RELIABILITY OF INDIVIDUAL DIAGNOSTIC CRITERION ITEMS FOR PSYCHOACTIVESUBSTANCE DEPENDENCE AND THE IMPACT ON DIAGNOSIS

Objective: Reliability of diagnostic criterion items for psychoactive substance dependence and the impact of each on the reliability of the diagnosis were analyzed. Method: As part of a reliability study for a new interview developed for the multisite Collaborative Study on the G enetics of Alcoholism (COGA), data were collected from both within-cen ter and across centers. The impact of each diagnostic item on the reli ability of the substance dependence diagnosis was studied by forcing e ach item to be reliable one at a time and recomputing the kappa statis tic for the diagnosis. Results: Findings indicated that the majority o f individual diagnostic criterion items were reliable; 87% and 81% wer e in the fair or better range of reliability for the within- and cross -center studies, respectively. Individual kappa estimates were statist ically similar for the two studies. Reliability findings for two class es of substance, alcohol and cocaine, were good, while those for stimu lants were less satisfactory. Conclusions: Forcing items one at a time to be reliable did not affect reliability of the overall substance de pendence diagnosis, because more than one criterion item changed from Time 1 to Time 2. Because no single item was influential, weighting cr iteria equally, as is done in the DSM and ICD classification systems, appears to be a reasonable approach.