To investigate the correlation between protein intake and prognosis in critically ill elderly patients.

A retrospective survey was conducted on 103 elderly patients with severe illness who were admitted to the intensive care unit (ICU) of the First Hospital of Shanxi Medical University from July 2019 to July 2020 for nutritional support treatment. According to whether the protein intake reached 1.2 g/(kg·d) within 1 week after admission or not, the patients were divided into either a standard group or a non-high-protein group. APACHE Ⅱ score, NRS 2002 score, mechanical ventilation time, length of ICU stay, nosocomial infection rate, 28 d mortality rate, and levels of albumin (ALB), transferrin (TFR), and prealbumin (PAB) before and 1 and 7 days after treatment were compared between the two groups. Univariate Logistic regression was used to analyze nine factors (age, gender, caloric intake, protein intake, APACHE Ⅱ score, NRS 2002 score, duration of mechanical ventilation, length of ICU stay, and nosocomial infection) that may affect 28 d mortality. Multivariate Logistic regression was constructed with 28 d mortality as the dependent variable to analyze the relationship between protein intake and the prognosis of critically ill elderly patients.

There were no significant differences in gender, age, APACHE Ⅱ score, or NRS2002 score between the two groups (P＞0.05). There was no significant difference in caloric intake on day 7 between the two groups [(27.52±8.77) kcal/(kg·d) vs (25.73±8.20) kcal/(kg·d), P＞0.05]. The daily protein intake of the high-protein group was significantly higher than that of the non-high-protein group [(1.59±0.32) g/(kg·d) vs (0.84±0.25) g/(kg·d), P＜0.05]. There was no statistically significant difference in ALB, TFR, or PAB levels on day 1 after nutritional support between the two groups; the levels of ALB, TFR, and PAB on day 7 in the standard group were further improved compared with the non-high-protein group (P＜0.05). The nosocomial infection rate and 28 d mortality rate in the standard group were lower than those in the non-high-protein group; the difference in nosocomial infection rate was not statistically significant (P＞0.05), but the difference in the 28 d mortality rate was statistically significant (P＜0.05). Multivariate Logistic regression analysis showed that older age [odds ratio (OR)=1.113, 95% confidence interval (CI): 1.023-1.211, P=0.012], higher protein intake (OR=0.089, 95%CI: 0.017-0.476, P=0.005), and non-nosocomial infection (OR=0.097, 95%CI: 0.016-0.597, P=0.012) were significantly associated with the 28 d mortality rate.

Critically ill elderly patients are prone to poor clinical nutrition, long mechanical ventilation, long hospital stay, and poor prognosis. Increasing protein intake can significantly improve clinical nutritional status, the time of mechanical ventilation and hospitalization, and 28 d mortality. Age, protein intake, and nosocomial infection are independent factors affecting 28 d mortality. Increasing protein intake and no nosocomial infection are protective factors for 28 d mortality. Advanced age is a risk factor for 28 d mortality in critically ill elderly patients.