Ryota Matsuzawa

Habitual Physical Activity Measured by Accelerometer and Survival in Maintenance Hemodialysis Patients

BACKGROUND AND OBJECTIVES The association between mortality and physical activity based on self-report questionnaire in hemodialysis patients has been reported previously. However, because self-report is a subjective assessment, evaluating true physical activity is difficult. This study investigated the prognostic significance of habitual physical activity on 7-year survival in a cohort of clinically stable and adequately dialyzed patients. DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS A total of 202 Japanese outpatients who were undergoing maintenance hemodialysis three times per week at the hemodialysis center of Sagami Junkanki Clinic (Japan) from October 2002 to February 2012 were followed for up to 7 years. Physical activity was evaluated using an accelerometer at study entry and is expressed as the amount of time a patient engaged in physical activity on nondialysis days. Cox proportional hazard regression was used to assess the contribution of habitual physical activity to all-cause mortality. RESULTS The median patient age was 64 (25th, 75th percentiles, 57, 72) years, 52.0% of the patients were women, and the median time on hemodialysis was 40.0 (25th, 75th percentiles, 16.8, 119.3) months at baseline. During a median follow-up of 45 months, 34 patients died. On multivariable analysis, the hazard ratio for all-cause mortality per 10 min/d increase in physical activity was 0.78 (95% confidence interval, 0.66-0.92; P=0.002). CONCLUSIONS Engaging in habitual physical activity among outpatients undergoing maintenance hemodialysis was associated with decreased mortality risk.

Relationship Between Lower Extremity Muscle Strength and All-Cause Mortality in Japanese Patients Undergoing Dialysis

Background Skeletal muscle wasting is common and insidious in patients who are undergoing hemodialysis. However, the association between lower extremity muscle strength and all-cause mortality remains unclear in this population. Objective The purpose of this study was to investigate the prognostic significance of lower extremity muscle strength on 7-year survival in a cohort of patients who were clinically stable and undergoing hemodialysis. Design A prospective cohort study was conducted. Methods A total of 190 Japanese outpatients who were undergoing maintenance hemodialysis 3 times per week at a hemodialysis center were followed for up to 7 years. Lower extremity muscle strength was evaluated using a handheld dynamometer at the time of patient enrollment in the study. Muscle strength data were divided by dry weight and expressed as a percentage. A Cox proportional hazards regression model was used to assess the contribution of lower extremity muscle strength to all-cause mortality. Results The median age (25th and 75th percentiles) of this study population was 64 years (57 and 72 years), 53.2% of the patients were women, and the time on hemodialysis was 39.0 months (15.9 and 110.5 months) at baseline. During a median follow-up of 36.0 months, there were 30 deaths. With a multivariate Cox model, the hazard ratio in the group with a knee extensor strength of <40% was 2.73 (95% confidence interval=1.14–6.52) compared with that in the ≥40% group. Limitations This was a small-scale observational study, and the mechanisms underlying the higher mortality risk in patients with poor muscle strength undergoing hemodialysis than in other patients undergoing hemodialysis remain to be elucidated. Conclusions Decreased lower extremity muscle strength was strongly associated with increased mortality risk in patients undergoing hemodialysis.

Quadriceps Strength as a Predictor of Mortality in Coronary Artery Disease

BACKGROUND The purpose of this study was to investigate the prognostic value of quadriceps isometric strength (QIS) in coronary artery disease (CAD). METHODS The study population consisted of 1314 patients aged >30 years (64.7 ± 10.6 years, 1051 male) with CAD who were hospitalized for acute coronary syndrome or coronary artery bypass grafting. Maximal QIS was evaluated as a marker of leg strength and expressed relative to body weight (% body weight). The primary and secondary endpoints were all-cause death and cardiovascular (CV) death, respectively. RESULTS During a mean follow-up of 5.0 ± 3.5 years, corresponding to 6537 person-years, there were 118 all-cause deaths and 63 CV deaths. A higher QIS remained associated with decreased all-cause mortality and CV mortality risks (hazard ratio for increasing 10% body weight of QIS 0.77, 95% confidence interval 0.67-0.89, P < .001 for all-cause death; hazard ratio 0.66, 95% confidence interval 0.54-0.82, P < .001 for CV death) after adjustment for other prognostic factors. The inclusion of QIS significantly increased both continuous net reclassification improvement (cNRI) and integrated discrimination improvement (IDI) for all-cause death (cNRI: 0.25, P = .009; IDI: 0.007, P = .030) and CV death (cNRI: 0.34, P = .008; IDI: 0.013, P = .008). CONCLUSIONS A high level of quadriceps strength was strongly associated with a lower risk of both all-cause and CV mortality in patients with CAD. Evaluation of QIS offered incremental prognostic information beyond pre-existing risk factors.

Complementary Role of Arm Circumference to Body Mass Index in Risk Stratification in Heart Failure.

OBJECTIVES This study was performed to investigate the complementary role of arm circumference to body mass index (BMI) in risk stratification of patients with heart failure (HF). BACKGROUND High BMI is associated with improved survival in patients with HF. However, it does not discriminate between fat and lean muscle as a predominant factor. METHODS BMI, waist circumference (WC), and mid-upper arm circumference (MUAC) were evaluated in 570 consecutive Japanese patients with HF (mean age 67.4 ± 14.0 years). Patients were stratified into low and high groups according to BMI, WC, and MUAC and combined into low- or high-BMI and low- or high-WC groups or low- or high-BMI and low- or high-MUAC groups. The endpoint was all-cause mortality. RESULTS Seventy deaths occurred over a median follow-up period of 1.5 years (interquartile range: 0.7 to 2.8 years). After adjusting for several pre-existing prognostic factors, including Seattle Heart Failure Score and exercise capacity, BMI (hazard ratio [HR]: 0.68; p = 0.016), WC (HR: 0.76; p = 0.044), and MUAC (HR: 0.52; p < 0.001) were all inversely associated with prognosis. Compared with the high-BMI/high-WC group, both the low-BMI/high-WC and low-BMI/low-WC groups showed comparably poorer prognosis. However, the low-BMI/low-MUAC group but not the low-BMI/high-MUAC group showed poorer prognosis than the high-BMI/high-MUAC group. Adding MUAC to BMI (0.70 vs. 0.63, p = 0.012) but not WC to BMI (0.64 vs. 0.63, p = 0.763) significantly increased the area under the curve on receiver-operating characteristic curve analysis. CONCLUSIONS MUAC, but not WC, plays a complementary role to BMI in predicting prognosis in patients with HF.

Association of Habitual Physical Activity Measured by an Accelerometer with High-Density Lipoprotein Cholesterol Levels in Maintenance Hemodialysis Patients

After confirming the relationship between high-density lipoprotein cholesterol (HDL-C) levels and mortality in hemodialysis patients for study 1, we investigated the effect of physical activity on their HDL-C levels for study 2. In study 1, 266 hemodialysis patients were monitored prospectively for five years, and Cox proportional hazard regression confirmed the contribution of HDL-C to mortality. In study 2, 116 patients were recruited after excluding those with severe comorbidities or requiring assistance from another person to walk. Baseline characteristics, such as demographic factors, physical constitution, primary kidney disease, comorbid conditions, smoking habits, drug use, and laboratory parameters, were collected from patient hospital records. An accelerometer measured physical activity as the number of steps per day over five consecutive days, and multiple regression evaluated the association between physical activity and HDL-C levels. Seventy-seven patients died during the follow-up period. In study 1, we confirmed that HDL-C level was a significant predictor of mortality (P = 0.03). After adjusting for patient characteristics in study 2, physical activity was independently associated with HDL-C levels (adjusted R 2 = 0.255; P = 0.005). In conclusion, physical inactivity was strongly associated with decreased HDL-C levels in hemodialysis patients.

Clinical Characteristics of Patients on Hemodialysis With Peripheral Arterial Disease.

Patients on hemodialysis (HD; n = 210) were examined for peripheral arterial disease (PAD) using ankle-brachial index (ABI) and toe-brachial index (TBI). The prevalence of PAD was 38.1%. Among patients with PAD, 87.5% were newly diagnosed with PAD, 42.5% were diagnosed with TBI <0.6 despite ABI ≥ 0.9, and 68.7% had no lower limb symptoms. In patients with PAD, the prevalence rate of cerebrovascular disease was 36.3%, coronary artery disease was 42.5%, spinal stenosis was 33.2%, and vertebral fracture 15.0% and was significantly higher than those of the non-PAD patients. Low high-density lipoprotein cholesterol was the most important biomarker among patients with PAD. PAD has been underdiagnosed and untreated in patients on HD because most patients do not have symptoms that could be due to diabetic neuropathy or have insufficient daily activity to experience exertional leg symptoms. Screening for PAD using the ABI and TBI increased diagnostic efficiency in patients on HD and may lead to effective early treatments, including pharmacotherapy, revascularization therapy, and exercise rehabilitation to avoid the worst possible scenario such as lower limb amputation, cardiovascular event, and death.

Safety of neuromuscular electrical stimulation in patients implanted with cardioverter defibrillators.

Neuromuscular electrical stimulation (NMES) is one of the few exercise modes that have been confirmed to be effective for advanced heart failure patients. Previous clinical trials that verified the effects of NMES excluded patients with implantable cardioverter defibrillators (ICDs). We investigated whether NMES to leg muscles could be applied in heart failure patients implanted with ICDs. As a result, we found that NMES could be conducted without any instances of electromagnetic interference. NMES to leg muscles could be applied safely to ICD patients if the aforementioned common stimulation methods were used with sufficient monitoring during NMES.

Determinants of Slow Walking Speed in Ambulatory Patients Undergoing Maintenance Hemodialysis

Walking ability is significantly lower in hemodialysis patients compared to healthy people. Decreased walking ability characterized by slow walking speed is associated with adverse clinical events, but determinants of decreased walking speed in hemodialysis patients are unknown. The purpose of this study was to identify factors associated with slow walking speed in ambulatory hemodialysis patients. Subjects were 122 outpatients (64 men, 58 women; mean age, 68 years) undergoing hemodialysis. Clinical characteristics including comorbidities, motor function (strength, flexibility, and balance), and maximum walking speed (MWS) were measured and compared across sex-specific tertiles of MWS. Univariate and multivariate logistic regression analyses were performed to examine whether clinical characteristics and motor function could discriminate between the lowest, middle, and highest tertiles of MWS. Significant and common factors that discriminated the lowest and highest tertiles of MWS from other categories were presence of cardiac disease (lowest: odds ratio [OR] = 3.33, 95% confidence interval [CI] = 1.26–8.83, P<0.05; highest: OR = 2.84, 95% CI = 1.18–6.84, P<0.05), leg strength (OR = 0.62, 95% CI = 0.40–0.95, P<0.05; OR = 0.57, 95% CI = 0.39–0.82, P<0.01), and standing balance (OR = 0.76, 95% CI = 0.63–0.92, P<0.01; OR = 0.81, 95% CI = 0.68–0.97, P<0.05). History of fracture (OR = 3.35, 95% CI = 1.08–10.38; P<0.05) was a significant factor only in the lowest tertile. Cardiac disease, history of fracture, decreased leg strength, and poor standing balance were independently associated with slow walking speed in ambulatory hemodialysis patients. These findings provide useful data for planning effective therapeutic regimens to prevent decreases in walking ability in ambulatory hemodialysis patients.

Gait speed has comparable prognostic capability to six-minute walk distance in older patients with cardiovascular disease

Background Although gait speed and six-minute walk distance are used to assess functional capacity in older patients with cardiovascular disease, their prognostic capabilities have not been directly compared. Methods The study population was identified from the Kitasato University Cardiac Rehabilitation Database and consisted of 1474 patients ≥60 years old with a mean age of 72.2 ± 7.1 years that underwent evaluation of both usual gait speed and six-minute walk distance in routine geriatric assessment between 1 June 2008–30 September 2015. Both gait speed and six-minute walk distance were determined on the same day at hospital discharge. Results Mean gait speed and six-minute walk distance in the whole population were 1.04 m/s and 381 m, respectively, and were strongly positively correlated (r = 0.80, p < 0.001). A total of 180 deaths occurred during a follow-up of 2.3 ± 1.9 years. After adjusting for confounding factors, both gait speed (adjusted hazard ratio per 0.1 m/s increase: 0.87, 95% confidence interval: 0.81–0.93, p < 0.001) and six-minute walk distance (adjusted hazard ratio per 10-metre increase: 0.96, 95% confidence interval: 0.94–0.97, p < 0.001) were independent predictors of all-cause mortality. There was no significant difference in prognostic capability between gait speed and six-minute walk distance (c-index: 0.64 (95% confidence interval: 0.60–0.69) and 0.66 (95% confidence interval: 0.61–0.70), respectively, p = 0.357). Conclusions Gait speed and six-minute walk distance showed similar prognostic predictive ability for all-cause mortality in older cardiovascular disease patients, indicating the potential utility of gait speed as a simple risk stratification tool in older cardiovascular disease patients.

Evaluating the effectiveness of exercise training on elderly patients who require haemodialysis: study protocol for a systematic review and meta-analysis

Introduction As the average age of haemodialysis patients rapidly increases around the world, the number of frail, elderly patients has increased. Frailty is well known to be an indicator of disability and a poor prognosis for haemodialysis patients. Exercise interventions have been safely and successfully implemented for middle-aged or younger patients undergoing haemodialysis. However, the benefits of exercise interventions on elderly patients undergoing haemodialysis remain controversial. The main objective of this study is to systematically review the effects of exercise training on the physical function, exercise capacity and quality of life of elderly patients undergoing haemodialysis, and to provide an update on the relevant evidence. Methods and analyses Published randomised controlled trials (RCTs) that assessed the effectiveness of exercise training on haemodialysis patients with respect to physical function, exercise tolerance and quality of life will be included. Bibliographic databases include MEDLINE, EMBASE, the Cochrane Central Register of Controlled Trials, the Cochrane Database of Systematic Reviews, CINAHL, Web of Science, PsycINFO and PEDro. The risk of bias of the included RCTs will be assessed using the Cochrane Collaborations tool and TESTEX. The primary outcome will be physical function and exercise tolerance. This review protocol is reported according to the PRISMA-P 2015 checklist. Statistical analysis will be performed using review manager software (RevMan V.5.3, Cochrane Collaboration, Oxford, England). Ethics and dissemination Ethical approval is not required because this study does not include confidential personal data nor does it perform interventions on patients. This review is expected to inform readers on the effectiveness of exercise training in elderly patients undergoing haemodialysis. Findings will be presented at conferences and submitted to a peer-reviewed journal for publication. PROSPERO registration number CRD42015020701.