The impact of ongoing illicit drug use on methadone adherence in illicit drug users receiving treatment for HIV in a directly observed therapy program.
BACKGROUND
Studies evaluating the effectiveness of opioid agonist therapy programs typically evaluate drug abstinence or treatment retention as their primary outcomes. However, in many circumstances (e.g. directly observed therapy (DOT) programs within methadone maintenance programs), methadone adherence is an extremely relevant clinical outcome. We sought to evaluate the impact of ongoing illicit drug use on methadone adherence within a DOT program for the treatment of HIV-infection.


METHODS
Patients were enrolled in a DOT program, where methadone and HIV medication are co-administered by a community pharmacist. Drug use (amphetamines, benzodiazepines, cocaine, and opiates) was assessed by repeated urinalysis results. Methadone adherence was calculated as the fraction of days methadone was administered.


RESULTS
Ongoing drug use, and poly-substance use was common, with only 4 of 60 patients abstaining from all illicit drug use. Overall methadone adherence was 84.5%. Amphetamine use (without benzodiazepine and cocaine use), benzodiazepine use (without amphetamines) and higher methadone doses were associated with higher methadone adherence. When patients used benzodiazepines or cocaine, any positive effect associated with amphetamine use was negated. In addition, opiate use was associated with decreased methadone adherence.


CONCLUSIONS
The effect of many illicit drugs on methadone adherence may differ from reports using other treatment outcomes.
Raffa
Jesse D
JD
Department of Statistics, University of British Columbia, Vancouver, BC, Canada. jdraffa@uwaterloo.ca
Grebely
Jason
J
Tossonian
Harout
H
Wong
Tiffany
T
Viljoen
Mark
M
Khara
Milan
M
Mead
Annabel
A
McLean
Mark
M
Duncan
Fiona
F
Petkau
A John
AJ
DeVlaming
Stanley
S
Conway
Brian
B
D019969:Amphetamine-Related Disorders / Q000453:epidemiology / Q000523:psychology / Q000534:rehabilitation; D023241:Antiretroviral Therapy, Highly Active; D001569:Benzodiazepines; D019970:Cocaine-Related Disorders / Q000453:epidemiology / Q000523:psychology / Q000534:rehabilitation; D003131:Combined Modality Therapy; D015897:Comorbidity; D004305:Dose-Response Relationship, Drug; D005260:Female; D015658:HIV Infections / Q000453:epidemiology / Q000523:psychology / Q000534:rehabilitation*; D006801:Humans; D013287:Illicit Drugs; D008137:Longitudinal Studies; D008297:Male; D008691:Methadone / Q000627:therapeutic use*; D009294:Narcotics / Q000627:therapeutic use*; D009293:Opioid-Related Disorders / Q000453:epidemiology / Q000523:psychology / Q000534:rehabilitation; D010349:Patient Compliance / Q000523:psychology* / Q000706:statistics & numerical data; D012189:Retrospective Studies; D018570:Risk Assessment; D015813:Substance Abuse Detection / Q000706:statistics & numerical data*; D019966:Substance-Related Disorders / Q000453:epidemiology / Q000523:psychology / Q000534:rehabilitation*
D013287:Illicit Drugs; D009294:Narcotics; D001569:Benzodiazepines; D008691:Methadone