title: Case study of supply induced demand: the case of provision of imaging scans (computed tomography and magnetic resonance) at Unimed-Manaus.
abstract: OBJECTIVE
  To present the experience of a health plan operator (Unimed-Manaus) in Manaus, Amazonas, Brazil, with the accreditation of imaging services and the demand induced by the supply of new services (Roemer's Law).
  
  
  METHODS
  This is a retrospective work studying a time series covering the period from January 1998 to June 2004, in which the computed tomography and the magnetic resonance imaging services were implemented as part of the services offered by that health plan operator. Statistical analysis consisted of a descriptive and an inferential part, with the latter using a mean parametric test (Student T-test and ANOVA) and the Pearson correlation test. A 5% alpha and a 95% confidence interval were adopted.
  
  
  RESULTS
  At Unimed-Manaus, the supply of new imaging services, by itself, was identified as capable of generating an increased service demand, thus characterizing the phenomenon described by Roemer.
  
  
  CONCLUSIONS
  The results underscore the need to be aware of the fact that the supply of new health services could bring about their increased use without a real demand.
authors.affiliation: Medicine School, Universidade Federal do Amazonas, Manaus, Amazonas, Brazil. dredsonandrade@gmail.com
authors.forename: Edson de Oliveira
authors.initials: Ede O
authors.lastname: Andrade
authors.forename: Elizabeth Nogueira de
authors.initials: EN
authors.lastname: Andrade
authors.forename: José Hiran
authors.initials: JH
authors.lastname: Gallo
mesh_terms: D001938:Brazil; D006301:Health Services Needs and Demand / Q000191:economics / Q000706:statistics & numerical data*; D006801:Humans; D007348:Insurance, Health / Q000191:economics / Q000706:statistics & numerical data*; D008279:Magnetic Resonance Imaging / Q000191:economics / Q000706:statistics & numerical data*; D012189:Retrospective Studies; D014057:Tomography, X-Ray Computed / Q000191:economics / Q000706:statistics & numerical data*