Checklist for quality assessment and scoring* of non-randomised studies
| *Studies were graded on an ordinal star scoring scale with higher scores indicating studies of higher quality. A study could be awarded a maximum of one star for each numbered item within the selection and exposure categories, and a maximum of four stars could be given for the comparability of the two groups. The quality of each study was graded as either level 1 (0–5) or level 2 (6–9). | |
| †Comparability variables: 1, age; 2, sex; 3, diabetes; 4, hypertension; 5, ejection fraction; 6, history of vascular disease (cerebrovascular and peripheral); 7, non-elective operation; 8, unstable angina; 9, repeat operation. | |
| CABG, coronary artery bypass grafting. | |
| Selection | |
| 1. | Assignment for treatment: were any criteria reported? (If yes, one star) |
| 2. | Was the reference group (on-pump coronary artery bypass) representative of the general elderly population for CABG? (If yes, one star; no star if the patients were selected or selection of group was not described.) |
| 3. | Was the treatment group (off-pump coronary artery bypass) representative of the elderly population for CABG? (If drawn from the same community as the reference group, one star; no star if drawn from a different source or selection of group was not described.) |
| Comparability | |
| 4. | Was the group comparable for variables† 1, 2, 3, 4 and 5? (If yes, two stars; one star was assigned if one of these five characteristics was not reported even if there were no other differences between the two groups and other characteristics had been controlled for. No star was assigned if the two groups differed.) |
| 5. | Was the group comparable for variables† 6, 7, 8 and 9? (If yes, two stars; one star was assigned if one of these four characteristics was not reported even if there were no other differences between the two groups and other characteristics had been controlled for. No star was assigned if the two groups differed.) |
| Outcome assessment | |
| 6. | Was the outcome of interest clearly defined? (If yes, one star for information ascertained by record lineage or interview; no star was assigned if this information was not reported.) |
| 7. | Was follow up adequate? (One star if follow up was >90%.) |