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AM. J. DRUG ALCOHOL ABUSE, 18(3), pp. 289-303 (1992)
Ten-Year Follow-up after Admission to Methadone Maintenance James F. Maddux,* M.D. David P. Desmond, M.S.W. Department of Psychiatry The University of Texas Health Science Center at San Antonio 7703 Fioyd Curl Drive, San Antonio, Texas 78284-7792 Telephone: (572)567-5480
ABSTRACT To assess the long-term effects of methadone maintenance, we compared the 10-year outcomes of 95 chronic opioid users who spent at least one cumulative year on methadone with those of 77 chronic opioid users who spent less than one cumulative year on methadone. All subjects were men and 90% were Mexican-American. The two groups were similar on 12 of 15 background variables. During the 10-year period, the methadone group had a cumulative mean of 54 months on methadone, while the comparison group had a cumulative mean of only 2 months on methadone. On social performance, as measured by months employed and months institutionalized, the methadone group did significantly better than did the comparison group. On months of voluntary abstinence, however, the comparison group did significantly better than did the methadone group. The mean of the comparison group, 36 months, was three times greater than that, 12 months, of the methadone group. At the end of the 10-year period, 26% of the comparison group but only 7 % of the methadone group had been in continuous voluntary abstinence for 3 years or longer. Methadone maintenance for 1 year or longer was inversely related to abstinence during and at the end of the 10 years. This finding seems consistent with the hypothesis that methadone maintenance for 1 year or longer impedes eventual recovery from opioid dependence. For many patients, however, the benefits of prolonged maintenance could outweigh the possible cost of diminished likelihood of eventual recovery.
~~
*To whom requests for reprints should be addressed.
289
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290
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INTRODUCTION In a recent review [ l ] of 5-year or longer follow-up studies of opioid users admitted to methadone maintenance or to drug-free treatment, we attempted to assess the effect of methadone maintenance on eventual recovery from opioid dependence. The long-term outcomes after both modes of treatment seemed remarkably similar. Small percentages of subjects, 9 to 2 1% , were found abstinent from opioids at the time of follow-up after methadone maintenance, and similar small percentages, 10 to 19%, after drug-free treatment. These comparisons failed to suggest that methadone maintenance impedes eventual recovery from opioid dependence, but they did not clearly exclude such an effect. With one exception [2], the methadone maintenance follow-up studies did not report the time that the patients spent on methadone. Any effect of methadone maintenance on long-term outcome may have been obscured by the outcomes of patients who spent only short periods on methadone. We report here a follow-up study of chronic opioid users during 10 years after their first admission to methadone maintenance, controlling for time on methadone. The 10-year outcomes of subjects who spent 1 year or longer on methadone were compared with those of similar opioid users who spent less than 1 year on methadone during a corresponding 10-year period. The study had the purpose of assessing the long-term effects of methadone maintenance on substance abuse, social performance, and recovery from opioid dependence. We use voluntary abstinence as an indicator of partial recovery from opioid dependence.
SUBJECTS AND METHODS Data Collection The data came from a prospective study of the careers of 248 chronic opioid users who resided in San Antonio and who were hospitalized at the former Public Health Service Hospital in Fort Worth, Texas, during the years 1964 into 1967. The follow-up study began in 1966 and ended in 1988. The study group consisted entirely of men, of whom 87 % were Mexican-American. All used heroin at some time, and 95% reported that heroin was the principal opioid used. Longitudinal data were collected by periodic interviews with subjects, by reviews of criminal justice records, drug abuse treatment records, and hospital records, and from other sources. Detailed life history data accounting continuously for all time were obtained for residence, opioid use, alcohol use, employment and
Am J Drug Alcohol Abuse Downloaded from informahealthcare.com by University of British Columbia on 12/10/14 For personal use only.
FOLLOW-UP TO METHADONE MAINTENANCE ADMISSION
29 I
institutionalization in jail, prison, or treatment facility. In addition, life history information was obtained about education, marriage and reproduction, arrests, treatment and correctional interactions, serious illnesses and injuries, and death. The methods and other findings have been previously reported [3-lo]. By the end of 1986, 154 (68%) of the 248 subjects had been admitted to methadone maintenance. Thirteen subjects were first admitted during 1968 and 1969 to two small methadone maintenance programs which opened in San Antonio during those years, but most were first admitted during the 1970s to the Drug Dependence Program of the Bexar County Mental Health Mental Retardation Center. It was not until 1970, when this program opened, that methadone maintenance became available to large numbers of opioid users in San Antonio. Some of the subjects were admitted to methadone maintenance programs in other cities. Two groups of subjects, a methadone group and a comparison group, were selected for study. Subjects in the methadone group were initially selected if they were admitted to methadone maintenance for the first time by the end of 1977. Those admitted after 1977 (n = 13) were excluded because a 10-year follow-up required data through 1987, and 1987 was the last complete year of data collection. Thirty-two were excluded because they spent less than one cumulative year on methadone during the 10-year period, and 14 were excluded because the research records did not contain complete 10-year data. These exclusions left a group of 95 subjects first admitted to methadone maintenance during the years 1968 through 1977 who spent at least one cumulative year on methadone during the 10 years following admission. The l-year cut-off period was selected because our clinical experience has inclined us to believe that the typical chronic heroin user needs at least a year of methadone maintenance with supportive services to show distinct change toward a stable, heroin-free, prosocial lifestyle. In support of this clinical impression, a follow-up study [l 11 in San Antonio showed that patients retained on methadone maintenance for 1 year after admission did significantly better on employment than did those retained for less than 1 year. The comparison group consisted of the 32 subjects with less than one cumulative year on methadone plus others who were eligible for and had the opportunity to enter methadone maintenance during the years 1970-1977 but were never admitted. The year 1970 was selected as the first year of opportunity for the neveradmitted subjects because, as noted, this was the first year in San Antonio in which methadone mainteiiance became available tc rge numbers of opioid users. Since 141 subjects were admitted to methadone maintenance during the years 1968 through 1977, a pool of 107 (248 less 141) remained as potential comparison subjects who were never admitted. Forty-six were excluded because they did not
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become eligible for methadone maintenance during the years 1970- 1977. These subjects had no periods of daily opioid use; they had varied sequences of incarceration, occasional illicit opioid use, voluntary abstinence, and death. Another 16 subjects were excluded because the research records did not contain complete 10-year data. These exclusions left 45 subjects with complete 10-year data who were eligible for and who had the opportunity to enter methadone maintenance during the years 1970-1977 but who were never admitted. Although the neveradmitted subjects were not admitted to methadone maintenance, nearly all of them probably received methadone on one or more occasions during the 10-year period when treated for withdrawal. Consequently they did not remain naive about the subjective effects of methadone. The 10-year comparison period for these subjects was selected by first matching each with a subject in the methadone group on birthyear and age of first opioid use. Then the month and year of the first admission of the methadone maintenance subject was selected as the start of the 10-year period for the comparison subject. We subsequently refer to this time as the “simulated” first admission to methadone maintenance. The 32 subjects with less than one cumulative year on methadone combined with the 45 neveradmitted subjects made a comparison group of 77 subjects.
Data Analysis Background variables and 10-year treatment and outcome variables of the 95 methadone subjects were compared with those of the 77 comparison subjects. Fifteen background variables provided information about ethnic status, parental family, education, illicit opioid use, problem drinking, substance abuse treatment, employment, arrest, conviction, and incarceration. Five of the eight 10-year outcome variables were measured in months spent in specified statuses as follows: daily illicit opioid use, occasional illicit opioid use, voluntary abstinence, institutionalization, and employment. Occasional use meant use at least once a month but less than daily. Voluntary abstinence meant abstinence from all opioid drugs, including methadone, while in the community. Nearly all the months of institutionalization were months in prison. Arrests were counted only for drug law violations or income-producing crimes. The criteria for problem drinking consisted of a social or occupational dysfunction due to alcohol consumption or a chronic health disorder due to alcohol consumption. The research files did not contain uniformly complete information with respect to the DSM-IlI-R criteria [121, but we believe that nearly all of the problem drinking would, with more information, have met the criteria for alcohol abuse or dependence.
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With one exception, all of the distributions of values on measures considered interval scales bears, months, arrests, and treatment admissions) were significantly skewed in the methadone group or the comparison group or both. The exception was years of education. For this variable, the t-test was used to estimate the significance of the difference between the two groups. For the other interval scale variables, the Savage test [13] was used. This is a rank test especially suited for exponential distributions. For the categorical variables the significance of differences in frequencies was estimated by the chi-square test. The significance of change in prevalence of problem drinking before and after first admission to methadone maintenance was estimated by the McNemar test [ 141. Two-tailed tests were used in all the analyses. The .05 level was accepted for statistical significance.
FINDINGS Background Characteristics As shown in Table 1, both groups of subjects were predominantly MexicanAmerican, and approximately half of both groups were reared in broken families. About one-third had disciplinary problems in school, and they left school with a median of only 8 years of education. The mean age of first arrest preceded that of first opioid use. For both groups, a mean of 16 years elapsed from first opioid use, which typically occurred in late adolescence, to first admission to methadone maintenance. During that time, both groups of subjects spent a mean of over 5 years in jail and prison. The methadone subjects closely resembled the comparison subjects on most background variables. Statistically significant differences were found on only three of the 15 background variables. These were years of education, years of daily illicit opioid use before admission to methadone maintenance, and number of substance abuse treatment admissions before admission to methadone maintenance. While statistically significant, the difference in years of education was small; the means were 8.3 years for the methadone subjects and 7.6 years for the comparison subjects; the medians were 8 years for both. Although both groups had the same mean of years, 16, from first opioid use to methadone maintenance, the methadone group had significantly more years (mean = 6.6) of daily illicit opioid use than did the comparison group (mean = 5.4). The methadone group also had significantly more substance abuse treatment admissions (mean = 4.2) than did the comparison group (mean = 3.0).
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Table 1. Background Characteristics of Methadone Maintenance Subjects and Comparison Subjects before First Admission or Simulated First Admission to Methadone Maintenance
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Methadone subjects ( N = 95)
Comparison subjects ( N = 77)
Number (%) MexicamAmerican
82
(86.3%)
73
(94.8%)
Number (%) reared in broken family
44
(46.3%)
45
(58.4%
Mean (median) years of education
8.3 (8)
7.6 (8)a
Number (%) with disciplinary problem in school
32
(33.7%)
30
(39.0%
Mean (median) age of first arrest
16
(15)
16
(16)
Mean (median) age of first opioid use
18
(18)
17
(16)
Number (%) arrested before opioid use
63
(66.3%)
47
(61.0%)
Number (%) with felony conviction before first opioid use
25
(26.3%)
18
(23.4%)
Mean (median) years from first opioid use to first admission to methadone maintenance
16
(14)
16
(15)
Mean (median) years of daily illicit opioid use before first admission to methadone maintenance Number (%) with problem drinking before first admission to methadone maintenance
6.6 (6) 75
(78.9%)
5.4 ( 5 i b 52
(67.5%)
Mean (median) years jail and prison before first admission to methadone maintenance
5 3 (3)
5.2 (4)
Mean (median) months employed in year before first admission to methadone maintenance
4.0 (3)
3.1 (0)
Mean (median) substance abuse treatment admissions before first admission to methadone maintenance
4.3 (3)
3.0 (2)'
Mean (median) age of first admission to methadone maintenance
34
(33)
33
(31)d
= 2.03, df = 169, p = ,044. bSavage S = 13.6, z = 2.1, p = .033. CSavage S = 17.4, z = 2.7, p = ,007. dThe age of first admission of never-admitted comparison subjects was simulated by selecting the age at the start of the 10-year comparison period.
Treatment during Ten Years Most methadone subjects did not remain continuously on methadone from the time of first admission until discharge or completion of the 10-year study period.
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Table 2. Methadone Subjects and Comparison Subjects Who Had One or More Substance Abuse Treatment Admissions during 10 Years after First Admission or Simulated First Admission to Methadone Maintenance, by Type of Treatmentd ~
~
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Methadone subjects ( N = 95)
Methadone maintenance Inpatient withdrawal Outpatient withdrawal Outpaitent drug-free Religious program Residential treatment Other treatment
Comparison subjects ( N = 77)
N
%
N
%
66 33
69.5 34.7 8.4 5.3 9.5 13.7 2.1
15a 19 6 15b 10 22c 4
19.5 24.7 7.8 19.5 13.0 28.6 5.2
8 5 9
13 2
ax 2 ,
40.7, df = 1 , p < ,001. 7.0, df = 1, p = .008. ‘,y2 = 4.9, df = 1, p = .026.
b ~ = 2
dChi-square computations were adjusted for continuity
The typical pattern was discharge from methadone maintenance, followed by one or more readmissions during the 10-year period. Table 2 shows that 66 (69.5%) of the methadone subjects were discharged after the first admission to methadone maintenance and then readmitted one or more times. Twenty-three (24.2%; not shown in the table) were discharged after the first admission and not readmitted during the 10-year period. Only 6 (6.3%) subjects remained continuously on methadone throughout the 10-year period. The mean number of readmissions to methadone maintenance was 1.4; the maximum, seven. In contrast to the methadone subjects, only 15 (19.5%)of the comparison subjects were readmitted after the first (or simulated first) admission to methadone maintenance. The mean number of readmissions to methadone maintenance was 0.3. During the 10 years, the methadone subjects spent a cumulative mean of 54 months on methadone, while the comparison subjects spent a cumulative mean of only 2 months on methadone. The respective medians were 46 and zero. This difference is statistically significant (Savage S = 56.2, z = 8.8, p < ,001). As determined partly by definition of the two groups, the time on methadone ranged from 12 to 120 months for the methadone subjects and from none to 11 months for the comparison subjects. In addition to methadone maintenance, subjects of both groups were admitted to several other types of substance abuse treatment during the 10-year period.
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Table 2 shows the number and percentages of subjects of both groups admitted one or more times to other types of treatment. Only a minority of subjects in both groups was admitted to each of these types of treatment. The number of admissions (not shown in the table) to any specified treatment (except methadone maintenance) was small, ranging from none to four; the means were less than one in all cases, and the medians were zero. As shown in Table 2, the percentages of subjects admitted one or more times to the other types of treatment was similar for both groups, except for the percentages admitted to outpatient drug-free treatment and to residential treatment. Fifteen (19.5%)of the comparison subjects but only five (5.3 %) of the methadone subjects were admitted to outpatient drugfree treatment, and 22 (28.6%)of the comparison subjects but only 14 (13.7%) of the methadone subjects were admitted to residential treatment. As shown in the table, these differences were statistically significant. The comparison subjects also spent more time in residential treatment (mean = 1.4 months) than did the methadone subjects (mean = 0.7 months), but this difference did not achieve statistical significance (Savage S = 10.0, z = 1.8, p = ,078). While only a minority of both groups was admitted to any specified type of treatment, except methadone maintenance, a majority of both groups was admitted to at least one of the types of treatment shown in Table 2 during the 10-year period. Seventy-seven (81.1%) of the methadone subjects and 51 (66.2%) of the comparison subjects were admitted during the 10-year period to at least one of the types of treatment. This difference is statistically significant (x2 = 4.1, df = 1, p = .041). If admissions to methadone maintenance are excluded, then 49 (51.6%) of the methadone subjects and 45 (58.4%) of the comparison subjects were admitted to at least one of the types of treatment. This difference is not significant. Some of the subjects were admitted primarily for treatment of alcohol abuse or dependence. They were admitted to inpatient withdrawal or to outpatient disulfiram treatment. They are counted in Table 2 in the “Inpatient withdrawal” and “Other treatment” categories.
Outcomes As shown in Table 3, the two groups had only a small and nonsignificant difference in months of daily illicit opioid use during the 10-year period. The means were 12 months for the methadone group and 14 for the comparison group. The methadone group, however, had significantly more months (mean = 18) of occasional illicit opioid use than did the comparison group (mean = 6.6). Most
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Table 3. Outcomes of Methadone Maintenance Subjects and Comparison Subjects during 10 Years aAer First Admission or Simulated First Admission to Methadone Maintenance
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Methadone subjects ( N = 95) Mean (median) months of daily illicit opioid use Mean (median) months of occasional illicit opioid use Mean (median) months of voluntary abstinence Number (%) with problem drinking Mean (median) months employed Mean (median) arrests Mean (mdeian) months institutionalized *Savage S bSavage S %avage S dSavage S
= 30.1,z = 4.8,p < = 31.8,z = 5.0,p < = 15.0,z = 2.4,p = = 33.0,z = 5.2,p
AM. J. DRUG ALCOHOL ABUSE, 18(3), pp. 289-303 (1992)
Ten-Year Follow-up after Admission to Methadone Maintenance James F. Maddux,* M.D. David P. Desmond, M.S.W. Department of Psychiatry The University of Texas Health Science Center at San Antonio 7703 Fioyd Curl Drive, San Antonio, Texas 78284-7792 Telephone: (572)567-5480
ABSTRACT To assess the long-term effects of methadone maintenance, we compared the 10-year outcomes of 95 chronic opioid users who spent at least one cumulative year on methadone with those of 77 chronic opioid users who spent less than one cumulative year on methadone. All subjects were men and 90% were Mexican-American. The two groups were similar on 12 of 15 background variables. During the 10-year period, the methadone group had a cumulative mean of 54 months on methadone, while the comparison group had a cumulative mean of only 2 months on methadone. On social performance, as measured by months employed and months institutionalized, the methadone group did significantly better than did the comparison group. On months of voluntary abstinence, however, the comparison group did significantly better than did the methadone group. The mean of the comparison group, 36 months, was three times greater than that, 12 months, of the methadone group. At the end of the 10-year period, 26% of the comparison group but only 7 % of the methadone group had been in continuous voluntary abstinence for 3 years or longer. Methadone maintenance for 1 year or longer was inversely related to abstinence during and at the end of the 10 years. This finding seems consistent with the hypothesis that methadone maintenance for 1 year or longer impedes eventual recovery from opioid dependence. For many patients, however, the benefits of prolonged maintenance could outweigh the possible cost of diminished likelihood of eventual recovery.
~~
*To whom requests for reprints should be addressed.
289
MADDUX AND DESMOND
290
Am J Drug Alcohol Abuse Downloaded from informahealthcare.com by University of British Columbia on 12/10/14 For personal use only.
INTRODUCTION In a recent review [ l ] of 5-year or longer follow-up studies of opioid users admitted to methadone maintenance or to drug-free treatment, we attempted to assess the effect of methadone maintenance on eventual recovery from opioid dependence. The long-term outcomes after both modes of treatment seemed remarkably similar. Small percentages of subjects, 9 to 2 1% , were found abstinent from opioids at the time of follow-up after methadone maintenance, and similar small percentages, 10 to 19%, after drug-free treatment. These comparisons failed to suggest that methadone maintenance impedes eventual recovery from opioid dependence, but they did not clearly exclude such an effect. With one exception [2], the methadone maintenance follow-up studies did not report the time that the patients spent on methadone. Any effect of methadone maintenance on long-term outcome may have been obscured by the outcomes of patients who spent only short periods on methadone. We report here a follow-up study of chronic opioid users during 10 years after their first admission to methadone maintenance, controlling for time on methadone. The 10-year outcomes of subjects who spent 1 year or longer on methadone were compared with those of similar opioid users who spent less than 1 year on methadone during a corresponding 10-year period. The study had the purpose of assessing the long-term effects of methadone maintenance on substance abuse, social performance, and recovery from opioid dependence. We use voluntary abstinence as an indicator of partial recovery from opioid dependence.
SUBJECTS AND METHODS Data Collection The data came from a prospective study of the careers of 248 chronic opioid users who resided in San Antonio and who were hospitalized at the former Public Health Service Hospital in Fort Worth, Texas, during the years 1964 into 1967. The follow-up study began in 1966 and ended in 1988. The study group consisted entirely of men, of whom 87 % were Mexican-American. All used heroin at some time, and 95% reported that heroin was the principal opioid used. Longitudinal data were collected by periodic interviews with subjects, by reviews of criminal justice records, drug abuse treatment records, and hospital records, and from other sources. Detailed life history data accounting continuously for all time were obtained for residence, opioid use, alcohol use, employment and
Am J Drug Alcohol Abuse Downloaded from informahealthcare.com by University of British Columbia on 12/10/14 For personal use only.
FOLLOW-UP TO METHADONE MAINTENANCE ADMISSION
29 I
institutionalization in jail, prison, or treatment facility. In addition, life history information was obtained about education, marriage and reproduction, arrests, treatment and correctional interactions, serious illnesses and injuries, and death. The methods and other findings have been previously reported [3-lo]. By the end of 1986, 154 (68%) of the 248 subjects had been admitted to methadone maintenance. Thirteen subjects were first admitted during 1968 and 1969 to two small methadone maintenance programs which opened in San Antonio during those years, but most were first admitted during the 1970s to the Drug Dependence Program of the Bexar County Mental Health Mental Retardation Center. It was not until 1970, when this program opened, that methadone maintenance became available to large numbers of opioid users in San Antonio. Some of the subjects were admitted to methadone maintenance programs in other cities. Two groups of subjects, a methadone group and a comparison group, were selected for study. Subjects in the methadone group were initially selected if they were admitted to methadone maintenance for the first time by the end of 1977. Those admitted after 1977 (n = 13) were excluded because a 10-year follow-up required data through 1987, and 1987 was the last complete year of data collection. Thirty-two were excluded because they spent less than one cumulative year on methadone during the 10-year period, and 14 were excluded because the research records did not contain complete 10-year data. These exclusions left a group of 95 subjects first admitted to methadone maintenance during the years 1968 through 1977 who spent at least one cumulative year on methadone during the 10 years following admission. The l-year cut-off period was selected because our clinical experience has inclined us to believe that the typical chronic heroin user needs at least a year of methadone maintenance with supportive services to show distinct change toward a stable, heroin-free, prosocial lifestyle. In support of this clinical impression, a follow-up study [l 11 in San Antonio showed that patients retained on methadone maintenance for 1 year after admission did significantly better on employment than did those retained for less than 1 year. The comparison group consisted of the 32 subjects with less than one cumulative year on methadone plus others who were eligible for and had the opportunity to enter methadone maintenance during the years 1970-1977 but were never admitted. The year 1970 was selected as the first year of opportunity for the neveradmitted subjects because, as noted, this was the first year in San Antonio in which methadone mainteiiance became available tc rge numbers of opioid users. Since 141 subjects were admitted to methadone maintenance during the years 1968 through 1977, a pool of 107 (248 less 141) remained as potential comparison subjects who were never admitted. Forty-six were excluded because they did not
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become eligible for methadone maintenance during the years 1970- 1977. These subjects had no periods of daily opioid use; they had varied sequences of incarceration, occasional illicit opioid use, voluntary abstinence, and death. Another 16 subjects were excluded because the research records did not contain complete 10-year data. These exclusions left 45 subjects with complete 10-year data who were eligible for and who had the opportunity to enter methadone maintenance during the years 1970-1977 but who were never admitted. Although the neveradmitted subjects were not admitted to methadone maintenance, nearly all of them probably received methadone on one or more occasions during the 10-year period when treated for withdrawal. Consequently they did not remain naive about the subjective effects of methadone. The 10-year comparison period for these subjects was selected by first matching each with a subject in the methadone group on birthyear and age of first opioid use. Then the month and year of the first admission of the methadone maintenance subject was selected as the start of the 10-year period for the comparison subject. We subsequently refer to this time as the “simulated” first admission to methadone maintenance. The 32 subjects with less than one cumulative year on methadone combined with the 45 neveradmitted subjects made a comparison group of 77 subjects.
Data Analysis Background variables and 10-year treatment and outcome variables of the 95 methadone subjects were compared with those of the 77 comparison subjects. Fifteen background variables provided information about ethnic status, parental family, education, illicit opioid use, problem drinking, substance abuse treatment, employment, arrest, conviction, and incarceration. Five of the eight 10-year outcome variables were measured in months spent in specified statuses as follows: daily illicit opioid use, occasional illicit opioid use, voluntary abstinence, institutionalization, and employment. Occasional use meant use at least once a month but less than daily. Voluntary abstinence meant abstinence from all opioid drugs, including methadone, while in the community. Nearly all the months of institutionalization were months in prison. Arrests were counted only for drug law violations or income-producing crimes. The criteria for problem drinking consisted of a social or occupational dysfunction due to alcohol consumption or a chronic health disorder due to alcohol consumption. The research files did not contain uniformly complete information with respect to the DSM-IlI-R criteria [121, but we believe that nearly all of the problem drinking would, with more information, have met the criteria for alcohol abuse or dependence.
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With one exception, all of the distributions of values on measures considered interval scales bears, months, arrests, and treatment admissions) were significantly skewed in the methadone group or the comparison group or both. The exception was years of education. For this variable, the t-test was used to estimate the significance of the difference between the two groups. For the other interval scale variables, the Savage test [13] was used. This is a rank test especially suited for exponential distributions. For the categorical variables the significance of differences in frequencies was estimated by the chi-square test. The significance of change in prevalence of problem drinking before and after first admission to methadone maintenance was estimated by the McNemar test [ 141. Two-tailed tests were used in all the analyses. The .05 level was accepted for statistical significance.
FINDINGS Background Characteristics As shown in Table 1, both groups of subjects were predominantly MexicanAmerican, and approximately half of both groups were reared in broken families. About one-third had disciplinary problems in school, and they left school with a median of only 8 years of education. The mean age of first arrest preceded that of first opioid use. For both groups, a mean of 16 years elapsed from first opioid use, which typically occurred in late adolescence, to first admission to methadone maintenance. During that time, both groups of subjects spent a mean of over 5 years in jail and prison. The methadone subjects closely resembled the comparison subjects on most background variables. Statistically significant differences were found on only three of the 15 background variables. These were years of education, years of daily illicit opioid use before admission to methadone maintenance, and number of substance abuse treatment admissions before admission to methadone maintenance. While statistically significant, the difference in years of education was small; the means were 8.3 years for the methadone subjects and 7.6 years for the comparison subjects; the medians were 8 years for both. Although both groups had the same mean of years, 16, from first opioid use to methadone maintenance, the methadone group had significantly more years (mean = 6.6) of daily illicit opioid use than did the comparison group (mean = 5.4). The methadone group also had significantly more substance abuse treatment admissions (mean = 4.2) than did the comparison group (mean = 3.0).
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Table 1. Background Characteristics of Methadone Maintenance Subjects and Comparison Subjects before First Admission or Simulated First Admission to Methadone Maintenance
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Methadone subjects ( N = 95)
Comparison subjects ( N = 77)
Number (%) MexicamAmerican
82
(86.3%)
73
(94.8%)
Number (%) reared in broken family
44
(46.3%)
45
(58.4%
Mean (median) years of education
8.3 (8)
7.6 (8)a
Number (%) with disciplinary problem in school
32
(33.7%)
30
(39.0%
Mean (median) age of first arrest
16
(15)
16
(16)
Mean (median) age of first opioid use
18
(18)
17
(16)
Number (%) arrested before opioid use
63
(66.3%)
47
(61.0%)
Number (%) with felony conviction before first opioid use
25
(26.3%)
18
(23.4%)
Mean (median) years from first opioid use to first admission to methadone maintenance
16
(14)
16
(15)
Mean (median) years of daily illicit opioid use before first admission to methadone maintenance Number (%) with problem drinking before first admission to methadone maintenance
6.6 (6) 75
(78.9%)
5.4 ( 5 i b 52
(67.5%)
Mean (median) years jail and prison before first admission to methadone maintenance
5 3 (3)
5.2 (4)
Mean (median) months employed in year before first admission to methadone maintenance
4.0 (3)
3.1 (0)
Mean (median) substance abuse treatment admissions before first admission to methadone maintenance
4.3 (3)
3.0 (2)'
Mean (median) age of first admission to methadone maintenance
34
(33)
33
(31)d
= 2.03, df = 169, p = ,044. bSavage S = 13.6, z = 2.1, p = .033. CSavage S = 17.4, z = 2.7, p = ,007. dThe age of first admission of never-admitted comparison subjects was simulated by selecting the age at the start of the 10-year comparison period.
Treatment during Ten Years Most methadone subjects did not remain continuously on methadone from the time of first admission until discharge or completion of the 10-year study period.
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Table 2. Methadone Subjects and Comparison Subjects Who Had One or More Substance Abuse Treatment Admissions during 10 Years after First Admission or Simulated First Admission to Methadone Maintenance, by Type of Treatmentd ~
~
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Methadone subjects ( N = 95)
Methadone maintenance Inpatient withdrawal Outpatient withdrawal Outpaitent drug-free Religious program Residential treatment Other treatment
Comparison subjects ( N = 77)
N
%
N
%
66 33
69.5 34.7 8.4 5.3 9.5 13.7 2.1
15a 19 6 15b 10 22c 4
19.5 24.7 7.8 19.5 13.0 28.6 5.2
8 5 9
13 2
ax 2 ,
40.7, df = 1 , p < ,001. 7.0, df = 1, p = .008. ‘,y2 = 4.9, df = 1, p = .026.
b ~ = 2
dChi-square computations were adjusted for continuity
The typical pattern was discharge from methadone maintenance, followed by one or more readmissions during the 10-year period. Table 2 shows that 66 (69.5%) of the methadone subjects were discharged after the first admission to methadone maintenance and then readmitted one or more times. Twenty-three (24.2%; not shown in the table) were discharged after the first admission and not readmitted during the 10-year period. Only 6 (6.3%) subjects remained continuously on methadone throughout the 10-year period. The mean number of readmissions to methadone maintenance was 1.4; the maximum, seven. In contrast to the methadone subjects, only 15 (19.5%)of the comparison subjects were readmitted after the first (or simulated first) admission to methadone maintenance. The mean number of readmissions to methadone maintenance was 0.3. During the 10 years, the methadone subjects spent a cumulative mean of 54 months on methadone, while the comparison subjects spent a cumulative mean of only 2 months on methadone. The respective medians were 46 and zero. This difference is statistically significant (Savage S = 56.2, z = 8.8, p < ,001). As determined partly by definition of the two groups, the time on methadone ranged from 12 to 120 months for the methadone subjects and from none to 11 months for the comparison subjects. In addition to methadone maintenance, subjects of both groups were admitted to several other types of substance abuse treatment during the 10-year period.
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MADDUX AND DESMOND
Table 2 shows the number and percentages of subjects of both groups admitted one or more times to other types of treatment. Only a minority of subjects in both groups was admitted to each of these types of treatment. The number of admissions (not shown in the table) to any specified treatment (except methadone maintenance) was small, ranging from none to four; the means were less than one in all cases, and the medians were zero. As shown in Table 2, the percentages of subjects admitted one or more times to the other types of treatment was similar for both groups, except for the percentages admitted to outpatient drug-free treatment and to residential treatment. Fifteen (19.5%)of the comparison subjects but only five (5.3 %) of the methadone subjects were admitted to outpatient drugfree treatment, and 22 (28.6%)of the comparison subjects but only 14 (13.7%) of the methadone subjects were admitted to residential treatment. As shown in the table, these differences were statistically significant. The comparison subjects also spent more time in residential treatment (mean = 1.4 months) than did the methadone subjects (mean = 0.7 months), but this difference did not achieve statistical significance (Savage S = 10.0, z = 1.8, p = ,078). While only a minority of both groups was admitted to any specified type of treatment, except methadone maintenance, a majority of both groups was admitted to at least one of the types of treatment shown in Table 2 during the 10-year period. Seventy-seven (81.1%) of the methadone subjects and 51 (66.2%) of the comparison subjects were admitted during the 10-year period to at least one of the types of treatment. This difference is statistically significant (x2 = 4.1, df = 1, p = .041). If admissions to methadone maintenance are excluded, then 49 (51.6%) of the methadone subjects and 45 (58.4%) of the comparison subjects were admitted to at least one of the types of treatment. This difference is not significant. Some of the subjects were admitted primarily for treatment of alcohol abuse or dependence. They were admitted to inpatient withdrawal or to outpatient disulfiram treatment. They are counted in Table 2 in the “Inpatient withdrawal” and “Other treatment” categories.
Outcomes As shown in Table 3, the two groups had only a small and nonsignificant difference in months of daily illicit opioid use during the 10-year period. The means were 12 months for the methadone group and 14 for the comparison group. The methadone group, however, had significantly more months (mean = 18) of occasional illicit opioid use than did the comparison group (mean = 6.6). Most
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Table 3. Outcomes of Methadone Maintenance Subjects and Comparison Subjects during 10 Years aAer First Admission or Simulated First Admission to Methadone Maintenance
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Methadone subjects ( N = 95) Mean (median) months of daily illicit opioid use Mean (median) months of occasional illicit opioid use Mean (median) months of voluntary abstinence Number (%) with problem drinking Mean (median) months employed Mean (median) arrests Mean (mdeian) months institutionalized *Savage S bSavage S %avage S dSavage S
= 30.1,z = 4.8,p < = 31.8,z = 5.0,p < = 15.0,z = 2.4,p = = 33.0,z = 5.2,p
