The meta-analysis included 28 studies with a total of 985 patients. The authors reported that all selected studies were randomised, double blind and had adequate allocation concealment. There was no evidence of selective reporting or incomplete data reporting.
Medium to large improvement was associated with NSAIDs plus opioids compared with NSAIDs alone for many of the outcomes but there was very high heterogeneity. NSAIDs were associated with less opioid consumption postanaesthesia (SMD -0.66, 95% CI -0.84 to -0.48; 30 data points from 21 trials; Ι²= 66%) and during the first 24 hours postoperatively (SMD -0.83, 95% CI -1.11 to -0.55; 17 data points from 15 trials; Ι²=79%), and less pain intensity during postanaesthesia care unit stay (SMD -0.85, 95% CI -1.24 to -0.47; 17 data points from 15 trials; Ι²=90%).
There was no difference in postoperative nausea and vomiting during postanaesthesia care unit stay (OR 1.02, 95% CI 0.73 to 1.44, 14 data points from nine trials; Ι²=0%). Postoperative nausea and vomiting was reduced during the first 24 hours postoperatively (OR 0.75, 95% CI 0.57 to 0.99; 21 data points in meta-analysis from 17 trials; Ι²=0%).
There was no evidence of a preventive effect of the intervention for postoperative urinary retention (OR 0.96, 95% CI 0.25 to 3.65; four studies; Ι²=49%) and pruritis (OR 0.96, 95% CI 0.34 to 2.71; three studies; Ι²=0%).
Subgroup analyses were conducted according to timing of NSAID administration, type of surgery and coadministration of paracetamol. There was no influence on study outcomes in most analyses. Pain intensity in first 24 hours differed between groups for coadministration of paracetamol. Postoperative nausea and vomiting differed between groups for type of surgery.
There was statistically significant evidence of publication bias for opioid consumption during first 24 hours and pain during postanaesthesia care unit stay.