Professor Daleen Casteleijn of the University of Pretoria’s (UP) Department of Occupational Therapy recently delivered her inaugural address, which focused on her research to transform a South African theory – the Vona du Toit Model of Creative Ability (VdTMoCA) – into an evidence-based, globally influential model for clinical practice. An inaugural address is a formal event for newly appointed professors or those who have been promoted to full professor.

​Prof Casteleijn framed her presentation around a central challenge that has resonated with her throughout her career – the “space between theory and practice”. As such, she has been working to build a bridge between the two, using the VdTMoCA as her primary focus.

“It felt as if we were standing on one side of a river with knowledge, while patients and communities stood on the other side waiting for solutions,” she said in her address.

​The VdTMoCA, Prof Casteleijn explained, defines different levels of creative ability to indicate an individual’s level of functioning in order to provide an understanding of how people engage in everyday life. These levels are often described in a spiral, with the lowest level representing limited energy and ability to participate (such as an unconscious person). Prof Casteleijn provided an example of “mid-level imitative participation”, where most people function comfortably. These individuals can manage daily life well and thrive if they have a routine.

“They’ll tackle day-to-day problems without fuss, but if something unusual or complex comes up, they might prefer to wait for someone else to figure it out first,” she explained. “The model helps therapists to meet people exactly where they are ... and helps them take the next step towards fuller, more meaningful participation in life.”

​The model was developed out of necessity in 1963 by South African occupational therapist Vona du Toit when the value of occupational therapy training was questioned, and even threatened with closure. Du Toit laid the theoretical foundation, thereby grounding the profession through a model that explained how people are motivated and able to participate in life’s activities. However, for years, it existed without the research and evidence to develop it further.

Prof Casteleijn addressed this lack of evidence during her master’s and PhD studies, with the aim of developing a psychometrically sound assessment tool. The result was the Activity Participation Outcome Measure (APOM), a tool with eight domains and 53 items, which scores a patient’s functioning based on the first six VdTMoCA levels.

“I remember having fleeting thoughts like, ‘What if occupational therapists actually used this tool after my PhD?’” Prof Casteleijn said. “But I never truly imagined that it would happen.”

Yet even before its formal launch, demand for the APOM grew quickly among clinicians in South Africa and abroad, especially in the UK. ​Today, the APOM has become a routine outcome measure in practices across South Africa, the UK and Australia, where an allied health practice uses it as a key determinant of disability insurance benefits. In South Africa, the APOM is listed as a preferred assessment tool in the Ideal Hospital Framework.

The measure has been transformative. One South African psychiatric hospital initially found its therapy programmes were making little impact.

“Guided by APOM results and data-driven insights, the occupational therapy team redesigned their entire service,” Prof Casteleijn said. This resulted in “significant improvements in all domains of activity participation” for patients. The results are now understood by the entire multidisciplinary team, with major clinical decisions about a patient’s care now being guided by the APOM and the levels of creative ability.

“What started as a tool for one profession has become the backbone of hospital-wide transformation,” Prof Casteleijn said, adding that the APOM has led to “significantly fewer relapses”.

​To confirm the VdTMoCA’s scientific foundation, Prof Casteleijn and her collaborators applied the Rasch measurement model, a psychometric method that examines whether items in a tool assess a single underlying construct in a consistent, hierarchical manner. The analysis confirmed that the VdTMoCA levels are “not arbitrary, and form a true hierarchy of human functioning”, Prof Casteleijn said.

“The science backs the theory,” she added. “We now have a validated measure of human functioning, with levels that are statistically robust and clinically meaningful.”

This precision allows practitioners to measure small, meaningful shifts in functioning and, importantly, demonstrate cost-effectiveness for value-based healthcare, which is critical as South Africa prepares for the National Health Insurance.

​Prof Casteleijn continues to expand her research. This includes the co-creation of the Work Participation Matrix – where the levels of the VdTMoCA are applied to workforce development – and supervising students as they apply the APOM in diverse areas such as traumatic brain injury, stroke rehabilitation and forensic settings.

“In my field, I believe the true measure of impact lies not only in citations but in implementation, when research takes root in practice, changes services and improves lives,” Prof Casteleijn said.