title: Practice variation in a longitudinal perspective: a multilevel analysis of the prescription of simvastatin in general practices between 2003 and 2009.
abstract: OBJECTIVE
  The Dutch national guideline for Cardiovascular Risk Management advised in 2006 initiation of statin therapy in new patients with simvastatin. After the introduction of this guideline several measures were taken to increase the prescription of simvastatin in general practice. The aim of this paper is to describe the trend and interpractice variation in the relative share of simvastatin in statin prescription over a 7-year period (2003-2009) in Dutch general practices.
  
  
  METHODS
  Data were used from the National Registration Network of General Practice (LINH) in the Netherlands. We used multilevel logistic regression analysis with individuals nested within practices. We evaluated the variance at different time points by the intra-class correlation (ICC).
  
  
  RESULTS
  The share of simvastatin prescriptions of all statin prescriptions increased from 40% in 2003 to 82% in 2009. While the ICC was above 20% during the periods 2005 to 2007, it decreased rapidly from 25% in 2007 to only 9% in 2009.
  
  
  CONCLUSIONS
  Our results indicate that a combination of several intervention measures seems to have been successful. While it seems like the implementation of the guidelines alone had some effect, there was an additional effect when reimbursement measures were implemented. Furthermore, the practice seemed to have affected the adoption of the national CVRM guideline as the variation initially increased after the guideline implementation. By including information on both the proportion of simvastatin prescribed and interpractice variation, we achieved a more complete evaluation of how simvastatin prescription developed over time and how it was related to the different measures taken.
authors.affiliation: Center for Primary Health Care Research, Lund University & Region Skåne, CRC, ing 72, SUS, 205 02 Malmö, Sweden. henrik.ohlsson@med.lu.se
authors.forename: Henrik
authors.initials: H
authors.lastname: Ohlsson
authors.forename: Marcia
authors.initials: M
authors.lastname: Vervloet
authors.forename: Liset
authors.initials: L
authors.lastname: van Dijk
mesh_terms: D058006:General Practice / Q000639:trends; D019983:Guideline Adherence; D006801:Humans; D019161:Hydroxymethylglutaryl-CoA Reductase Inhibitors / Q000627:therapeutic use*; D007356:Insurance, Pharmaceutical Services; D016015:Logistic Models; D009426:Netherlands; D017410:Practice Guidelines as Topic; D010818:Practice Patterns, Physicians' / Q000639:trends*; D019821:Simvastatin / Q000627:therapeutic use*
chemical_list: D019161:Hydroxymethylglutaryl-CoA Reductase Inhibitors; D019821:Simvastatin