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BMJ. Nov 19, 1994; 309(6965): 1351–1355.
PMCID: PMC2541868

Why sources of heterogeneity in meta-analysis should be investigated.

Abstract

Although meta-analysis is now well established as a method of reviewing evidence, an uncritical use of the technique can be very misleading. One common problem is the failure to investigate appropriately the sources of heterogeneity, in particular the clinical differences between the studies included. This paper distinguishes between the concepts of clinical and statistical heterogeneity and exemplifies the importance of investigating heterogeneity by using published meta-analyses of epidemiological studies of serum cholesterol concentration and clinical trials of its reduction. Although not without some dangers of speculative conclusions, prompted by overzealous inspection of the data to hand, a sensible investigation of sources of heterogeneity should increase both the scientific and the clinical relevance of the results of meta-analyses.

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Selected References

These references are in PubMed. This may not be the complete list of references from this article.
  • Dickersin K, Berlin JA. Meta-analysis: state-of-the-science. Epidemiol Rev. 1992;14:154–176. [PubMed]
  • Pagliaro L, D'Amico G, Sörensen TI, Lebrec D, Burroughs AK, Morabito A, Tiné F, Politi F, Traina M. Prevention of first bleeding in cirrhosis. A meta-analysis of randomized trials of nonsurgical treatment. Ann Intern Med. 1992 Jul 1;117(1):59–70. [PubMed]
  • Whitehead A, Whitehead J. A general parametric approach to the meta-analysis of randomized clinical trials. Stat Med. 1991 Nov;10(11):1665–1677. [PubMed]
  • Grantham-McGregor SM, Powell CA, Walker SP, Himes JH. Nutritional supplementation, psychosocial stimulation, and mental development of stunted children: the Jamaican Study. Lancet. 1991 Jul 6;338(8758):1–5. [PubMed]
  • DerSimonian R, Laird N. Meta-analysis in clinical trials. Control Clin Trials. 1986 Sep;7(3):177–188. [PubMed]
  • Peto R. Why do we need systematic overviews of randomized trials? Stat Med. 1987 Apr-May;6(3):233–244. [PubMed]
  • Law MR, Wald NJ, Thompson SG. By how much and how quickly does reduction in serum cholesterol concentration lower risk of ischaemic heart disease? BMJ. 1994 Feb 5;308(6925):367–372. [PMC free article] [PubMed]
  • MacMahon S, Peto R, Cutler J, Collins R, Sorlie P, Neaton J, Abbott R, Godwin J, Dyer A, Stamler J. Blood pressure, stroke, and coronary heart disease. Part 1, Prolonged differences in blood pressure: prospective observational studies corrected for the regression dilution bias. Lancet. 1990 Mar 31;335(8692):765–774. [PubMed]
  • Manolio TA, Pearson TA, Wenger NK, Barrett-Connor E, Payne GH, Harlan WR. Cholesterol and heart disease in older persons and women. Review of an NHLBI workshop. Ann Epidemiol. 1992 Jan-Mar;2(1-2):161–176. [PubMed]
  • Shipley MJ, Pocock SJ, Marmot MG. Does plasma cholesterol concentration predict mortality from coronary heart disease in elderly people? 18 year follow up in Whitehall study. BMJ. 1991 Jul 13;303(6794):89–92. [PMC free article] [PubMed]
  • Ravnskov U. Cholesterol lowering trials in coronary heart disease: frequency of citation and outcome. BMJ. 1992 Jul 4;305(6844):15–19. [PMC free article] [PubMed]
  • Smith GD, Song F, Sheldon TA. Cholesterol lowering and mortality: the importance of considering initial level of risk. BMJ. 1993 May 22;306(6889):1367–1373. [PMC free article] [PubMed]
  • Galbraith RF. A note on graphical presentation of estimated odds ratios from several clinical trials. Stat Med. 1988 Aug;7(8):889–894. [PubMed]
  • Thompson SG. Controversies in meta-analysis: the case of the trials of serum cholesterol reduction. Stat Methods Med Res. 1993;2(2):173–192. [PubMed]
  • Brand R, Kragt H. Importance of trends in the interpretation of an overall odds ratio in the meta-analysis of clinical trials. Stat Med. 1992 Dec;11(16):2077–2082. [PubMed]
  • Senn S. Importance of trends in the interpretation of an overall odds ratio in the meta-analysis of clinical trials. Stat Med. 1994 Feb 15;13(3):293–296. [PubMed]
  • Law MR, Thompson SG. Low serum cholesterol and the risk of cancer: an analysis of the published prospective studies. Cancer Causes Control. 1991 Jul;2(4):253–261. [PubMed]
  • Bailey KR. Inter-study differences: how should they influence the interpretation and analysis of results? Stat Med. 1987 Apr-May;6(3):351–360. [PubMed]
  • Yusuf S, Wittes J, Probstfield J, Tyroler HA. Analysis and interpretation of treatment effects in subgroups of patients in randomized clinical trials. JAMA. 1991 Jul 3;266(1):93–98. [PubMed]
  • Oxman AD, Guyatt GH. A consumer's guide to subgroup analyses. Ann Intern Med. 1992 Jan 1;116(1):78–84. [PubMed]
  • Stewart LA, Parmar MK. Meta-analysis of the literature or of individual patient data: is there a difference? Lancet. 1993 Feb 13;341(8842):418–422. [PubMed]
  • Easterbrook PJ, Berlin JA, Gopalan R, Matthews DR. Publication bias in clinical research. Lancet. 1991 Apr 13;337(8746):867–872. [PubMed]
  • Hughes MD, Freedman LS, Pocock SJ. The impact of stopping rules on heterogeneity of results in overviews of clinical trials. Biometrics. 1992 Mar;48(1):41–53. [PubMed]

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