The UK addiction sector has long pushed residential rehabilitation to the margins, treating it as expensive, uncertain, and hard to justify. Now Dominic McCann, chief executive of Castle Health, has published a paper that challenges this view directly. It draws on residential rehabilitation evidence spanning four decades and calls on providers to unite behind the country’s first collaborative, multi-site effectiveness study.

The paper reviews research from major national cohort studies, a systematic review, and individual treatment centre evaluations. Its conclusion is not that rehab has failed to produce results. It is that the sector has failed to measure them properly.

Residential Rehabilitation Evidence Shows the Wrong Standard Has Been Applied

The paper’s central argument is straightforward: residential rehabilitation has consistently been judged by the wrong standard.

“Rehab is not a one-off cure,” McCann writes. “It is a time-limited but uniquely powerful window of opportunity.” Measuring it against an acute medical model, where a single treatment episode produces a permanent result, misrepresents what recovery actually looks like.

Research by Kelly and colleagues (2019) found the median number of serious recovery attempts before achieving lasting remission sits at around two. Those most severely affected may need considerably more over several years. Sustained recovery is a trajectory, not a single event. Any single treatment episode, however intensive, is one contribution to a longer journey. Judging it as a one-off cure is not just imprecise. It applies entirely the wrong framework.

The residential rehabilitation evidence that does exist, McCann argues, is far more encouraging than most people acknowledge.

What the Large-Scale Studies Found

Four major national cohort studies form the backbone of the residential rehabilitation evidence reviewed in the paper: NTORS in the UK, DATOS in the United States, DORIS in Scotland, and ATOS in Australia.

Their findings deserve to be stated plainly.

NTORS found that nearly half of residential rehab patients remained abstinent from heroin at five-year follow-up. Psychological health and criminal activity also improved substantially. Crucially, residential clients presented with some of the most severe problems and complex needs, yet they made some of the greatest treatment gains. The assumption that rehab works primarily because it attracts easier cases does not hold up.

DATOS showed that longer retention in residential treatment linked consistently to greater reductions in drug use, criminal activity, and unemployment. The Australian ATOS study found that people who engaged in residential rehabilitation, particularly when combined with aftercare, were more likely to achieve sustained recovery over an 11-year follow-up period.

DORIS is often cited against residential treatment, given Scotland’s overall low abstinence rates. But a closer look tells a more nuanced story. Researchers tested whether residential clients achieved better results simply because they had less severe dependencies. Using the Severity of Dependence Scale, they found virtually no difference in dependence levels between residential and community treatment groups. Better rehab treatment outcomes could not be explained away by patient selection.

These findings form the core of the residential rehabilitation evidence base. Randomised controlled trials are largely impractical and ethically problematic in this field. But the available evidence is substantial, consistent, and drawn from thousands of patients tracked over years.

Rehab Treatment Outcomes Extend Well Beyond Abstinence

One of the paper’s more important contributions is its challenge to abstinence rates as the main measure of success.

Treatment centre data tells a consistent story. A Castle Craig study from 2000 tracked 206 patients over an average of 429 days after discharge. Over 60% reported much improved physical health. Over 50% reported much improved mental health. Nearly 70% reported much improved quality of life. A 2015 Castle Craig study found that 91.8% of respondents had improved or remained stable, with none showing deterioration, including many who had not maintained complete abstinence.

Cook made a similar observation as far back as the 1980s, reviewing Minnesota Model outcomes: “all patients appear to have gained some therapeutic benefit.” Decades of rehab treatment outcomes data point to the same conclusion. When broader measures are used, the picture is considerably more positive than abstinence figures alone suggest.

A 2019 systematic review by De Andrade and colleagues identified 23 studies published between 2013 and 2018. It found moderate quality evidence for improvements across substance use, mental health, social outcomes, and mortality. This was the first comprehensive review to focus specifically on residential rehabilitation.

What Actually Drives Recovery in Residential Settings

The paper also brings together what research tells us about the mechanisms behind successful treatment.

Rudolf Moos studied more than 3,000 individuals across 15 Veterans Affairs residential programmes in the United States. He found that the quality of the treatment environment accounted for seven to eight times more of the variance in outcomes than individual patient characteristics. What happens during treatment, and how the programme structures it, matters far more than who arrives at the door.

George Vaillant’s decades-long longitudinal research identified four consistent predictors of sustained recovery. These were: experiencing the real consequences of addiction; finding a substitute engagement such as a recovery fellowship; building new, supportive relationships; and developing meaning, purpose, and hope. These are not abstract ideals. A well-run residential programme can actively create the conditions for all four.

Process research by John Kelly and colleagues has clarified how 12-Step participation produces its effects: by building self-efficacy, shifting social networks away from substance-using contacts, and strengthening coping skills. A 1997 study by Morgenstern and colleagues found that 12-Step participation actively increases self-efficacy and coping efforts. This directly challenges the criticism that such approaches leave people feeling helpless.

At Castle Health, this residential rehabilitation evidence directly shaped the development of ALAANA (Assertive Linkage to Alcoholics Anonymous and Narcotics Anonymous). Castle Craig introduced this structured four-part 12-Step Facilitation workshop in 2025. It draws on the American MAAEZ model, adapted for a UK context, and targets the recovery mechanisms the research most consistently identifies.

The Measurement Problem Undermining the Sector

Despite the weight of residential rehabilitation evidence, poor outcome reporting continues to undermine the sector’s credibility.

McCann is candid about this gap. Some providers claim success rates of 50 to 70%. A 2001 composite review by Miller, Walters, and Bennett found just 24% of patients achieved one-year continuous abstinence across all treatment modalities. According to researcher William White, the main cause of these discrepancies is the quality of study methods, not the treatments themselves.

The problem runs deep. Most UK residential providers run their own evaluations using their own methods, with no shared instruments, no common benchmarks, and no independent oversight. Studies routinely exclude early dropouts. Baseline data is often incomplete. Follow-up periods vary widely. The result is a set of isolated findings that no one can meaningfully compare.

Policy decisions have compounded the problem. A 2006 review by Raistrick, Heather, and Godfrey concluded that 12-Step residential treatment offered no added benefit over other forms and was less cost-effective than outpatient alternatives. NICE guidelines from 2007 and 2011 set high eligibility thresholds on similar grounds. Yet both assessments assumed that suitable intensive outpatient services would be accessible. In practice, they are not available to most patients who need them across the UK. Residential rehabilitation has repeatedly faced comparisons against services that do not, in practice, exist.

A Framework for Stronger Rehab Treatment Outcomes Research

McCann sets out a detailed, standardised model for outcome evaluation, developed with Dr Tim Leighton, whose doctoral research examined change mechanisms in residential rehabilitation.

The framework starts with comprehensive baseline data collection. This covers demographics, substance use history, prior treatment, and social network composition. Validated, public-domain instruments allow comparison across services. These include the EUROHIS-QOL for quality of life, the PHQ-9 for depression, the Alcohol and Drug Abstinence Self-Efficacy Scale, and the Multi-Dimensional Inventory of Recovery Capital.

Follow-up at six and twelve months post-discharge uses the same instruments from admission onwards. Crucially, the model requires non-completers wherever possible. A Clouds House study by Georgiakis found that late dropouts did at least as well as completers, while early dropouts fared considerably worse. That finding carries direct implications for retention strategies. A completers-only study would miss it entirely.

A Call to the Sector

The paper ends with a direct challenge to UK residential treatment providers: participate in a collaborative, multi-site effectiveness study built on this shared framework.

McCann is clear about what this could deliver. With 15 to 20 participating sites using common instruments from admission through 12-month follow-up, the study would build the statistical power no single-centre evaluation can match. It would allow meaningful comparison across providers, enable analysis of what actually drives sustained recovery, and give every participating centre benchmarking data they can use to improve their service.

“Residential rehabilitation has been asked to justify itself for decades,” the paper states. “A sector that can present credible, comparable, independently overseen outcome data from multiple sites running different models has an answer that no single provider, however rigorous, can offer alone.”

Castle Health has committed to participating in and helping to convene the study. Providers, researchers, and sector bodies can make contact directly.

The residential rehabilitation evidence base has grown steadily over four decades, through national cohort studies, systematic reviews, and treatment centre evaluations. What the sector has lacked is a shared infrastructure for producing and comparing that evidence. If McCann’s call finds a response, that may be about to change.

Source: dbrecoveryresources