Decreasing incidence of adenotonsillar problems in Dutch general practice: real or artefact?
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.
Biermans
Marion C J
MC
Department of Medical Informatics, Radboud University Nijmegen Medical Centre, 152 MI, PO Box 9101, 6500 HB Nijmegen, The Netherlands. m.biermans@elg.umcn.nl
Theuns-Lamers
Ellen H M
EH
Spreeuwenberg
Peter
P
Verheij
Robert A
RA
van der Wouden
Johannes C
JC
de Vries Robbé
Pieter F
PF
Zielhuis
Gerhard A
GA
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