Browsing by Author "Stitzer, Maxine L"

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Open Access
An item response theory modeling of alcohol and marijuana dependences: a National Drug Abuse Treatment Clinical Trials Network study.
(Journal of studies on alcohol and drugs, 2009-05) Wu, Li-Tzy; Pan, Jeng-Jong; Blazer, Dan G; Tai, Betty; Stitzer, Maxine L; Brooner, Robert K; Woody, George E; Patkar, Ashwin A; Blaine, Jack D
OBJECTIVE:The aim of this study was to examine psychometric properties of the Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition (DSM-IV), diagnostics criteria for alcohol and marijuana dependences among 462 alcohol users and 311 marijuana users enrolled in two multisite trials of the National Drug Abuse Treatment Clinical Trials Network. METHOD:Diagnostic questions were assessed by the DSM-IV checklist. Data were analyzed by the item response theory and the multiple indicators-multiple causes method procedures. RESULTS:Criterion symptoms of alcohol and marijuana dependences exhibited a high level of internal consistency. All individual symptoms showed good discrimination in distinguishing alcohol or marijuana users between high and low severity levels of the continuum. In both groups, "withdrawal" appeared to measure the most severe symptom of the dependence continuum. There was little evidence of measurement nonequivalence in assessing symptoms of dependence by gender, age, race/ethnicity, and educational level. CONCLUSIONS:These findings highlight the clinical utility of the DSM-IV checklist in assessing alcohol- and marijuana dependence syndromes among treatment-seeking substance users.
Open Access
Heterogeneity of stimulant dependence: a national drug abuse treatment clinical trials network study.
(The American journal on addictions, 2009-05) Wu, Li-Tzy; Blazer, Dan G; Patkar, Ashwin A; Stitzer, Maxine L; Wakim, Paul G; Brooner, Robert K
We investigated the presence of DSM-IV subtyping for dependence on cocaine and amphetamines (with versus without physical dependence) among outpatient stimulant users enrolled in a multisite study of the Clinical Trials Network (CTN). Three mutually exclusive groups were identified: primary cocaine users (n = 287), primary amphetamine users (n = 99), and dual users (cocaine and amphetamines; n = 29). Distinct subtypes were examined with latent class and logistic regression procedures. Cocaine users were distinct from amphetamine users in age and race/ethnicity. There were four distinct classes of primary cocaine users: non-dependence (15%), compulsive use (14%), tolerance and compulsive use (15%), and physiological dependence (tolerance, withdrawal, and compulsive use; 56%). Three distinct classes of primary amphetamine users were identified: non-dependence (11%), intermediate physiological dependence (31%), and physiological dependence (58%). Regardless of stimulants used, most female users were in the most severe or the physiological dependence group. These results lend support for subtyping dependence in the emerging DSM-V.
Open Access
Infrequent illicit methadone use among stimulant-using patients in methadone maintenance treatment programs: a national drug abuse treatment clinical trials network study.
(The American journal on addictions, 2008-07) Wu, Li-Tzy; Blazer, Dan G; Stitzer, Maxine L; Patkar, Ashwin A; Blaine, Jack D
We sought to determine the prevalence, patterns, and correlates of past-month illicit methadone use and history of regular illicit use among stimulant-using methadone maintenance treatment patients. We obtained self-reported information on illicit methadone use from 383 participants recruited from six community-based methadone maintenance programs. Overall, 1.6% of participants reported illicit use in the past month, and 4.7% reported a history of regular use. Younger age and history of outpatient psychological treatment were associated with increased odds of past-month illicit use. Illicit methadone use among patients in maintenance programs is infrequent; however, a number of factors may increase risk of illicit use.
Open Access
The construct and measurement equivalence of cocaine and opioid dependences: a National Drug Abuse Treatment Clinical Trials Network (CTN) study.
(Drug and alcohol dependence, 2009-08) Wu, Li-Tzy; Pan, Jeng-Jong; Blazer, Dan G; Tai, Betty; Brooner, Robert K; Stitzer, Maxine L; Patkar, Ashwin A; Blaine, Jack D
INTRODUCTION:Although DSM-IV criteria are widely used in making diagnoses of substance use disorders, gaps exist regarding diagnosis classification, use of dependence criteria, and effects of measurement bias on diagnosis assessment. We examined the construct and measurement equivalence of diagnostic criteria for cocaine and opioid dependences, including whether each criterion maps onto the dependence construct, how well each criterion performs, how much information each contributes to a diagnosis, and whether symptom-endorsing is equivalent between demographic groups. METHODS:Item response theory (IRT) and multiple indicators-multiple causes (MIMIC) modeling were performed on a sample of stimulant-using methadone maintenance patients enrolled in a multisite study of the National Drug Abuse Treatment Clinical Trials Network (CTN) (N=383). Participants were recruited from six community-based methadone maintenance treatment programs associated with the CTN and major U.S. providers. Cocaine and opioid dependences were assessed by DSM-IV Checklist. RESULTS:IRT modeling showed that symptoms of cocaine and opioid dependences, respectively, were arrayed along a continuum of severity. All symptoms had moderate to high discrimination in distinguishing drug users between severity levels. "Withdrawal" identified the most severe symptom of the cocaine dependence continuum. MIMIC modeling revealed some support for measurement equivalence. CONCLUSIONS:Study results suggest that self-reported symptoms of cocaine and opioid dependences and their underlying constructs can be measured appropriately among treatment-seeking polysubstance users.
Open Access
Using a latent variable approach to inform gender and racial/ethnic differences in cocaine dependence: a National Drug Abuse Treatment Clinical Trials Network study.
(Journal of substance abuse treatment, 2010-06) Wu, Li-Tzy; Pan, Jeng-Jong; Blazer, Dan G; Tai, Betty; Stitzer, Maxine L; Woody, George E
This study applies a latent variable approach to examine gender and racial/ethnic differences in cocaine dependence, to determine the presence of differential item functioning (DIF) or item-response bias to diagnostic questions of cocaine dependence, and to explore the effects of DIF on the predictor analysis of cocaine dependence. The analysis sample included 682 cocaine users enrolled in two national multisite studies of the National Drug Abuse Treatment Clinical Trials Network (CTN). Participants were recruited from 14 community-based substance abuse treatment programs associated with the CTN, including 6 methadone and 8 outpatient nonmethadone programs. Factor and multiple indicators-multiple causes (MIMIC) procedures evaluated the latent continuum of cocaine dependence and its correlates. MIMIC analysis showed that men exhibited lower odds of cocaine dependence than women (regression coefficient, beta = -0.34), controlling for the effects of DIF, years of cocaine use, addiction treatment history, comorbid drug dependence diagnoses, and treatment setting. There were no racial/ethnic differences in cocaine dependence; however, DIF by race/ethnicity was noted. Within the context of multiple community-based addiction treatment settings, women were more likely than men to exhibit cocaine dependence. Addiction treatment research needs to further evaluate gender-related differences in drug dependence in treatment entry and to investigate how these differences may affect study participation, retention, and treatment response to better serve this population.