Exercise May Reduce Mortality Among Patients on Dialysis, But Low Compliance Makes Concrete Recommendations Difficult

Patients on dialysis tend to be extremely sedentary, says Kirsten Johansen, MD, Director of Nephrology at Hennepin Healthcare in Minneapolis, Minnesota, who discussed the clinical benefits of exercise for this patient population in a session at the American Society of Nephrology’s (ASN) 2023 Kidney Week Annual Meeting, November 2 to 5 in Philadelphia, Pennsylvania. Emerging studies confirm the benefits of exercise for this patient population, but helping these patients to maintain exercise goals may require a multidisciplinary approach, Johansen said.

“There is an association with physical activity and survival in patients on dialysis,” Johansen said during the session. “[But] sedentary behavior and chronic kidney disease (CKD) itself, aging, and other things can lead to low fitness, low muscle mass, [and] poor physical performance.”

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During a randomized study of patients on dialysis, investigators observed that low physical activity led to the worst survival outcomes during follow-up. This makes sense, Johansen said. Patients with CKD who lead a sedentary lifestyle could be at risk of developing hypertension, insulin resistance, vascular disfunction, and inflammation.

Conversely, exercise has been shown to reduce inflammation, improve heart health (improving oxygen use and reducing oxidative stress) protect against ischemic injury, and improve insulin sensitivity and vascular function in the general healthy public. Johansen noted that these benefits, especially on vascular function, can extend to patients with kidney disease on dialysis.

Augmentation index (arterial stiffness) and endothelial function—both measures of vascular function—have been shown to improve with exercise, Johansen said. Different types of exercise may also be beneficial, although studies have shown different results; some support aerobic training (AT) and others resistance training (RT). Still others have observed health benefits from participating in both, Johansen said.

Despite efficacy findings from numerous (but oftentimes smaller) studies, compliance is a leading barrier preventing patients on dialysis from exercising. This was observed during the randomized PEDAL study, which evaluated compliance and adherence to moderate-to-vigorous intradialytic cycling (exercise during dialysis) against no intradialytic exercise.

These results showed that 33% of patients in the intervention group dropped out of the study, compared to 21% of patients who did not exercise during dialysis, Johansen said. Further, less than 50% of patients who continued the study were able to complete a full exercise session. At the end of the intervention, just 18% of intervention participants fully adhered to the moderate-to-vigorous exercise regimen.

“Although long-term, moderate-to-vigorous exercise may be needed to improve vascular function or cardiovascular risk, few patients are actually willing to completely adhere to such a program,” Johansen said.

Most participants dropped out because of fatigue, Johansen said. Other patients had other medical events, refused to continue treatment, lost interest, or became sick and were hospitalized.

Notably, most studies of exercise (or lack thereof) for health outcomes in dialysis patients focus on moderate or vigorous activity, according to Johansen. EXCITE, a relatively large, randomized trial, is a recent and unique trial that evaluated an intervention with 10 minutes of moderate-to-low intensity exercise (walking) on non-dialysis days in approximately 300 patients. Although there was an insignificant difference in hospitalization rate, the investigators said more studies are needed to understand low-intensity exercise and compliance.

In a similar fashion, the randomized PED study looked at weekly step goals (low-to-moderate intensity exercise) in an intervention of patients with access to a pedometer and counseling versus a group who received traditional care. With intervention patients able to set goals and discuss barriers with the counselor, they walked an average of 2256 more steps at 3 months compared to the control arm, Johansen said. Counseling incentivized patients to be more active, and this multidisciplinary type of intervention was significantly more effective.

Unfortunately, when the intervention was complete, “We [investigators] did nothing else, and so did [the patients],” Johnsen admitted. “They went right back to where they are.”

Johansen concluded, “I think we urgently need larger trials of lower intensity exercise [and] I think these trials need to incorporate strategies to motivate behavioral change, rather than just prescribing and monitoring the exercise activity. We need explicit trials to deal with hospitalizations and other clinical events because they do happen, and just dropping people out of the exercise isn't going to get us the answers we need.”

Reference

Johansen K. Let’s Get Moving! The Role of Exercise in Cardiovascular Health of Patients on Dialysis. Session. ASN Kidney Week Annual Meeting. November 2 to 5, 2023. Philadelphia, PA.