Therapist Drift – Does it Really Matter?

What is Therapist Drift?

Therapeutic drift is defined in many ways. Generally, it is when the therapist stops using therapeutic methods. However, it also includes the concept of fidelity. Therapist drift is discussed in this blog article too.

In considering drift and fidelity the Cambridge dictionary definition of drift and fidelity are useful.

Drift is defined as: to move slowly, especially as a result of outside forces, with no control over direction.

Fidelity is defined as the degree to which a copy of something shows the true character of the original.

Outside forces are an important factor, one of the outside forces that has played out in Australia recently is the change in Medicare funding from 20 session to 10 sessions. It is worth considering how much does this influence the delivery, or fidelity of therapy compared to how the therapy was originally developed. How much does one cut corners to fit therapy to a set number of sessions rather that what might be clinically indicated or supported by the research? Organizations can also impose outside forces, such as fortnightly session policies, or session number limits. Sometimes the forces are in the form of the culture of the organisation or the therapist working within the organisation.

Therapist Drift – Does it Really Matter?

If therapists are pressured to complete therapy in a certain number of sessions, therapy can be rushed, key components brushed over rather than comprehensively examined, possibly the urgency could affect the development of the therapeutic alliance. Additionally, as will be outlined below higher levels of fidelity, or less drift can have an effect on outcomes.

Trauma Therapy, Drift and Fidelity

In regard to trauma therapy, and specifically Cognitive Processing Therapy, there are a number of research articles demonstrating the importance of fidelity and therapeutic drift upon client outcomes, that is PTSD symptoms.

Nicholas Holder and colleagues (2018) reported that participants treated by a therapist (using CPT) with “good” treatment fidelity experienced significantly greater reductions in PTSD symptoms, Negative Cognitions, and depression symptoms than patients treated by a therapist with “below average” treatment fidelity.

John Keefe and colleagues (2022) reported that  more CPT competent (higher fidelity) delivery was associated with lower next-session PTSD symptoms. They also reported that CPT competence was more predictive of outcomes when alliance was also strong. Specifically, they outlined that in their study, therapy sessions high in both therapist competence and therapeutic alliance more strongly predicted lower subsequent-session PCL-IV scores than either high competence or alliance scores alone. More evidence for the role of alliance and a therapeutic method having an effect.

Courtney Farmer and colleagues (2016) studied the critical elements, or key aspects of fidelity, they found that there were some key aspects of fidelity that were linked with improved client outcomes.

They found that there that “overall high therapist competence for ’skill in Socratic questioning’ and ‘prioritizing assimilation before overaccommodation’ were related to greater client improvement in PTSD severity, but ‘attention to practice assignments’ and ‘emphasis on expression of natural affect’ were not.” (pg195)

Making changes to therapy – does that mean I am drifting?

Changes to therapy are sometimes necessary in the clinic context. However, consideration of fidelity is important. Keeping in mind fidelity is defined as the degree to which a copy of something shows the true character of the original.  If this is done it can help buffer the risk of modifications becoming drift.

Luana Marques and team (2019) studied modifications to Cognitive Processing Therapy and therapist fidelity.  They defined modifications in terms of fidelity-consistent or inconsistent. 

1) Fidelity-consistent Modifications:  Do not change core elements of the treatment in such a way that reduces adherence to the intervention protocol.  Similarly, fidelity consistent modifications do not make it difficult to differentiate between treatments.

Examples of fidelity-consistent modifications include changes such as, modifying the language, cultural adaptations, and lengthening sessions to more than 60 min.

In our clinic modifications that we have made include 90-minute sessions for clients who have English as their second language.

Using words to describe the continuum of an emotion rather than a zero to 100% scale.

2)  Fidelity-inconsistent modifications alter the delivery of core elements of the intervention protocol, they may include elements not in the original protocol. Fidelity-inconsistent modifications make it difficult to differentiate between treatments.

Example of fidelity-inconsistent modifications in CPT include removing/skipping a CPT module, worksheet, or psychoeducation element. Similarly, integrating other approaches or techniques from other treatment are fidelity inconsistent. For instance, adding a couple of in vivo exposure tasks during the course of CPT. Similarly, adding in some imaginal exposure to CPT would be fidelity-inconsistent.

The most common fidelity-inconsistent modification I am asked about is repeating sessions, “can I do session two again.” eg session 2 (a), 2 (b), 2(c). Examination of this often shows that a client has not done an impact statement and is avoiding doing it.

Marques and team (2019) found that higher numbers of fidelity consistent modifications were associated with larger reductions in posttraumatic stress and depressive symptoms. High adherence ratings were associated with greater reductions in depressive symptoms, whereas higher competence ratings were associated with greater reduction in posttraumatic stress symptoms.


Fidelity to a therapy can have great benefits to client outcomes. There are a number of potential outside forces that therapists could be aware of that may lead to drift in therapy and the associated poor outcomes. However, sometimes changes in therapy are needed in the clinical context. Therapists may benefit from checking if the changes are consistent or inconsistent with the therapy as it was developed.


Farmer CC, Mitchell KS, Parker-Guilbert K, Galovski TE. Fidelity to the Cognitive Processing Therapy Protocol: Evaluation of Critical Elements. Behav Ther. 2017 Mar;48(2):195-206. doi: 10.1016/j.beth.2016.02.009. Epub 2016 Mar 2. PMID: 28270330.

Keefe JR, Hernandez S, Johanek C, Landy MSH, Sijercic I, Shnaider P, Wagner AC, Lane JEM, Monson CM, Stirman SW. Competence in Delivering Cognitive Processing Therapy and the Therapeutic Alliance Both Predict PTSD Symptom Outcomes. Behav Ther. 2022 Sep;53(5):763-775. doi: 10.1016/j.beth.2021.12.003. Epub 2021 Dec 18. PMID: 35987537.

Marques L, Valentine SE, Kaysen D, Mackintosh MA, Dixon De Silva LE, Ahles EM, Youn SJ, Shtasel DL, Simon NM, Wiltsey-Stirman S. Provider fidelity and modifications to cognitive processing therapy in a diverse community health clinic: Associations with clinical change. J Consult Clin Psychol. 2019 Apr;87(4):357-369. doi: 10.1037/ccp0000384. PMID: 30883163; PMCID: PMC6430611.

Nicholas Holder, Ryan Holliday, Rush Williams, Kacy Mullen & Alina Surís (2018) A preliminary examination of the role of psychotherapist fidelity on outcomes of cognitive processing therapy during an RCT for military sexual trauma-related PTSD, Cognitive Behaviour Therapy, 47:1, 76-89, DOI: 10.1080/16506073.2017.1357750