The usage rate of rescue analgesia
Eleven studies (26, 29-32, 37, 43-46, 48) compared results for participants receiving rescue analgesia between IVIB group and placebo or acetaminophen group. IVIB (RR, 0.27; 95% CI, 0.15 to 0.47, 11 trials, low certainty) was found to be associated with a lower usage rate of rescue analgesia compared with other treatments. However, the further subgroup analysis showed that there was no significant difference between the IVIB group and the placebo group (RR, 0.16; 95% CI, 0.02 to 1.29, 9 trials, moderate certainty), and acetaminophen group (RR, 0.30; 95% CI, 0.06 to 1.35, 6 trials, moderate certainty), respectively (Supplementary Figure 6, Supplementary Table 7).
Safety
A total of 18 studies (23, 26-29, 31, 32, 34, 35, 42, 43, 45-50, 52) reported adverse events, mainly including nausea or vomiting, pruritus, dizziness, headache, flatulence, and dyspepsia. 15 studies (23, 26, 27, 29, 32, 34, 35, 42, 43, 46-48, 50, 52) with 1,746 participants compared IVIB with placebo. Meta-analysis showed that IVIB was associated with a lower incidence of nausea or vomiting (RR, 0.71; 95% CI, 0.56 to 0.91, 14 trials, moderate certainty). There was no significant difference in the incidence of pruritus (RR, 0.94; 95% CI, 0.67 to 1.32, 8 trials, moderate certainty), dizziness (RR, 0.77; 95% CI, 0.25 to 2.39, 7 trials, moderate certainty), headache (RR, 0.82; 95% CI, 0.43 to 1.58, 4 trials, moderate certainty), dyspepsia (RR, 0.87; 95% CI, 0.33 to 2.32, 4 trials, moderate certainty), or flatulence (RR, 1.08; 95% CI, 0.76 to 1.54, 4 trials, moderate certainty) (Figure 6, Supplementary Table 7).
Ten studies (26, 29, 31, 35, 39, 42, 43, 45, 46, 49) consisting of 670 participants reported the difference in the safety between IVIB and acetaminophen. As a result, IVIB was associated with a lower incidence of nausea or vomiting (RR, 0.65; 95% CI, 0.51 to 0.83, 9 trials, moderate certainty). There was no significant difference in the incidence of pruritus (RR, 0.64; 95% CI, 0.22 to 1.84, 3 trials, moderate certainty) or headache (RR, 0.98; 95% CI, 0.48 to 2.00, 3 trials, moderate certainty) (Supplementary Figure7, Supplementary Table 7).