Minor change in the diagnostic threshold leads into major alteration in the prevalence estimate of depression

Karlsson, Linnea; Marttunen, Mauri; Karlsson, Hasse; Kaprio, Jaakko; Hillevi, Aro

doi:10.1016/j.jad.2009.06.025

« Previous Next »Journal of Affective Disorders
Volume 122, Issue 1 , Pages 96-101, April 2010

Minor change in the diagnostic threshold leads into major alteration in the prevalence estimate of depression

Linnea Karlsson
- National Institute for Health and Welfare, Department for Mental Health and Services for Substance Abuse, Helsinki, Finland
- Turku University Central Hospital, Departments of Child and Adolescent Psychiatry, Turku, Finland
- Corresponding author. Lehmustie 12 b, 20720 Turku, Finland. Tel.: +358 40 744 5052; fax: +358 9 4744 8788.
Mauri Marttunen
- National Institute for Health and Welfare, Department for Mental Health and Services for Substance Abuse, Helsinki, Finland
- University of Helsinki and Department of Adolescent Psychiatry, Helsinki University Central Hospital, Helsinki, Finland
Hasse Karlsson
- University of Helsinki, Department of Psychiatry, Helsinki, Finland
Jaakko Kaprio
- National Institute for Health and Welfare, Department for Mental Health and Services for Substance Abuse, Helsinki, Finland
- University of Helsinki, Department of Public Health, Helsinki, Finland
- Institute of Molecular Medicine, Helsinki, Finland
Aro Hillevi
- National Institute for Health and Welfare, Department for Mental Health and Services for Substance Abuse, Helsinki, Finland

Received 27 February 2009; received in revised form 19 June 2009; accepted 19 June 2009.

Abstract

Background

Although highly structured diagnostic interview instruments are reportedly reliable, it has been suggested that even small changes in the diagnostic threshold or wording of the questions may substantially affect the results. General population data on this topic are scarce.

Methods

A random sample of 15–75-year-old Finnish men and women was interviewed in 1996 (N=5993). The diagnosis of DSM-III-R major depressive episode (MDE) was made by using the Composite International Diagnostic Interview Short Form (CIDI-SF). Prevalence estimates derived by using three different thresholds for the intensity of the depressed mood (“depressed mood all day” vs. “most of the day” vs. “half of the day”) are compared.

Results

The use of the threshold “depressed mood all day”, yielded the prevalence estimate of 4.67% [95% CI 4.12, 5.22] for MDE, while according to the thresholds of “depressed mood most time of the day” and “at least half of the day” the prevalences were 9.23% [95% CI 8.47, 9.99] and 11.9% [95% CI 11.0, 12.8], respectively. A consistent female to male ratio was observed across the categories, while an age effect was noted so that younger age associated with less frequent depressed mood. The diagnostic thresholds associated with impairment, episode duration, treatment need and use.

Conclusions

Minor changes in case definition within the same measuring instrument may produce major differences in prevalence estimates. The categories defined for the purposes of this study were on a continuum where the frequency of depressed mood associated with other measures of the depressive episode.

Keywords: Depression, Diagnosis, Epidemiology, Prevalence, Diagnostic threshold