Background: The diagnostic stability of the ICD-10 diagnosis of depressive disorder has not been investigated in clinical practice.
Sampling and methods: All patients who were diagnosed with depressive disorder at least once in a period from 1994 to 2002 in psychiatric out- or inpatient settings in Denmark were identified in a nationwide register.
Results: A total of 39,741 patients were diagnosed with depressive disorder at least once; among these, 81% were diagnosed at the first contact. In approximately 56% of patients, the initial diagnosis of depressive disorder eventually changed during follow-up mainly to the schizophrenic spectrum (16%), but also to personality disorders (9%), neurotic, stress-related and somatoform disorders (8%) and to bipolar disorder (8%). Among the 18% of patients who were later diagnosed with depressive disorder, 23% initially had a diagnosis of adjustment disorder.
Conclusions: When the ICD-10 diagnoses are used in clinical practice, the diagnosis of depressive disorder has a low stability over time. These findings emphasize the need for a longitudinally based diagnostic process in the diagnostic systems.