Gender differences in client-provider relationship as active ingredient in substance abuse treatment.
Marsh J.C., Shin H-C, Cao D. Evaluation and Program Planning: 2010, 33(2), p. 81–90.

From the comprehensive treatment process data collected by a major national US study emerges the important lesson that retention in itself is not an active ingredient in post-treatment outcomes but reflects influences such having one's needs met (especially important for women) and developing a good relationship with the service and your key worker.

Summary
The US National Treatment Improvement Evaluation Study collected data between 1993 and 1995 from a nationally representative sample of treatment programmes funded by the US government, serving mainly vulnerable and underserved populations including minorities, pregnant women, young people, public housing residents, welfare recipients, and those involved in the criminal justice system. It remains one of the few treatment effectiveness studies to have collected detailed information from clients on their relationships with the treatment provider and their receipt of services.

The featured analysis used this data to test whether stays in treatment and drug and alcohol use a year after leaving were (as in other studies) related to the intensity of the following types of services/processes as reported by patients and clients when they left treatment:
• Access services like child care and transportation intended to improve access to treatment.
• Substance use counselling and other services (12-step meetings and medications for alcohol/drug problems) intended to directly reduce substance use.
• The service–needs ratio assessed the degree to which the needs for services patients expressed when they started treatment were met by actually receiving those particular services.
• Client–provider relationship: whether a positive therapeutic partnership had developed between the treatment service (in particular the client's key worker) and the client, assessed via ten questions, to most of which the client could indicate magnitude or degree.

The analysis aimed to unpick not just the presumed effects of these variables, but also how they worked, and whether effects and mechanisms differed for men and women and were affected by other characteristics of the client or service.

The source study had interviewed 6593 patients when they started treatment. Of these, the featured analysis included 3027 from 59 services who had completed all intake, treatment discharge, and follow-up interviews, were not in prisons or jails, and had expressed some need for services at treatment intake. A year after leaving treatment they had told researchers the number of days in the last 30 on which they had used the five most frequently used substances: alcohol; cannabis; crack cocaine; cocaine powder; and heroin. These use days were summed to give an index of the intensity of their polydrug use. The fact that the variables presumed to influence substance use were measured a year before means that they could have had a causal influence, but the study was unable to be sure of this because other influences could not be excluded.