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Article Excerpt
Psychometric properties of the Inventory of Drug Use Consequences (InDUC; W. M. Miller, J. S. Tonigan, & R. Longabaugh, 1995), a self-report assessment of negative consequences associated with alcohol and other drug use, were investigated. The InDUC demonstrated sound psychometric characteristics and can be a valuable clinical tool for chemical dependency counselors.
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A consistent finding in alcohol and other drug (AOD) research is that adverse consequences related to substance use are only moderately correlated with quantity and frequency of use and with measures of dependence (Institute of Medicine, 1990; Maisto & McKay, 1995). The assessment of AOD use consequences, however, has traditionally been confounded with measures of such things as consumption, pathological drinking/use, cravings, and others (Babor et al., 1994). The Inventory of Drug Use Consequences (InDUC; Miller, Tonigan, & Longabaugh, 1995) was developed in response to the need for a separate, comprehensive measure of adverse consequences experienced due to AOD use. The InDUC consists of 50 items that measure five dimensions of commonly experienced adverse consequences: (a) physical, (b) intrapersonal, (c) interpersonal, (d) social responsibility, and (e) impulse control. Consequences can be assessed for two time frames: recent and lifetime. Items on the recent version of the InDUC are scored on a 4-point Likert scale from (never) to 3 (daily or almost daily). Lifetime InDUC items are scored in a dichotomous "yes/no" format. Higher scores reflect more severe consequences. Scores can be computed for each subscale and for a total score of overall substance use consequences.
The InDUC is a potentially useful tool for AOD counselors and researchers. Since its development, the InDUC has been used in a variety of clinical research. For example, it has been used to measure treatment outcome (Gillaspy, Wright, Stokes, Campbell, & Adinoff, 2002), to compare consequences across ethnic groups (Arciniega, Arroyo, & Miller, 1996), to differentiate clients with a family history of drug use (Comtois, Tisdall, Holdcraft, & Simpson, 2005), and to explore the association between sexual abuse and AOD use consequences (Liebschutz et al., 2002). The InDUC may be especially helpful for AOD counselors who want to evaluate specific adverse consequences related to AOD use. In this context, the InDUC may be used as a supplement to traditional assessment instruments such as the Addiction Severity Index (McLellan et al., 1992). InDUC scores may also be useful during the implementation of interventions designed to increase client motivations for change. For example, feedback about the severity of adverse consequences related to AOD use has been shown to be an essential component of Motivational Interviewing (Miller & Rollnick, 2002).
The utility of any assessment tool, however, depends on the reliability and validity of its scores. If InDUC scores are not reliable and valid, they will be of little use to AOD counselors. To date, only two studies have addressed score characteristics of the InDUC. In a two-part study involving both inpatient and outpatient clients, Tonigan and Miller (2002) sought to evaluate (a) the test-retest reliability of lifetime InDUC scores, (b) the instrument's sensitivity to detect change, and (c) the underlying factor structure of recent (90-day) scores. Results indicated that (a) test-retest reliabilities ranged from .75 to .93 for lifetime InDUC scores on four of the five subscales (Intrapersonal = .34), (b) magnitudes of change due to treatment were found to be large for the total and subscale scores; and (c) confirmatory factor analytic methods revealed that a four-factor model (excluding the Intrapersonal subscale) fit the data better than the originally proposed five-factor model. In contrast, Blanchard, Morgenstern, Morgan, Labouvie, and Bux (2003) provided evidence that InDUC items reflect one general consequence factor. Examining data provided by 252 clients seeking substance abuse treatment, Blanchard et al. reported high internal consistency estimates for the total score ([alpha] = .96), large amounts of shared variance among the subscale scores, and that InDUC items loaded primarily on a single factor.
Although Blanchard et al. (2003) and Tonigan and Miller (2002) addressed important psychometric issues, questions remain about the reliability and validity of InDUC scores, in particular whether the subscales scores reflect separate dimensions of AOD consequences. Blanchard et al.'s results of a one-factor model are in contrast to Tonigan and Miller's findings in favor of a four-factor model. It should be noted, however, that Tonigan and Miller did not report testing other competing models, such as the one-factor model. Because there are numerous factor structures that may underlie any factor matrix, researchers must choose from many possibilities regarding which factor solution...
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