#3657 ASSOCIATION BETWEEN AGE, SARCOPENIA, AND MORTALITY IN PATIENTS UNDERGOING HEMODIALYSIS: A PROSPECTIVE COHORT STUDY
Authors: Imai Hiroto , Matsuzawa Ryota , Yamamoto Shohei , Suzuki Yuta , Harada Manae , Imamura Keigo , Yoshikoshi Shun , Kakita Daisuke , Tsujimoto Naoyuki , Osada Shiwori , Shimokado Kiyoshi , Matsunaga Atsuhiko , Tamaki Akira 
Published: June 2023

Abstract

Background and Aims
The mean age of Japanese patients undergoing hemodialysis at the end of 2018 was 68.75 years, demonstrating a 15-year increase since 1985. The healthcare management of the geriatric patients presents significant challenges, encompassing both clinical and societal aspects, as they often experience overlapping comorbidities while undergoing hemodialysis. A systematic review and meta-analysis published in 2022 reported that sarcopenia was associated with heightened mortality rates in patients undergoing dialysis therapy. However, only a limited number of studies have investigated this association among Asian populations, whose differences in body composition, nutritional status, and socio-economic background distinguish them from those in the United States and Europe. Notably, no studies have targeted the older demographic, who constitute the majority of Asian patients on hemodialysis and possess numerous risk factors for death. This study categorized Japanese patients undergoing hemodialysis by age, &lt;75 and 75≤, and examined the impact of sarcopenia on mortality according to age.

Method
This multicenter prospective cohort study enrolled 404 outpatients undergoing hemodialysis from three facilities in Japan and followed them up for three years. At baseline, information on age, sex, dialysis vintage, body mass index, primary kidney diseases, comorbid conditions, and laboratory parameters (serum albumin, serum hemoglobin, and hematocrit) were collected from medical records. The geriatric nutritional risk index (GNRI) was calculated based on the patient's serum albumin level and body weight. Sarcopenia was diagnosed in patients who had low muscle mass (skeletal muscle mass index &lt;7.0 kg/m² for males and &lt;5.7 kg/m² for females) and low muscle strength (handgrip strength &lt;28.0kg for males and &lt;18 kg for females) or low physical performance (short physical performance battery score ≤9), according to the Asian Working Group for Sarcopenia 2019 criteria. The Kaplan-Meier method and Cox proportional hazard analysis were used to evaluate the independent association between sarcopenia and mortality after adjusting for baseline characteristics in patients aged &lt;75 and ≥75 years.

Results
A total of 404 patients participated in this study, with a mean follow-up period of 30 months, during which 50 (12.4%) patients died. Participants had a mean age of 68.4 ± 12.6 years and 62.6% of them were male and the mean GNRI was 91.1 ± 21.2. Diabetes mellitus was the most prevalent underlying kidney disease among the study cohort (38.1%). The prevalence of sarcopenia in all patients, those under 75 years of age, and those 75 years and older was 37.6%, 22.7%, and 63.1%, respectively. Kaplan-Meier analyses indicated a higher mortality rate among patients with sarcopenia compared to those without. In the subgroup analysis for patients aged &lt;75 years, sarcopenia was significantly associated with increased mortality risk after full adjustment (hazard ratio [HR], 2.50; 95% confidence interval [CI], 1.05–5.95). Conversely, in the subgroup of patients 75 years and older, sarcopenia was not significantly associated with all-cause mortality (HR, 0.69; 95% CI, 0.28–1.68), and only a low GNRI was independently associated with poor survival (HR, 0.98; 95% CI, 0.96–1.00).

Conclusion
This present study determined that the impact of sarcopenia on mortality among patients undergoing hemodialysis may be altered by their age. Specifically, among those aged 75 years and above, malnutrition was found to be a strong predictor of poor survival, rather than sarcopenia.