title: Decreasing incidence of adenotonsillar problems in Dutch general practice: real or artefact?
abstract: BACKGROUND
  The incidence of hypertrophy and recurrent infections of the tonsils/adenoids appears to be decreasing in the Netherlands. It is uncertain whether this is a 'real' decrease in the incidence of disease or an 'artefact'.
  
  
  OBJECTIVE
  To investigate possible causes of the decreasing incidence of adenotonsillar problems among Dutch children.
  
  
  METHODS
  Observational.
  
  
  METHODS
  A nationally representative general practice database.
  
  
  METHODS
  Incidence rates were calculated over 2002-2005 among children aged 0-14 years. Multilevel Poisson regression analyses were used to examine the following possible causes of changing incidence rates: change in recording (more substitution codes), change in the demand for care (fewer visits to the GP), and change in the supply of care (fewer antibiotic prescriptions and referrals). Indications for a 'real' change in the incidence of disease were examined by calculating incidence rates of other clinical manifestations of microbial pathogens that may cause adenotonsillar problems.
  
  
  RESULTS
  The incidence rate decreased significantly (P = 0.017) from 3.0 to 1.3 per 1000 children per year. Correcting for demand for and supply of care led to a smaller decline in yearly incidence, from 2.9 to 1.7 per 1000 children per year (P = 0.105). No clearly similar trend was found in other clinical manifestations of viruses and bacteria that may cause adenotonsillar problems.
  
  
  CONCLUSIONS
  Part of the declining trend can be explained by a change in the demand for and supply of care, but no apparent causal clue emerged for the residual declining trend in the incidence of disease.
authors.affiliation: Department of Medical Informatics, Radboud University Nijmegen Medical Centre, 152 MI, PO Box 9101, 6500 HB Nijmegen, The Netherlands. m.biermans@elg.umcn.nl
authors.forename: Marion C J
authors.initials: MC
authors.lastname: Biermans
authors.forename: Ellen H M
authors.initials: EH
authors.lastname: Theuns-Lamers
authors.forename: Peter
authors.initials: P
authors.lastname: Spreeuwenberg
authors.forename: Robert A
authors.initials: RA
authors.lastname: Verheij
authors.forename: Johannes C
authors.initials: JC
authors.lastname: van der Wouden
authors.forename: Pieter F
authors.initials: PF
authors.lastname: de Vries Robbé
authors.forename: Gerhard A
authors.initials: GA
authors.lastname: Zielhuis
mesh_terms: D000234:Adenoids; D000293:Adolescent; D002648:Child; D002675:Child, Preschool; D005194:Family Practice / Q000458:organization & administration; D006801:Humans; D015994:Incidence; D007223:Infant; D009426:Netherlands / Q000453:epidemiology; D014066:Palatine Tonsil; D010342:Patient Acceptance of Health Care / Q000706:statistics & numerical data; D010608:Pharyngeal Diseases / Q000453:epidemiology* / Q000473:pathology