title: Should morphine dosing be weight based for analgesia in the emergency department?
abstract: OBJECTIVE
  To determine if patient weight is predictive of the degree of analgesic response to morphine in opioid naïve patients in the emergency department (ED).
  
  
  METHODS
  Prospective observational study.
  
  
  METHODS
  Academic, tertiary ED, designated as a level 1 trauma center.
  
  
  METHODS
  Fifty opioid naive adult patients who were administered a single fixed intravenous dose of 4 mg morphine on initial presentation to the ED.
  
  
  METHODS
  Pain was assessed at baseline and then repeated at 15- and 30-minute postdose using an 11-point (0-10) verbal numerical rating scale (NRS).
  
  
  METHODS
  The primary outcome was maximum analgesic response, which is defined as the difference between initial pain score and lowest pain score achieved postdose at 15 or 30 minutes. Linear regression was used to analyze the relationship between maximum pain reduction and patient weight.
  
  
  RESULTS
  Mean patient weight was 85.4 kg (standard deviation = +/- 24.2; range 47.6-170). Median initial pain score was 8 (range 6-10) and median lowest pain score achieved postdose was 4 (range 0-10). In the linear regression analysis, patient weight did not predict the degree of pain reduction on the NRS (coefficient = 0.002 [95% confidence interval (CI) = -0.029-0.032], R2 < 0.001, p = 0.91). The only variable predictive of the degree of pain reduction was initial pain score (coefficient = 0.537/95% CI = 0.013-1.0611, R2 = 0.081,p = 0.045).
  
  
  CONCLUSIONS
  Patient weight was not significantly associated with the degree of analgesic response to morphine in opioid naive adults. Morphine dosing based on patient weight alone is not necessary in adults in the ED.
authors.affiliation: Department of Pharmacy Practice and Science, College of Pharmacy, University of Arizona, Tucson, Arizona, USA.
authors.forename: Asad E
authors.initials: AE
authors.lastname: Patanwala
authors.forename: Christopher J
authors.initials: CJ
authors.lastname: Edwards
authors.forename: Lori
authors.initials: L
authors.lastname: Stolz
authors.forename: Richard
authors.initials: R
authors.lastname: Amini
authors.forename: Amol
authors.initials: A
authors.lastname: Desai
authors.forename: Uwe
authors.initials: U
authors.lastname: Stolz
mesh_terms: D000328:Adult; D000701:Analgesics, Opioid / Q000008:administration & dosage* / Q000627:therapeutic use; D001835:Body Weight; D004305:Dose-Response Relationship, Drug; D054796:Drug Dosage Calculations; D004636:Emergency Service, Hospital; D005260:Female; D006801:Humans; D016014:Linear Models; D008297:Male; D008875:Middle Aged; D009020:Morphine / Q000008:administration & dosage* / Q000627:therapeutic use; D010146:Pain / Q000188:drug therapy*; D011446:Prospective Studies
chemical_list: D000701:Analgesics, Opioid; D009020:Morphine