Therapist effects in a NIDA CTN intervention trial with pregnant substance abusing women: Findings from a RCT with MET and TAU conditions.

This ancillary investigation examined whether therapist effects may account for treatment outcomes among pregnant substance users in controlled and naturalistic treatments. Therapists participating in protocol CTN-0013 (“Motivational Enhancement Therapy to Improve Treatment Utilization and Outcome in Pregnant Substance Users”) who were randomized to Motivational Enhancement Therapy (MET) and treatment as usual (TAU) conditions and assigned at least five clients were included. Client self-reported substance use and urine toxicology at post-treatment, 1- and 3-month follow-ups were obtained. A therapist main effect was found across therapy conditions and within MET (five therapists) but not within TAU (five therapists). When substance use was treated as a dichotomous measure (abstinence/nonabstinence) corroborated with urine toxicology screening, no therapist effect was found. Clients perceived therapists to vary in their supportiveness and listening skills, for example, but these impressions were not associated with therapist effectiveness to reduce substance use.

Conclusions: The researchers found support for a limited therapist effect, but only within the MET condition and only with a continuous outcome variable. Secondary analyses identified differences in client impressions of their therapist, but those impressions did not predict therapist effectiveness in reducing substance use. Although these findings warrant replication, they suggest that client substance use outcomes among pregnant women may be rather homogeneous regardless of the type of intervention or therapist.

Related protocols: CTN-0013