Primary care physicians’ own exercise habits influence exercise counseling for patients with chronic kidney disease: a cross-sectional study

Chronic kidney disease (CKD) patients show gradual decline in maximal exercise capacity in accordance with the progression of their CKD stage [1, 2]. Actually, CKD stage 3–5 patients have been reported to show lower peak oxygen consumption, averaging 50-80% compared with healthy subjects [3, 4]. This decreased exercise capacity decreases quality of life and enhances sarcopenia, which can be defined as the age-related (1% per year after the age of 25) loss of muscle [5, 6]. Several studies reported that sarcopenia progressed much more intensively in CKD patients in association with several factors often observed in CKD, such as nutritional deficiencies, acidosis, and vitamin D deficiency [7, 8]. Sarcopenia is an independent predictor of low physical performance activities and fractures [9]. Recently, accumulated evidence has demonstrated that all CKD patients, irrespective of CKD stage and treatment modality, can improve their physical functioning and reduce the risk of sarcopenia by exercise training [10, 11]. Previous studies have reported beneficial effects of resistance exercise training on muscle mass and contractile function in CKD patients [12‐15]. In addition, several studies also have reported the beneficial effects of exercise on potential mediators of cardiovascular disease in CKD [12, 16]. Since the prevalence of CKD has been increasing globally [17, 18] and it has become a common disease globally, like cardiovascular diseases and metabolic syndrome, appropriate exercise counseling by primary care physicians as well as nephrologists for CKD patients is crucial to improve their prognosis. However, physicians reported limited medical school and residency training education about the beneficial effects of exercise, as well as inadequate guidelines for writing exercise prescriptions or referrals as barriers to exercise counseling [19, 20]. Several studies reported that physicians who exercise are more likely to counsel their patients to do so as well [21, 22]. However, there have been few studies about exercise counseling by primary care physicians for CKD patients. Therefore, in the present study, we investigated primary care physicians’ exercise counseling practices for CKD patients. Furthermore, we also investigated the associations of primary care physicians’ own exercise habits with their exercise counseling, as well as major barriers for exercise counseling for CKD patients.

This study was conducted in accordance with the Declaration of Helsinki and was approved by the ethics committee of Jichi Medical University. Since this study was analysis of anonymous self-administered questionnaire, responses were considered as consents for this study. This study was registered at University Hospital Medical Information Network Clinical Trial Registry (UMIN-CTR). The identification number is UMIN000011803.

The survey was mailed to 3310 medical doctors, with responses being received from 933 in total (28.2%). 37 responses were excluded from this study due to their inadequacy. Among the remaining 896, 581 (64.8%) medical doctors managed CKD patients. In this study, these 581 medical doctors were defined as CKD primary care physicians and their answers to the self-administered questionnaire were analyzed.

The results in the present study show that primary care physicians’ exercise recommendation levels for CKD patients were limited because their rate of positive exercise recommendations (high recommendation: 5.4% + moderate recommendation: 30.9%) was < 40% and their rate of negative exercise recommendations was > 50% (low recommendation: 44.1% + no recommendation: 15.8%) for such patients. In addition, the CKD primary care physicians’ exercise recommendation (general) for CKD patients was significantly associated with their own exercise frequencies, but not with their age, specialty, workplace or their own exercise intensity. Furthermore, in the CKD primary care physicians who had positive exercise recommendations (high and moderate) for CKD patients, their exercise frequency recommendations for CKD patients were significantly associated with their own exercise frequency; however, they were not associated with their age class, specialty, or workplace, or with their own exercise intensity, and their exercise intensity recommendations for CKD patients were not associated with their age class, specialty, or workplace, or with their own exercise frequency and intensity.

There have been few studies about exercise counseling by primary care physicians for CKD patients. To the best of our knowledge, this is the first study to report on such exercise counseling. Several studies reported that physicians who have substantial exercise habits are more likely to counsel their patients to exercise [21, 22]. In the present study, we also found associations of the CKD primary care physicians’ exercise frequency recommendations with their own exercise frequency.

Recently, several studies have demonstrated that all CKD patients, irrespective of their CKD stage, treatment modality, age, and functional impairment, can benefit from exercise [10‐15]. Exercise including resistance exercise training can improve their physical capacity and reduce the risk of sarcopenia [10‐15]. In addition, although the direct cardiovascular outcome in CKD patients due to exercise has not been reported, several studies have reported the beneficial effects of exercise on potential mediators of cardiovascular disease such as arterial stiffness, C-reactive protein, and interleukin 6 [12, 16]. In terms of renal function, although there have been no large studies that clearly showed the effects of exercise on renal function, several studies have shown that exercise decreased proteinuria and glomerular sclerosis in an animal model with CKD [23, 24]. The European Association of Rehabilitation in Chronic Kidney Disease recommends maintaining CKD patients on a fairly intense level of exercise [25]. The National Kidney Foundation Kidney Disease Outcome Quality Initiative (K/DOQI) clinical practice guidelines recommend that physical functioning assessment and encouragement to participate in physical activity should be part of the routine care plan for dialysis patients [26]. However, these recommendations do not seem to have been widely adopted and have been insufficiently referred to CKD primary care physicians because positive exercise recommendations by CKD primary care physicians in the present study were limited at <40% (high recommendation: 5.4% + moderate recommendation: 30.9%), and the rate of negative exercise recommendation was > 50% (low recommendation: 44.1% + no recommendation: 15.8%) for CKD patients; however, they highly recommended exercise for patients with metabolic syndrome, such as diabetic mellitus (97.0%), hyperlipidemia (87.9%), and hypertension (70.8%). In addition, in the CKD primary care physicians who had negative exercise recommendations for CKD patients, the main reasons why these physicians did not recommend exercise for CKD patients in the present study were inadequate knowledge on the effects of exercise (59.3%) and inadequate knowledge to prescribe exercise (68.7%). Each CKD patient has a different type of disease, such as cardiovascular disease, heart disease, and metabolic syndrome. These complicated conditions may contribute to difficulty in establishing clear exercise guidelines for CKD patients. Clyne reported that physicians should preferably prescribe exercise training and nephrologists or physiologists should design a program and evaluate its progress for CKD patients [25]. The cooperative planning and management of exercise for CKD patients may be useful to encourage exercise and improve their prognosis. In the management of CKD patients, appropriate pharmacological medication in CKD also very impotent. We investigated and reported medication-prescribing patterns of the primary care physicians in CKD. In that analysis, there were certain associations between the prescribing patterns of the CKD primary care physicians for CKD and their specialty and workplace (in press); however, there was no association between their prescribing patterns for CKD and their exercise habits (unpublished data).

There are several limitations in this study. First, this was cross-sectional study, which limits the generalizability of the results. Seconds, since the study instrument was a mailed self-administered questionnaire, there may be self-selection bias, and it may also contribute to low response rate (28.2%) to questionnaire. Second, the primary care physicians in this study may not be a representative population of all primary care physicians because all medical doctors in this study graduated from one medical university; however, majority of graduates of this medical university work as primary care physicians. Third, the results were from a self-administered questionnaire and were not objectively evaluated in terms of primary care physicians’ personal exercise habits and exercise recommendations for CKD patients. These confounding factors in cross-sectional study might affect the results. Further studies will thus need to investigate more accurately the exercise prescription patterns for CKD patients and the exercise habits of primary care physicians using instruments such as exercise recording devices for both primary care physicians and CKD patients.

CKD primary care physicians’ exercise recommendation level for CKD patients was limited. In addition, CKD primary care physicians’ own exercise habits influenced the exercise counseling for CKD patients. The establishment of guidelines for exercise by CKD patients and their dissemination among primary care physicians are needed.