"I like taking part in studies because it's for the greater good, like giving blood."(1)As reports of medical research show, there are almost no limits to what patients Will put up with if they believe that their actions may benefit others. Seemingly, no questionnaire is too probing, no programme of clinic visits and tests too gruelling, and no drug too vile to stop patients volunteering for research.
Yet much of their goodwill is wasted. Many more research projects are begun than are completed, many more projects are completed than are written up, and many more papers are written up than are published. Of those that are published many are of poor quality,2 and few provide their raw data in a form that readers could use to check the authors' claims. Patients could justifiably argue that they are being sold short, given the inconvenience and risk that research often entails.
Access to raw data, and their interpretation, lie at the heart of the latest skirmish in the salt wars, which dominate this week's BMJ. The president of the Salt Institute argues that "the entire Intersalt database... must be made available in its entirety to independent third parties for a thorough re-evaluation."3 Intersalt's researchers respond that they have done the further analyses suggested by the Salt Institute only to see the results either misused or ignored.4
Intersalt has hardly been sparing with its data: an appendix accompanying the original paper gave 27 columns of data for each of the 52 population samples. Subsequently, an issue of the Journal Hypertension devoted to the study carried 38 appendix tables, with 20 columns of data each. Further data have been published in peer reviewed journals. In addition, Intersalt researchers have said they are willing to do any scientifically sound and practically feasible further analyses proposed by the Salt Institute.
But what they will not do is hand over the raw Intersalt data. "As is customary in scientific investigation, raw data on individuals remain the confidential property of local investigators, in this case the 52 investigators in 32 countries."' Their justification is "the need to preserve the independence of scientific investigation, the integrity of the data, and the confidentiality of information on individuals."5
It is time for the customs to change if these are the strongest arguments that can be mustered in their support. Firstly, truly independent scientific investigation does not exist. The best we can hope for is for authors to be explicit about their methods and candid about any other relevant interests thus alerting us to possible biases. Secondly, data have no intrinsic integrity of their own, such that sharing them with someone else might lead to their corruption. Undoubtedly, misuse of data is one of the downsides of sharing, but it is a price worth paying. And as long as avenues exist for criticising subsequent analyses that are seriously flawed then no lasting harm need result.
Compelling arguments exist for sharing data; George Davey Smith listed several in a recent BMJ editorial (see box). To facilitate the process grant giving bodies could make funding conditional on willingness to share data. Clearing houses for shared data could be set up, thereby reducing the burden on primary researchers. Searchable registers of active and completed projects would help. Ethics committees could insist that protocols allow for data sharing, meaning that unpalatable findings could still see the light of day even if the original researchers do not submit them for formal publication. The problems of publication bias would recede.
- Arguments for sharing data (6)
- Using existing data to answer questions not directly addressed by the primary researchers is an efficient use of resources
Replicating findings from one study within other datasets increases their robustness
In planning a study data from earlier studies can help to formulate the research question, refine measurement instruments, and calculate sample sizes
New datasets can be created through linkage of different sets of records on the same people
It facilitates meta-analyses that combine data on individual patients
Other researchers can check whether conclusions are justified
Access to the original data from published studies makes fraud more difficult
Medical journals also have a role. Some, such as the American Journal of Public Health, stipulate that data should be available to the editors and interested researchers. But the infinite capacity of the Internet allows us to go much further. Constraints on space no longer exist, and electronic files containing a study's raw data can be linked to the electronic version of the paper, guaranteeing its availability to subsequent researchers, whatever their aims. The BMJ welcomes the inclusion of such files with submissions (providing subjects have given their consent).We would also welcome researchers' views on how this facility might develop and whether inclusion of such files should become obligatory. Prudent researchers will start obtaining their patients' consent for data sharing now.
Many different interests are at stake in clinical research: a recently published book on the topic, A Decent Proposal, lists future patients, present patients, clinicians, research subjects, purchasers of health care, sponsors of research, health research institutions, and individual researchers; Given the authors' claim that "conflicts of interest are not merely possible but pretty well inevitable," whose interests should we be most concerned to protect in medical research? The authors come down unequivocally on the side of the research subject. "This view is so widely accepted in modern Western medical practice, so well grounded in modern Western liberal thought, and moreover so firmly established at the heart of the whole institution of ethical review of clinical research, that we shall state it here without further justification."
If we give priority to the interests of the research subject then answering the question of how widely their data should be shared is easy. Patients volunteer for research because they want to benefit others. It is in their interests for the usefulness of their contribution to be maximised. Data sharing, rather than data hoarding, achieves this goal.
TONY DELAMOTHE Deputy editor, BMJ
2 Altman DG. The scandel of poor medical research . BMJ 1994;308:283-4
3 Hanneman RL, Intersalt: hypertension rise with age revisited. BMJ 1996;312:1283-4
4 Stamler J, Elliott P, Dyer AR, Stamler R, Kesteloot H, Marmot M, for the Intersalt Steering and Editorial Committee. Sodium and blood pressure in the Intersalt study and other studies; in reply to the Salt Institute. BMJ 1996;312:1285-7
5 Elliott P, Stamler J, Nichols R, Dyer A R, Stamler R, Kesteloot H, et al for the Intersalt Cooperative Research Group. Intersalt revisited: further analyses of 24 hour sodium excretion and blood pressure within and across populations. BMJ 1994:312:1249-53
6 Davey Smith G. Increasing the accessibility of data. BMJ 1994:308:1519-20
7 Evans D, Evans M. A decent proposal: ethical review of clinical research. Chichester Wiley 1996.