title: Influence of patient and hospital characteristics on anesthesia time in medicare patients undergoing general and orthopedic surgery.
abstract: BACKGROUND
  Procedure time is a clinically important variable that is often analyzed when studying quality and efficiency. Norms for procedure length have not been reported from Medicare data sets, nor has the influence of patient and hospital characteristics on procedure time been estimated using Medicare data.
  
  
  METHODS
  The authors obtained Medicare claims on all patients aged 65-85 years who underwent general surgical and orthopedic surgical procedures in Pennsylvania. Anesthesia procedure time was estimated from anesthesia time units bills supplied from Medicare on 20 common general and orthopedic surgery procedures, and models to determine the influence of hospital and patient characteristics were developed.
  
  
  RESULTS
  Of the 77,638 patients, 31,472 had general surgery and 46,166 underwent orthopedic procedures. The median anesthesia time for general surgery was 133 min, and for orthopedic surgery it was 146 min. After adjusting for principal procedure, hospital, and physiologic severity, covariates associated with increased anesthesia time included: multiple procedure on same day + 18.3 min (P < 0.0001); transfer-in + 6.7 min (P = 0.0002); black race + 5.5 (P < 0.0001); coagulation disorders + 4.9 (P = 0.0012); and paraplegia + 4.5 (P = 0.0006). Lower-income black patients had significantly longer procedure times than lower-income white patients (+ 7 min; P < 0.0001). Among the 15 hospitals with the largest black surgical populations, 5 hospitals had statistically significant procedure lengths for black versus white patients, ranging from + 9 to + 16 min.
  
  
  CONCLUSIONS
  In addition to variation by patient comorbidities and procedure, anesthesia procedure time varies with hospital, medical history, and sociodemographic characteristics.
authors.affiliation: The Center for Outcomes Research, The Children's Hospital of Philadelphia, PA 19104, USA. silber@email.chop.edu
authors.forename: Jeffrey H
authors.initials: JH
authors.lastname: Silber
authors.forename: Paul R
authors.initials: PR
authors.lastname: Rosenbaum
authors.forename: Xuemei
authors.initials: X
authors.lastname: Zhang
authors.forename: Orit
authors.initials: O
authors.lastname: Even-Shoshan
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000758:Anesthesia; D044383:Black People; D006761:Hospitals; D006801:Humans; D007182:Income; D006278:Medicare; D009765:Obesity / Q000601:surgery; D019637:Orthopedic Procedures; D013514:Surgical Procedures, Operative; D013997:Time Factors; D044465:White People