Systematic reviews can, if done well, provide a convenient and unbiased summary of the evidence on a particular topic. The presence of substantial heterogeneity in a meta-analysis is always of interest. On the one hand, it may indicate that there is excessive clinical diversity in the studies included, and that it is inappropriate to derive an estimate of overall effect from that particular set of studies. On the other hand, appropriate exploration of the source of heterogeneity may either identify poor design of the studies included or perhaps not even identify the cause; in either case, investigating the source of the heterogeneity may be identified as a topic for future research.

Keywords:
Systematic review, Meta-analysis, Heterogeneity
1.
Cochrane Handbook for Systematic Reviews of Interventions Version 5.0.2. 2009. www.cochrane-handbook.org.
2.
Wardlaw JM, Murray V, Berge E, del Zoppo GJ: Thrombolysis for acute ischaemic stroke. Cochrane Database Syst Rev 2009;4:CD000213.
3.
Collins R, MacMahon S: Reliable assessment of the effects of treatment on mortality and major morbidity. 1. Clinical trials. Lancet 2001;357:373–380.
4.
Schulz KF, Grimes DA: Multiplicity in randomised trials. 2. Subgroup and interim analyses. Lancet 2005;365:1657–1661.
5.
Counsell CE, Clarke MJ, Slattery J, Sandercock PA: The miracle of DICE therapy for acute stroke: fact or fictional product of subgroup analysis? BMJ 1994;309:1677–1681.
6.
Lees KR, Bluhmki E, von Kummer R, Brott TG, Toni D, Grotta JC, Albers GW, Kaste M, Marler JR, Hamilton SA, Tilley BC, Davis SM, Donnan GA, Hacke W, ECASS, ATLANTIS, NINDS and EPITHET rt-PA Study Group, Allen K, Mau J, Meier D, del Zoppo G, de Silva DA, Butcher KS, Parsons MW, Barber PA, Levi C, Bladin C, Byrnes G: Time to treatment with intravenous alteplase and outcome in stroke: an updated pooled analysis of ECASS, ATLANTIS, NINDS, and EPITHET trials. Lancet 2010;375:1695–1703.
© 2011 S. Karger AG, Basel
2011
Copyright / Drug Dosage / Disclaimer
Copyright: All rights reserved. No part of this publication may be translated into other languages, reproduced or utilized in any form or by any means, electronic or mechanical, including photocopying, recording, microcopying, or by any information storage and retrieval system, without permission in writing from the publisher.
Drug Dosage: The authors and the publisher have exerted every effort to ensure that drug selection and dosage set forth in this text are in accord with current recommendations and practice at the time of publication. However, in view of ongoing research, changes in government regulations, and the constant flow of information relating to drug therapy and drug reactions, the reader is urged to check the package insert for each drug for any changes in indications and dosage and for added warnings and precautions. This is particularly important when the recommended agent is a new and/or infrequently employed drug.
Disclaimer: The statements, opinions and data contained in this publication are solely those of the individual authors and contributors and not of the publishers and the editor(s). The appearance of advertisements or/and product references in the publication is not a warranty, endorsement, or approval of the products or services advertised or of their effectiveness, quality or safety. The publisher and the editor(s) disclaim responsibility for any injury to persons or property resulting from any ideas, methods, instructions or products referred to in the content or advertisements.
You do not currently have access to this content.