In the most recent decades, the percentage of physical therapy research publications grew exponentially among both human health and physical rehabilitation research.1 For example, in recent years, cost-effectiveness studies have shown physical therapy interventions to be cost-effective in a range of conditions. Data from Australia and recent data from the United States of America, show an average net-benefit ranging from 1320 to 39,533 dollars for the management of several conditions, such as chronic obstructive pulmonary disease, carpal tunnel syndrome, and back pain.2-4 Development and validation of new physical therapy techniques and new methods/measures are ever emerging and are other areas responsible for this research growth.

To improve research efficiency, it is imperative to identify knowledge gaps of the profession and establish key priorities of investigation for the future. Research agendas provide clear forward-thinking viewpoints for the progression of the profession, can promote research in the field, and influence decisions of funding bodies. They also enable the alignment of research with the needs of consumers, healthcare professionals, and policy makers, reducing the research waste when there is patient and public involvement (PPI).5 In fact, establishing a research agenda for physical therapy, might not only reduce low quality research and channel research efforts into common and crucial goals, but also foster the development of recommendations for clinical practice, towards a contemporary, evidence and value-based physical therapy.

Although physical therapy practices, resources, and settings vary greatly around the world,6,7 and certain questions may be country-specific to address local policies, it is likely that most research priorities are relevant for the overall advancement of the profession. Nonetheless, to our best knowledge, physical therapy research agendas of different initiatives have never been compared nor reviewed.

Therefore, the aim of this scoping review was to identify priorities for physical therapy research, and to summarize the evidence into a global research agenda for physical therapy. As secondary aims we sought to compare the establishment of priorities across studies, in terms of the priorities chosen, the methods used, and geographical location.

This review synthesized the literature on priorities for physical therapy research and compiled research priorities into a global physical therapy research agenda. These 9 priority categories can now be used to design future physical therapy studies and channel research efforts into questions that are relevant for multiple stakeholders (e.g., physical therapists, patients, regulatory authorities) and nationalities.

Defining the cost-effectiveness of physical therapy interventions and the best structure and processes of the interventions were two of the areas with more priorities established. An Australian study has documented the cost-effectiveness of physical therapy for 11 conditions.2 However, there are global disparities in service delivery and resources among countries,6,7 and therefore conducting an economic evaluation might be necessary for a vast number of conditions in different countries, to demonstrate to the public, policy makers, and insurance companies the added value of physical therapy within the healthcare landscape. Additionally, defining the optimal service delivery models, especially the structure of interventions (e.g., setting, resources – human and material, knowledge) and processes (e.g., waiting lists, timing of treatment, components of interventions, referral rates), together with defining the core outcomes of interventions, can aid quality assurance.40,41 This can be achieved through an iterative process of assessing these indicators and making adjustments to practice, commonly performed under the framework Plan-Do-Study-Act (PDSA).42

The third category with highest number of research priorities was education, professional development, and quality. Education in physical therapy and professional development (pursuit of short courses, master and doctoral degrees) varies greatly globally. Nevertheless, to protect citizens, it is imperative to ensure that physical therapy degrees have a minimum quality and that physical therapists evolve as new evidence and techniques arise. Researchers should investigate new education models and compare them with more traditional models (e.g., problem-based learning/flipped classroom vs. standard theoretical and practical lectures),43,44 and the added-value of short or long-term courses/degrees on the skillset of the physical therapist. In the interim, educators and professionals can use the physical therapist education framework developed by the World Physiotherapy, to develop the physical therapy curricula to minimum standards, and advance the physical therapist from novice to expert, keeping in mind the specificities and needs of each physical therapy specialty.45

Regarding measurement instruments, although developing instruments relevant for physical therapy is important, studying their psychometric properties and feasibility in clinical practice (e.g., associated cost, space needed, training required) is equally if not more valuable, to avoid using measures of poor quality and low applicability. In fact, systematic reviews of measurement properties, commonly expose a lack of clinimetric data in original studies.46,47 Additionally, similar to other fields, it is possible that physical therapists misuse measurement instruments despite their limitations.48 Hence, future reviews of measurement instruments using the COnsensus-based Standards for the selection of health Measurement Instruments (COSMIN) methodology could be conducted,49 to determine issues with physical therapy instruments and ascertain needs of future research in this field.

Another key priority for physical therapy research is to better understand the mechanisms behind disability and classification systems, and especially why some treatments might work or not. Physical therapy is an ever-evolving area with new techniques being frequently implemented in clinical practice before their effectiveness is well established or the rationale for their use clearly understood.50 Hence, researchers should prioritize investigating the mechanisms that explain the effects of different therapies. The Rehabilitation Treatment Specification System (RTSS), a theoretical framework developed for this purpose, can be used to guide the design and reporting of studies.51

Patients’ needs, expectations, experience, and contextual factors can contribute to the clinical reasoning of the physical therapist and the success of an intervention.52,53 Hence, it is important to study physical therapy interventions from the patient's point of view, to improve the health alliance between the patient and the physical therapist, and optimize treatment outcomes. Additionally, having PPI in research, and using patient-reported outcome measures (PROMs) and patient-reported experience measures (PREMs) might foster the adoption of a truly patient-centered physical therapy approach.54,55

Although it was not a highly ranked category, investigating clear prognostic criteria, patients’ classification, and understanding how patients might respond to a certain therapy is important to aid clinical decision making. Predicting patient's disability based on cut-offs of measurement instruments can help tailor physical therapy treatments,56 and therefore diagnostic test studies are encouraged. Similarly, responder analyses have been conducted in hopes to understand why some patients do not achieve a clinically meaningful outcome with physical therapy, and to try to estimate a priori if they will be responders or not to an intervention, to ultimately choose the best clinical paths for each patient.57,58 Furthermore, researching and establishing the best decision-making strategies is key. In fact, tools such as decision trees, and artificial intelligence might be useful for clinical practice, with a greater research investment in this area needed.59-61

The last category for physical therapy research identified was to investigate the added value of technology and big data for physical therapy. In the last years, a vast amount of technology-aided physical therapy interventions has rose. These can go from simple wearable technology to inform physical activity interventions, to a full virtual therapist for home-based physical therapy.62 Nonetheless studies showing the reliability of these mHealth tools and their added value to standard clinical practice are scarce. With the crescendo of commercial devices, it is imperative to consistently conduct research in this area. Moreover, although the use of big data in physical therapy is only marginal, analyzing big datasets from electronic health records can inform strategies for continuous improvement of health services, and should therefore be a priority for the future.63

In this review we found that the research methodology of included studies varied greatly, with less than half of studies using the Delphi methodology. This is consistent with the many methods described as useful to achieve a list of priorities for research,64 and with a systematic review conducted for research priority setting for Black and minority ethnic health.65 This however contrasts with a review for dementia, where up to 70% of studies had a Delphi or multi-step design.66 Our review also found patient participation in 56% of studies, which is below the engagement in other fields (65–70% of studies),65,66 and few participations of policy makers (24% of studies). These results highlight the need to establish the optimal study design for establishing research priorities, and the promotion of PPI initiatives, facilitating the involvement of non-experts, such as patients, carers, decision makers, and citizens.

Except for 1 study conducted in 3 different countries, all other research priority setting exercises of the included documents were developed for specific regions. Thus, future studies investigating research priorities could combine views from different countries, to establish internationally applicable research agendas. Furthermore, although the research priorities in the original studies cover a range of physical therapy areas, to our knowledge there is no priority setting document for women's health or geriatrics. It is possible that some physical therapy-related priorities of these areas are embedded in priority setting documents of other health-areas and could have been missed by our search strategy. Yet, it is still important to understand from the clinicians, patients, and researchers’ point of view, which gaps of the literature should be filled in these areas.

This review provides a global agenda for physical therapy research which can be useful for physical therapy researchers designing new studies. Nonetheless, some limitations need to be acknowledged. Our search was restricted to priorities relevant for physical therapy, and therefore other priorities that could be relevant for the profession might have been excluded (e.g., generic priorities for rehabilitation). Searching for priorities applicable to physical therapy in any field of medicine would be dependent on our judgement and could increase the level of bias. Moreover, we did not conduct searches to verify if research questions have already been answered in the literature, and therefore this step should be performed in the future. Our search was conducted in English, which might have hindered our ability to identify important reports of non-English speaking countries. Most research questions identified were developed in North America, Europe, and Asia, and therefore their applicability for low- and middle-income countries, and specifically the South American, African, and Australian continents is unclear. Hence, future research should explore the applicability of these research questions for such regions or develop new ones. Our scoping review was designed and conducted without PPI, which could have provided an important viewpoint for the methodology and findings. Nevertheless, using the global physical therapy research agenda gathered, a priority setting exercise can be conducted grounded in PPI, to ascertain the research priorities in each country/region. Finally, we did not find priorities related to some emergent topics such as exoskeleton-assisted therapy, or physical therapy during emergency situations (e.g., natural disasters, pandemics), which will likely be important topics in the future.

This review provides a global agenda for physical therapy research, with 9 research priority categories that should be explored. Researchers can use this research agenda to confirm the relevance of these priorities in their context/regions (e.g., low- and middle-income countries), to design studies, and conduct relevant and contemporary investigations to answer these questions.