The Drug Matrix is concerned with the treatment of problems related to the use of illegal drugs by adults (another deals with alcohol-related problems). It maps the treatment universe and for each sub-territory (a cell) lists the most important UK-relevant research and guidance. Across the top columns move from specific interventions through how their impacts are affected by staff, the management of the service, and the nature of the organisation, to the impact of local area treatment systems. Down the rows are the major intervention types implemented at these levels.

What is cell B2 about?

Whether medical or psychosocial, chosen positively or under pressure, among the ‘common factors’ affecting treatment’s success is the nature of the patient’s relationships with referral and treatment staff. Relationships affect whether people want to enter treatment after initial contact, whether they stay, and the services they receive. In these ways among others (Key studies above for examples), ultimately relationships can (but not always) affect the degree to which treatment helps patients overcome their drug problems and improve their lives.

Relationships emerge partly from the patient, but of most interest is the therapist’s contribution, because this is what can be changed by recruitment, training and experience. The interpersonal style and other features of treatment staff are much less commonly researched than the nature of the intervention, and many studies try to eliminate these influences in order to focus on the specific content of the intervention. In doing so they risk eliminating what matters in order to focus on what generally matters little or not at all.

Relative neglect means that associations between therapist factors and retention or outcomes often emerge from studies intended to investigate interventions, not interventionists. Without the reassurance of randomising patients to different therapists or therapist styles, it is usually impossible to be sure that these associations represent causal effects.

Here the focus is on therapist-related factors; common factors more generally are dealt with in cell A2.