Substance use disorders are highly prevalent among persons with schizophrenia and other major mental illnesses. Persons with major (Axis I) mental disorders have three times the risk of drug or alcohol diagnoses compared to the rest of the population (Regier et al., 1990
). Persons with schizophrenia represent a particularly high risk group for problems related to substance use. Among all persons with a diagnosis of schizophrenia, 47% meet lifetime criteria for a substance use disorder (Regier et al., 1990
). This prevalence rate is often higher in samples of schizophrenic patients in treatment (Mueser et al., 1990
; Test, Wallisch, Allness, & Ripp, 1989
A diagnosis of substance abuse or dependence impairs both the process and outcome of mental health treatment. Symptom exacerbation and psychiatric admissions have both been linked to acute drug use in outpatients with a severe and persistent mental illness (SPMI), such as schizophrenia (Haywood et al., 1995
; Shaner et al., 1995
). Individuals enrolled in outpatient treatment and “dually diagnosed” with psychiatric and substance use disorders exhibit poor medication compliance (Keck, McElroy, Strakowski, Bourne, & West, 1997
; Owen, Fischer, Booth, & Cuffel, 1996
; Pristach & Smith, 1990
), report more severe psychiatric symptoms (Carey, Carey, & Meisler, 1991
), and involve themselves minimally in structured treatment programs (Carey & Carey, 1990
; Lehman, Herron, Schwartz, & Myers, 1993
; Richardson, Craig, & Haugland, 1985
). This pattern of poor treatment compliance and exacerbated symptoms leads to greater use of institutional and emergency services, with higher associated costs (Bartels et al., 1993
; Kivlahan, Heiman, Wright, Mundt, & Shupe, 1991
Even consistent participation in psychiatric treatment need not imply that a dually diagnosed person has acknowledged substance use as a problem. Despite continuing substance misuse, treatment relationships are often maintained with dually diagnosed persons in order to monitor medications and manage crises associated with the psychiatric disorder (Carey, 1996
; Kofoed, Kania, Walsh, & Atkinson, 1986
). One influential model of intervention for dually diagnosed patients proposes that efforts to engage
a person in relationships with helping professionals and to persuade
him/her to accept substance use reduction as a treatment goal precede involvement in active treatment (Osher & Kofoed, 1989
). Toward this end, there is a need to attend to individual differences in motivation, or readiness, to change substance use among persons with a SPMI.
Within the treatment field there is growing recognition that individuals vary in their readiness-to-change (Carey, Purnine, Maisto, & Carey, 1999a
). For example, Prochaska and DiClemente (1992)
have provided a useful heuristic for understanding varying levels of motivation for change. Within their Transtheoretical Model, they posit five stages to represent the continuous and cyclic process by which people change addictive behaviors (precontemplation, contemplation, preparation, action, and maintenance), and note that the vast majority of persons addicted to substances are not
in the action stage (Prochaska & DiClemente, 1992
). Even persons admitted to alcohol and drug treatment programs vary in their level of motivation for change (DiClemente & Hughes, 1990
; Project Match Research Group, 1997
). Consistent with these findings, when Ziedonis and Trudeau administered a staging algorithm to 224 outpatient dually diagnosed with schizophrenia-spectrum and substance use disorders, they found that 50% were in the precontemplation stage with respect to changing their substance use behavior; 2% were in contemplation stage; 8% in preparation; 4% in action; and 36% in maintenance (Ziedonis & Trudeau, 1997
). Thus low levels of motivation for changing substance use behavior can be observed within a variety of treatment settings.
Readiness-to-change may be considered a motivational state that is strongly influenced by cognitive, affective, environmental and interpersonal events (DiClemente, 1993
). In addition, the notion of decisional balance (e.g., subjective pros and cons, or benefits and costs of a certain behavior) has been identified as a related construct that is a sensitive marker of movement through the early stages of change (Prochaska et al., 1994
). Self-report methods have often been used to measure readiness-to-change (Carey et al., 1999a
). A considerable literature has developed on the psychometrics of instruments purporting to assess readiness-to-change in substance abusing populations (Carey et al., 1999a
). However, little evaluation of basic psychometric indices, such as reliability of measurement and construct validity, has been conducted with persons who have severe mental illness. In this special population of substance users, concerns have been raised regarding the degree to which diagnostic status, cognitive function, or psychotic symptoms may influence the accuracy of a readiness-to-change assessment (Bellack & DiClemente, 1999
). For example, deficits in self-awareness or abstract thinking seen in persons with schizophrenia may compromise their ability to self-report interest in and intentions to change. Also, the presence of negative symptoms (e.g., avolition, anergia, and anhedonia) may interfere with the assessment of such motivational constructs as readiness-to-change. For these reasons, it is important to determine empirically whether readiness-to-change and/or decisional balance can be assessed reliably and validly in dually diagnosed persons.
Only two studies have investigated the measurement of readiness-to-change among persons with dual disorders. Addington and colleagues evaluated 39 outpatients diagnosed with both schizophrenia and substance use disorders (Addington, ed-Guebaly, Duchak, & Hodgins, 1999
). These authors found little correspondence between interviewer-assigned stage of change (assessed by an algorithm supplemented by clinician and chart data) and stage derived from the Stages of Change Readiness and Treatment Eagerness Scale (SOCRATES) (Miller & Tonigan, 1996
) or the Readiness to Change Questionnaire (Rollnick, Heather, Gold, & Hall, 1992
). Kappas for alcohol stage of change (n
=30) were .20 and .08, and kappas for drug stage of change (n
=22) were .38 and .45, respectively. These data are difficult to interpret due to the small sample size and lack of information about how stage assignments were obtained from the self-report scales. Furthermore, the authors of the SOCRATES discourage its use to classify respondents according to stage of change (Miller & Tonigan, 1996
), suggesting that the instruments were used in ways other than originally intended.
Velasquez and colleagues (Velasquez, Carbonari, & DiClemente, 1999
) also assessed readiness-to-change, decisional balance and other constructs related to the Transtheoretical Model (TTM) in a sample of 132 alcohol-dependent outpatients in a dual diagnosis program. A variety of Axis I disorders was represented in this sample, including major depressive disorder, schizophenia, and bipolar disorder. These investigators reported acceptable alpha coefficients for measures of the pros of drinking (.90), the cons of drinking (.91), and the readiness-to-change score (.91) derived from University of Rhode Island Change Assessment-Alcohol version (DiClemente & Hughes, 1990
). This preliminary evidence suggests that the presence of an Axis I mental disorder may not
be associated with poor internal consistency of instruments designed to assess readiness-to-change substance misuse. However, test-retest reliability was not assessed in this study, nor were correlations among the decisional balance and readiness variables reported. These investigators merely stated that these intercorrelations “were in the direction and of the magnitude of those found in most other studies” (p. 488) (Velasquez et al., 1999
). Taken together, these studies leave unanswered many questions about the ability of persons with schizophrenia and other SPMIs to provide meaningful information regarding their readiness-to-change substance use behavior.
The main purpose of this study was to provide additional empirical evidence on whether readiness-to-change patterns of substance misuse can be measured reliably and validly in a sample of persons dually diagnosed with SPMI and co-occurring substance abuse or dependence. We expanded the assessment of readiness-to-change variables to include the following self-report measures: (a) the Recognition, Ambivalence, and Taking Steps subscales from the SOCRATES, (b) pros and cons of continuing to use substances (from the Decisional Balance Scale; King & DiClemente, 1993
), and (c) pros and cons of quitting (from the Alcohol and Drug Consequences Questionnaire; Cunningham, Sobell, Gavin, Sobell, & Breslin, 1997
). Psychometric evaluation of these theoretically related constructs may provide tools to enhance our understanding of the generalizability of models of change to different populations of substance users.
We explored the following four research questions. First, we evaluated internal consistency and the temporal stability of the seven readiness-to-change scores. Based on the findings reported by Velasquez et al. (1999)
we predicted that these self-report measures of decisional balance and readiness-to-change would be internally consistent. Because motivational variables are considered to be changeable over time and responsive to both therapeutic and naturally-occurring events (DiClemente, 1993
; Miller & Rollnick, 1991
), we chose a relatively brief interval (less than one week) for evaluating temporal stability. We had no basis for predictions regarding test-retest reliability. Second, we evaluated the extent to which psychiatric diagnosis (schizophrenia vs. mood disorder), cognitive status, and positive and negative symptoms influenced the reliability indices. These analyses were exploratory, and we did not have empirical precedent for a priori predictions.
Third, we assembled convergent evidence for the validity of the motivational measures, based on the pattern of relationships among the 7 scale scores. Within each instrument, we compared our intercorrelations with that of the scale developers and others. For example, we expected a positive correlation between the Recognition and Taking Steps subscales from the SOCRATES, and negative correlations between subscales of the two decisional balance measures. In addition, we made the following predictions, based on theoretical relationships among these constructs: (1) we expected positive correlations between complementary constructs, (i.e., the Pros of Using and Costs of Quitting, and the Benefits of Quitting and Cons of Using); (2) we expected positive correlations between the Recognition scale and Cons of Using and Benefits of Quitting; and (3) we expected the Taking Steps scale would be positively related to Benefits of Quitting and negatively related to Costs of Quitting. Finally, discriminant evidence of validity was derived by observing relationships among the motivational variables and theoretically independent variables; we expected no significant correlations with demographic indices, measures of positive and negative symptoms, cognitive and functional status, or social desirability.