Plasma Amino Acid Profile in Severely Frail Elderly Patients in Japan

Severe frailty, which is the highest level of frailty, leads to multiple health impairments that may individually affect the plasma-free amino acid (PFAA) profile. However, the PFAA profile of severely frail patients has not been clarified. The aim of this study was to describe the PFAA profile of severely frail elderly patients. Elderly patients (aged ≥65 years) who were admitted to the Nukada Institute for Medical and Biological Research (Chiba, Japan) were included. Severe frailty was defined using the Canadian Study of Health and Aging Clinical Frailty Scale. Subjects were divided into non-frail and severely frail groups. The PFAA profile and clinical characteristics of the subjects were analyzed. Compared to the non-frail group (n = 31), the severely frail group (n = 28) had lower body mass index (BMI), serum albumin, serum prealbumin, hemoglobin, and blood pressure and higher C-reactive protein. Seventy-nine percent of severely frail patients had cognitive impairment. Severely frail patients had significantly lower essential amino acid (EAA) plasma concentrations than non-frail patients. Multiple linear regression analysis identified that valine (p = 0.005) was strongly associated with BMI. Valine (p = 0.004), leucine (p = 0.004), tryptophan (p = 0.006), lysine (p < 0.001), and total EAA (p < 0.001) levels were significantly associated with serum prealbumin levels. Severely frail patients had multiple health impairments. BMI and nutritional status were most significantly associated with low EAA levels.