Adverse outcomes and opioid analgesic administration in acute abdominal pain

To the authors' knowledge, no outcome-based, randomized clinical trial of t he safety of opioid analgesics in acute abdominal pain exists. Objectives: 1) To assess the feasibility of a randomized clinical trial of opioid safet y by estimating the adverse outcome rate among patients with abdominal pain severe enough to necessitate opioid analgesics. 2) To explore the associat ion of opioid administration with adverse outcomes in acute abdominal pain. Methods: The authors conducted a prospective observational study of emerge ncy department (ED) abdominal pain patients, and followed them by telephone at three weeks to determine whether an adverse outcome occurred (defined a s obstruction, perforation, ischemia, hemorrhage, peritonitis, sepsis, or d eath). A logistic regression of factors predicting adverse outcome was perf ormed. Results: Adverse outcomes occurred in 67 of 860 abdominal pain patie nts (7.8%, 95% CI = 6.1% to 9.8%), and 252 of 860 (29%) received opioids. T he adverse outcome rate was 12.7% (95% CI = 9.0% to 17.0%) among patients w ho received opioids. Variables predictive of adverse outcome in logistic re gression included: ED diagnosis of adverse outcome (OR 12.4), age (OR 1.6 p er decade), fever (OR 4.6), received opioids (OR 2.1), pain duration (OR 1. 5 per day), and leukocytosis (OR 2.0). Conclusions: A clinical trial would need to randomize more than 1,500 patients to establish the equivalent adve rse outcome rates of opioids and placebo: the sample size of all existing s tudies combined is insufficient to make such a conclusion. Although opioids were associated with a higher adverse outcome rate in this logistic regres sion, the authors believe this may be due to confounding by pain severity. They emphasize that the study's design precludes conclusion of a causal lin k. No change in clinical practice is warranted. A randomized clinical trial of sufficient size to definitively resolve this issue is needed.