The test-retest reliability of the inventory to diagnose depression, lifetime version

The test-retest reliability of the Inventory to Diagnose Depression, Lifetime Version (IDDL) was investigated, based on 57 first-degree relatives of probands with major depression. The subjects were first interviewed using the SCID, and then the IDDL was administered to them twice at a 1-month interval. The chance-corrected agreement in diagnosing a lifetime history of DSM-III-R major depression was high between the 2 trials of the IDDL (kappa = 0.77), and between the SCID and each of the 2 IDDL trials (kappa = 0.75 for the 1 trial, and 0.68 for the 2nd trial). The positiveness on all items except "increased appetite' and "weight gain' was also highly concordant between the 2 trials. These results strongly suggest that time-stable data with sufficient validity for diagnosing a lifetime history of depression can be given by using the IDDL.