Opioid analgesia for acute abdominal pain in children: A systematic review and meta-analysis

There are long-held concerns that analgesia in patients with acute abdominal pain may obscure the physical examination and lead to missing a diagnosis of appendicitis. Despite evidence to the contrary, analgesia continues to be underutilized and suboptimally dosed in children with acute abdominal pain. The objective of this systematic review and meta-analysis was to determine if opioids provide analgesia without an increase in side effects and appendicitis-related complications.

Trials were identified through electronic searches of MEDLINE (1946-2013), EMBASE (1980-2013), Cochrane Central Register of Controlled Trials (2013), CINAHL (1981-2013), and Google Scholar (2013). All randomized controlled trials (RCTs) of children aged 0-18 years with acute abdominal pain that compared any opioid analgesic to placebo were included. The methodologic qualities of studies and the overall quality of evidence were evaluated using the Cochrane Collaboration's Risk of Bias tool and the Grading of Recommendations Assessment, Development, and Evaluation system, respectively.

Six RCTs met inclusion criteria, and each compared a single-dose parenteral opioid to a placebo, providing data on 342 children aged 5 to 18 years. The pooled mean pre/post difference in self-reported pain scores was 19.61 mm (95% confidence interval [CI] = -1.16 to 40.37 mm) lower in those receiving opioid analgesia. There was no significant increase in the risk of perforation or abscess associated with opioids in cases of appendicitis (relative risk [RR] = 1.03, 95% CI = 0.55 to 1.93). The risk of side effects was significantly greater in patients who received opioids (RR = 6.06, 95% CI = 1.10 to 33.49). Subtherapeutic dosing of opioids was detected in all six trials.

The use of opioids in undifferentiated acute abdominal pain in children is associated with no difference in pain scores and an increased risk of mild side effects. However, there is no increased risk of perforation or abscess. The overall quality of evidence is low, suggesting the need for larger, high-quality trials that are powered to detect both serious complications of appendicitis and determine the most efficacious opioid dosing for children.