Exploring strength exercise prescription and its dose in rheumatoid arthritis

Abstract

Rheumatoid arthritis (RA) is a significant global burden. It causes pain and disability and has significant socio-economic implications. Non-pharmacological interventions are commonly prescribed to mitigate the impact of the disease. Strengthening exercise, supported by evidence from randomised controlled trials (RCTs), has gained wider acceptance. The National Institute for Health and Care Excellence (NICE) recommends strengthening exercise for managing the functional impairments associated with the disease. Whilst modest benefits have been demonstrated, uncertainties persist regarding the optimal dosage. This thesis endeavours to enhance our understanding of the prescription of strengthening exercise and its dose in RA through three original interrelated studies. Study one systematically reviewed contemporary RCTs where strengthening exercise was a main component of the intervention being evaluated. How dose of strengthening exercise was determined for the trial intervention was investigated. The majority of included RCTs did not: (1) Report piloting the intervention and its dose prior to conducting the RCT and (2) Cite any evidence underpinning the dose of strengthening exercise prescribed for participants taking part in the trial. Moreover, when evidence was cited, it varied in quality. Often the dose used or recommended in the underpinning evidence was inconsistently applied in the intervention being evaluated by the RCT. Frequently, the underpinning evidence was not directly applicable to individuals living with RA. The findings of this review cast doubt on whether dose of strengthening exercise is optimised for individuals with RA in RCTS. Study two investigated the dose in hand strengthening exercise prescribed and completed during the Strengthening And Stretching For Rheumatoid Arthritis of the Hand (SARAH) multicentre RCT. The study utilised the area under the curve (AUC) method to quantify the overall dosage of hand strengthening exercise prescribed across the five face-to-face exercise sessions. General estimating equation (GEE) multiple regression analysis was then employed to determine: (1) The relationship between prescribed overall dose and key outcomes (overall hand function and grip strength) and (2) What factors were associated with the overall dose prescribed. Results indicated that participants who were prescribed a higher overall dose of hand strengthening exercise exhibited better overall hand function and grip strength. Factors that influenced overall dose prescribed included the professional background of the therapist (i.e. occupational therapist or physiotherapist) and baseline participant characteristics including metacarpophalangeal joint deformity, number of swollen wrist/hand joints, grip strength, participant mood, and confidence to exercise without fear of making symptoms worse. Study three employed judgement analysis (JA) to evaluate how occupational therapists and physiotherapists (therapists) judge what intensity (a key dose parameter) of hand strengthening exercise to prescribe an individual with pain and dysfunction of the hand associated with RA. A modified Delphi process involving therapists experienced in managing hand impairments associated with RA was used to prioritise the key clinical cues included in the case scenarios. Therapists based in the United Kingdom (UK) were then invited to assess a set of sixty-nine case scenarios (54 + 15 repeats) via an online platform. Their judgements on prescribed intensity of hand strengthening exercise were explored using multiple regression analysis. Results indicated all therapists reduced the intensity of the exercise as the severity of the clinical cue increased. The cues that influenced therapists the most included: (1) Patient’s pain performing the exercise, (2) Disease activity and (3) Average pain over the preceding week, (4) Hand range of movement, (5) Ulnar drift and (6) Patient grip strength. Sub-analysis employing the Cochran-Weiss-Shanteau (CWS) index of expertise identified therapists who were more consistent in their prescribing judgements relied on fewer clinical cues (1-3), implying a form of pattern recognition may be associated with their prescribing judgements. In summary, dose is a crucial aspect of therapeutic exercise prescription. These studies provide new insights into prescribing and dosing of strengthening exercises for RA in both clinical trials and practice. Based on these findings, this thesis proposes several future research directions. First, the issues identified in study one may not be limited to strengthening exercises and RA. Investigating whether similar issues exist in RCTs evaluating other therapeutic exercise-based interventions used to manage other musculoskeletal disorders is urgently needed to understand whether dose is sufficiently optimised in rehabilitation research more broadly. Second, to actualise the full potential of therapeutic exercise-based interventions, alternative methods for optimising dose warrant investigation. Dose escalation methodology may offer healthcare researchers a viable alternative to employing past research, which for strengthening exercise in RA, is often low quality and not applicable to the clinical population of interest. Third, further exploration around how healthcare professionals optimise dose of exercise-based interventions at the point of contact is essential for optimising exercise prescription in clinical practice.