Association between protein intake and mortality in older patients receiving parenteral nutrition: A retrospective observational study

Background: Malnutrition of inpatients is often overlooked and remains a serious concern. However, there are few studies on the relations between infused energy and amino acid intakes and clinical outcomes in older patients on parenteral nutrition. Objectives: We aimed to determine the short-Term outcomes of infused energy and amino acid intakes in older patients receiving parenteral nutrition. Methods: We conducted a retrospective observational study using a national inpatient database covering >1000 hospitals in Japan. Participants were those who underwent central venous (CV) port insertion between 2011 and 2016, were aged ≥65 y, and did not have cancer. Based on the types and amounts of products used for enteral feeding and intravenous feeding on postoperative day (POD) 7 after CV port insertion, the infused energy and amino acid intakes were estimated. The primary end point was mortality on POD 90. Multivariable logistic regression was performed to investigate the relations of infused energy and amino acid intakes with mortality on POD 90. Results: A total of 10,153 patients aged ≥65 y who underwent CV port insertion were included. The mortality rates at 90 d after central venous port insertion were 14.9% and 14.0% (risk difference, 0.9%; 95% CI:-0.5%, 2.3%; P = 0.216) with infused energy intakes <20 and ≥20 kcal/kg, respectively, and 15.4% and 13.2% (risk difference, 2.2%; 95% CI: 0.9%, 3.6%; P = 0.001) with infused amino acid intakes <0.8 and ≥0.8 g/kg, respectively. The differences were retained after adjustment for multiple variables including hospital, age, sex, BMI, emergency admission, and 27 major underlying diseases. The OR for the ≥0.8-g/kg group compared with the <0.8-g/kg group was 0.87 (95% CI: 0.77, 0.99; P = 0.028). Conclusions: A positive relation between infused amino acid intake and mortality was found in older patients receiving parenteral nutrition.