Author: Sheradyn Matthews
Matthews, Sheradyn, 2025 Integrating clinical and economic perspectives to effectively evaluate PTSD treatments: improving consistency, methodology and data availability, Flinders University, College of Education, Psychology and Social Work
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Posttraumatic stress disorder (PTSD) is a debilitating condition associated with significant distress, impairment, and economic burden. Despite strong evidence supporting numerous treatments for PTSD, access remains limited, particularly in public healthcare settings, where resource constraints can be a barrier to implementation. Economic evaluations are critical for informing funding decisions and supporting advocacy for training and resources, yet evaluations of PTSD treatments are scarce. This thesis addressed key methodological gaps impacting the rigour, consistency, and applicability of economic evaluations of PTSD treatments through three interrelated studies, informed in part by an open trial of Cognitive Processing Therapy (CPT) in an Australian public mental health setting.
Chapter 1 presents a concise and critical summary of the literature relevant to the evidence base for psychological therapies such as PTSD, as well as highlighting key issues that underpin our understanding economic evaluations. Chapter 2 presents a systematic review, where substantial variability across existing model-based economic evaluations of PTSD treatments was identified. Differences in model structures, assumptions, and cost components limited comparability and relevance for decision-makers. These findings highlight the need for a standardised reference model to ensure consistent, clinically relevant, and policy-informed economic evaluations.
Chapter 3 examines the suitability of the Assessment of Quality of Life-8 Dimension (AQoL-8D) for capturing PTSD-related treatment effects. Quality-adjusted life years (QALYs), derived from generic preference-based quality-of-life measures (GPQoLs) such as the AQoL-8D, are the recommended outcome metric for economic evaluations, as they allow comparisons across conditions. However, research suggests that GPQoLs may not fully capture the complexities of mental health disorders. This study found that while the AQoL-8D detected some PTSD-related changes, it was less sensitive to treatment effects than the PTSD Checklist for DSM-5 (PCL-5). These findings highlight that economic evaluations relying solely on QALY-based outcomes may underestimate the benefits of PTSD treatments, reinforcing the need for more responsive outcome measures.
Chapters 4 and 5 report findings from an open trial of CPT conducted in the South Australian public mental health system, examining clinical effectiveness, treatment costs, and healthcare utilisation. The study demonstrated significant PTSD symptom reductions and quality-of-life improvements, consistent with international implementation studies. Importantly, the study captured key cost components, including training and supervision, to enhance real-world applicability of economic evaluations. Healthcare utilisation data, derived from Commonwealth sources, indicated reductions in mental health service use following CPT; changes in medication use were more variable. The importance of incorporating data from national data sources such as Medicare-funded services into Australian economic evaluations of PTSD treatments, is highlighted.
The broader implications of this program of research are summarised in Chapter 6. Together, findings from these studies illustrate the critical methodological challenges as well as opportunities for improving economic evaluations of PTSD treatments. Strengthening collaboration between clinicians and health economists, developing a standardised reference model, improving the sensitivity of GPQoL measures, and embedding economic data collection into routine clinical research are argued to be key next steps in advancing the field. By addressing these issues, this thesis succeeds in its goal to provide more robust foundational economic evidence and guidance that will ultimately support future research that will lead to improved funding decisions and expanded access to cost-effective PTSD treatments in public healthcare settings.
Keywords: Posttraumatic stress disorder, PTSD, trauma, economic evaluation, health economics, cognitive processing therapy, public mental health care, health care utilisation, cost-effectiveness
Subject: Psychology thesis
Thesis type: Doctor of Philosophy
Completed: 2025
School: College of Education, Psychology and Social Work
Supervisor: Reg Nixon