Registration of observational studies

Observational studies, such as cohort and case-control studies, are an important form of medical research, but they are also vulnerable to bias and selective reporting.1 They often produce large datasets that can be subjected to multiple analyses. Researchers may then craft a paper that selectively emphasises certain results, often those that are statistically significant or provocative. These decisions may reflect strong financial or academic interests and prior beliefs. At present, consumers of observational research cannot easily distinguish hypothesis driven studies from exploratory, post hoc data analyses. Researchers do not routinely disclose the number of additional analyses performed. Nor is there any satisfactory way to know whether the research questions or methods of statistical analysis diverged from those initially planned. It has been observed that there is “little or no penalty” for data dredging and selective reporting. Rather than attracting censure it can “get you into the BMJ and the Friday papers.”2

In the linked article (doi: 10.1136/bmj.b4184), Hemingway and colleagues reinforce many of these arguments, particularly with respect to studies of prognosis, because these can be important clinically but are often flawed.3 This group, which includes two of the BMJ’s statistics editors, Doug Altman and Richard Riley, recommends that “all research on humans should have a protocol.” Such calls for registries of observational research are gathering pace, and indeed an international meeting held …