Walking the line between fidelity and flexibility: A conceptual review of personalized approaches to manualized treatments for posttraumatic stress disorder.

The heterogeneity of the core symptoms of posttraumatic stress disorder (PTSD), high rates of comorbid mental and physical health conditions, and substantial impact of the disorder on functioning and well-being contribute to complex clinical presentations that can be challenging to treat. Despite these challenges, there are excellent manualized treatments for PTSD with significant empirical support. Although the success of frontline treatments for PTSD is evident, there remains room for improvement as indicated by suboptimal response and attrition rates. To address challenges to optimal therapy outcomes (COTOs), researchers have conducted numerous clinical trials designed to (a) enhance the core structure of treatment protocols to increase flexibility or (b) expand the protocols to address comorbid conditions that inhibit recovery. However, it is implausible to ever conduct the number of enhancement and expansion clinical trials necessary to test manual modifications for the universe of possible COTOs. This conceptual review describes the concept of a personalized model of therapy that leverages a case formulation approach to implementing an evidence-based treatment for PTSD. This personalized approach provides guidance for the clinician in assessing the patient's COTOs, monitoring them throughout treatment, and relying on the patient's idiosyncratic data to inform treatment decisions, including how and when to diverge from treatment when clinically indicated and ensuring a clear path to return to trauma-focused work when the COTO is stabilized. This personalized, case formulation approach to treating PTSD provides guidance for adopting a more flexible approach to treating clinically complex patients while ensuring fidelity to the protocol.