
Evidence Based Treatment
Table of Contents
This webpage summarises key evidence supporting the effectiveness of residential rehab and 12 Step treatment programmes, drawing on significant studies and research findings.
From long-term outcomes in residential settings to the role of 12 Step facilitation in sustained recovery, the evidence presented highlights the transformative potential of these approaches. These insights reinforce the importance of combining evidence-based treatment with community support to achieve lasting sobriety and improved quality of life.
At Castle Craig, our treatment model integrates these proven principles, offering a comprehensive and supportive pathway to sustained sobriety.
Effectiveness of Residential Rehab Services
NTORS
An important study in 1995 was the National Treatment Outcome Research Study (NTORS)1 published by the Department of Health. The researchers recruited 1,075 former patients who received treatment in one of four modalities of addiction service in the UK. A random sample of 650 clients was followed up over one and five years.
The study demonstrated that:
47% of patients treated in residential rehabilitation services achieved abstinence after five years vs. 35% of those in community-based services.
The researchers also commented that clients who attended residential rehabilitation were some of “the most severely disturbed and they made some of the greatest treatment gains”. The greater level of poor social and personal functioning presented by rehab clients lends further weight to the high success level of the results for residential rehabilitation.
It is interesting to note that in this particular study, those who are receiving a methadone prescription are described as ‘abstinent’.
Drug Outcome Research Study (DORIS)
The 2006 DORIS2 study measured 1033 drug users from Scotland 33 months after they left treatment. The aim was to see whether they had managed to be abstinent for at least 90 days after discharge.
The results showed that:
- 25% of those who had attended residential rehab services were abstinent vs. 6% from community-based services.
- 30% of those admitted to residential treatment at any point since the start of the trial were abstinent for 90 days at follow-up vs. 3% who had received methadone maintenance
The evidence from this study also confirms the fact that quality residential treatment can help improve mental and physical health, reduce offending, improve employability and enhance social functioning.
The DORIS study also showed that drug users contacting drug treatment services in Scotland want abstinence. However, the majority will still receive Methadone maintenance.
Is Residential Rehab a Key Factor in Abstinence?
In 2008, Dr. David Best and researchers followed 269 people in full (abstinent) recovery. Their report3 concluded that: “The only type of formal treatment service which was a key factor in helping drug users to stay abstinent was residential rehab.”
Effectiveness of 12 Step Rehab Programmes
Many researchers see 12 Step groups as essential to effective addiction treatment. There are over 2 million members of Alcoholics Anonymous (AA) worldwide. AA has played a unique role in helping people to recover from dependence and has become the prototype for other similar self-help groups such as Narcotics Anonymous (NA), which helps drug addicts to recover from addiction to drugs other than alcohol.
There have been over 180 research studies into the effectiveness of 12 Step treatment. Below we have summarised a few of the most important ones.
Project MATCH (1998)
Project MATCH (Matching Alcoholism Treatments to Client Heterogeneity) was one of the largest and most comprehensive research studies on alcoholism treatment ever conducted. Sponsored by the National Institute on Alcohol Abuse and Alcoholism (NIAAA) in the United States, it was launched in the late 1980s and continued into the 1990s. The study aimed to determine whether specific types of psychotherapy for alcoholism were more effective for particular types of patients based on their personal characteristics. Two independent but parallel matching studies were conducted, one with clients recruited to the “outpatient arm” who received non-residential treatment, the other with patients receiving continuing care treatment (also known as ‘aftercare’) following inpatient care (“the Aftercare arm”). Patients were randomly assigned to:
- 12 Step facilitation, or
- Cognitive behavioural therapy (CBT), or
- Motivational enhancement therapy.
After 12 weeks of treatment, both groups were followed up for one year and were evaluated for changes in drinking patterns, quality of life, and use of treatment services. The researchers concluded:
“The findings of this trial support the effectiveness of the 12 Step programme and continued attendance at Alcoholics Anonymous in the patient’s home community”.
Major improvements in the well-being of the patients occurred relatively rapidly, in all three treatments, and persisted for three years afterwards. The results indicated that all three treatments were effective in vastly reducing drinking and that these reductions were maintained.
Severely dependent clients benefited more from 12 Step facilitation than CBT.
The results show that 12 Step principles play an important role in the maintenance of sobriety, especially for severely dependent patients. Overall 12 Step treatment produced a greater rate of total abstinence.
Other results include:
- 46% of continuing care clients were abstinent when contacted after 15 months and a further 7% were drinking without problems.
- 30% of patients in the ‘outpatient group’ were abstinent when contacted after 15 months and a further 12% were drinking without problems.
- The ‘outpatient group’ was followed up after three years and the results showed that 36% of patients who received 12 Step treatment reported abstinence vs. 24% of those who had CBT and 26% of those who had motivational enhancement therapy.
- Continuing care participants who had already been introduced to AA were more likely to attend AA meetings.
- Patients who had received inpatient treatment were more likely to attend AA meetings throughout the trial.

Success of 12 Step Groups
In a study by Fiorentine and Hillhouse6, 356 addicts were followed up for 8 months after entering outpatient treatment. The researchers found that when clients attended 12 Step meetings before treatment that they remained longer in treatment and were more likely to complete treatment. Those clients who completed treatment and then attended AA were more likely to remain abstinent than those who did not.
Conclusion: When people combine treatment and 12 Step support groups, they experience a powerful advantage over using treatment or self-help groups separately.
Summary of Research Evidence
The evidence supporting residential rehab and 12 Step treatment programmes highlights their transformative potential in helping people who are suffering from addiction to achieve lasting recovery. Studies like NTORS, DORIS, and Project MATCH underscore the effectiveness of these approaches, particularly for those with severe dependencies. By combining evidence-based therapies with the power of community support, these programmes not only foster abstinence but also improve mental health, social functioning, and overall quality of life.
References
- Gossop, M., Marsden, J., Stewart, D. (2001) NTORS After Five Years The National Treatment Outcome Research Study Changes in substance use, health and criminal behaviour during the five years after intake. National Addiction Centre
- McKeganey N. et al. Abstinence and drug misuse treatment: results from the Drug Outcome Research in Scotland study. Drugs: Education, Prevention & Policy: 2006, 13(6), p. 537–550.
- Best, Loaring, Ghufran, Day; Does treating people increase their chance for abstinence. Addiction Today. 2008.
- Project MATCH Research Group (1998). Matching alcoholism treatment to client heterogeneity: Project MATCH three-year drinking outcomes. Alcoholism: Clinical and Experimental Research, 22, 6, 1300-1311.
- Fiorentine, R. &Hillhouse, M.P. (2000). Drug treatment and 12-step program participation: The additive effects of integrated recovery activities. Journal of Substance Abuse Treatment, 18, 65-74.
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