Estimating treatment duration for psychotherapy in primary care

Mental health problems are increasing in society. To deal with these problems effectively, it is imperative that appropriate treatments are delivered. Some evidence suggests that patients often do not complete the full course of many psychotherapy treatments. The aim of this study was to estimate the average length of treatment for patients referred to the adult specialty of a large clinical psychology department. A stratified sampling strategy was chosen to obtain an unbiased and precise estimator of the average treatment length for the population of patients whose files had been closed in one calendar year (n = 3021). The stratified sampling mean estimator for the population mean was 3.9 appointments; standard psychotherapy treatments are often planned to be more than ten appointments. These results suggest that many patients are failing to receive the full treatment planned by mental health professionals. Perhaps more psychotherapy treatments need to be delivered in a smaller number of appointments. Stratified sampling could be used to estimate treatment duration in particular contexts, thereby allowing treatments to be designed to meet local needs.