|
Does off-pump coronary artery bypass reduce mortality, morbidity, and resource utilization when compared with conventional coronary artery bypass: a meta-analysis of randomized trials |
Cheng D C, Bainbridge D, Martin J E, Novick R J |
|
|
CRD summary This review compared off-pump coronary artery bypass (CAB) with conventional CAB. The authors concluded that off-pump CAB did not reduce mortality, stroke or myocardial infarction; however, selected short-term and mid-term clinical and resource outcomes were improved. This was a reasonable review, but some conclusions were based on estimates derived by combining dissimilar studies and may be unreliable.
Authors' objectives To assess whether off-pump coronary artery bypass (CAB) reduces mortality or resource utilisation compared with conventional CAB.
Searching MEDLINE, the Cochrane CENTRAL Register, EMBASE, Current Contents, DARE, NHS EED and HTA were searched from their inception to May 2004. The search terms were reported and no language restrictions were applied. The bibliographies of articles, relevant meeting abstracts and related journals were also handsearched.
Study selection Study designs of evaluations included in the reviewBlinded or unblinded randomised controlled trials (RCTs) were eligible for inclusion in the review.
Specific interventions included in the reviewStudies of off-pump CAB on the beating heart compared with conventional CAB on the asystolic heart with cardiopulmonary bypass circuit were eligible for inclusion. Hybrid (such as off-pump CAB plus balloon angioplasty) and robotically assisted surgery studies were excluded.
Participants included in the reviewStudies of adults undergoing single- or multiple-vessel bypass were eligible for inclusion. The participants in the majority of the included studies were undergoing first time and/or elective coronary artery bypass graft.
Outcomes assessed in the reviewStudies reporting at least one pertinent clinical or economic outcome were eligible for inclusion. The primary outcome was defined as all-cause mortality at 30 days, 6 months and greater than one year. A wide variety of secondary outcomes were defined.
How were decisions on the relevance of primary studies made?Three reviewers independently identified trials for inclusion in the review.
Assessment of study quality Studies were assessed for randomisation, blinding and completeness of follow-up using the 5-point Jadad scale. Two reviewers independently assigned quality scores to each trial included in the review. Any disagreements were resolved by consensus.
Data extraction Three reviewers independently extracted data from the studies included in the review. Where necessary, authors were contacted for clarification of data.
Methods of synthesis How were the studies combined?For dichotomous variables, the combined odds ratio (OR) with 95% confidence intervals (CIs) was calculated. For continuous variables, the combined weighted mean difference (WMD) was calculated. For each outcome, the Mantel-Haenszel fixed-effect model or DerSimonian and Laird random-effects model were used, depending on the suggested lack of or presence of heterogeneity, respectively. Wherever possible, data analysis was by intention-to-treat. Publication bias was assessed visually by the use of funnel plots.
How were differences between studies investigated?Heterogeneity was assessed using the Q-statistic, with a P-value of less than 0.10 indicating the possible presence of heterogeneity. In addition, the I-squared statistic was calculated to quantify the degree of heterogeneity across trials. Subgroup analyses on the following were undertaken: trials with elderly patients (older than 70 years); patients undergoing urgent or re-do bypass; patients with chronic obstructive pulmonary disease or renal failure at baseline; patients requiring conversion from off-pump to conventional CAB; and trials where ventricular assist devices were used. These trials were grouped according to whether patients had single-, multiple- or mixed-vessel disease, and differences were tested using a chi-squared test. Sensitivity analyses assessing the effects of trial quality (Jadad score <3 versus >3), publication status (published versus unpublished), and 'worst-case scenario' assumptions for trials with non intent-to-treat analyses were performed. Other potential reasons for heterogeneity were discussed in the paper,
Results of the review Thirty-seven RCTs (n=3,369) were included.
The median quality score was 2 (range: 1 to 3). There was no evidence of publication bias for any end point. There was no evidence of statistical heterogeneity with regards to all-cause mortality. However, heterogeneity was identified in relation to atrial fibrillation, transfused patients, neurocognitive dysfunction at 30 days, ventilation time, intensive care unit and hospital length of stay.
There was no evidence of any significant differences between off-pump CAB and conventional CAB for 30-day mortality, myocardial infarction, stroke, renal dysfunction, intra-aortic balloon pump, wound infection, rethoracotomy or re-intervention. There was evidence of significant differences in favour of off-pump CAB for decreasing atrial fibrillation (OR 0.58, 95% CI: 0.44, 0.77), transfusion (OR 0.43, 95% CI: 0.29, 0.65), inotrope requirements (OR 0.48, 95% CI: 0.32, 0.73), respiratory infections (OR 0.41, 95% CI: 0.23, 0.74), ventilation time (WMD -3.4 hours, 95% CI: -5.1, -1.7), intensive care unit stay (WMD -0.3 days, 95% CI: -0.6, -0.1) and hospital stay (WMD -1.0 days, 95% CI: -1.5, -0.5).
Of the subgroup analyses that were performed, the only statistically significant difference identified was for patients transfused when evaluated by number of grafts performed (P=0.001). The results of the meta-analyses did not change substantially during the sensitivity analyses.
Cost information Five studies presented cost information. Each of these trials found off-pump CAB to be less costly than conventional CAB, with in-hospital cost reductions ranging from approximately 15 to 35%.
Authors' conclusions Mortality, stroke, myocardial infarction and renal failure were not reduced for off-pump CAB compared with conventional CAB; however, selected short-term and mid-term clinical and resource outcomes were improved.
CRD commentary This review addressed a clear question in terms of the interventions, participants, outcomes and study designs of interest. Several relevant sources were searched with attempts made to limit language and publication bias. The methods employed during the study selection, validity assessment and data extraction processes were adequate to ensure that the possibility of reviewer bias or error was minimised. The quality of the included studies was assessed using an appropriate, validated scale. Limited details about the individual study results were presented. The studies were combined using meta-analysis but, since the results were not consistent across studies for some meta-analyses, it may have been inappropriate to use meta-analysis to summarise treatment effects for some of the outcomes included in the review. Overall, this was a reasonable review but the value of some of the conclusions, which were based on meta-analyses of heterogeneous studies, is questionable.
Implications of the review for practice and research Practice: The authors stated that the decision between using off-pump or conventional CAB should be made with careful consideration of such uncertainties as operator experience, contemporary practice patterns (e.g. blood conserving strategies) and clinical pathways for expedited discharge.
Research: The authors stated that further research on defining long-term clinical, economic and quality-of-life outcomes associated with differing revascularisation techniques is required. Consideration should also be given to exploration of the net treatment benefit according to well-defined patient risk groups: ideally, randomised trials in high-risk patients.
Bibliographic details Cheng D C, Bainbridge D, Martin J E, Novick R J. Does off-pump coronary artery bypass reduce mortality, morbidity, and resource utilization when compared with conventional coronary artery bypass: a meta-analysis of randomized trials. Anesthesiology 2005; 102(1): 188-203 Indexing Status Subject indexing assigned by NLM MeSH Coronary Artery Bypass /adverse effects /economics /mortality; Coronary Artery Bypass, Off-Pump; Data Interpretation, Statistical; Endpoint Determination; Extracorporeal Circulation /adverse effects /economics /mortality; Humans; Postoperative Complications /economics /epidemiology /psychology; Quality of Life; Randomized Controlled Trials as Topic; Resource Allocation; Treatment Outcome AccessionNumber 12005009422 Date bibliographic record published 30/06/2006 Date abstract record published 30/06/2006 Record Status This is a critical abstract of a systematic review that meets the criteria for inclusion on DARE. Each critical abstract contains a brief summary of the review methods, results and conclusions followed by a detailed critical assessment on the reliability of the review and the conclusions drawn. |
|
|
|