title: The influence of population characteristics on variation in general practice based morbidity estimations.
abstract: BACKGROUND
  General practice based registration networks (GPRNs) provide information on morbidity rates in the population. Morbidity rate estimates from different GPRNs, however, reveal considerable, unexplained differences. We studied the range and variation in morbidity estimates, as well as the extent to which the differences in morbidity rates between general practices and networks change if socio-demographic characteristics of the listed patient populations are taken into account.
  
  
  METHODS
  The variation in incidence and prevalence rates of thirteen diseases among six Dutch GPRNs and the influence of age, gender, socio economic status (SES), urbanization level, and ethnicity are analyzed using multilevel logistic regression analysis. Results are expressed in median odds ratios (MOR).
  
  
  RESULTS
  We observed large differences in morbidity rate estimates both on the level of general practices as on the level of networks. The differences in SES, urbanization level and ethnicity distribution among the networks' practice populations are substantial. The variation in morbidity rate estimates among networks did not decrease after adjusting for these socio-demographic characteristics.
  
  
  CONCLUSIONS
  Socio-demographic characteristics of populations do not explain the differences in morbidity estimations among GPRNs.
authors: National Institute for Public Health and the Environment (RIVM), PO Box 1, 3720 BA, Bilthoven, the Netherlands. karin.van.den.dungen@rivm.nl
authors: C
authors: C
authors: van den Dungen
authors: N
authors: N
authors: Hoeymans
authors: H C
authors: HC
authors: Boshuizen
authors: M
authors: M
authors: van den Akker
authors: M C J
authors: MC
authors: Biermans
authors: K
authors: K
authors: van Boven
authors: H J
authors: HJ
authors: Brouwer
authors: R A
authors: RA
authors: Verheij
authors: M W M
authors: MW
authors: de Waal
authors: F G
authors: FG
authors: Schellevis
authors: G P
authors: GP
authors: Westert
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D002648:Child; D002675:Child, Preschool; D016208:Databases, Factual; D005006:Ethnicity; D005260:Female; D058006:General Practice / Q000706:statistics & numerical data*; D006801:Humans; D007223:Infant; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D009017:Morbidity / Q000639:trends*; D009426:Netherlands; D011634:Public Health; D012737:Sex Factors; D012923:Social Class; D012924:Social Conditions; D014506:Urban Renewal; D055815:Young Adult