupled the chances of being published.
Many trials were also registered as ongoing, although in some cases 10 years had passed from the reported trial initiation date.
The report concludes: "The need for robust, transparent, and independent trials in nutrition research consists of a public health priority, and for this, specific guidelines have recently been developed by the NOURISH working group. Recently, the science of nutrition has been criticized for using inaccurate assessment methods and weak study designs, all of which undermine its integrity and usefulness for public health...
"...Research integrity and transparency through a collective effort are required to improve medical practice and medical nutrition therapy
"Selective publication of a trial’s findings endangers the fields of evidence-based medicine and nutrition and reduces the public’s trust to the industry. These fields are of critical importance to public health; thus, a collective approach is required to increase trial transparency. Moreover, the future calls for shared clinical data on the individual patient level, aiming to increase the application, aggregation, and reuse of clinical trial findings. At the moment however, trial data sharing appears inadequate in the EU, despite the fact that trial results affect the health of millions of people across the continent."
"Clinical Trials of Vitamin Supplements: Are They Meeting the European Medicines Agency Prompt Dissemination Regulation?"
Lampropoulou, M.A.; Grammatikopoulou, M.G.; Theodoridis, X.; Katsaridis, S.; Bobora, D.; Patsatsi, A.; Haidich, A.-B.; Goulis, D.G.