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Drug Use History and Treatment Effectiveness

Treatment History and Outcomes

There was considerable diversity in patterns of drug use and in treatment histories for the DATOS admission sample (Anglin, Hser, & Grella, 1997).

  • For about half of the clients, DATOS was their first treatment experience; the other half averaged about 3.5 prior episodes of treatment.
  • Individuals in STI and ODF were least likely to report prior treatment (about 50%), while those in LTR and OMT were 10-25% more likely to have previous treatment experience.
  • Across all modalities, the average age at first treatment admission was 30 years, and the average interval between initiation of regular drug use and first treatment was 7 years.
  • Admissions to OMT reported longer addiction and treatment careers, while clients in STI and ODF reported shorter and less severe histories.
  • ODF admitted the most eclectic mix of clients, including a higher proportion of individuals who were not dependent on cocaine, heroin, or alcohol.
  • Cocaine- and alcohol-dependent individuals were more likely than heroin users to have been treated in STI, perhaps reflecting the growth in short-term chemical dependency treatment in response to the cocaine epidemic of the 1980s and the historical use of this modality for alcohol treatment.
  • Cocaine- and heroin-dependent individuals who had no prior treatment experience were more likely than those with prior treatment history to enter STI.
  • Higher levels of prior treatment were associated with more severe addiction career characteristics, injection drug use, and criminal activities at treatment admission.
  • Treatment approaches should focus on strategic interventions that recognize and address the diversity of client treatment histories in order to maximize effectiveness.


Hser, Grella, Hsieh, Anglin, & Brown (1999) contrasted cocaine-abusing clients who were in treatment for the first time (n=406) and who had extensive histories of prior treatment (n=383) in an effort to identify factors associated with better outcomes in each group. Treatment history was defined as the number of treatment episodes, total length of time in previous treatment, and the number of years between the client’s first and the current DATOS treatment episode.

  • Treatment-experienced clients had more severe drug problems, greater recognition of their drug problems, greater perceived needs for services upon admission to treatment in DATOS, and generally poorer treatment outcomes as compared with first-time clients.
  • Early engagement in DATOS treatment was associated with higher levels of posttreatment abstinence, regardless of prior treatment history.
  • Across modalities, treatment-experienced clients received fewer individual counseling sessions while in treatment, were less likely to comply with program rules, and had more unmet service needs. However, they were more likely to be abstinent following treatment if they received more individual counseling sessions and complied with program rules (in outpatient drug-free treatment) and if they had higher levels of rapport with their counselors (in outpatient methadone treatment).
  • These findings suggest the importance of considering treatment processes and aftercare in developing and implementing strategies to improve treatment outcomes for clients at differing stages of their treatment careers.


Anglin, M. D., Hser, Y. I.,& Grella, C. E. (1997).  Drug addiction and treatment careers among clients in the Drug Abuse Treatment Outcome Study (DATOS).  Psychology of Addictive Behaviors, 11(4), 308-323. [Abstract]

Hser, Y., Grella, C. E., Hsieh, S., Anglin, M. D., & Brown, B. S. (1999).  Prior treatment experience related to process and outcomes in DATOS.  Drug and Alcohol Dependence, 57, 137-150.   [Abstract]

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Drug Use History and Treatment Effectiveness

The relationship of lifetime patterns of drug dependence (based on DSM-III-R criteria) with treatment follow-up outcomes was examined using data from 2,966 clients in all four treatment modalities (OMT, LTR, ODF, and STI) represented in DATOS (Hser, Anglin, & Fletcher, 1998).

  • Rates of lifetime drug dependence and current drug use at admission to the DATOS treatment episode were highest among clients admitted into methadone maintenance treatment (OMT) and lowest among outpatient drug-free (ODF) clients.
  • Although clients treated in all four modalities reduced their drug use at follow-up, individuals who met criteria for a clinical diagnosis of drug dependence improved less, even after controlling for level of pretreatment drug use.
  • Reductions in cocaine use were greater among clients treated in LTR, STI, and ODF programs, as compared with clients treated in OMT programs.
  • Findings suggest that characteristics of the clients’ drug dependence history, in addition to the current or presenting drug problem, should be assessed at intake into treatment in order to guide treatment planning.


Hser, Y. I., Anglin, M. D., & Fletcher, B. W. (1998). Comparative treatment effectiveness: Effects of program modality and client drug dependence history on drug use reduction. Journal of Substance Abuse Treatment,15(6), 513-523. [Abstract]

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Last Revised:
13 December 2001

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