Amphetamine-related Disorders
Conditions
Keywords
Adherence, Amphetamine-Related Disorders, Behavior Therapy, Contingency management, Drug Counseling, health behaviors, methamphetamine, sexual risk behaviors, substance dependence
Brief summary
The purpose of this study is to determine if different reinforcement procedures (i.e., schedules) produce different patterns of long-term abstinence from methamphetamine. We anticipate that the three contingency management conditions will promote longer periods of abstinence in the year following treatment relative to the standard control group. Furthermore, we predict that the intermittent reinforcement procedures will produce longer periods of continued abstinence (i.e., long-term behavior change) in the year following treatment than the continuous reinforcement procedure. Finally, we predict that the intermittent unpredictable schedule will produce longer lasting behavior change than the intermittent predictable schedule. Methamphetamine use will be measured using urine toxicology and self-report of methamphetamine use.
Detailed description
Briefly the four study conditions are: (1) standard treatment which consists of 16 weeks of psychosocial treatment, (2) continuous contingency management which consists of 16 weeks of psychosocial treatment with a contingency management procedure in effect during the first twelve weeks in which vouchers are made available after each provision of a methamphetamine-negative urine test, (3) intermittent predictable contingency management which consists of 16 weeks of psychosocial treatment with a contingency management procedure in effect during the first twelve weeks in which vouchers are available after the provision of every three consecutive methamphetamine-negative urine samples, and (4) intermittent unpredictable contingency management which consists of 16 weeks of psychosocial treatment with a contingency management procedure in effect during the first twelve weeks in which vouchers are available on one day each week (randomly selected after the first week) for the provision of methamphetamine-negative urine samples provided all urine samples since delivery of the last reinforcer were also methamphetamine negative.
Interventions
BEHAVIORALcontingency management voucher
participants receive vouchers for the provision of methamphetamine-negative urines. Vouchers can be redeemed for goods and services compatible with non-drug using behaviors.
Sponsors
National Institute on Drug Abuse (NIDA)
Friends Research Institute, Inc.
Study design
Allocation
RANDOMIZED
Intervention model
PARALLEL
Primary purpose
TREATMENT
Masking
NONE
Eligibility
Sex/Gender
ALL
Age
18 Years to 65 Years
Healthy volunteers
No
Inclusion criteria
* Meet Diagnostic and Statistical Manual of Mental Disorders (DSM-IV) criteria for methamphetamine dependence * Willing and able to comply with study procedures * Willing and able to provide written informed consent
Exclusion criteria
* Have a medical condition that, in the study Principal Investigator (PI's) judgment, might interfere with safe study participation * Have a recent (past 30 days) history of suicide attempts and/or current serious suicidal intention or plan as assessed by the Beck Depression Inventory (BDI) * Have a history of violent criminal behavior or be on parole * Any other circumstances that, in the opinion of the PI, would interfere with safe study participation
Design outcomes
Primary
| Measure | Time frame | Description |
|---|---|---|
| Methamphetamine Use During Intervention | 3x/week for 16 weeks | Drug use measured by urine toxicology conducted by on site Enzyme-multiplied immunoassay technique (EMIT) assay over time. |
| Methamphetamine Use, Measured by Number of Consecutive Days of Abstinence | 16 Weeks | Drug use measured by urine toxicology conducted by on site EMIT assay and added up to obtain how many days of consecutive abstinence were observed for each individual |
| Methamphetamine Use, Follow-Up | 1x/month for 4 months | Drug use measured by urine toxicology conducted by on site EMIT assay over time |
Countries
United States
Participant flow
Recruitment details
Recruitment and enrollment began in January 2005 and ended . Individuals were recruited from the community via radio and newspaper ads, flyers, and word of mouth.
Pre-assignment details
The main reasons individuals were excluded from the trial prior to group assignment was not meeting inclusion criteria and discontinuing treatment prior to randomization.
Participants by arm
| Arm | Count |
|---|---|
| Intermittent Predictable Schedule Those in the intermittent predictable condition will earn a voucher when they provide three consecutive methamphetamine-negative urine tests. Participants in the intermittent predictable condition will receive $22.00 for the provision of their first three consecutive methamphetamine-negative urine samples, $35.50 for the provision of their second set of three consecutive instances of methamphetamine-negative urine samples, and so forth. There are no bonuses for consecutive instances of abstinence in the intermittent predictable condition. Provision of a methamphetamine-positive urine sample, or failure to test, will result in a reset in the voucher magnitude back to its original level from whence the progression can begin again.
contingency managment voucher : participants receive vouchers for the provision of methamphetamine-negative urines. Vouchers can be redeemed for goods and services compatible with non-drug using behaviors. | 32 |
| Continuous Voucher Schedule Those in the continuous condition will receive a voucher each time they test negative for methamphetamine. The initial voucher value will be $2.50. Each consecutive instance of abstinence will increase the magnitude of the voucher by $1.50. Three consecutive abstinences will result in the delivery of a $10.00 bonus. Provision of a methamphetamine-positive urine sample, or failure to test, will result in a reset in the voucher magnitude back to its original level from whence the progression can begin again.
contingency managment voucher : participants receive vouchers for the provision of methamphetamine-negative urines. Vouchers can be redeemed for goods and services compatible with non-drug using behaviors. | 30 |
| Intermittent Unpredictable Schedule Those in the intermittent unpredictable condition will be eligible to receive a voucher on one day a week. This date will be randomly determined and they will not know in advance what day it will be. Participants in this group will receive a voucher following their first three methamphetamine-negative urine tests. Following that they will be eligible to receive a voucher one day a week if all of their urine tests since the receipt of their last voucher were methamphetamine negative. The day of the week on which the voucher will be available will be randomly selected for each week and the participants will not know which day of the week they will be eligible to receive a voucher until they have provided their urine test.
contingency managment voucher : participants receive vouchers for the provision of methamphetamine-negative urines. Vouchers can be redeemed for goods and services compatible with non-drug using behaviors. | 28 |
| Standard Participants assigned to the standard condition will not receive vouchers for the provision of clean urines. | 29 |
| Total | 119 |
Baseline characteristics
| Characteristic | Continuous Voucher Schedule | Intermittent Unpredictable Schedule | Intermittent Predictable Schedule | Standard | Total |
|---|---|---|---|---|---|
| Age, Categorical <=18 years | 0 Participants | 0 Participants | 0 Participants | 0 Participants | 0 Participants |
| Age, Categorical >=65 years | 0 Participants | 0 Participants | 0 Participants | 0 Participants | 0 Participants |
| Age, Categorical Between 18 and 65 years | 30 Participants | 28 Participants | 32 Participants | 29 Participants | 119 Participants |
| Age, Continuous | 32.5 years STANDARD_DEVIATION 10 | 30.3 years STANDARD_DEVIATION 10.9 | 33.1 years STANDARD_DEVIATION 8.2 | 24.8 years STANDARD_DEVIATION 10.1 | 32 years STANDARD_DEVIATION 10 |
| Region of Enrollment United States | 30 participants | 28 participants | 32 participants | 29 participants | 119 participants |
| Sex: Female, Male Female | 10 Participants | 13 Participants | 13 Participants | 14 Participants | 50 Participants |
| Sex: Female, Male Male | 20 Participants | 15 Participants | 19 Participants | 15 Participants | 69 Participants |
Adverse events
| Event type | EG000 affected / at risk | EG001 affected / at risk | EG002 affected / at risk | EG003 affected / at risk |
|---|---|---|---|---|
| deaths Total, all-cause mortality | — / — | — / — | — / — | — / — |
| other Total, other adverse events | 1 / 119 | 5 / 119 | 1 / 119 | 3 / 119 |
| serious Total, serious adverse events | 5 / 119 | 3 / 119 | 1 / 119 | 1 / 119 |
Outcome results
Primary
Methamphetamine Use During Intervention
Drug use measured by urine toxicology conducted by on site Enzyme-multiplied immunoassay technique (EMIT) assay over time.
Time frame: 3x/week for 16 weeks
Population: All individuals randomized were included in the analysis (i.e., intention to treat).
| Arm | Measure | Value (NUMBER) |
|---|---|---|
| Intermittent Predictable Schedule | Methamphetamine Use During Intervention | 65.17 percentage of negative urine samples |
| Continuous Voucher Schedule | Methamphetamine Use During Intervention | 60.35 percentage of negative urine samples |
| Intermittent Unpredictable Schedule | Methamphetamine Use During Intervention | 57.74 percentage of negative urine samples |
| Standard | Methamphetamine Use During Intervention | 42.81 percentage of negative urine samples |
p-value: <0.01Generalized estimating equations
p-value: <0.01Generalized estimating equations
p-value: <0.01Generalized estimating equations
Primary
Methamphetamine Use, Follow-Up
Drug use measured by urine toxicology conducted by on site EMIT assay over time
Time frame: 1x/month for 4 months
| Arm | Measure | Value (NUMBER) |
|---|---|---|
| Intermittent Predictable Schedule | Methamphetamine Use, Follow-Up | 90.79 percentage of negative urine samples |
| Continuous Voucher Schedule | Methamphetamine Use, Follow-Up | 88.89 percentage of negative urine samples |
| Intermittent Unpredictable Schedule | Methamphetamine Use, Follow-Up | 88.62 percentage of negative urine samples |
| Standard | Methamphetamine Use, Follow-Up | 87.30 percentage of negative urine samples |
Comparison: We used GEE to investigate change in methamphetamine abstinence (i.e., provision of a negative methamphetamine UA) during the follow-up period.p-value: 0.78Generalized estimating equations
Comparison: We used GEE to investigate change in methamphetamine abstinence (i.e., provision of a negative methamphetamine UA) during the follow-up period.p-value: 0.68Generalized estimating equations
Comparison: We used GEE to investigate change in methamphetamine abstinence (i.e., provision of a negative methamphetamine UA) during the follow-up period.p-value: 0.2Generalized estimating equations
Primary
Methamphetamine Use, Measured by Number of Consecutive Days of Abstinence
Drug use measured by urine toxicology conducted by on site EMIT assay and added up to obtain how many days of consecutive abstinence were observed for each individual
Time frame: 16 Weeks
| Arm | Measure | Value (MEAN) | Dispersion |
|---|---|---|---|
| Intermittent Predictable Schedule | Methamphetamine Use, Measured by Number of Consecutive Days of Abstinence | 22.42 days | Standard Deviation 15.36 |
| Continuous Voucher Schedule | Methamphetamine Use, Measured by Number of Consecutive Days of Abstinence | 22.7 days | Standard Deviation 17.6 |
| Intermittent Unpredictable Schedule | Methamphetamine Use, Measured by Number of Consecutive Days of Abstinence | 20.32 days | Standard Deviation 18.64 |
| Standard | Methamphetamine Use, Measured by Number of Consecutive Days of Abstinence | 11.10 days | Standard Deviation 12.58 |
p-value: 0.02ANOVA
p-value: <0.01t-test, 2 sided
p-value: <0.01t-test, 2 sided
p-value: 0.2t-test, 2 sided