Table 1 Definition of methadone treatment outcomes for assessment

Drug use-related behavior

Response to treatment

Abstaining from illicit opioid use throughout treatment duration

Urine screening

Percentage

[36–39]

Self reported opioid use (daily or weekly) over specified time period

Mixed model ANOVA Cochran-Mantel-Haenszel statistic

Treatment retention or duration

Proportion of participants completing treatment; days in treatment from first to last day of therapy

Number of days patient remains in treatment

Cox proportional hazards model

[36–38]

Proportion of patients retained in treatment for pre-specified duration of study

Kaplan-Meier survival curve

Remission status post-treatment

Abstinence from use of illicit opioids at follow-up

Urine screening

t-test

[37, 39–41]

Self-reported opioid use (any) after treatment

2x2 factorial ANOVA

Polysubstance use

Use of at least two (non-opioid) substances throughout the course of treatment

Self-reported use of substances daily or weekly or in last 30 days

Percentage

[37, 38]

Fischer’s Exact Test

Net reduction in proportion of drug abuse after specific duration

Health and methadone-related outcomes

Methadone dose

Average daily methadone dose

Milligrams/day

Difference in means (SD)

[38]

Mean methadone dose after specific duration in treatment

Drug-related adverse events

Reaction to treatment drug

Interview/physical examination

Percentage

[17]

Number of hospitalizations

t-test

Health status

Change in health status during course of therapy

Interview/physical examination

ANOVA

[17, 40]

Number of hospitalizations

Psychological status

Comorbidity of psychiatric disorders

Self-reported psychiatric problems

Percentage

[17, 42–44]

Number of reported symptoms

Relative risk

Validated psychiatric assessments

ANOVA

Chi-square

Mortality

Treatment-related death or illicit drug use mortality

Mortality causes

Standardized mortality ratio (SMR) Kaplan-Meier survival curve

[45]

Number of deaths

Annual death rate per year of age

Sociobehavioral functioning

Criminal behavior

Involvement in illegal activities, arrests, or incarcerations throughout treatment or at follow-up

Interview/self-report

Percentage

[17, 37, 39]

Current legal status

t-test

ANOVA

High-risk sexual behavior

Involvement in behaviors that put the patient at high risk for HIV and other infections

Use of injection methods (30 days prior)

Weighted least-squares estimation procedure

[46, 47]

Number of sex partners

Repeated measures ANOVA

Incidence of unprotected sex

Social relations/support

Patient’s relationship status and conception of his/her relationship with others

Self-report

ANOVA

[17]

Number of close friends/family

Marital and family status

Ratings of interactions

Employment

Status of employment and evidence of financial income

Change in self-reported employment status during treatment

Percentage

[17, 37, 39, 40]

Difference in means (SD)

Employment status after treatment

ANOVA, analysis of variance.