The causes, consequences and detection of publication bias in psychiatry

Objective: Publication bias threatens the validity of published research, a lthough this topic has received little attention in psychiatry. The purpose of this article is to produce a systematic overview of the causes and cons equences of publication bias and to summarize the available methods with wh ich it is detected and corrected. Method: Empirical evidence for the existence of publication bias is reviewe d and the following methods are applied to an illustrative case example fro m psychiatry: funnel plot analysis; the 'file drawer method'; linear regres sion techniques; rank correlation; 'trim and fill'. Results: Small studies are particularly susceptible to publication and rela ted bias. All methods to detect publication bias depend upon the availabili ty of a number of individual studies with a range of sample sizes. Unfortun ately, large numbers of studies of varying sample size are not always avail able in many areas of psychiatric research. Conclusion: Where possible researchers should always test for the presence of publication bias. The problem of publication bias will not be solved by anything other than a prospective trials register.