Changes in Methadone Treatment Practices:  Results From a National Panel Study, 1988-2000 FREE

How well do the nation's methadone maintenance treatment facilities meet established standards for best practice care?

This is a critical question for public health policy and, more broadly, for social policy.¹ Changes in methadone treatment practices are important in responding to the changing prevalence and modalities of heroin use, to the continued role of injection drug use in the human immunodeficiency virus (HIV) and hepatitis C epidemics, and to changes in the financing and regulation of methadone treatment. Assessing methadone treatment practices is also important in light of recent research results about methadone treatment effectiveness.

An upsurge in heroin use has increased the need for effective treatment services for opioid dependence. Admissions for opioid dependence have surpassed admissions for cocaine abuse in the nation's drug abuse treatment programs.² Population-based epidemiological studies also show a marked increase in heroin use.³ The Office of National Drug Control Policy now estimates that the number of heroin users in the United States has increased by more than half in less than a decade, from 600 000 in the early 1990s to 980 000 in 2001.⁴

Analysts agree that increased heroin use is influenced by declining heroin prices and by increased purity. Increased purity creates additional concern because this may increase the addictive potential of street heroin.⁵ Average pure heroin content contained in a $100 purchase has increased 3-fold between 1988 and 1995 in cities across the United States.⁵ High purity also facilitates noninjecting forms of heroin use, such as smoking and snorting, which may attract new users who are deterred by injection-related risks. Newly available modalities of heroin use may thus have attracted new users, most of whom are younger than 26 years of age.² The long-term risk behaviors of noninjection heroin users are currently unknown. Public health consequences would be significant if initial noninjectors frequently convert to needle use.

Injection heroin use also remains central to HIV transmission and to the transmission of other infectious agents.⁶ Many studies indicate that methadone treatment is associated with reduced HIV seroconversion among methadone patients and is also associated with reduced needle-sharing and other risk behaviors.^7- 8 A recent Institute of Medicine report concludes, as have previous expert reports,^1,8 that effective methadone treatment for opioid dependence is critical to prevent HIV transmission. The majority of injection drug users have now contracted hepatitis C. Effective methadone treatment may be important to slowing this epidemic as well.^9- 10

Moreover, important changes are occurring in financing and regulation that may carry significant implications for methadone treatment effectiveness. One prominent change is the introduction of managed care as a payment and administrative mechanism for methadone treatment. Although a recent study indicates that methadone treatment programs are less likely to be involved in managed care than are their nonmethadone counterparts,¹¹ some 30% of all methadone treatment programs participate in some form of managed care.¹¹ For those programs and the tens of thousands of patients they serve, managed care can potentially improve treatment practices. At the same time, managed care might hinder treatment effectiveness through practices such as limiting treatment duration, a central factor in treatment effectiveness.^12- 13

A second prominent change is the pending move to regulate methadone treatment facilities through the Center for Substance Abuse Treatment (CSAT) rather than through the Drug Enforcement Agency and the Food and Drug Administration (FDA). This substantial shift was prompted by concerns about quality of care in methadone treatment programs.^14- 15 The CSAT, which is part of the federal Substance Abuse and Mental Health Services Administration, brings extensive experience working with treatment programs to improve quality. This regulatory shift may therefore create opportunities to improve patient care.

Finally, results from prior studies of methadone treatment practices¹⁶ and treatment effectiveness¹⁷ support the need for a current assessment of treatment practices. Data from the few national studies of methadone dose levels published in the early 1990s indicate that patients typically received suboptimal doses.^18- 20 Data collected in 1988 from a nationally representative sample of 172 methadone maintenance facilities showed that the average dosage was 45 mg/d; 1990 data from the same panel of facilities showed virtually identical average dosages, 46 mg/d.¹⁸ Data from a random sample of patient discharge abstracts (N = 261) at 26 randomly selected treatment facilities in 1990 showed that the average methadone dosage per day was 50 mg.¹⁹ Yet another study of 24 methadone treatment facilities conducted in 1990 by the General Accounting Office concluded that, on average, dose levels were too low.²⁰

In response to these study results, several initiatives were launched to improve treatment practices. The CSAT developed methadone treatment guidelines and distributed them to state substance abuse agencies and to treatment programs across the nation.^21- 22 The Institute of Medicine convened a study panel that recommended several changes in treatment practices and their regulation.¹⁴ Cooper²³ published an editorial encouraging physicians to use effective dose levels. The National Institute on Drug Abuse funded a study to examine the development of a quality assurance program for methadone treatment.¹⁵ More recently, a National Institutes of Health consensus panel (1997) produced guidelines for effective methadone treatment practices.¹

Subsequent surveys indicate at least partial successes of such efforts. National panel data indicate that methadone dosages increased significantly from an average of 45 mg/d in 1988 to 59 mg/d in 1995.¹⁶ This increase raised average dosages to the minimum level recommended by national consensus panels (60 mg/d).¹ Other significant improvements in treatment practices were documented over the same period. Average time in treatment increased from 20 months to 21 months; the average upper dosage limit increased from 79 mg/d to 93 mg/d; the percentage of patients receiving progressively decreasing methadone doses decreased from 34% to 22%. Programs also waited longer before encouraging patients to detoxify from methadone. In 1990, only 27% of programs waited more than 1 year to encourage detoxification, but, by 1995, 55% of programs exceeded the same threshold.

Although these trends reflect important progress, recent studies suggest that methadone dosages between 80 and 100 mg/d are more effective than are dosages in the range of 60 to 80 mg/d.^17,24 Strain et al¹⁷ randomly assigned patients at an urban treatment program to a moderate (40-50 mg/d) or high (80-100 mg/d) methadone dose group. After 30 weeks, both patient self-report and urinalysis indicated significantly higher prevalence of recent opioid use within the moderate-dose group. There were no differences between the 2 groups in self-reported adverse effects from methadone use. Thus, documented increases in methadone dose levels may be insufficient to yield effective treatment outcomes. Given the current price and purity of heroin, even higher methadone doses may be warranted.^5,17

It is important to note, however, the long-standing resistance to methadone maintenance treatment in general, and in particular to high-dose, long-term treatment.^25- 26 Some citizens, drug users, and drug treatment professionals and staff have expressed concern that methadone treatment "substitutes one addiction for another." This view is particularly likely to be held by individuals who support an abstinence model of treatment and recovery. Vaughn²⁷ showed that the more that clinical supervisors in methadone treatment programs supported an abstinence model of treatment, the more likely their programs were to provide low methadone doses.

In sum, the current study adds to prior research^16,28 by examining changes in methadone treatment practices using 1988-2000 data from a nationally representative panel of methadone maintenance programs. We also examine how important characteristics of these programs (eg, Joint Commission on Accreditation of Healthcare Organizations [JCAHO] accreditation) are related to differences in average methadone dose levels.

This study uses data from a panel survey conducted in 1988, 1990, 1995, and 2000 by the Institute for Social Research at the University of Michigan and by the National Opinion Research Center at the University of Chicago.²⁹

We define a methadone treatment unit as a physical facility with resources dedicated specifically to treating opiate dependence through methadone. Methadone programs with multiple treatment units or multiple sites were identified, and units were sampled randomly from such programs. The initial sampling frame consisted of the FDA's 1988 list of the nation's methadone maintenance treatment units (N = 587). Because the population of methadone treatment units has changed in the past several years as a result of the founding of new treatment units, we augmented the 1988 sampling frame with the FDA's 1998 list of methadone units (N = 871). Because the FDA licenses all methadone providers, one can identify the entire US population of methadone treatment units with a relatively high degree of certainty.

Of the 210 units selected for the 1988 study, 172 participated, a response rate of 82%. Participating units did not differ significantly from nonrespondents in 1988.¹⁸ Thus, in 1990, we contacted only the participating units from 1988. Of these 172 units, 11 were no longer providing methadone treatment and thus 161 units were still eligible for the study. Of the 161 eligible units, 140 (87%) participated in the 1990 study. In 1995, we contacted the 140 participating units that provided methadone in 1990. Thirteen of these units were no longer eligible because they had stopped providing methadone treatment by 1995. Four units that had begun providing methadone treatment in the interim were added to the 1995 sample. Of the combined 131 eligible units, 116 participated and 15 declined to do so, a response rate of 89%. Analyses showed no evidence of nonresponse bias due to units that dropped out from the study from 1988 to 1990 or from 1990 to 1995.¹⁶

For the 2000 data collection, we contacted the 116 participating units from 1995, and of these, 112 agreed to participate, a 97% response rate. In addition, we added 47 new methadone units to the 2000 sample. These units were selected at random from among methadone programs that had begun since 1988. The purpose of adding this subsample to the panel units was to ensure that the 2000 cross-section as a whole was representative of the population of methadone treatment units; the panel sample alone would not have represented these newer units. The response rate among these new sample units was 81% (n = 38). To determine if these new sample units had a significantly different relationship with the study's dependent variables than the panel units, we entered a control variable into the regression analyses. This control for new sample units was not significant in any equations, and we dropped it in the results reported herein. Thus, the total sample for 2000 was 150 units, with a combined response rate of 92%.

The unit director and supervisor of clinical services of each participating unit completed telephone surveys. The survey team followed established methodologies shown in previous research to maximize data reliability and validity in telephone surveys.³⁰ Respondents received a worksheet in advance of our call that informed them of the requested data. This enabled respondents to consult financial and administrative records prior to the call. The survey team conducted dozens of internal consistency checks as soon as the data were collected.

Methadone Treatment Practices Using data from clinical supervisors, we calculated the percentage of patients in each treatment unit who received dosages that were below 40, 60, or 80 mg/d. These measures were calculated only for patients who had been receiving the same methadone dose for at least 2 weeks. They therefore measure the dose level that units dispense for patients whose dose levels have stabilized.

Patient Characteristics Clinical supervisors reported 4 important characteristics of patient mix that could be correlated with methadone treatment practices: employment status (percentage of patients who are currently unemployed), race/ethnicity (percentage of African American and Hispanic/Latino patients), sex (percentage of male patients), and average patient age. All of these measures are characteristics of the mix of patients at the unit level of analysis; we do not have data from individual patients.

Unit Characteristics We measured several organizational characteristics that could relate to variation in treatment practices.^16,18 Clinical supervisors reported the percentage of staff members who are ex-addicts. Directors reported unit ownership (public, private for-profit, or private not-for-profit; we used private not-for-profit as the referent category). Finally, given recent efforts to improve the quality of methadone treatment through accreditation, we used data from the unit director to measure JCAHO accreditation (1 = yes; 0 = no).

Geographic Location and Time Effects Previous research suggests important geographic variation in methadone treatment practices.^16,18 We measured geographic location using a census division scale (Northeast, Midwest, South, and West) with the Northeast region serving as the referent category. To capture time effects, we created dummy variables corresponding to the year in which survey data were collected, with 1988 serving as the referent year.

This study uses a longitudinal, panel design. This design is most effective for examining changes in treatment practices over time. Panel data analysis is complicated, however, by unobserved unit heterogeneity and by potential nonresponse bias.^31- 33 Methadone doses within the same treatment units are likely to be correlated over time due to unobserved characteristics of these same units. Standard linear and logistic regression models, which assume independence among observations, must be modified for panel data analyses. Nonrandom attrition may also bias subsequent results.

To address these concerns, we analyzed the data using a random-effects specification that accounts for repeated measures over time.^16,31 For each dependent variable, a random-effects model uses all data from the 4 waves simultaneously, but allows for the possibility of random unit effects. Explanatory variables included patient characteristics, unit characteristics, environmental factors, and 3 dummy variables to model changes in the outcome variables across 1988, 1990, 1995, and 2000.

Random-effects models are also helpful to mitigate bias due to nonrandom attrition over time.^32- 33 In the presence of attrition, naive analysis using only the data from units that participated in all 4 surveys can produce biased results.³³ All available data from the 4 surveys were used, including data from those units that did not participate in 1990, 1995, or 2000.

A related advantage of random-effects models is that they help to address effects due to unobserved unit heterogeneity. Though we measure unit characteristics in our multivariate model, we did not measure some important characteristics, such as features of local drug markets and the attitudes of specific payers, managers, patients, and treatment staff. Because these unmeasured characteristics are rather stable over time, and because we wish to examine the impact of observed unit characteristics such as patient mix, our baseline model is the random-effects regression specification estimated by D'Aunno et al.¹⁶

Finally, because this random-effects specification relies on important statistical assumptions, we also estimated a more restrictive fixed-effects model and compared the 2 models using a Hausman test. This procedure compared our random-effects results with a fixed-effects model that allowed for the possibility that unit characteristics that we did not measure (eg, staff training) are correlated with the observed covariates. When the random-effects model is correctly specified, the fixed-effects estimator yields consistent (though inefficient) point estimates for all time-varying covariates. If point estimates from the 2 models yield statistically significant differences, unobserved heterogeneity may bias the random-effects coefficients. Analyses were performed using Stata 6.0 (Stata Corp, College Station, Tex) and P<.05 was the level of significance.

Table 1 shows mean methadone dosages by year within the study sample. A substantial decline was observed between 1995 and 2000 in the prevalence of low doses. By 2000, 64.5% of methadone patients received dosages that exceeded 60 mg/d, the minimum recommended by the Institute of Medicine and by consensus panels. Among those patients receiving dosages below this threshold, most received doses between 40 and 60 mg/d. However, 13.2% of all methadone patients continued to receive less than 40 mg/d. Only 7.9% of methadone units reported maximum methadone dose levels below Institute of Medicine guidelines. Although these trends indicate increasing provider adherence to the dose levels recommended by consensus panels, few methadone patients appear to receive optimal doses as indicated by recent research. Only 32.4% of patients receive more than 80 mg/d, the range marked as optimal by Strain et al.¹⁷

Table 2 shows the results of our random-effects regressions. Controlling for unit characteristics, our regressions confirm the trends indicated by Table 1. Compared with the 1988 baseline, the percentage of patients receiving dosages below 40 mg/d declined by 30.20 percentage points by the year 2000. The percentage of patients below 60 mg/d dropped by more than 42 percentage points. The percentage of patients receiving dosages below 80 mg/d declined more slowly, but still declined by more than 25 percentage points. All of these trend results were significant (P<.001).

As in previous analyses,¹⁶ units with a greater percentage of African American patients were especially likely to dispense low doses. Each percentage point increase in the proportion of African American patients was associated with a 0.27 percentage point increase in the proportion of patients receiving doses below the 60 mg recommended minimum. No statistically or clinically significant differences were observed by patients' Hispanic/Latino status.

Other unit characteristics were also correlated with methadone dose. Units with a smaller number of methadone patients were more likely to dispense low doses. Facilities with JCAHO accreditation were less likely to provide low doses.

No differences were observed by for-profit status or by public ownership status. Units with high percentages of unemployed patients were less likely than other units to provide low dosages. The percentage of ex-addicts among unit staffs was not associated with significant differences in methadone dosage.

Although our statistical model includes several variables to capture treatment practices and case mix of specific units, the variables included in our model may be correlated with unit characteristics that we did not measure, such as staff training, that may influence methadone dose levels. We examined this possibility by estimating a fixed-effects model. When we compare the 2 models, we find nearly identical results for yearly trends and for the estimated effects of number of methadone patients.

The effect of African American case mix is also smaller (though less precisely measured) in the fixed-effects specification. These results suggest that units that treat a large proportion of African American patients have characteristics associated with lower doses. For example, perhaps counselors in units that treat a high percentage of African American patients are not trained adequately about proper dose levels. Or, perhaps there is more turnover of staff members in such units that prevents them from establishing relationships with patients that would support higher doses.

A Hausman test formally supports these possible explanations. This procedure rejects the similarity of the 2 models (P<.004), indicating that unit characteristics that we did not measure are correlated with observed covariates in our model. Comparing specific point estimates, we find quite similar year effects in the fixed-effects and random-effects specifications. In our fixed-effects specification, we found that private for-profit status was associated with lower doses. We also found weaker effects for JCAHO accreditation, supporting the interpretation that units with more effective practices have self-selected into the JCAHO-accredited group.

Because current variations in methadone dosage practices are most important for public policy, we also examined the 2000 cross-section (Table 3). Within this 2000 cross-section, JCAHO accreditation displayed the largest correlation with methadone dose. Patients in JCAHO-accredited units were 10 percentage points more likely to receive doses above the minimum recommended guidelines and were also significantly more likely to receive dosages exceeding 80 mg/d.

In additional analyses (data not shown), we identified several other variables correlated with methadone dose. Units that predominantly serve drug users younger than 30 years of age or that rapidly seek to "detoxify" patients from methadone were more likely than other units to dispense lower dosages. In addition, units whose directors believed "strongly" or "very strongly" in 12-step programs were more likely to give dosages below 40 mg/d.

Results from this panel study indicate considerable progress in meeting consensus guidelines for methadone treatment. Two thirds of all patients now receive dosages above 60 mg/d. Treatment practices in the year 2000 contrast strongly with 1988, when 80% of patients received dosages below this level.

Despite these trends, only 32.4% of patients are receiving dosages above 80 mg/d, the level indicated as optimal in recent randomized trials. Increasing dosage levels to 80 mg/d may be the most pressing current issue, in light of recent clinical evidence and in light of increased heroin purity of street drugs. In fact, the increase in dose levels we have observed may reflect increased purity: treatment providers may have increased dosage in response to more severe abuse or dependence among their patients. Treatment providers may remain one step behind if they do not continue to increase dosages to the 80 mg/d level. At a minimum, individuals who have responsibility and authority for determining dose levels should conduct a review of policies and practices to ensure that dose levels are tailored to meet the needs of individual patients.

We expect, however, that increasing dosage levels to 80 mg/d will be difficult in many programs, especially those that hold strong abstinence orientation or those whose patients or staff are otherwise ambivalent regarding the clinical or values trade-offs inherent to methadone use. It is also true that some patients can do well on lower doses of methadone; "more" is not always better. Because this study did not collect outcome data from patients, we are not able to examine this possibility.

Further, some drug treatment professionals and staff (and some patients) do not fully support the use of methadone to treat heroin use disorders. Others do not support the principle that methadone is an appropriate long-term solution to heroin dependence or abuse. Perhaps these programs should consider alternative therapies such as buprenorphrine, shown in clinical trials to be effective when properly dispensed.³⁴Alternative medications do not carry the stigma associated with methadone, nor do they carry the symbolic importance of methadone within the drug treatment community and broader society.

Another critical result is that units that treat predominately African American patients continue to provide low doses. Within-unit changes in the percentage of African American patients had smaller association with dosage than did comparisons across treatment units with different proportions of African American patients. This pattern of results—indicated formally through comparison of fixed-effects and random-effects specifications—indicates that these low doses reflect characteristics of treatment programs that are widely used by African American patients. It is possible that African American patients are receiving treatment at programs that have underlying weaknesses in resources, including funds and staff, that make them less likely to keep up with best practices. These programs are located disproportionately in urban settings that have difficulty attracting and retaining well-educated and well-motivated staff members. Further, these programs are not likely to have funds to spend on training or educational sessions that could improve their practices.

These patterns are of special concern, since adherence to methadone dose recommendations may be correlated with other aspects of the quality of care. Further research on quality of treatment available to African Americans is warranted, especially in light of the high HIV incidence and prevalence among African American injection drug users.

Finally, the results indicate that JCAHO accreditation seems to play an important role in adherence to consensus guidelines. Because JCAHO does not set explicit standards for methadone dose levels, we suspect that the higher doses that accredited units give to patients reflect some of their underlying characteristics. Specifically, one possible reason that units with JCAHO accreditation are more likely to provide higher methadone doses is that such units have more adequate resources overall, including staff and funds for training.

Additional research is needed to understand how JCAHO accreditation affects conformity to consensus guidelines. But the relationship between accreditation and adequate dosage practices may suggest directions for the CSAT to pursue as it begins its regulatory control of the nation's methadone treatment programs.