| Characteristics of nonrandomized studies, n = 41 | Characteristic status; no. studies (OR)* [95% CI] | |
|---|---|---|
| Present | Absent | |
| Prospective data collection | 25 (0.67) [0.60–0.76] | 16 (0.68) [0.52–0.89] |
| Concurrent (v. historical) controls | 39 (0.70) [0.64–0.76] | 2 (0.61) [0.22–1.63] |
| Matching of groups | 12 (0.52) [0.35–0.78] | 29 (0.71) [0.66–0.78] |
| Systematic outcome assessment | 9 (0.76) [0.72–0.80] | 32 (0.60) [0.49–0.74] |
CI = confidence interval; OR = odds ratio.
↵* Odds ratio for experiencing a complication following laparoscopic-assisted surgery, compared with conventional surgery.