6. Sensitivity analyses ‐ risk of bias (selection bias).
| All studies | Without high/unclear risk of bias studies (selection bias) | ||||
| Outcome | Statistical method | Studies | Effect estimate | Studies | Effect estimate |
| Pain score, rest, 'early time points' (1 hr to 4 hrs, PACU) | SMD (IV, Random, 95% CI) | 29 | −0.50 (−0.72 to −0.28) | 6 | −0.23 (−0.51 to 0.05) |
| Pain score, rest, 'intermediate time points' (24 hrs) | SMD (IV, Random, 95% CI) | 33 | −0.14 (−0.25 to −0.04) | 6 | 0.09 (−0.13 to 0.30) |
| Pain score, rest, 'late time points' (48 hrs) | SMD (IV, Random, 95% CI) | 24 | −0.11 (−0.25 to 0.04) | 3 | 0.03 (−0.24 to 0.29) |
| Postoperative ileus (dichotomous) | RR (MH, Random, 95% CI) | 4 | 0.37 (0.15 to 0.87) | 0 | Not estimable |
| Time to first defaecation/bowel movement (hrs) | MD (IV, Random, 95% CI) | 12 | −7.92 (−12.71 to −3.13) | 2 | −6.18 (−11.19 to −1.18) |
| Time to first flatus (hrs) | MD (IV, Random, 95% CI) | 13 | −4.09 (−6.30 to −1.87) | 2 | −3.27 (−6.33 to −0.21) |
| Time to first bowel sounds (hrs) | MD (IV, Random, 95% CI) | 2 | −6.08 (−13.77 to 1.60) | 0 | Not estimable |
| Length of hospital stay (days) | MD (IV, Random, 95% CI) | 32 | −0.37 (−0.60 to −0.15) | 3 | −0.13 (−0.70 to 0.44) |
| Length of hospital stay (outpatient surgery, mins) | MD (IV, Random, 95% CI) | 3 | −10.81 (−36.93 to 15.31) | 3 | −10.81 (−36.93 to 15.31) |
| Surgical complications ‐ anastomotic leak | RR (MH, Random, 95% CI) | 3 | 0.61 (0.08 to 4.80) | 0 | Not estimable |
| Surgical complications ‐ bleeding | RR (MH, Random, 95% CI) | 3 | 1.79 (0.41 to 7.89) | 0 | Not estimable |
| Surgical complications ‐ postoperative infection | RR (MH, Random, 95% CI) | 5 | 1.64 (0.41 to 6.52) | 0 | Not estimable |
| Patient satisfaction | MD (IV, Random, 95% CI) | 6 | 0.76 (0.46 to 1.06) | 2 | 0.59 (−0.09 to 1.26) |
| Postoperative nausea, early (PACU) | RR (MH, Random, 95% CI) | 8 | 0.72 (0.53 to 0.98) | 3 | 0.64 (0.30 to 1.37) |
| Postoperative nausea, overall (0 to 24 hrs, to 48 hrs, to 72 hrs) | RR (MH, Random, 95% CI) | 35 | 0.78 (0.67 to 0.91) | 8 | 0.99 (0.69 to 1.42) |
| Postoperative vomiting, early (PACU) | RR (MH, Random, 95% CI) | 4 | 0.49 (0.16 to 1.48) | 2 | 0.39 (0.11 to 1.38) |
| Postoperative vomiting, overall (0 to 24 hrs, to 48 hrs, to 72 hrs) | RR (MH, Random, 95% CI) | 19 | 0.83 (0.63 to 1.08) | 3 | 1.33 (0.50 to 3.53) |
| Intraoperative opioid consumption (MEQ, mg) | MD (IV, Random, 95% CI) | 18 | −2.14 (−3.87 to −0.40) | 3 | −3.28 (−6.56 to −0.00) |
| Intraoperative opioid consumption with remifentanil (MEQ, mg) | MD (IV, Random, 95% CI) | 6 | −14.17 (−35.27 to 6.92) | 2 | −9.53 (−59.18 to 40.12) |
| Postoperative opioid consumption, PACU (MEQ, mg) | MD (IV, Random, 95% CI) | 21 | −3.10 (−3.87 to −2.32) | 6 | −2.69 (−4.13 to −1.24) |
| Postoperative opioid consumption, overall (MEQ, mg) | MD (IV, Random, 95% CI) | 40 | −4.52 (−6.25 to −2.79) | 10 | −2.74 (−5.60 to 0.13) |
Acronyms and abbreviations used in this table:
CI = confidence interval, IV = inverse variance, MD = mean difference, MEQ = morphine equivalent dose, MH = Mantel Haenszel, PACU = postanaesthesia care unit, RR = risk ratio, SMD = standardized mean difference