title: The association of gender and body mass index with postoperative pain scores when undergoing ankle fracture surgery.
abstract: BACKGROUND
  Intraoperative administration of opiates for postoperative analgesia requires a dosing strategy without clear indicators of pain in an anesthetized patient. Preoperative patient characteristics such as body mass index (BMI), gender, age, and other patient characteristics may provide important information regarding opiate requirements. This study intends to determine if there is an association between gender or BMI and the immediate postoperative pain scores after undergoing an open reduction and internal fixation (ORIF) of an ankle fracture with general anesthesia and morphine only analgesia.
  
  
  METHODS
  Using a retrospective cohort design, the perioperative records were reviewed at a university healthcare hospital. One hundred and thirty-seven cases met all inclusion and no exclusion criteria. Postanesthesia care unit (PACU) records were reviewed for pain scores at first report and 30 min later as well as PACU opiate requirements. T-test, chi-square, and Mann-Whitney tests compared univariate data and multivariate analysis was performed by linear regression.
  
  
  RESULTS
  There were no statistically significant PACU pain score group differences based on gender or BMI. Post hoc analysis revealed that in the setting of similar pain scores, obese patients received a similar weight based intraoperative morphine dose when using adjusted body weight (ABW) compared to nonobese subjects. A further finding revealed a negative correlation between age and pain score (P = 0.001).
  
  
  CONCLUSIONS
  This study did not find an association between obesity or gender and postoperative pain when receiving morphine only preemptive analgesia. This study does support the use of ABW as a means to calculate morphine dosing for obese patients and that age is associated with lower immediate pain scores.
authors.affiliation: Department of Anesthesiology and Critical Care, University of Pennsylvania, Philadelphia, Pennsylvania, USA.
authors.forename: Samuel Robert
authors.initials: SR
authors.lastname: Grodofsky
authors.affiliation: Department of Anesthesiology and Critical Care, University of Pennsylvania, Philadelphia, Pennsylvania, USA ; Department of Anesthesiology, Drexel University College of Medicine/Hahnemann University Hospital, Philadelphia, Pennsylvania, USA.
authors.forename: Ashish C
authors.initials: AC
authors.lastname: Sinha
keywords: Acute pain; BMI; gender; morphine