title: Costing hospital surgery services: the method matters.
abstract: BACKGROUND
  Accurate hospital costs are required for policy-makers, hospital managers and clinicians to improve efficiency and transparency. However, different methods are used to allocate direct costs, and their agreement is poorly understood. The aim of this study was to assess the agreement between bottom-up and top-down unit costs of a large sample of surgical operations in a French tertiary centre.
  
  
  METHODS
  Two thousand one hundred and thirty consecutive procedures performed between January and October 2010 were analysed. Top-down costs were based on pre-determined weights, while bottom-up costs were calculated through an activity-based costing (ABC) model. The agreement was assessed using correlation coefficients and the Bland and Altman method. Variables associated with the difference between methods were identified with bivariate and multivariate linear regressions.
  
  
  RESULTS
  The correlation coefficient amounted to 0.73 (95%CI: 0.72; 0.76). The overall agreement between methods was poor. In a multivariate analysis, the cost difference was independently associated with age (Beta = -2.4; p = 0.02), ASA score (Beta = 76.3; p<0.001), RCI (Beta = 5.5; p<0.001), staffing level (Beta = 437.0; p<0.001) and intervention duration (Beta = -10.5; p<0.001).
  
  
  CONCLUSIONS
  The ability of the current method to provide relevant information to managers, clinicians and payers is questionable. As in other European countries, a shift towards time-driven activity-based costing should be advocated.
authors.affiliation: CHU de Montpellier, Montpellier, France; Montpellier Research in Management, Universite Montpellier 1, Montpellier, France.
authors.forename: Gregoire
authors.initials: G
authors.lastname: Mercier
authors.affiliation: Montpellier Research in Management, Universite Montpellier 1, Montpellier, France.
authors.forename: Gerald
authors.initials: G
authors.lastname: Naro
mesh_terms: D003365:Costs and Cost Analysis / Q000379:methods*; D005602:France; D017721:Hospital Costs / Q000706:statistics & numerical data*; D016014:Linear Models; D013503:Surgery Department, Hospital / Q000191:economics*