MEASUREMENT OF ANTECEDENTS TO DRUG AND ALCOHOL-USE - PSYCHOMETRIC PROPERTIES OF THE INVENTORY OF DRUG-TAKING SITUATIONS (IDTS)

The development, factor structure, and validity of the Inventory of Dr ug-Taking Situations (IDTS) is described. This 50-item self-report que stionnaire, which is an extension of the Inventory of Drinking Situati ons (Annis, 1982, Inventory of drinking situations; Annis, Graham & Da vis, 1987, Inventory of drinking situations (IDS): User's guide), is d esigned to assess the situational antecedents to use of a wide range o f drugs of abuse. The IDTS consists of 8 subscales that measure a clie nt's substance use in the 8 situations identified in the work of Marla tt (1978, Alcoholism. New directions in behavioral research and treatm ent): Unpleasant Emotions, Physical Discomfort, Pleasant Emotions, Tes ting Personal Control, Urges and Temptations to Use, Conflict with Oth ers, Social Pressure to Use, and Pleasant Times with Others. Reliabili ty, factor structure and validity of the IDTS were assessed on 699 cli ents admitted to the Addiction Research Foundation's treatment facilit y in Toronto. The IDTS was shown to have reliable subscales. The IDTS total score correlated with self-ratings of the severity of the client s' substance use problem, and with retrospective reports of frequency of use (drugs) and quantity of use (alcohol), years of usage, and seve rity of dependence. Confirmatory factor analysis was used to test the fit of the data to Marlatt's model of substance use situations, as wel l as to several alternative models. The goodness-of-fit indicators sug gested that the best it for the data was an 8-factor model correspondi ng to the 8 subscales based on the Marlatt categories. Evidence was pr esented that the 8 subscales can be further grouped into 3 second-orde r factors: (1) negative situations, (2) positive situations, and (3) t emptation situations. The negative situation subscales of Unpleasant E motions, Conflict with Others and Physical Discomfort were found to be correlated with the SCL-90(R) Depression scale, Interpersonal Sensiti vity scale and Somatization scale respectively. The positive social si tuation subscales of Pleasant Times with Others and Social Pressure to Use were found to be negatively correlated with percentage of time us ing alone, and positively correlated with pressure from friends and fa mily to use. On the States of Change Readiness and Treatment Eagerness Scales (SOCRATES), clients at the precontemplation stage of change ha d relatively flat, undifferentiated IDTS profiles (i.e. little scatter of subscale scores), whereas clients in the determination stage had t he most differentiation in their IDTS subscale scores. Excellent compa rability was found for alcohol clients between the IDS and the IDTS. E vidence was also presented for adequate comparability between the comp uter and paper and pencil administrative formats of the IDTS. (C) 1997 Elsevier Science Ltd.