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Thirty-year trends in dementia: a nationwide population study of Swedish inpatient records

Authors Seblova D, Quiroga ML, Fors S, Johnell K, Lövdén M, Ponce de Leon A, Svensson AC, Wicks S, Lager A

Received 2 July 2018

Accepted for publication 6 September 2018

Published 16 November 2018 Volume 2018:10 Pages 1679—1693


Checked for plagiarism Yes

Review by Single anonymous peer review

Peer reviewer comments 3

Editor who approved publication: Professor Henrik Toft Sørensen

Dominika Seblova,1,2 Maria Lopez Quiroga,3 Stefan Fors,1 Kristina Johnell,1 Martin Lövdén,1 Antonio Ponce de Leon,2,4 Anna Christina Svensson,2 Susanne Wicks,2,4 Anton Lager1,2,4

1Aging Research Center, Karolinska Institutet, Stockholm, Sweden; 2Department of Public Health Sciences, Karolinska Institutet, Stockholm, Sweden; 3Complutense University of Madrid, Madrid, Spain; 4Center for Epidemiology and Community Medicine, Stockholm County Council, Stockholm, Sweden

Background: The continuous growth of the current dementia epidemic is contingent on the stability of age- and sex-specific trends over time. However, recent evidence suggests declining or stable trends. The aim of this study was to evaluate the real-world changes in the burden of dementia in older adults in Sweden from 1987 to 2016 by estimating age- and sex-specific incidence of dementia diagnosis in hospital inpatient records (dementia incidence). Differences in trends by sex, age, and educational levels were also examined.
Methods: The entire Swedish population aged 65 years and older was followed up from 1987 to 2016. Age-, sex-, and education-stratified dementia incidence rates for every follow-up year were estimated using the National Patient Register. Hazard ratio of receiving a dementia diagnosis in the inpatient records per 1 calendar year increase was estimated with discrete time logistic models with a complementary log–log link.
Results: After increase, especially in those >85 years of age, dementia incidence started to decrease in the last 5 years of the study period. After 2011, 1 calendar year increase was associated with lower hazard ratio of receiving a hospital diagnosis of dementia. The decrease had the highest magnitude in 70–74-year-olds (–5.5%), followed by 75–79-year-olds (–4.5%) and 80–84-year-olds (–4.0%). The decrease was present in both sexes and at all educational levels up to 90 years of age. Age was associated with the level of dementia incidence, and the trends differed by age group. Educational gradient was observed. University-educated older adults had the lowest rates of dementia. However, the trend over time did not substantially differ by sex or educational level.
Conclusion: Our results provide more evidence that dementia incidence may be declining. They also suggest that at least in hospitals, the number of new patients with dementia may decrease in the future.

Keywords: incidence, Alzheimer’s, hospitalization, population study, heterogeneous association, education

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