Publication and other selection biases in systematic reviews


Literature review is becoming increasingly important in summarising research evidence for clinical and health policy decision making because of a rapidly expanding volume of medical research. However, the results of literature reviews will be misleading if the published studies comprise a biased sample of all the studies that have been conducted. This review aimed to identify systematically and appraise studies that have examined methodological issues and provided empirical evidence about publication bias and other dissemination-related biases, including biases due to the time, type and language of publication, multiple publication, selective citation of references, database index bias, and biased media attention.


Although the extent, direction and impact of publication and related biases are uncertain and may vary greatly depending on circumstances, it seems reasonable to conclude that studies with significant or favourable results are more widely disseminated than those with non-significant or unfavourable results. The potential problem of publication and related biases should be taken into consideration in the field of health technology assessment. All funded or approved studies should be prospectively registered. The risk of publication bias should be assessed in all systematic reviews.

Conducted by: F Song1, AJ Eastwood1, S Gilbody1, L Duley2, AJ Sutton3

1. NHS Centre for Reviews and Dissemination; 2. Magpie Trial, Institute of Health Sciences, Oxford; 3. Department of Epidemiology and Public Health, University of Leicester

Further details

Project page on HTA Programme website


Song F, Eastwood AJ, Gilbody S, Duley L, Sutton AJ. Publication and related biases. Health Technol Assess. 2000;4(10):1-115

Gilbody SM, Song F, Eastwood AJ, Sutton A. The causes, consequences and detection of publication bias in psychiatry. Acta Psychiatr Scand. 2000;102(4):241-9


Commissioned by the HTA Programme