EFFECT OF RENAL DIALYSIS DURATION ON PATIENT PHYSICAL PERFORMANCE AND BLOOD METABOLITES

Abstract

 Maintenance hemodialysis (MHD) is a common method for preventing complications of end-stage renal disease (ESRD) and physical performance serves as an important indicator of patient health.  In this cross-sectional study, we aimed to determine what the effects of extended hemodialysis (HD) sessions and long-term MHD had on subject physical performance and laboratory testing in order to determine what was the best length of a HD session that could optimize subject physical performance and laboratory tests and identify possible problems associated with the length of HD sessions.  Study subjects were chosen randomly from 7 HD centers in Shanghai, People’s Republic of China during July 2020-March 2023.  The minimum number of subjects determined to be needed for the study was 350.  Inclusion criteria for study subjects were being aged ≥40 years, undergoing maintenance hemodialysis for ≥3 months and giving consent to be included in the study.  Exclusion criteria for study subjects were being unwilling to participate in the study, not completing the required questionnaire, physical performance assessment or laboratory testing or having a serious health condition that could interfere with the physical performance assessment or blood tests.  Subjects were categorized based on duration of each dialysis session into a conventional group (duration of each HD session of ≤4 hours or having ≤3 HD sessions per week) and extended group (duration of each HD session of >4 hours or having >3 HD sessions per week).  Subjects were also classified by total length of time they had been undergoing MHD into a short-term group (total duration of ≤12 months) and a long-term group (total duration of >12 months).  Each subject completed a questionnaire asking their age, gender, education level, alcohol consumption level and smoking status.  The following physical performance tests were performed in each subject: grip strength categorized into low (males <28 kg and females <18 kg) and normal (males ≥28 kg and females ≥18 kg), a 4-meter walk test categorized into slow speed (<1.0 m/s) and normal speed (≥1.0 m/s), a knee-extension strength test categorized into weak (males <0.5×their body weight and females <0.4×their body weight) and normal (male ≥0.5×their body weight, female ≥0.4×their body weight).  Subject heights and weights were checked and the body mass index (BMI) of each subject was calculated as weight in kilograms divided by height in meters squared (kg/m²).  The following laboratory tests were performed on each subject: total cholesterol (TC) (normal: ≤5.2 g), triglycerides (TG) (normal: ≤1.7 mmol/l ), high-density lipoprotein-cholesterol (HDL-C) (normal:<1.04 mmol/l), low-density lipoprotein-cholesterol (LDL-C) (normal:<3.12 mmol/l), hemoglobin (HGB) (normal: 120-160 g/l for males and 110-150 g/l for females), serum albumin (ALB) (normal: 35-55 g/l) and β2-microglobulin (β2-MG) (normal: 1.28-1.95 mg/l).  Statistical analyses were performed using non-parametric tests and subgroup comparisons were made.  A total of 875 subjects were included in the study, 586 (67%) males.  The mean (±standard deviation) age of subjects was 59 (±13) (range: 40-80) years.  Of these, 512 (58.5%) were in the conventional group for duration of each dialysis session and 363 (41.5%) were in the extended group for duration of each dialysis session.  Subjects in the extended group compared to the conventional group had significantly lower (p-value <0.010) (both males and females) mean grip strength (24.3 kg vs 19.4 kg), significantly lower (p-value = 0.010) overall knee extension strength (21.5 kg vs 17.0 kg), significantly lower (p-value <0.010) overall 4-meter walk speeds (1.0 m/s vs 0.7 m/s), significantly lower (p-value = 0.014) overall TG levels (2.4 mmol/l vs 1.7 mmol/l) and significantly lower (p-value <0.010) overall β2-MG levels (35.1 mg/l vs 20.5 mg/l), respectively.  Subjects in the long-term treatment group compared to subjects in the short-term group had a significantly lower (p-value <0.010) overall mean grip strength (25.0 kg vs 23.8 kg), a significantly lower (p-value = 0.004) overall mean knee extension strength (21.4 kg vs 21.3 kg), a significantly lower (p-value <0.010) overall mean BMI (23.9 vs 20.2) and a significantly lower (p-value <0.05) overall mean β2-MG level (35.8 mg/l vs 28.1 mg/l).  In summary, in our study population, subjects with extended HD sessions and long-term MHD both had significantly lower grip strength, knee extension strength, 4-meter walk speeds and TG and β2-MG levels and subjects with long-term MHD had significantly lower BMIs.  We conclude having extended HD sessions and long term MHD resulted in poorer performance and malnutrition showing conventional HD sessions are preferred over extended HD sessions.  Subjects having extended HD and with long term MHD need to have strength and nutritional assessments and possibly counseling to prevent or manage problems in these areas.  Further studies are needed to determine what methods should be employed to improve and prevent deterioration in physical performance and nutrition.