More physical activity may reduce mortality in CKD by 50%
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Higher physical activity levels were associated with a 52% lower mortality rate vs. lower levels of activity, according to a study that assessed the link between activity and health outcomes for patients with chronic kidney disease.
“Physical activity level has been shown to be a potentially modifiable risk factor for adverse outcomes in a number of populations, including individuals on [hemodialysis] HD and those with mild to moderate CKD,” Christie Rampersad, MD, of the University of Manitoba, Winnipeg, Canada, and colleagues wrote. “However, there is a paucity of studies examining this association in patients with advanced CKD who are not receiving renal replacement therapy (RRT). The Canadian Frailty Observation and Interventions Trial (CanFIT) study is a longitudinal observational multicenter study which measures multiple domains of frailty in this population. As part of study visits, patients self-reported their physical activity using the physical activity scale for the elderly (PASE), which is a well-validated questionnaire that includes activities commonly performed by older adults.”
In total, researchers recruited 579 patients with CKD stages G4 to G5 (defined as eGFR less than 30 mL/min/1.73m2) and considered all-cause mortality, progression to kidney failure and falls. Specific activities that comprised the physical activity score included occupational, household and leisure activities, as well as muscle strengthening and sports and recreation. Adjustments were made for age, sex and comorbidity.
Patients were followed for 1,193 days, during which 118 patients died, 204 progressed to dialysis and 129 reported a fall.
While researchers observed no associations between higher levels of physical activity and either slower progression to kidney failure or a lower rate of future falls, they determined higher levels of physical activity were associated with a 52% lower all-cause mortality (adjusted HR = 0.48).
Rampersad and colleagues acknowledged a variety of limitations to the study, including the lack of diversity within the cohort, which was predominately made up of white patients.
“As such, these findings should be replicated in other settings with a higher proportion of individuals of Hispanic, African and Indigenous descent,” the researchers wrote. “Furthermore, we were unable to adjust for smoking, BMI and proteinuria, which have been shown to be independently associated with mortality in patients with advanced CKD. Finally, it is important to note that these findings are observational in nature, and interventional studies targeting physical activity behavior in the CKD population are needed to confirm whether physical activity is truly a causal and modifiable risk factor for mortality.”
Perspective
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Ken Wilund, PhD
Physical inactivity is a hallmark of patients with chronic kidney disease, and its prevalence increases as the disease progresses. However, few studies have assessed the impact of low physical activity on clinical outcomes in patients with advanced CKD.
In this paper, Rampersad and colleagues examined the relationship between self-reported physical activity (PA) levels and all-cause mortality, progression to kidney failure and future falls in a cohort of 579 adults with CKD stages G4 to G5 who were followed for an average of 1,193 days.
While there was no relation between PA levels and progression to kidney failure or falls, there was an impressive 52% reduction in all-cause mortality in patients in the highest PA tertile compared with those in the lowest PA tertile. This inverse relationship between PA and mortality is not surprising, given similar findings cited by the authors in those with early stage CKD and patients on hemodialysis.
What is surprising is that little has been done to substantively address the problem of physical inactivity across the spectrum of CKD. After all, there is a plethora of evidence indicating that increasing physical activity levels improves the health and quality of life of patients with CKD.
While there are many limitations to this data, including a paucity of studies targeting hard (eg, hospitalizations, mortality) and patient-centered (eg, fatigue, pain) outcomes, the same arguments can be made regarding limitations in the data on many widely implemented pharmacological and nutritional therapies in CKD.
Increasing PA levels in patients with CKD will require a range of comprehensive strategies. This may include the following:
- providing better training for health professionals who prescribe exercise therapy for patients with CKD; and
- providing incentives to reimburse payers for exercise programs, similar to the model that is used for cardiac rehabilitation.
An encouraging development is the recent announcement of an American College of Sports Medicine task force that will lobby for exercise professionals to be recognized as health care practitioners who can be reimbursed for delivering exercise programs.
International organizations, such as the Global Renal Exercise Network (https://grexercise.kch.illinois.edu/), are also working to address this problem through the development of multinational research teams capable of conducting large clinical trials that will improve the evidence base for exercise in CKD.
It is imperative that the nephrology community support these and other similar efforts and move toward making renal rehabilitation a standard component of therapy for patients with CKD across the spectrum of the disease.
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