title: Methods for economic evaluation of a factorial-design cluster randomised controlled trial of a nutrition supplement and an exercise programme among healthy older people living in Santiago, Chile: the CENEX study.
abstract: BACKGROUND
  In an effort to promote healthy ageing and preserve health and function, the government of Chile has formulated a package of actions into the Programme for Complementary Food in Older People (Programa de Alimentación Complementaria para el Adulto Mayor - PACAM). The CENEX study was designed to evaluate the impact, cost and cost-effectiveness of the PACAM and a specially designed exercise programme on pneumonia incidence, walking capacity and body mass index in healthy older people living in low- to medium-socio-economic status areas of Santiago. The purpose of this paper is to describe in detail the methods that will be used to estimate the incremental costs and cost-effectiveness of the interventions.
  
  
  METHODS
  The base-case analysis will adopt a societal perspective, including the direct medical and non-medical costs borne by the government and patients. The cost of the interventions will be calculated by the ingredients approach, in which the total quantities of goods and services actually employed in applying the interventions will be estimated, and multiplied by their respective unit prices. Relevant information on costs of interventions will be obtained mainly from administrative records. The costs borne by patients will be collected via exit and telephone interviews. An annual discount rate of 8% will be used, consistent with the rate recommended by the Government of Chile. All costs will be converted from Chilean Peso to US dollars with the 2007 average period exchange rate of US$1 = 522.37 Chilean Peso. To test the robustness of model results, we will vary the assumptions over a plausible range in sensitivity analyses.
  
  
  CONCLUSIONS
  The protocol described here indicates our intent to conduct an economic evaluation alongside the CENEX study. It provides a detailed and transparent statement of planned data collection methods and analyses.
  
  
  BACKGROUND
  ISRCTN48153354.
authors.affiliation: Department of International Health, Bloomberg School of Public Health, Johns Hopkins University, Baltimore, MD, USA. dgwalker@jhsph.edu
authors.forename: Damian G
authors.initials: DG
authors.lastname: Walker
authors.forename: Cristian
authors.initials: C
authors.lastname: Aedo
authors.forename: Cecilia
authors.initials: C
authors.lastname: Albala
authors.forename: Elizabeth
authors.initials: E
authors.lastname: Allen
authors.forename: Alan D
authors.initials: AD
authors.lastname: Dangour
authors.forename: Diana
authors.initials: D
authors.lastname: Elbourne
authors.forename: Emily
authors.initials: E
authors.lastname: Grundy
authors.forename: Ricardo
authors.initials: R
authors.lastname: Uauy
mesh_terms: D000368:Aged; D000375:Aging / Q000502:physiology*; D015992:Body Mass Index; D002677:Chile / Q000453:epidemiology; D016000:Cluster Analysis; D003153:Community Health Services / Q000191:economics*; D003362:Cost-Benefit Analysis; D015444:Exercise; D006293:Health Promotion / Q000191:economics*; D006305:Health Status Indicators; D006801:Humans; D051346:Mobility Limitation; D018529:Nutritional Support; D017063:Outcome Assessment, Health Care; D011014:Pneumonia / Q000453:epidemiology* / Q000517:prevention & control; D012107:Research Design; D012959:Socioeconomic Factors; D016138:Walking / Q000502:physiology