title: Improved cost-effectiveness and efficiency with a slower shockwave delivery rate.
abstract: OBJECTIVE
  To determine the benefits of a slower shockwave (SW) delivery rate of 70 shocks/min on the treatment efficiency and cost-effectiveness of extracorporeal SW lithotripsy (ESWL).
  
  
  METHODS
  Patients who had ESWL for their upper urinary tract radio-opaque calculi were categorized into two groups: slow (70 SW/min) and fast (100 SW/min) delivery rate. All treatment was carried out using a lithotripter (Model S, Dornier MedTech, Wessling, Germany) as an outpatient procedure with no anaesthesia or sedation. The groups were followed for > or =6 months. The primary outcomes compared were the stone-free rate, re-treatment rate, additional procedure rate, perceived cost and actual cost. Clinical success was defined as stone-free status or asymptomatic insignificant residual fragments of <3 mm. Perceived cost was defined as the cost of ESWL alone, and actual cost included the cost of additional procedures and overhead costs to result in clinical success.
  
  
  RESULTS
  In all, the study included 102 patients, categorized into the fast (51) and slow (51) rate groups. The groups were comparable in terms of sex, age, body mass index, stone size and stone location. The slow group had a significantly better stone-free rate (67% vs 25.5%, P = 0.002, chi-square), fewer mean shocks to clinical success (3045 vs 4414, P < 0.001, U-test), lower re-treatment rate (22% vs 45%P = 0.013, chi -square), a lower additional procedure rate (12% vs 29%, P = 0.02, chi-square), greater efficiency quotient (0.51 vs 0.16) than the fast group. The mean perceived cost of ESWL (GB pound 297 vs 394 pounds, P = 0.013, U-test) and the mean actual cost of the slow group were significantly less (496 pounds vs 1002 pounds, P = 0.001, U-test).
  
  
  CONCLUSIONS
  Slowing the SW delivery rate to 70/min significantly reduced the actual cost by half and improved treatment efficiency.
authors.affiliation: Stone Treatment Centre, Craigavon Area Hospital, Portadown, Northern Ireland, UK. vkoo76@gmail.com
authors.forename: Vincent
authors.initials: V
authors.lastname: Koo
authors.forename: Irene
authors.initials: I
authors.lastname: Beattie
authors.forename: Michael
authors.initials: M
authors.lastname: Young
mesh_terms: D003362:Cost-Benefit Analysis; D004812:Epidemiologic Methods; D005260:Female; D006801:Humans; D007669:Kidney Calculi / Q000191:economics / Q000628:therapy*; D008096:Lithotripsy / Q000191:economics* / Q000379:methods; D008297:Male; D008875:Middle Aged; D016896:Treatment Outcome