Cross-national difference in the prevalence of depression caused by the diagnostic threshold

Background: According to published reports, the prevalence rates of major depressive disorder (MDD) in East-Asian countries are lower than in the West, but the reasons for this difference have not been fully investigated. Methods: This study compared the Korean Epidemiologic Catchment Area study (KECAS) sample with the National Comorbidity Survey (NCS, USA) sample. In total, this study included 5349 participants in KECAS and 7423 in NCS aged 18-54 years. The Composite International Diagnostic Interview (CIDI) assessed for MDD. Analysis of the individual symptoms of MDD was completed. Results: Diagnostic threshold of MDD was higher in KECAS participants than in NCS participants. Koreans diagnosed with MDD showed more work impairment than Americans with MDD. Koreans were more likely to express the symptoms like "low energy" and "concentration difficulty," but less to the symptoms like "depressed mood" and "thoughts of death" during an episode of MDD. Limitations: The Diagnostic and Statistical Manual of Mental Disorders (DSM) framework was the basis for the majority of the comparisons made in this study. Various depressive symptoms not included in the DSM framework were unlikely to be detected. Conclusions: Cross-cultural differences in rates of MDD are attributable to diagnostic thresholds. Symptom patterns and forms of depression in Korea, as defined by the DSM framework, are not identical to those in the U.S.