Indirect comparison meta-analysis of aspirin therapy after coronary surgery

doi:10.1136/bmj.327.7427.1309

BMJ 2003;327:1309 (6 December), doi:10.1136/bmj.327.7427.1309

Paper

Indirect comparison meta-analysis of aspirin therapy after coronary surgery

Eric Lim, specialist registrar in cardiothoracic surgery¹, Ziad Ali, senior house officer in cardiothoracic surgery¹, Ayyaz Ali, clinical fellow in cardiothoracic surgery¹, Tom Routledge, specialist registrar in cardiothoracic surgery¹, Lyn Edmonds, clinical library manager², Douglas G Altman, professor of statistics in medicine³, Stephen Large, consultant cardiothoracic surgeon¹

¹ Department of Cardiothoracic Surgery, Papworth Hospital, Cambridge CB3 8RE, ² Clinical Library Service, Papworth Hospital, ³ Cancer Research UK/NHS Centre for Statistics in Medicine, Institute for Health Services, Oxford OX3 7LF

Correspondence to: E Lim, Department of Cardiothoracic Surgery, Royal Brompton Hospital, London SW3 6NP eric.lim2{at}cvsnet.org

Objectives To evaluate the efficacy of low and medium dose aspirintherapy after coronary surgery by using an indirect comparisonmeta-analysis.

Data sources Systematic literature search of Medline, Embase,Cochrane controlled trials register, and trial register siteson the internet.

Study selection Outcome was evaluated by angiography and reportedas graft occlusion and rate of events in patients. Trials thatdid not include aspirin as the sole therapy or did not havea placebo control arm were excluded. Articles were assessedfor eligibility and quality and grouped according to dosage.The estimated difference in effect of low and medium dose aspirinon graft occlusion was obtained by combining the estimated logrelative risks of low dose with placebo and medium dose withplacebo.

Results For graft occlusion, the medium dose trials yieldeda relative risk reduction of 45% compared with 26% for the lowdose trials. The greater effect in the medium dose trials issummarised by a relative risk ratio of 0.74 (95% confidenceinterval 0.52 to 1.06; P = 0.10) for graft occlusion and 0.81(0.57 to 1.16; P = 0.25) for events in patients.

Conclusions Medium dose aspirin may more successfully reducegraft occlusion than low dose regimens within the first yearafter coronary surgery.

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Medium dose aspirin may improve graft patency
BMJ 2003 327: 0. [Full Text]

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Rapid Responses:

Read all Rapid Responses

BMJ save us: Simon Grant
bmj.com, 8 Dec 2003 [Full text]
Hype over substance: Saul G Myerson
bmj.com, 9 Dec 2003 [Full text]
The trials differ too much to make indirect comparisons: Christopher J Cates
bmj.com, 9 Dec 2003 [Full text]
Authors' Reply: Eric Lim
bmj.com, 12 Dec 2003 [Full text]
Independent Prospective Inclusion Criteria are vital for unbiased Meta-analysis: Joel Dunning, et al.
bmj.com, 22 Dec 2003 [Full text]
Aspirin after coronary bypass surgery - medium versus low dose improves graft patency: Thomas Hohlfeld
bmj.com, 7 Jan 2004 [Full text]
First principles or evidence based critique?: Eric Lim
bmj.com, 9 Jan 2004 [Full text]
Can we replace uncertainty with certainty ?: Joel Dunning
bmj.com, 13 Jan 2004 [Full text]
Reservations with Indirect Comparisons: Steven A. Julious
bmj.com, 1 Sep 2005 [Full text]