The original MTP sample (N=1016) was compared with the subset of participants who were included in the current investigation (N=526) by using t-tests and chi-square tests for age, education, gender, marital status, route of MA administration, employment, and baseline ASI composite scores. In all analyses, there were no significant differences between the patients in the current study and the original MTP sample.
Demographic characteristics of the original MTP sample are described elsewhere.1,16
At 3-year follow-up, the sample was 68% Caucasian, 2% African American, 12% Asian, and 14% Hispanic, with an average age of 36.2 (SD=8.0); 76% completed high school and 4% had college education and/or beyond. More than half (60%) of the participants were female. Regarding employment, 60% were working full-or part-time and 32% were unemployed; 4% were students, 2% were retired and 2% were in a controlled environment. Forty-seven percent were never married, 37% were divorced or separated, and 16% were married. At the baseline (i.e., pretreatment) assessment, participants reported using MA an average of 12 days out of the past 30 (SD=9.6). The preferred route of administration was smoking (62%), followed by i.v.-injecting (28%) and intranasal use (10%). There were no differences in demographic or substance use characteristics among those who completed the psychiatric assessment (n=526) relative to those who did not (n=61).
Participants with current (23.4%; N=123) and past (8.1%; N=43) anxiety disorders were compared on age, education, gender, marital status, route of MA administration, employment, and baseline MA use frequency and ASI composite scores. For each analysis, there were no significant differences between the patients with current and past anxiety disorders. Thus, current and past anxiety disorders were collapsed to form a single category indicating the presence of any anxiety disorder.
Of the 526 participants, 26.2% (N=138) met criteria for a current or past anxiety disorder at 3-year follow-up. The most common current disorder reported was Generalized Anxiety Disorder (12.3%; n=65), followed by Social Anxiety Disorder (8.5%; n=45), Post-Traumatic Stress Disorder (5.8%; n=31), Panic Disorder (2.6%; n=14), and Agoraphobia (2.6%; n=14). Self-reported MA use frequency during the follow-up period was significantly higher among those with (M=16.4 months, SD=1.2) versus without (M=13.3 months, SD=0.7) anxiety disorders. Likewise, participants with an anxiety disorder evidenced poorer treatment adherence relative to those without this diagnosis in terms of the number of scheduled weeks of treatment attended (M=6.25 vs. M=7.60, t=2.29, df=524, p=0.02), and were significantly more likely to meet criteria for alcohol- (OR=1.8, 95% C.I., 1.1–2.9) and other substance dependence (OR=2.2, 95% C.I., 1.5–3.3) at 3-year follow-up..
Those with an anxiety disorder had significantly greater odds of having been hospitalized within the 12 months prior to the 3-year follow-up interview relative to those without this diagnosis (Odds Ratio [OR]==1.8, 95% Confidence Interval [C.I.], 1.1–3.4) and had more than triple the odds of having attempted suicide once or more in their lifetime (OR=3.1, 95% C.I., 2.1–4.7).
ASI composite scores at baseline, discharge and follow-up for those with and without anxiety disorders are plotted in and , respectively, and the results of mixed model linear regressions testing the effects of time, anxiety disorder diagnosis, and their interaction on ASI scores are provided in . Controlling for demographics, pre-treatment MA use frequency and route of MA administration, these analyses revealed a main effect of anxiety disorder on the family and medical severity composites, indicating higher levels of impairment on these indices overall among those with an anxiety disorder, and a significant time×diagnosis interaction on two of the remaining five ASI composites (drug and psychiatric). These interactions indicated that the group with an anxiety disorder diagnosis reported problems of significantly greater severity over time in these areas.
Mean Addiction Severity Index (ASI) scale scores as a function of time among MA dependent adults with anxiety disorders at 3-year follow-up (N=138).
Mean Addiction Severity Index (ASI) scale scores as a function of time among MA dependent adults without anxiety disorders at 3-year follow-up (N=388).
Changes in psychosocial, psychiatric, and substance-related impairment among MA dependent adults at 3-year follow-up: linear mixed-effects models