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Review
. 2001 Jul 14;323(7304):101-5.
doi: 10.1136/bmj.323.7304.101.

Systematic reviews in health care: Investigating and dealing with publication and other biases in meta-analysis

J A Sterne  1 , M Egger, G D Smith
Affiliations
Review

Systematic reviews in health care: Investigating and dealing with publication and other biases in meta-analysis

J A Sterne et al. BMJ. .
No abstract available

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Figures

Figure 1
Figure 1
Hypothetical funnel plots: left, symmetrical plot in absence of bias (open circles are smaller studies showing no beneficial effects); centre, asymmetrical plot in presence of publication bias (smaller studies showing no beneficial effects are missing); right, asymmetrical plot in presence of bias due to low methodological quality of smaller studies (open circles are small studies of inadequate quality whose results are biased towards larger effects). Solid line is pooled odds ratio and dotted line is null effect (1). Pooled odds ratios exaggerate treatment effects in presence of bias
Figure 2
Figure 2
Regression lines, adjusted for number of measurements of urinary sodium concentration, of predicted change in blood pressure for change in concentration of urinary sodium from randomised controlled trials of reduction in dietary sodium. Intercepts indicate decline in blood pressure even if diets in intervention and control groups were identical, which may indicate presence of bias. Modified from Midgley et al20
Figure 3
Figure 3
Asymmetrical funnel plot of 89 randomised controlled trials comparing homoeopathic medicine with placebo identified by Linde et al25 (top) and application of the “trim and fill” method (bottom). Solid circles represent the 89 trials and open diamonds “filled” studies. Solid line is original (random effects) estimate of pooled odds ratio (0.41), dashed line is adjusted estimate (0.52, including filled studies), and dotted line is null value (1)
See this image and copyright information in PMC

References

    1. Easterbrook PJ, Berlin JA, Gopalan R, Matthews DR. Publication bias in clinical research. Lancet. 1991;337:867–872. - PubMed
    1. Dickersin K, Min YI, Meinert CL. Factors influencing publication of research results: follow-up of applications submitted to two institutional review boards. JAMA. 1992;263:374–378. - PubMed
    1. Stern JM, Simes RJ. Publication bias: evidence of delayed publication in a cohort study of clinical research projects. BMJ. 1997;315:640–645. - PMC - PubMed
    1. Egger M, Zellweger-Zähner T, Schneider M, Junker C, Lengeler C, Antes G. Language bias in randomised controlled trials published in English and German. Lancet. 1997;350:326–329. - PubMed
    1. Gøtzsche PC. Reference bias in reports of drug trials. BMJ. 1987;295:654–656. - PMC - PubMed