- Systematic reviews of published randomized clinical trials (RCTs) are considered the gold standard source of synthesized evidence for interventions, but their conclusions are vulnerable to distortion when trial sponsors have strong interests that might benefit from suppressing or promoting selected data.
- More reliable evidence synthesis would result from systematic reviewing of clinical study reports—standardized documents representing the most complete record of the planning, execution, and results of clinical trials, which are submitted by industry to government drug regulators.
- Unfortunately, industry and regulators have historically treated clinical study reports as confidential documents, impeding additional scrutiny by independent researchers.
- We propose clinical study reports become available to such scrutiny, and describe one manufacturer's unconvincing reasons for refusing to provide us access to full clinical study reports. We challenge industry to either provide open access to clinical study reports or publically defend their current position of RCT data secrecy.
Regulatory approval of new drugs is assumed to reflect a judgment that a medication's benefits outweigh its harms. Despite this, controversy over approved drugs is common. If sales can be considered a proxy for utility, the controversies surrounding even the most successful drugs (such as blockbuster drugs) seem all the more paradoxical, and have revealed the extent to which the success of many drugs has been driven by sophisticated marketing rather than verifiable evidence ,. But even among institutions that aim to provide the least biased, objective assessments of a drug's effects, determining “the truth” can be extremely difficult.
Consider the case of the influenza antiviral Tamiflu (oseltamivir). Prior to the global outbreak of H1N1 influenza in 2009, the United States alone had stockpiled nearly US$1.5 billion dollars worth of the antiviral . As the only drug in its class (neuraminidase inhibitors) available in oral form, Tamiflu was heralded as the key pharmacologic intervention for use during the early days of an influenza pandemic when a vaccine was yet to be produced. It would cut hospitalizations and save lives, said the US Department of Health and Human Services (HHS) . The Advisory Committee on Immunization Practices (ACIP, the group the US Centers for Disease Control and Prevention [CDC] uses to form national influenza control policy) said it would reduce the chances of developing complications from influenza . So, too, did the Australian Therapeutic Goods Administration  and the European Medicines Agency (EMA) .
Most (perhaps all) of these claims can be traced back to a single source: a meta-analysis published in 2003 that combined ten randomized clinical trials conducted during the late 1990s by the manufacturer prior to US registration of the drug . This analysis, conducted by Kaiser and colleagues, proposed that oseltamivir treatment of influenza reduced both secondary complications and hospital admission. In contrast, the Food and Drug Administration (FDA), which approved Tamiflu in 1999 and was aware of these same clinical trials, concluded that Tamiflu had not been shown to reduce complications, and required an explicit statement in the drug's label to that effect . FDA even cited Roche, Tamiflu's manufacturer, for violation of the law for claims made to the contrary .
Nor did the FDA approve an indication for Tamiflu in the prevention of transmission of influenza ,. This assumption was at the heart of the World Health Organization's (WHO) proposed plan to suppress an emergent pandemic through mass prophylaxis . While the WHO recently added Tamiflu to its Essential Medicines list, if FDA is right, the drug's effectiveness may be no better than aspirin or acetaminophen (paracetemol). The FDA has never clarified the many discrepancies in claims made over the effects of Tamiflu. Although it may have limited approval indications accordingly, the FDA has never challenged the US HHS or the US CDC for making far more ambitious claims. This means that critical analysis by an independent group such as a Cochrane review group is essential.
But which data should be used? In updating our Cochrane review of neuraminidase inhibitors, we have become convinced that the answer lies in analyzing clinical study reports rather than the traditional published trials appearing in biomedical journals . Clinical study reports contain the same information as journal papers (usually in standardized sections, including an introduction, methods, results, and conclusion ), but have far more detail: the study protocol, analysis plan, numerous tables, listings, and figures, among others. They are far larger (hundreds or thousands of pages), and represent the most complete synthesis of the planning, execution, and results of a clinical trial. Journal publications of clinical trials may generate media attention , propel researchers' careers, and generate some journals a revenue stream . However, when regulators decide whether to register a new drug in a manufacturer's application, they review the trial's clinical study report.
In 2010, we began our Cochrane review update using clinical study reports rather than published papers . We obtained some sections of these clinical study reports for the ten trials appearing in the Kaiser 2003 meta-analysis from Tamiflu's manufacturer, Roche—around 3,200 pages in total. In 2011, we obtained additional sections of clinical study reports for Tamiflu through a Freedom of Information request to the EMA, amounting to tens of thousands of pages. While extensive and detailed, it is important to note that what we have obtained is just a subset of the full clinical study reports in Roche's possession. Nonetheless, Box 1 provides a list of details we have already discovered—and would have never discovered without access to these documents. This information has turned our understanding of the drug's effects on its head. Other drugs for which previously unpublished, detailed clinical trial data have radically changed public knowledge of safety and efficacy include Avandia, Neurontin, and Vioxx (Table 1).
Box 1. What Is Missed without Access to Tamiflu Clinical Study Reports
- Knowledge of the total denominator. (How many trials were conducted on this drug that might fit the systematic review inclusion criteria?) 
- Realization that serious adverse events (SAEs) occurred in trials for which SAEs were not reported in published papers .
- Understanding what happened in some trials that were published 10 years after completion .
- Vital details of trials (content and toxicity profile of placebos, mode of action of drug, description and temporality of adverse events) .
- Authorship is not consistent with published papers  (although, if a review's inclusion criteria include clinical study reports, authorship is not an issue, as the responsibility is clearly the manufacturer's).
- Rationale for alternatively classifying outcomes such as pneumonia as a complication or an adverse event .
- Ability to know whether key subgroup analysis (influenza-infected subjects) is valid .
- Assessment of validity of previously released information on the drug (articles, reviews, conferences, media, etc.).
- Realization that Roche's claim of Tamiflu's mode of action  appears inconsistent with the evidence from trials ,.