title: Dementia incidence trend over 1992-2014 in the Netherlands: Analysis of primary care data.
abstract: BACKGROUND
  Recent reports have suggested declining age-specific incidence rates of dementia in high-income countries over time. Improved education and cardiovascular health in early age have been suggested to be bringing about this effect. The aim of this study was to estimate the age-specific dementia incidence trend in primary care records from a large population in the Netherlands.
  
  
  RESULTS
  A dynamic cohort representative of the Dutch population was composed using primary care records from general practice registration networks (GPRNs) across the country. Data regarding dementia incidence were obtained using general-practitioner-recorded diagnosis of dementia within the electronic health records. Age-specific dementia incidence rates were calculated for all persons aged 60 y and over; negative binomial regression analysis was used to estimate the time trend. Nine out of eleven GPRNs provided data on more than 800,000 older people for the years 1992 to 2014, corresponding to over 4 million person-years and 23,186 incident dementia cases. The annual growth in dementia incidence rate was estimated to be 2.1% (95% CI 0.5% to 3.8%), and incidence rates were 1.08 (95% CI 1.04 to 1.13) times higher for women compared to men. Despite their relatively low numbers of person-years, the highest age groups contributed most to the increasing trend. There was no significant overall change in incidence rates since the start of a national dementia program in 2003 (-0.025; 95% CI -0.062 to 0.011). Increased awareness of dementia by patients and doctors in more recent years may have influenced dementia diagnosis by general practitioners in electronic health records, and needs to be taken into account when interpreting the data.
  
  
  CONCLUSIONS
  Within the clinical records of a large, representative sample of the Dutch population, we found no evidence for a declining incidence trend of dementia in the Netherlands. This could indicate true stability in incidence rates, or a balance between increased detection and a true reduction. Irrespective of the exact rates and mechanisms underlying these findings, they illustrate that the burden of work for physicians and nurses in general practice associated with newly diagnosed dementia has not been subject to substantial change in the past two decades. Hence, with the ageing of Western societies, we still need to anticipate a dramatic absolute increase in dementia occurrence over the years to come.
authors.affiliation: Department of General Practice, Academic Medical Center Amsterdam, Amsterdam, The Netherlands.
authors.forename: Emma F
authors.initials: EF
authors.lastname: van Bussel
authors.affiliation: Department of Neurology, Donders Institute for Brain, Cognition and Behavior, Radboud University Medical Center, Nijmegen, The Netherlands.|Department of Neurology, Academic Medical Center Amsterdam, Amsterdam, The Netherlands.
authors.forename: Edo
authors.initials: E
authors.lastname: Richard
authors.affiliation: Department of General Practice, Academic Medical Center Amsterdam, Amsterdam, The Netherlands.
authors.forename: Derk L
authors.identifier: http://orcid.org/0000-0001-5702-5856
authors.initials: DL
authors.lastname: Arts
authors.affiliation: Centre for Nutrition, Prevention and Health Services, National Institute for Public Health and the Environment, Bilthoven, The Netherlands.
authors.forename: Astrid C J
authors.identifier: http://orcid.org/0000-0003-1412-3338
authors.initials: AC
authors.lastname: Nooyens
authors.affiliation: Department of Medical Informatics, Erasmus University Medical Center, Rotterdam, The Netherlands.
authors.forename: Preciosa M
authors.initials: PM
authors.lastname: Coloma
authors.affiliation: Department of Public Health and Primary Care, Leiden University Medical Center, Leiden, The Netherlands.
authors.forename: Margot W M
authors.initials: MW
authors.lastname: de Waal
authors.affiliation: CAPHRI School for Public Health and Primary Care, Department of Family Medicine, Maastricht University, Maastricht, The Netherlands.|Academic Center for General Practice, Department of Public Health and Primary Care, KU Leuven, Leuven, Belgium.
authors.forename: Marjan
authors.initials: M
authors.lastname: van den Akker
authors.affiliation: Department of Primary and Community Care, Radboud University Medical Center, Nijmegen, The Netherlands.
authors.forename: Marion C J
authors.identifier: http://orcid.org/0000-0001-5401-3817
authors.initials: MC
authors.lastname: Biermans
authors.affiliation: Department of General Practice, Netherlands Institute for Health Services Research, Utrecht, The Netherlands.
authors.forename: Markus M J
authors.initials: MM
authors.lastname: Nielen
authors.affiliation: Department of Primary and Community Care, Radboud University Medical Center, Nijmegen, The Netherlands.
authors.forename: Kees
authors.initials: K
authors.lastname: van Boven
authors.affiliation: Julius Center for Health Sciences and Primary Care, University Medical Center Utrecht, Utrecht, The Netherlands.
authors.forename: Hugo
authors.identifier: http://orcid.org/0000-0002-9718-1180
authors.initials: H
authors.lastname: Smeets
authors.affiliation: Institute for Health and Society, Newcastle University, Newcastle upon Tyne, United Kingdom.
authors.forename: Fiona E
authors.identifier: http://orcid.org/0000-0002-1728-2388
authors.initials: FE
authors.lastname: Matthews
authors.affiliation: Institute of Public Health, Cambridge University, Cambridge, United Kingdom.
authors.forename: Carol
authors.identifier: http://orcid.org/0000-0001-5307-663X
authors.initials: C
authors.lastname: Brayne
authors.affiliation: Department of General Practice, Academic Medical Center Amsterdam, Amsterdam, The Netherlands.
authors.forename: Wim B
authors.initials: WB
authors.lastname: Busschers
authors.affiliation: Department of Neurology, Academic Medical Center Amsterdam, Amsterdam, The Netherlands.
authors.forename: Willem A
authors.initials: WA
authors.lastname: van Gool
authors.affiliation: Department of General Practice, Academic Medical Center Amsterdam, Amsterdam, The Netherlands.
authors.forename: Eric P
authors.identifier: http://orcid.org/0000-0002-1489-5218
authors.initials: EP
authors.lastname: Moll van Charante
mesh_terms: D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D003704:Dementia / Q000453:epidemiology* / Q000209:etiology; D005260:Female; D006801:Humans; D015994:Incidence; D057187:Independent Living; D008297:Male; D008875:Middle Aged; D009426:Netherlands / Q000453:epidemiology; D011320:Primary Health Care