Critical appraisal and positive outcome bias in case reports published in Brazilian dental journals.

The aim of this study was to carry out a critical appraisal to detect the occurrence of publication bias, specifically positive-outcome bias, in Brazilian dental journals. A convenience sample of twenty-eight dental journals published in Brazil between 1994 and 2003 was selected (564 issues containing 5,453 articles). Each article was classified according to methodological design; 1,064 were classified as case reports. A simple random sample of 435 articles comprised the final study sample and was submitted to a critical appraisal by previously trained raters. Although a great part of case reports achieve proper structural aspects, most authors did not consider important aspects that could help the decision making process, such as discussion of alternative approaches, limitation of the performed procedures, lack of long-term clinical follow-up, possible variations in treatment outcome, and failure to discuss limitations of study design. In addition, unanimous reports of successful outcomes of clinical interventions strongly suggest that publication of case reports was influenced by positive outcome bias, which may influence readers' clinical decision making process.