title: Age of onset in chronic diseases: new method and application to dementia in Germany.
abstract: BACKGROUND
  Age of onset is an important outcome to characterize a population with a chronic disease. With respect to social, cognitive, and physical aspects for patients and families, dementia is especially burdensome. In Germany, like in many other countries, it is highly prevalent in the older population and imposes enormous efforts for caregivers and society.
  
  
  METHODS
  We develop an incidence-prevalence-mortality model to derive the mean and variance of the age of onset in chronic diseases. Age- and sex-specific incidence and prevalence of dementia is taken from published values based on health insurance data from 2002. Data about the age distribution in Germany in 2002 comes from the Federal Statistical Office.
  
  
  RESULTS
  Mean age of onset of a chronic disease depends on a) the age-specific incidence of the disease, b) the prevalence of the disease, and c) the age distribution of the population. The resulting age of onset of dementia in Germany in 2002 is 78.8 ± 8.1 years (mean ± standard deviation) for men and 81.9 ± 7.6 years for women.
  
  
  CONCLUSIONS
  Although incidence and prevalence of dementia in men are not greater than in women, men contract dementia approximately three years earlier than women. The reason lies in the different age distributions of the male and the female population in Germany.
authors: Institute for Biometry and Epidemiology, German Diabetes Center, Auf'm Hennekamp 65, Duesseldorf, 40225, Germany.
authors: Ralph
authors: R
authors: Brinks
authors: Institute for Biometry and Epidemiology, German Diabetes Center, Auf'm Hennekamp 65, Duesseldorf, 40225, Germany.
authors: Sandra
authors: S
authors: Landwehr
authors: Institute for Biometry and Epidemiology, German Diabetes Center, Auf'm Hennekamp 65, Duesseldorf, 40225, Germany ; Department of Public Health, Heinrich Heine University, Duesseldorf, 40225, Germany.
authors: Regina
authors: R
authors: Waldeyer
references: Genet Epidemiol. 1993;10(1):43-59
references: 8472934
references: Int J Epidemiol. 1997 Aug;26(4):867-72
references: 9279621
references: Alzheimer Dis Assoc Disord. 2009 Oct-Dec;23(4):306-14
references: 19568149
references: Gesundheitswesen. 2009 May;71(5):281-90
references: 19288422
references: Aging Ment Health. 2011 Nov;15(8):978-84
references: 21777080
references: Dement Geriatr Cogn Disord. 2012;34(1):7-14
references: 22854507
references: BMJ. 2010 Aug 05;341:c3584
references: 20688840
references: Bull World Health Organ. 1994;72(3):481-94
references: 8062403
references: Stat Med. 2013 May 30;32(12):2070-8
references: 23034867