A Cochrane review included 8 studies with a total of 923 subjects. The studies compared the use of opioid analgesia to placebo in adult patients with acute non traumatic abdominal pain. In 7 studies the intensity of pain (VAS pain scale) decreased significantly with the use of opioid analgesics, grouped weighted mean difference (WMD) -1.94 (95% CI -2.92 to -0.95). One study did not demonstrate any benefit in the reduction of pain. There was significant improvement in patient comfort with the use of opioids in the two studies reporting this outcome (RR 0.05, 95% CI 0.01 to 0.19, 1 study, n=100; WMD -2.10, 95% CI -3.00 to -1.20, 1 study, n=48). Incorrect diagnosis was reported in 6 studies (n=786) and no significant differences were found between the groups (RR 0.86, 95% CI 0.57 to 1.29).

Comments: The quality of evidence is downgraded by inconsistency (heterogeneity in outcomes and interventions) but upgraded by large magnitude of effect.