title: Cost-effectiveness analysis of shunt surgery for idiopathic normal pressure hydrocephalus based on the SINPHONI and SINPHONI-2 trials.
abstract: We showed that ventriculoperitoneal (VP) shunt and lumboperitoneal (LP) shunt surgeries are beneficial for patients with idiopathic normal pressure hydrocephalus (iNPH) in the Study of Idiopathic Normal Pressure Hydrocephalus on Neurological Improvement (SINPHONI; a multicenter prospective cohort study) and in SINPHONI-2 (a multicenter randomized trial). Although therapeutic efficacy is important, cost-effectiveness analysis is equally valuable.
  
  
  
  Using both a set of assumptions and using the data from SINPHONI and SINPHONI-2, we estimated the total cost of treatment for iNPH, which consists of medical expenses (e.g., operation fees) and costs to the long-term care insurance system (LCIS) in Japan. Regarding the natural course of iNPH patients, 10% or 20% of patients on each modified Rankin Scale (mRS) show aggravation (aggravation rate: 10% or 20%) every 3 months if the patients do not undergo shunt surgery, as described in a previous report. We performed cost-effectiveness analyses for the various scenarios, calculating the quality-adjusted life year (QALY) and the incremental cost-effective ratio (ICER). Then, based on the definition provided by a previous report, we assessed the cost-effectiveness of shunt surgery for iNPH.
  
  
  
  In the first year after shunt surgery, the ICER of VP shunt varies from 29,934 to 40,742 USD (aggravation rate 10% and 20%, respectively) and the ICER of LP shunt varies from 58,346 to 80,392 USD (aggravation rate 10% and 20%, respectively), which indicates that the shunt surgery for iNPH is a cost-effective treatment. In the 2nd postoperative year, the cost to the LCIS will continue to decrease because of the lasting improvement of the symptoms due to the surgery. The total cost for iNPH patients will show a positive return on investment in as soon as 18 months (VP) and 21 months (LP), indicating that shunt surgery for iNPH is a cost-effective treatment.
  
  
  
  Because the total cost for iNPH patients will show a positive return on investment within 2 years, shunt surgery for iNPH is a cost-effective treatment and therefore recommended. The SINPHONI-2 study was registered with the University Hospital Medical Information Network Clinical Trials registry: UMIN000002730) SINPHONI was registered with ClinicalTrials.gov, no. NCT00221091.
authors.affiliation: Department of Neurological Surgery, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, 2-5-1, Shikata-cho, Kita-ku, Okayama-Shi, Okayama, 700-8558, Japan. mrkameda@gmail.com.
authors.forename: Masahiro
authors.initials: M
authors.lastname: Kameda
authors.affiliation: Normal Pressure Hydrocephalus Center, Department of Neurosurgery and Stroke Center, Rakuwakai Otowa Hospital, Kyoto, Japan.
authors.forename: Shigeki
authors.initials: S
authors.lastname: Yamada
authors.affiliation: Department of Neurosurgery, Atsuchi Neurosurgical Hospital, Kagoshima, Japan.
authors.forename: Masamichi
authors.initials: M
authors.lastname: Atsuchi
authors.affiliation: Department of Neurosurgery, Dohtoh Neurosurgical Hospital, Hokkaido, Japan.
authors.forename: Teruo
authors.initials: T
authors.lastname: Kimura
authors.affiliation: Department of Psychiatry, Osaka University Graduate School of Medicine, Osaka, Japan.
authors.forename: Hiroaki
authors.initials: H
authors.lastname: Kazui
authors.affiliation: Department of Neurosurgery, Juntendo University Graduate School of Medicine, Tokyo, Japan.
authors.forename: Masakazu
authors.initials: M
authors.lastname: Miyajima
authors.affiliation: Department of Behavioral Neurology and Cognitive Neuroscience, Tohoku University Graduate School of Medicine, Miyagi, Japan.
authors.forename: Etsuro
authors.initials: E
authors.lastname: Mori
authors.affiliation: Normal Pressure Hydrocephalus Center, Department of Neurosurgery and Stroke Center, Rakuwakai Otowa Hospital, Kyoto, Japan.
authors.forename: Masatsune
authors.initials: M
authors.lastname: Ishikawa
authors.affiliation: Department of Neurological Surgery, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, 2-5-1, Shikata-cho, Kita-ku, Okayama-Shi, Okayama, 700-8558, Japan.
authors.forename: Isao
authors.initials: I
authors.lastname: Date
mesh_terms: D002986:Clinical Trials as Topic; D003362:Cost-Benefit Analysis; D005260:Female; D006801:Humans; D006850:Hydrocephalus, Normal Pressure / Q000191:economics / Q000601:surgery*; D007564:Japan; D008297:Male; D011183:Postoperative Complications / Q000191:economics / Q000453:epidemiology; D019057:Quality-Adjusted Life Years; D017287:Ventriculoperitoneal Shunt / Q000009:adverse effects / Q000191:economics*
keywords: Cost-effectiveness analysis; Lumboperitoneal shunt; Ventriculoperitoneal shunt; iNPH