Kraus, D. R., Bentley, J. H., Alexander, P. C., Boswell, J. F., Constantino, M. J., Baxter, E. E., & Castonguay, L. G. (2016). Predicting therapist effectiveness from their own practice-based evidence. Journal of Consulting and Clinical Psychology, 84(6), 473-483.
There is lots of evidence that there are differences between therapists in their patients’ outcomes. Some studies estimate that 5% to 7% of patient outcomes can be attributed to differences between therapists’ abilities and style of delivering treatment. But most of these studies measured outcomes only once, and so they could not estimate if therapist effects are stable across time. Further, many of these studies used only a global measure of patient distress as an outcome and did not measure domain-specific outcomes (e.g., depression, anxiety, mania, alcohol dependence, etc.). In this study by Krauss and colleagues, 59 therapists who treated 3,540 patients were included. Therapists had on average 10 years of experience and were from a variety of professions (psychologists, psychiatrists, social workers, counsellors etc.). The settings included mental health clinics, independent practice, hospitals, and others. The authors went to some effort to control for case-mix variables such as client problem difficulty, length of treatment, caseload size, and other variables. Client outcomes were measured for 12 different domains ranging from depression to sexual dysfunction to substance abuse. First, outcomes were assessed for 30 patients of each therapist, and then these were compared to outcomes of the same therapist’s next 30 patients. Therapists were classified as “exceptional”, “average”, or “below average” based on their patients’ outcomes. Fifty-seven percent of therapists who were rated as exceptional with the first 30 patients were likely to remain exceptional or above average with the next 30 patients. In other words, effective therapists tended to remain effective over time. Therapists had better patient outcomes when it came to depression, suicidality, and substance abuse, but therapists tended not to have as good outcomes when it came to mania, and sexual functioning.
Effective therapists tend to remain effective over time for particular client problem areas. However, therapists are seldom effective for more than 4 or 5 client presenting problems, and less than 10 % of therapists are effective with all client problem areas. Therefore patients with differing problems are likely to achieve better or worse outcomes depending on the particular therapist and his or her strengths. Therapists can regularly assess patient outcomes and use that information to help with continuing education to improve their practice for a particular problem area.