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Letter
‘There is nothing more deceptive than an obvious fact’: more evidence for the prescription of exercise during haemodialysis (intradialytic exercise) is still required
  1. Daniel S March1,2,
  2. Matthew PM Graham-Brown2,3,
  3. Hannah ML Young1,2,
  4. Sharlene A Greenwood4,
  5. James O Burton1,2
  1. 1 Department of Infection Immunity and Inflammation, College of Medicine, Biological Sciences and Psychology, University of Leicester, Leicester, UK
  2. 2 John Walls Renal Unit, University Hospitals of Leicester NHS Trust, Leicester, UK
  3. 3 National Centre for Sport and Exercise Medicine, and School of Sport, Exercise and Health Sciences, University of Loughborough, Loughborough, UK
  4. 4 Department of Physiotherapy and Renal Medicine, King's College London, London, UK
  1. Correspondence to Dr Daniel S March, Department of Infection, Immunity & Inflammation, University of Leicester, Leicester, Leicestershire, UK; dsm12{at}le.ac.uk

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With regard to the recent editorial,1 we applaud the author’s call to arms for nephrologists to ‘prescribe’ exercise during haemodialysis (HD). It is true that exercise has tremendous health benefits, with many likely benefits for HD patients. Staying physically active is essential to maintaining health, and unquestionably clinicians caring for HD patients should be counselling patients to increase physical activity levels. There are, however, unresolved questions that must be answered before structured programmes of intradialytic exercise (IDE) can simply be ‘prescribed’ by clinicians, as Deschamps suggests. The UK Renal Association clinical practice guidelines for cardiovascular disease state that exercise should be encouraged for all HD patients,2 but practical recommendations on prescribing and dosing of exercise (and indeed safest modes of exercise) cannot currently be made based on the available evidence.

Deschamps correctly pointed out that clinicians remain reluctant to ‘prescribe’ exercise for HD patients despite 40 years of research.3 This reluctance is understandable, as although there are a number of small trials showing the potential benefits of IDE, there is a paucity of high-quality, adequately powered randomised controlled trials (RCTs). This may explain the reluctance among nephrologists to prescribe exercise, further contributing to why HD patients remain so sedentary. That being said, there are two RCTs underway within the UK investigating the effect of programmes of IDE on both cardiovascular structure and function (ISRCTN11299707)4 and health-related quality of life (ISRCTN83508514). Data from these trials will aid in dissipating some of the confusion regarding the efficacy and safety of IDE.

Deschamps suggests that IDE is safe, and it is true that there are no reported serious adverse event (SAEs) related to exercise in trials involving HD patients. The absence of SAEs, however, does not confirm the absence of a pernicious effect for certain patients. Some trials have reported a significant drop in blood pressure an hour after IDE,5 with evidence from a small sample that patients experiencing the highest ultrafiltration volumes are at greatest risk of hypotension.6 Further evidence in larger data sets is needed to elucidate this. As episodes of intradialytic hypotension are associated with poor outcomes and increased mortality,7 exposing HD patients to an intervention that may precipitate intradialytic hypotension seems imprudent until we are sure it is not associated with adverse outcomes. If IDE does adversely affect cardiac structure and function in certain patient populations, then IDE can be targeted to those who will derive benefit and be avoided in those for whom it causes harm.

It is vital that IDE programmes are shown to be cost-effective. No previous trials have reported cost-effectiveness data and clinicians will not be able to simply ‘prescribe’ and deliver programmes of IDE if they are not a long-term, cost-effective intervention. Furthermore, an implementation strategy to facilitate the uptake and sustainability of IDE programmes in HD units is needed. This strategy should include dedicated personnel responsible for the delivery of these programmes, defined protocols for exercise prescription, and effective education for nephrologists to assess the benefit or risk at an individual patient level. Finally, the prescription of an exercise intervention can be thought of as a lifestyle change. Changing exercise and lifestyle habits can be incredibly difficult for anyone, let alone a sedentary population who are lacking motivation and energy. Understanding the psychosocial factors surrounding IDE and developing ways to engage and retain HD patients in IDE programmes are necessary before capital funds are invested.

There is no doubt that all patients receiving HD should be encouraged by clinicians to be more physically active. However, the current evidence to support the actual prescription of exercise during dialysis is insufficient. When unresolved questions around ‘prescribing’ IDE have been answered, then exercise training should be recommended as standard practice as Deschamps suggests.

References

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Footnotes

  • Contributors DSM developed the idea for the response.

    DSM and MPMG-B composed the letter.

    DSM, MPMG-B, HMLY, SG and JB revised the letter.

  • Competing interests None declared.

  • Patient consent Not commissioned; externally peer reviewed.

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