Occurrence, mortality and cost of brain disorders in Denmark: a population-based cohort study

Abstract

Objectives: To examine the occurrence of brain disorders (ie, neurological and mental disorders) in Denmark and mortality and cost of illness among affected persons.

Design: Matched cohort study.

Setting: We obtained routinely collected registry data on all Danish residents during 1995-2015.

Participants: We identified all persons alive on 1 January 2015 with a diagnosis of 25 specific brain disorders (prevalent cohort) and all persons with an incident diagnosis during 2011-2015 (incident cohort). Each person was matched on age and sex with 10 persons from the general population without the brain disorder of interest.

Primary and secondary outcome measures: Prevalence and incidence of hospital-diagnosed brain disorders, 1-year absolute and relative mortality, and attributable direct and indirect costs of illness compared with the corresponding matched cohorts.

Results: We identified 1 075 081 persons with at least one prevalent brain disorder (any brain disorder) on 1 January 2015, corresponding to 18.9% of the Danish population. The incidence rate of any brain disorder during 2011-2015 was 1349 per 100 000 person-years (95% CI 1345 to 1353). One-year mortality after diagnosis was increased in persons with any brain disorder (HR 4.7, 95% CI 4.7 to 4.8) and in persons in every group of specific brain disorders compared with the matched cohort from the general population. The total attributable direct costs of brain disorders in 2015 were €5.2 billion and total attributable indirect costs were €11.2 billion. Traumatic brain injury, stress-related disorders, depression and stroke were the most common brain disorders. Attributable costs were highest for depression, dementia, stress-related disorders and stroke.

Conclusions: One in five Danish residents alive on 1 January 2015 had been diagnosed with at least one brain disorder, and mortality was five times higher in persons with any diagnosed brain disorder than in the general population. We found high attributable direct and indirect costs of brain disorders.

Keywords: epidemiology; health economics; neurology; psychiatry.

Figure 1

Characteristics of patients with prevalent brain disorders in Denmark in 2015 sorted from highest to lowest prevalence (the white line in the age distribution represents the median age in each cohort). CNS, central nervous system; CCI, Charlson Comorbidity Index.

Figure 2

Occurrence of brain disorders in the Danish population sorted from highest to lowest incidence, including incidence during 2011–2015 and prevalence in 2015. CNS, central nervous system.

Figure 3

One-year mortality in patients with incident brain disorders in Denmark during 2011–2015 compared with the general population (comparison group). HRs are adjusted for age, sex and comorbidity score. Specific disorders are sorted by HRs. CNS, central nervous system.

Figure 4

Total attributable direct costs in persons with prevalent brain disorders in Denmark in 2015 (in 2015 prices) sorted from highest to lowest costs. CNS, central nervous system.

Figure 5

Attributable direct costs per person in individuals with prevalent brain disorders in Denmark in 2015 (in 2015 prices) sorted from highest to lowest costs. CNS, central nervous system.

Figure 6

Total attributable indirect costs due to lost productivity in persons with prevalent brain disorders in Denmark in 2015 (in 2015 prices) sorted from highest to lowest costs. CNS, central nervous system.