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Dr Arsenio Paez

DPhil title:

Intervention fidelity in clinical trials of complex interventions in healthcare.

Research abstract

Surgery and physiotherapy are complex interventions built up from many components which may influence the outcome of interventions. This creates unique challenges for researchers assessing the effectiveness of complex interventions. It is uncertain whether many RCTs show genuine treatment ineffectiveness or implementation infidelity contaminating intervention delivery and assessment of effectiveness. Imprecise descriptions of interventions is also common in physiotherapy and surgical papers, hindering the validity of systematic reviews.

My thesis will systematically review and analyze the quality of reporting and intervention fidelity monitoring in physiotherapy RCTs, using meta-epidemiological and meta-regression methods to investigate the association between intervention reporting and fidelity and estimates of treatment effects, incorporating these into a new and validated quality assessment tool specific to physiotherapy RCTs. A systematic analysis of intervention reporting and delivery fidelity in physiotherapy trials is essential for determining whether outcomes in RCTs can be correctly attributed to the intended interventions. It will provide quantitative and qualitative data for the development of evidenced, practicable recommendations for building a better evidence-base for physiotherapy and surgery with implications for other complex interventions.


Professor Richard Stevens

Professor David Beard ,

Professor Peter McCulloch


I completed the MSc in EBHC at Oxford (2017) and am now reading for the DPhil in EBHC. I am faculty in the Department of Physical Therapy, Movement and Rehabilitation Sciences at Northeastern University, Boston, USA, and have a pediatric practice in New York. I completed my undergraduate, graduate, and doctoral degrees in Physiotherapy and Early Intervention/ Development at Northeastern Univ. I was a fellow in Neurodevelopmental Disabilities (Lend Fellow) at the Harvard University-Children's Hospital of Boston Judge Baker Children's Center.  I am actively involved in the IDEAL Collaboration, Oxford, and am the IDEAL specialty lead for Physiotherapy.