Objectives and hypotheses
Are the objectives of the study clearly stated?
The objectives are to study whether revascularisation is less complete with OFFPUMP Surgery compared to ONPUMP surgery
Is the study design suitable for the objectives
This is an excellent design to answer this question, a single blinded randomised controlled trial
Who / what was studied?
200 non consecutive patients operated on over a 17-month period by a single surgeon in the USA
Was this the right sample to answer the objectives?
This was a single surgeon series operated on in the USA. There were few exclusion criteria except for emergency or salvage operations.
Is the study large enough to achieve its objectives? Have sample size estimates been performed?
Yes , good sample size calculations have been presented
Were all subjects accounted for?
Yes. 200 patients recruited but 3 patients were excluded post randomisation as they were found to need valve surgery after echocardiography.
Were all appropriate outcomes considered?
Graft patency, serial enzymes, length of stay ,
Future study will look at 6 month F/U and angiographic data
Has ethical approval been obtained if appropriate?
Were the patients randomised between treatments?
How was randomisation carried out?
computerised block randomisation stratified to sex and diabetes.
Are the outcomes clinically relevant?
Completness of revascularisation has been a major concern of OFF PUMP surgery thus this outcome is believed by many to be important.
Measurement and observation
Is it clear what was measured, how it was measured and what the outcomes were?
Baseline characteristics were similar. The number of grafts performed per
patient (mean 3.39 +/-1.04 for off-pump coronary artery bypass grafting,
3.40 +/- 1.08 for conventional coronary artery bypass grafting) and the index of completeness of revascularization (number of grafts performed/number of grafts intended, 1.00 +/-0.18 for off-pump coronary artery bypass grafting, 1.01 +/- 0.09 for conventional coronary artery bypass grafting) were similar. Likewise, the index of completeness of revascularization was similar between groups for the lateral wall.
Combined hospital and 30-day mortalities and stroke rates were similar. Postoperative myocardial serum enzyme measures were significantly lower after off-pump coronary artery bypass grafting, suggesting less myocardial injury. Adjusted postoperative thromboelastogram indices, fibrinogen, international normalized ratio, and platelet levels all showed significantly less coagulopathy after off-pump coronary
Are the measurements valid?
Primary outcome measure was completeness of revascularisation which is determined by comparing OFFPUMP to ONPUMP surgery.
This and all the other outcomes were hard outcome measures and therefore a valid measurement of the intended outcomes.
The issue as to whether completeness of revascularisation is a valid measure of the quality of the operation or the success of the operation is open to question
Are the measurements reliable?
Are the measurements reproducible?
Were the patients and the investigators blinded?
Surgeon and theatre staff were not blinded. Data collectors and ward staff were blinded to the method as was the patient. A rigorous method of off site data collection was instituted.
Presentation of results
Are the basic data adequately described?
Were groups comparable at baseline?
Yes, There were more histories of CVA and higher CCS score in the ONPUMP group but no other differences.
Are the results presented clearly, objectively and in sufficient detail to enable readers to make their own judgement?
Are the results internally consistent, i.e. do the numbers add up properly?
Were side effects reported?
4 Deaths were reported in each group, there were more effusions in the ONPUMP group and all other side effects were comparable
Are the data suitable for analysis?
Are the methods appropriate to the data?
Yes. Fishers Exact test for discrete variables and Wilcoxons-Rank sum test for rank variables eg completeness of revascularisation
Are any statistics correctly performed and interpreted?
Are the results discussed in relation to existing knowledge on the subject and study objectives?
Yes, the other 3 RCTs in this area are discussed and the concerning results from Cohort studies that showed lower levels of revascularisation are fairly discussed.
Is the discussion biased?
There are no mention of whether reduced revascularisation causes increased rates of angina or mortality and therefore whether it is important.
Are the authors' conclusions justified by the data?
They are perhaps inflated a little as this is a single surgeon demonstrating that he can place the same number of grafts in his ONPUMP and OFF PUMP patients. However his hospital stay, and cardiac enzyme data is impressive
What level of evidence has this paper presented? (using CEBM levels)
Does this paper help me answer my problem?
This adds to the supportive literature in favour of OFFPUMP surgery due to its high quality construction although this is still a single surgeon series
Can any necessary change be implemented in practice?
What aids to implementation exist?
What barriers to implementation exist?