Dissemination of the published results of an important clinical trial: an analysis of the citing literature.

The definitive clinical trial which demonstrated the beneficial effects of photocoagulation in treating diabetic retinopathy was reported in 1976 in the American Journal of Ophthalmology by the Diabetic Retinopathy Study (DRS) Research Group. Despite the importance of this report, eighteen months after it appeared in print the photocoagulation technique was still not widely known to a population of physicians whose practice included an appreciable number of diabetic patients. As part of a study in biomedical communication, the extent to which the results of this trial were disseminated through the published literature was investigated by citation analysis. Seventy citations to the DRS report, from 1976 to 1979, were found in Science Citation Index. Twenty-seven citations were in works outside the discipline of ophthalmology and nine of these came from articles in American journals which actually referred to the results of the trial. Not a single citation which appeared before 1978 came from a general American medical journal, unrestricted in geographic or subject scope. The results of this study suggest that a large number of citations in the literature to a clinically significant paper does not of itself ensure that the information reported will readily reach the appropriate practicing physician. More effective methods are needed for the rapid dissemination of important new findings to the medical community.