Psychotherapy 101: How long and how frequently should we see clients?
How long and how often we should see clients is a question that not only causes clients anxiety and therapists angst, but is currently under scrutiny in Australia within Medicare and Productivity Commission reviews. There is in fact a long tradition of research into the relationship between client outcomes and the number of psychotherapy sessions received, known as the “dose effect” literature. Because no one doing this research markets training products in Australia however, it can easily go undiscovered. This week, I spotlight a recent systematic review of this literature by Robinson, Delgadillo and Kellett (2019).
The review included 26 studies ranging in sample size from 20 to 26,430! Fourteen studies took place in university counselling centres with the remainder in primary health, private practice or specialist outpatient psychotherapy services. The studies employed a range of different methodologies which would strengthen our confidence in the results if they were consistent, but leave us guessing if the results weren’t. The most common criterion for an optimal treatment dose was the number of sessions necessary for 50% of the sample to achieve reliable change on the study’s main outcome questionnaire.
So, what’s the answer? It’s complicated. The first complication is whether or not the setting allows clients to receive as many sessions as they want (or at least a high upper limit) or offers only a small, limited number. To calculate an optimal dose, enough sessions need to be provided to see where responsiveness levels off or decreases. If this number is artificially curtailed, there may appear to be a linear relationship between number of sessions and improvement as found in Falkenstrom et al (2016); in other words, each extra session seems to be associated with an equivalent improvement in client symptoms. Studies that offer more than 12-15 sessions generally show a non-linear dose-response relationship in which there is clearly a number of sessions by which there are diminishing returns, either in the form of no further improvement, much less improvement, or far more gradual improvement.
The second major complication is that clients at different levels of severity improve at different rates and therefore require different ‘optimal’ numbers of sessions. This is most evident by contrasting sub-groups among treatment-seekers: clients with mild anxiety and depression who receive low-intensity structured CBT interventions in primary care have an optimal dose of 4 to 6 sessions. The more typical optimal dose range is 4-26 sessions for anxiety and depression of the severity typically seen in university clinics and private practice. There has been a little research on more severe clinical populations such as those with eating disorders, psychosis and intellectual disabilities, but to date, none of this indicates that there is a relationship between length of treatment and outcome or can establish an optimum dose. Instead, there appears to be either rapid responders who show signs of improvement by sessions 4-8 or gradual responders who may need up to 26 sessions to show optimal improvement (or of course, those who don't respond at all!).
In terms of frequency of sessions, one study demonstrated that clients attending weekly achieved reliable change and clinically significant change (i.e., scores within a recovered range) more quickly than those who attended fortnightly. Even though the total amount of change was not significantly different between groups, the greater efficiency translates to: 50% of those receiving weekly sessions achieve reliable improvement within 6 weeks, whereas it takes 21 weeks for 50% of those receiving fortnightly sessions to do the same (Erekson et al., 2015).
Take home: Clinical Implications
It’s rare to get reliable improvement in less than 4 sessions, so retaining clients for 4 sessions is an important first step.
Review client progress after 4 sessions for mild cases and 8 sessions for more severe cases.
For more severe cases who are not showing improvement, focus therapy on overcoming obstacles, such as disagreements about the tasks and goals of therapy, alliance strains, addressing problems outside therapy such as a lack of social support and need for medication. Allow for a trial period up to 26 sessions to see if further improvement can be achieved.
If a severe client has shown no improvement by 26 sessions and you have offered a sound course of therapy, the client is unlikely to respond to psychotherapy in their current circumstances and should be referred to other kinds of intervention (e.g., psychiatric review, personal support program). Your time would be better spent with the next person on the wait list who might have more capacity to respond.
Aim to offer at least weekly sessions for maximum efficiency.
This article is currently in press at Psychotherapy Research. Go to https://www.tandfonline.com/doi/full/10.1080/10503307.2019.1566676 for the full article.
References
Erekson, D.M., Lambert, M.J.,& Eggett, D.L. (2015). The relationship between session frequency and psychotherapy outcome in a naturalistic setting. Journal of Consulting and Clinical Psychology,83(6) : 1097-1107.
Falkenstrom, F., Josefsson, A., Berggren, T., & Holmqvist, R. (2016). How much therapy is enough? Comparing dose-effect and good-enough models in two different settings. Psychotherapy, 53(1): 130-139.
Robinson, L., Delgadillo, J., & Kellett, S. (2019). The dose-response effect in routinely delivered psychological therapies: A systematic review. Psychotherapy Research, 2019. https://doi.org/10.1080/10503307.2019.1566676