Incidence rates and employment trends in schizophrenia spectrum disorders, bipolar affective disorders and recurrent depression in the years 2000–2013: a Danish nationwide register-based study

Abstract

Aims

The study aimed to investigate time trends in incidence rates in schizophrenic spectrum disorders (ICD-10: F20–F29), bipolar affective disorder (ICD-10: F30, F31), and recurrent depression (ICD-10: F33) and to investigate the rates of employment for all incident cases.

Method

We used nationwide longitudinal data from 2000 to 2013 on all psychiatric inpatients and outpatients contacts in Denmark. Age-adjusted incidence rate ratios were calculated for the three diagnostic groups, and rates of employment, education, and disability pension were measured 1 year before and 2 years after the diagnosis for all the incident cases.

Results

The incidence rates increased significantly in all diagnostic groups and both sexes. Comparing the incidence rates in 2013 with 2000 yielded an incidence rate ratio of 1.67 (95% CI 1.51–1.84) for schizophrenic spectrum disorders, 3.82 (95% CI 3.23–4.52) for bipolar affective disorder, and 2.80 (95% CI 2.58–3.04) for recurrent depression. During the same observation period, the employment rates decreased, both 1 year before and 2 years after diagnosis in all three subgroups. In the year 2002, employment rates, 2 years after diagnosis, were 24.6% for schizophrenia spectrum disorder, 35.0% for bipolar affective disorder and 47.1% for recurrent depression. These rates had declined to 15.8%, 26.8%, and 34.7%, respectively, in 2013.

Conclusion

This study of three severe mental illness subgroups shows significant increasing incidence rates and decreasing employment rates both before and after the diagnosis between 2000 and 2013, highlighting the importance of timely and correct volume of the psychiatric treatment and vocational rehabilitation programs.

Keywords:

• Incidence rates
• employment trends
• schizophrenia spectrum disorders
• bipolar affective disorders
• recurrent depression

Ethical approval

The study was conducted with permission from the Danish Data Protection Agency. Since data were exclusively obtained from registers approval from the national committee on health research ethics was not necessary.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Data availability statement

Data will not be shared due to restrictions from the Danish protection agency.

Additional information

Notes on contributors

Thomas Nordahl Christensen

Thomas Nordahl Christensen, MSc, PhD and senior researcher at CORE - Copenhagen Research Center for Mental Health.

Iben Gammelgård Wallstrøm

Iben Gammelgård Wallstrøm, MD, PhD Working as a psychiatrist in the region of southern Denmark, and postdoc researcher at research Unit of Psychiatry, Institute of Clinical Research, University of Southern Denmark.

Lene Falgaard Eplov

Lene Falgaard Eplov, MD, PhD and Senior Consultant, head of the program for research in Recovery & Inclusion, Copenhagen Research Centre for Mental Health – CORE.

Thomas Munk Laursen

Thomas Munk Laursen, PhD, and Professor at The National Centre for Register-Based Research, Aarhus University, Denmark, specialized in psychiatric epidemiology.

Merete Nordentoft

Merete Nordentoft, MD, PhD, professor in clinical psychiatry and head of CORE – Copenhagen Research Center for Mental Health.