Improving reports of research and preparing and updating systematic reviews of reliable studies are essential foundations of effective health care.

Fair treatment comparisons avoid biases and reduce as far as possible the likelihood that users of research will be misled by the play of chance. These problems and their potential solutions have been discussed in earlier Explanatory Essays. However, even if the problems have been reduced as far as possible, health professionals, patients, policy makers and the public more generally may often find it difficult to make direct use of reports of research.

Often, this is because both the individual studies and systematic reviews of them are of poor quality. Too often reports fail to provide important details about the design, conduct and analysis of research studies; adequate descriptions of who participated in them; what was done to participants; and what effects treatments had on outcome measures of importance to patients and others (EE 4.1 Altman 1994).

Very occasionally, a single well conducted and well reported study provides really strong evidence of the beneficial effects of an easily given treatment. For example, tens of thousands of people participated in a remarkable study that showed that an aspirin tablet could substantially reduce the risk of death among people who are experiencing heart attacks (ISIS-2 1988). However, only very rarely does a single study provide such strong evidence, so it’s important when reading reports of individual studies to ask what other evidence – published and unpublished – is relevant. This is why treatment and policy choices should, as far as possible, be informed by systematic reviews of as high a proportion as possible of the relevant evidence.

Systematic reviews are necessary, but they too, are insufficient for informing decisions about treatments for individual patients and policies. Other important factors – needs, resources and priorities – need to be taken into account. And this is the point at which the art as well as the science of health care needs to be deployed for the benefit of patients and the public (EE 4.3 Chalmers 1993; Rothwell 2007).

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