Physician knowledge, attitudes, and practices regarding physical activity restrictions in pediatric hemodialysis patients

Epidemiologic studies of physical activity among pediatric hemodialysis (HD) patients are lacking. A sedentary lifestyle in End‐Stage Kidney Disease is associated with a higher cardiovascular mortality risk. In those patients receiving HD, time spent on dialysis and restrictions on physical activity due to access also contribute. No consensus exists regarding physical activity restrictions based on vascular access type.

The aim of this study was to describe the patterns of physical activity restrictions imposed by pediatric nephrologists on pediatric HD patients and to understand the basis for these restrictions.
Methods: We conducted a cross-sectional study involving US pediatric nephrologists using an anonymized survey through Pediatric Nephrology Research Consortium.The survey consisted of 19 items, 6 questions detailed physician characteristics with the subsequent 13 addressing physical activity restrictions.
Findings: A total of 35 responses (35% response rate) were received.The average years in practice after fellowship was 11.5 years.Significant restrictions were placed on physical activity and water exposure.None of the participants reported accesses damage or loss that was attributed to physical activity and sport participation.Physicians practice is based on their personal experience, standard practice at their HD center, and clinical practices they were taught.Discussion: There is no consensus among pediatric nephrologists about allowable physical activity in children receiving HD.Due to the lack of objective data, individual physician beliefs have been utilized to restrict activities in the absence of any deleterious effects to accesses.This survey clearly demonstrates the need for more prospective and detailed studies to develop guidelines regarding physical activity and dialysis access in order to optimize quality of care in these children.

INTRODUCTION
Despite increase in rates of transplantation, hemodialysis (HD) remains a commonly used renal replacement therapy (RRT) for the treatment of End-Stage Kidney Disease (ESKD).The percentage of children initiating HD as modality of RRT increases with age: 7.4% in patients <1 year of age versus 58.1% in patients 13-17 years of age.In 2019, of the 663 children who initiated dialysis in the United States, 370 (55.8%) children did so with HD.Vascular access (VA) is a fundamental requirement for patients receiving HD and can be achieved with either a central venous catheter, arteriovenous fistula, or arteriovenous graft, with each type having pros and cons. 1,2ccording to the United States Renal Data System (USRDS), central venous catheters (CVC) remain the most commonly used VA, particularly in children 12 years and younger.The data also demonstrate a stepwise increase in the utilization of arteriovenous fistulae or arteriovenous grafts with increasing patient age, including either AVF or AVG in 40.3% for those aged 14-17 and 67.4% for those aged 18-21 years. 3he benefits of exercise are numerous, regardless of type, intensity, or length of exercise: it helps to preserve or increase muscle mass and function, improve aerobic capacity, and enhance cardiovascular function. 4,5The advantages of regular exercise are especially pronounced in children with ESKD as they often become victims of decreased physical activity due to chronic fatigue, malnutrition, and an overall catabolic state due to multiple hospitalizations and interventions.This sedentary lifestyle in chronic kidney disease (CKD) is associated with a higher cardiovascular mortality risk when compared to the general population. 5In those patients receiving HD, additional contributory factors to inactivity include time spent on dialysis as well as restrictions on physical activity due to VA type.
Even though the benefits of exercise in patients with CKD are well known, there has been no published literature examining physical activity restrictions based on VA type.Furthermore, there are no guidelines or consensus regarding physical activity restrictions based on VA type; yet even without scientific basis, many pediatric nephrologists restrict physical activities for fear of injury to the access.Similarly, while patients are often allowed to shower and bathe with an internal access (i.e., AVF or AVG), exposure to water is often restricted in the setting of a CVC.
Practice patterns have historically varied and remain poorly understood.Due to this knowledge gap, the aim of this study was to assess pediatric nephrologists' philosophies and practices regarding physical activity restrictions placed on HD patients with different VA types to identify trends that require further study.

MATERIALS AND METHODS
This was an anonymized self-administered survey, completed by pediatric nephrologists through the Pediatric Nephrology Research consortium (PNRC) to assess physician knowledge, attitudes, and practices about physical activity restrictions placed on HD patients with either a central venous catheter, arteriovenous fistula, or arteriovenous graft.The PNRC (formerly Midwest Pediatric Nephrology Consortium) was established in 2004 and consists of practicing pediatric nephrologists throughout North America and includes over 125 member centers.Members of the PNRC have conducted pediatric dialysis research in a global forum, resulting in numerous publications through collaborative data collection for more than a decade.This study was granted Internal Review Board (IRB) exemption as no patient information was obtained and no identifiable demographic data were collected from pediatric nephrologists.
One hundred surveys were distributed.Nephrologists were informed that the confidentiality of data would be protected and that only aggregate results would be disseminated.

Survey instrument
The survey consisted of 19 items, 6 questions detailed physician characteristics (Table 1) and 13 addressed various physical activity restrictions in place for children on HD (Table 2).For ease and generalizability regarding beliefs, VA type was not subcategorized.
For the purposes of this study, individual activities were inquired about; however, for description of results, the following definitions were used with respect to exercise and organized sports: • Strength and resistance training was defined as use of weight resistance to muscular contraction to build strength, anaerobic endurance, and size of skeletal muscles.• An organized sport is defined as a sport that includes individual play and/or practice together regularly as a team in a league or association and/or as after-school activities that occur on a regular basis under adult-supervision.
T A B L E 1 Characteristics of provider characteristics.

Domain Response
No. of years of practice post-fellowship How many stations are in your dialysis unit?
How many patients are currently receiving hemodialysis in your unit?
Similar to physical activity restrictions, the survey also inquired about physician practice beliefs with respect to water exposure.Water exposure can be a broadly used term, so this survey was designed to delineate which water exposures are being restricted in the presence of a CVC.

Statistical analyses
Descriptive analyses were performed for all variables.Furthermore, results were dichotomized into two groups based on physician years of practice (<10 years' experience and >10 years of experience) and chi-square test used to assess if differences in attitudes and practices existed based on experience level.

RESULTS
Thirty-five survey responses (35% response rate) were received from attending pediatric nephrologists practicing across North America with a mean 11.5 (range 1-35) The results of the survey in regards to the resistance training and organized sports are summarized in Table 3.A majority of pediatric nephrologists (65.7%) do not allow their patients to participate in competitive sports and over 60% do not allow resistance training.With respect to types of resistance training, 80% of nephrologists did not provide a response regarding allowance of bench press or free weights, yet approximately 80% did provide a response to push-ups and chin up, and over half prohibited these activities.
Approximately 65% of those surveyed allow participation in competitive sports, however most commonly prohibited participation in American football, wrestling, and martial arts.Participation was more often allowed in rifle/shooting, racquet sports, rowing, soccer, basketball, baseball, skiing, and gymnastics.Survey respondents were mixed with respect to field hockey and ice hockey (Table 3).

Central venous catheter and water exposure
When asked specifically about effects on VA, none of the participants reported access damage or loss that was attributed to physical activity or sport participation.Results depicting the amount of water exposure allowed is shown in Figure 1.While many pediatric nephrologists (22; 62.9%) do allow their patients to shower, only 12 (34.3%)allow patients to bathe.For nearly all respondents, swimming in swimming pools, oceans, and freshwater lakes was not allowed.When asked about the rationale for activity limitations, the response was very diverse with no evidencebased practice as depicted in Figure 2.There was a nearly even distribution between "personal experience," "standard of care at center," and "that was what I was taught."One respondent said their practice was based on published literature.
Chi-square testing comparing physicians with <10 years' experience to those with >10 years of experience with respect to differences in attitudes and practices in each response yielded no significant differences (p > 0.05 for each individual component).

DISCUSSION
This survey illustrates numerous restrictions that are placed on children receiving HD, including participation in sports, strength training, and water exposure.Interestingly, when types of activities were further examined, patients were prohibited from participation in wrestling and football; however, sports such as basketball, soccer, and hockey were allowed.This variance of inclusion is concerning as many of the sports restricted as well as the ones allowed are considered high impact.This highlights the lack of objectivity when imposing restrictions on sports/activities.Admittedly, survey respondents stated they did not have any VA loss due to physical activity, yet they continue to place these restrictions.Despite the push for increased activity in children with CKD, and lack of published evidence for VA loss from physical activity, restrictions continue to be placed on children undergoing dialysis.Additionally, there were many differences among pediatric nephrologists about allowed physical activity, and exercise among HD patients, again based on either experience or the way they were taught.
Endurance and strength training have been evaluated and deemed beneficial for adult dialysis patients without negative consequences.Aerobic exercise training improves exercise capacity, endurance and cardiopulmonary fitness training in dialysis patients 6 ; and resistance training stimulates muscle growth by increasing oxygen consumption. 7Furthermore, Kowalska et al. described the benefits after implementing a 6-month exercise regimen (at the beginning of the first 4 h of dialysis, three times a week) in 28 adult dialysis patients: 20 were randomized to endurance training and 8 were randomized to resistance training.An evaluation of depression and anxiety at the initial and final examination time points indicated a significant reduction in both depression and anxiety in the entire study group.The authors concluded physical training during dialysis is beneficial at reducing anxiety and depression. 8he importance of exercise and physical fitness in the general population and in adults with ESKD is well known to reduce morbidity and mortality from cardiovascular disease.Children with ESKD are more likely to die of cardiovascular causes than their peers; and the most common cause of death in ESKD patients is cardiovascular.Multiple comorbid conditions contribute to this risk including obesity, hypertension, atherosclerosis, and dyslipidemia. 9Additionally, patients with CKD have muscle wasting, anemia, and poor physical functioning, all of which contribute to poor overall health and increased morbidity. 10Furthermore, reduced physical activity leads to low exercise tolerance, muscle wasting, and sarcopenia. 11,12Many of these risk factors and consequent comorbidities are mitigatable through a healthy lifestyle including regular exercise.
Given that all sports are not equal, there can be a bias against team sports due to the nature of high impact, F I G U R E 1 Box plot demonstrating the various sources of water exposure with central venous catheters.The total number of responses received were 35.Showers were allowed by 63%, baths were allowed by 34% of respondents.Swimming pool exposure was allowed by 6% and exposure to ocean water was allowed by 3% of respondents.Fresh water exposure was universally restricted by 100% of respondents.
F I G U R E 2 Box plot demonstrating the rational for activity restriction.
with some activities.Based on data from the US Consumer Product Safety Commission (CPSC), which tracks injuries through its National Electronic Injury Surveillance System (NEISS), the highest number of estimated head injuries treated in US hospital emergency rooms in 2018 in children 14 years of age or younger were due to injuries from playground equipment, football, basketball, cycling, baseball and softball, soccer, swimming, trampolines, powered recreational vehicles, and skateboards.4][15] Hence, restrictions in physical activity, namely organized sports needs to be further understood and clarified using evidence-based approaches.
Psychological benefits should also not be minimized.The ultimate management goal for children with ESKD is to allow them to be healthy both physically and mentally, socially well-adjusted productive members of society.Psychologic effects of chronic diseases are well known and children with ESKD have reported low levels of health-related quality of life (HRQOL) compared to their healthy peers.Specifically, Gerson et al. conducted a cross-sectional assessment of HRQOL in 402 children with CKD enrolled in the NIH-funded multicenter CKiD study. 16They reported that overall HRQOL as well as physical, social, emotional, and school functioning is poorer in children with CKD than healthy youth, even in early stages of CKD.The most marked differences from norms were in school functioning scores.The negative impact on HRQOL scores in the physical and social domains may be due to growth impairment and pubertal delay associated with childhood onset CKD.For all of these reasons, every opportunity to "normalize" activity in children with ESKD should be considered.
The benefits of exercise in children with CKD, at all stages, and after renal transplantation have been well described.A study conducted by Hamiwka et al. in pediatric renal transplant recipients as compared to healthy controls showed children with renal transplant were less physically active than their peers with respect to total exercise time ( p = 0.00). 17As such, the control group reported higher HRQOL than transplant recipients (p = 0.001).Renal transplant patients showed significantly lower perceptions of sports competence (p = 0.007) and physical conditioning (p = 0.001) than the control group.Higher activity scores were significantly correlated with higher perceptions of body attractiveness (p = 0.019) as well.The authors concluded physical activity may play a role in overall well-being and HRQOL in children with renal transplants.As many children receive HD as a bridge to renal transplantation, it can hardly be expected that patients will suddenly develop a desire to exercise once transplanted.As such, the benefits of exercise and team sports should be supported even while the patients are receiving dialysis.
Another topic of interest is whether HD access type influences practitioners' views with respect to activity restrictions.Optimal VA remains the cornerstone for HD.While AVFs and AVGs are preferable as compared to CVCs, CVC use remains a mainstay in children undergoing HD.There have been no published data to date describing VA loss due to exercise participation or injury from physical activity.Rather, in the EXCITE (EXerCise Introduction To Enhance performance in dialysis patients) study, an analysis of AV-fistula "events" in randomized patients who started the trial showed that the incidence rate of these outcomes did not significantly differ (p = 0.22) between the exercise (22 events in 6 patients, 35 events per 100 person-years; 95% CI: 22-53) and control (13 events in 6 patients, 23 events per 100 person-years; 95% CI: 12-39) groups. 18The nature of events was not described; however, access loss was noted.Inui et al. described their experience in situations where surgical repairs of dialysis access hemorrhage was warranted, the etiology of the hemorrhage was bleeding from a skin eschar/ulcer over the AVG or AVG, not due to injury of the VA. 19This further supports the low risk of exerciserelated VA malfunctions.
Based on the results of this survey, we suggest this is a call to action for renal providers to consider an evidencebased, benefit-risk approach when advising about exercise in dialysis patients.Specifically, the physical and psychological benefits of exercise outweigh a theoretical risk of VA injury.Furthermore, provisions may be needed for added protective gear (e.g., a forearm guard can be custom made for an archer to protect a forearm AVF).If contact sports are deemed impractical, alternative forms of cardiovascular exercise may be recommended to optimize physical and psycho-social outcomes.
In summary, although physical activity has shown significant improvement in the quality of life and decrease in patient mortality in dialysis patients, there is no agreement among the pediatric nephrologists about the physical activity and sports that can be allowed in children with dialysis accesses.Due to lack of consensus among nephrologists, many of the physical activities and sports were restricted.This survey clearly demonstrates the need for revisions in care practices, as well as the conduction of detailed studies with subsequent evidencebased guidelines regarding physical activity and dialysis access.
T A B L E 2 Survey: Physician views about physical activity.With respect to dialysis unit size based on the number of treatment stations in each dialysis unit, there was a wide distribution: 1-12, with a mean of 6.3 stations.
Physician responses to resistance training and sports participation.
T A B L E 3