title: Medical expulsive therapy versus early endoscopic stone removal for acute renal colic: an instrumental variable analysis.
abstract: OBJECTIVE
  The use of medical expulsive therapy to hasten stone passage potentially decreases expenditures around episodes of renal colic. However, these efficiency gains may be mitigated if patients treated with medical expulsive therapy have frequent health care encounters due to pain while waiting for the stones to pass.
  
  
  METHODS
  Using claims data (2002 to 2006) we identified adult men with acute renal colic. We compared 6-week payments as well as frequency of hospitalization and emergency department revisits associated with an initial course of medical expulsive therapy with those for early endoscopic stone removal. To account for unmeasured confounding we performed an instrumental variable analysis, exploiting variation in recommended treatments based on the day of the week that a patient's first emergency department visit occurred.
  
  
  RESULTS
  Overall 1,835 and 4,397 men underwent medical expulsive therapy or early endoscopic stone removal, respectively. Although minimal differences existed between men with respect to the day of the week of emergency department presentation, weekend encounters were strongly associated with receiving medical expulsive therapy (p <0.001). Two-stage least squares regression revealed 6-week payments to be tenfold lower for men on medical expulsive therapy who were candidates for either treatment (p <0.001). While there was no difference in frequency of hospitalization, these men were more likely to have a repeat emergency department visit compared to those who underwent endoscopic stone removal (68.8% vs 39.6%, respectively, p = 0.025).
  
  
  CONCLUSIONS
  Findings on medical expulsive therapy are mixed, with lower 6-week payments but more frequent repeat emergency department visits. These data inform patients who are candidates for medical expulsive therapy or endoscopic stone removal when making decisions about their care.
authors.affiliation: Department of Urology, University of Michigan Medical School, Ann Arbor, Michigan 48109-2800, USA. kinks@med.umich.edu
authors.forename: John M
authors.initials: JM
authors.lastname: Hollingsworth
authors.forename: Edward C
authors.initials: EC
authors.lastname: Norton
authors.forename: Samuel R
authors.initials: SR
authors.lastname: Kaufman
authors.forename: R Matt
authors.initials: RM
authors.lastname: Smith
authors.forename: J Stuart
authors.initials: JS
authors.lastname: Wolf
authors.forename: Brent K
authors.initials: BK
authors.lastname: Hollenbeck
mesh_terms: D000317:Adrenergic alpha-Antagonists / Q000191:economics / Q000627:therapeutic use; D000328:Adult; D002121:Calcium Channel Blockers / Q000191:economics / Q000627:therapeutic use; D015331:Cohort Studies; D017281:Cost of Illness; D003362:Cost-Benefit Analysis; D016208:Databases, Factual; D004636:Emergency Service, Hospital / Q000191:economics* / Q000706:statistics & numerical data; D004724:Endoscopy / Q000191:economics* / Q000379:methods; D006760:Hospitalization / Q000191:economics / Q000706:statistics & numerical data; D006801:Humans; D007669:Kidney Calculi / Q000175:diagnosis / Q000188:drug therapy / Q000191:economics / Q000601:surgery; D008297:Male; D008875:Middle Aged; D056844:Renal Colic / Q000188:drug therapy / Q000191:economics* / Q000601:surgery; D012189:Retrospective Studies; D052878:Urolithiasis / Q000188:drug therapy / Q000191:economics / Q000601:surgery
chemical_list: D000317:Adrenergic alpha-Antagonists; D002121:Calcium Channel Blockers
keywords: ED; MET; POS; PPO; adrenergic alpha-antagonists; calcium channel blockers; emergency department; medical expulsive therapy; point of service; preferred provider organization; ureteroscopy; urinary calculi