From the United States National Institute of Health, Principles of Drug Addiction Treatment: A Research Based Guide - Why can’t drug addicts quit on their own?
Nearly all addicted individuals believe in the beginning that they can stop using drugs on their own, and most try to stop without treatment. However, most of these attempts result [...]

National Institute on Drug Abuse, NIH on how effective is drug addiction treatment:
According to several studies, drug treatment reduces drug use by 40 to 60 percent and significantly decreases criminal activity during and after treatment. For example, a study of therapeutic community treatment for drug offenders (See Treatment Section) demonstrated that arrests for violent and [...]

The Center for Substance Abuse Treatment is part of the United States Department for Health and Human Services. CSAT promote the quality and availability of community-based substance abuse treatment services. CSAT also supports free treatment referral service to link people with the community-based substance abuse services they need.
The treatment locator includes more than 11,000 [...]

Trends in drop out, drug free discharge and rates of re-presentation: a retrospective cohort study of drug treatment clients in the North West of England, published in 2006.
The proportion of individuals dropping out has increased from 7.2% in 1998 to 9.6% in 2001/02 (P < 0.001). The proportion DDF [Discharged Drug Free] has fallen from [...]

The six steps that are included in many addition treatment programs are: detoxification, diagnosis, cognitive therapy, family therapy, medication and some 12-step type program. WebMD has an article examining Rehab’s Role in Treating Addiction
Experts now agree that addiction is a brain disease with a genetic component, Gordon says. But it’s also affected by behavior. [...]