Test-retest stability of the Onset of Depression Inventory.

ABSTRACT

BACKGROUND: The 'Onset of Depression Inventory' (ODI) is a patient interview developed for systematically registering the speed of onset of depression. The ODI might contribute to the detection of hidden bipolarity because in previous studies a more rapid depression onset was found in patients with bipolar compared to unipolar depression. The aim of this study was to evaluate the test-retest stability of the ODI. Patients were asked concerning the speed of onset at the time of hospitalization and again before discharge. SAMPLING AND METHODS: Test-retest stability of the ODI was investigated in 37 patients with a depressive episode. Each patient was interviewed concerning his present depressive episode by the same person at two different time points. Severity of depression at the different time points was assessed using the Hamilton Depression Rating Scale (HAMD-17) and the Inventory of Depressive Symptomatology (IDS-C). RESULTS: The speed of onset as assessed with the ODI showed good test-retest stability (rho = 0.83, p < 0.001). This parameter was not influenced by changes in depression severity. CONCLUSIONS: The ODI allows reliable assessment of the speed of onset of depressive episodes. The instrument might be useful for the detection of hidden bipolarity.