title: [Cost variation in care groups?]
abstract: OBJECTIVE
  Is the simple mean of the costs per diabetes patient a suitable tool with which to compare care groups? Do the total costs of care per diabetes patient really give the best insight into care group performance?
  
  
  METHODS
  Cross-sectional, multi-level study.
  
  
  METHODS
  The 2009 insurance claims of 104,544 diabetes patients managed by care groups in the Netherlands were analysed. The data were obtained from Vektis care information centre. For each care group we determined the mean costs per patient of all the curative care and diabetes-specific hospital care using the simple mean method, then repeated it using the 'generalized linear mixed model'. We also calculated for which proportion the differences found could be attributed to the care groups themselves.
  
  
  RESULTS
  The mean costs of the total curative care per patient were €3,092 - €6,546; there were no significant differences between care groups. The mixed model method resulted in less variation (€2,884 - €3,511), and there were a few significant differences. We found a similar result for diabetes-specific hospital care and the ranking position of the care groups proved to be dependent on the method used. The care group effect was limited, although it was greater in the diabetes-specific hospital costs than in the total costs of curative care (6.7% vs. 0.4%).
  
  
  CONCLUSIONS
  The method used to benchmark care groups carries considerable weight. Simply stated, determining the mean costs of care (still often done) leads to an overestimation of the differences between care groups. The generalized linear mixed model is more accurate and yields better comparisons. However, the fact remains that 'total costs of care' is a faulty indicator since care groups have little impact on them. A more informative indicator is 'costs of diabetes-specific hospital care' as these costs are more influenced by care groups.
authors.affiliation: * Dit onderzoek werd eerder gepubliceerd in Health Services Research (16 maart 2016, doi:10.1111/1475-6773.12483) met als titel 'Cost variation in diabetes care across Dutch care groups'. Afgedrukt met toestemming.
authors.forename: S M
authors.initials: SM
authors.lastname: Mohnen
authors.forename: C C M
authors.initials: CC
authors.lastname: Molema
authors.forename: W
authors.initials: W
authors.lastname: Steenbeek
authors.forename: M J
authors.initials: MJ
authors.lastname: van den Berg
authors.forename: S R
authors.initials: SR
authors.lastname: de Bruin
authors.forename: C A
authors.initials: CA
authors.lastname: Baan
authors.forename: J N
authors.initials: JN
authors.lastname: Struijs