Why do emergency providers choose one opioid over another? A prospective cohort analysis.

The reasons providers choose one parenteral opioid over another are not well understood. The authors sought to determine why emergency department (ED) providers choose one parenteral opioid over another. In a cohort of ED patients who received intravenous morphine or hydromorphone, the authors prospectively assessed patient and provider factors associated with choice of opioid, which were included in regression analyses to identify independent predictors of hydromorphone prescription. Providers were also asked in real time why they chose one opioid over another for a specific patient. Narrative responses were coded and analyzed. Opioid choice was tightly linked with equianalgesic dose, with the median hydromorphone dosage more than 50 percent higher than the dosage of morphine. Besides dose, choice of hydromorphone was most strongly associated with home opioid use and a diagnosis of kidney stone. Provider preference or habit was the most commonly cited reason for choosing the prescribed opioid, with the majority of those responses given by providers who prescribed morphine. One-fourth of morphine prescribers stated that the patient required a lower dosage or less potent option; one-fourth of hydromorphone prescribers stated that either the patient required a higher dosage or more potent option or hydromorphone is more effective. In total, 46 percent of providers gave a reason that does not seem to have pharmacologic validity. ED providers seem to prescribe "usual" dosages of morphine and relatively higher usual dosages of hydromorphone. The reasons for choosing one opioid over the other for a specific patient vary from simple preference to common misconceptions about opioid pharmacology. Improved understanding of opioid pharmacology may improve analgesic outcomes for some patients.