Background: Elderly people with acute respiratory failure (ARF) have prolonged length of hospital stay (LOS) and high mortality rates. Malnutrition is negatively correlated with these LOS and mortality. However, no tools have been used to detect the risk of malnutrition and assist in designing nutritional support for these patients. The geriatric nutritional risk index (GNRI) is reported as a novel tool for evaluating the risk of malnutrition. The aim of this study is to explore the relationship of the GNRI score with mortality and LOS in elderly patients with ARF. Methods: Data of elderly patients diagnosed with ARF were retrieved from the Medical Information Mart for Intensive Care III (MIMIC-III) database. A total of 1250 patients were divided into two groups based on their GNRI score: the malnutrition risk group (GNRI 98) and no risk group (GNRI > 98). The primary endpoints of this study were hospital mortality and hospital LOS. Results: The higher GNRI score was associated with lower hospital mortality and shorter hospital LOS. Odds ratio (OR) for hospital mortality of patients with nutritional risk (GNRI 98) was 1.264 (95% CI:1.067À1.497) in the adjusted model. Patients with GNRI 98 had longer hospital LOS (adjusted OR: 1.142, 95%CI: 1.044À1.250) compared with those with GNRI > 98. Subgroup analysis showed that higher GNRI was only significantly associated with lower hospital mortality in the patients that did not undergo mechanical ventilator (MV) treatment (adjusted OR: 0.985, 95% CI: 0.977À0.992, P < 0.01). Kaplan-Meier curve analysis showed that the 90-day survival was significantly lower in the group with nutrition risk (GNRI98) compared with the no risk group (GNRI > 98, p < 0.05). Conclusion: These findings imply that GNRI is a useful prognostic tool in elderly patients with ARF.

Purpose The purpose of our study was to investigate the relationship between serum sodium levels and 1-year and 3-year mortality in critically ill patients with comorbid chronic obstructive pulmonary disease using real-world data. Methods The data of this study were collected from the Medical Information Mart for Intensive Care-IV (MIMIC-IV) database. First of all, we used the Kaplan–Meier curves and multivariable Cox regression analyses to measure the relationship between serum sodium levels and 1-year and 3-year mortality for critically ill patients with comorbid COPD. Next, a restricted cubic spline was used to analyze non-parametrically the relationship between mortality and serum sodium as a continuous variable. In addition, we also analyzed the mortality of different subgroups. Results A total of 5540 eligible subjects were extracted. Compared to normal serum sodium levels, adjusted multivariable Cox regression analysis confirmed that hyponatremia and hypernatremia were still significantly associated with 1-year mortality (HR = 1.551, 95% CI = 1.333~1.805, P<0.001; HR = 1.683, 95% CI = 1.317~2.151, P<0.001, respectively) and 3-year mortality (HR = 1.507, 95% CI = 1.302~1.744, P<0.001; HR = 1.612, 95% CI = 1.269~2.048, P<0.001, respectively). In patients with or without adjustment variables, there was an obvious U-shaped non-linear relationship between serum sodium levels and 1-year and 3-year mortality with a reference level of 139 mmol/L, which indicated that patients in both hyponatremia and hypernatremia had higher mortality than normal serum sodium levels. Conclusion This study showed that both hyponatremia and hypernatremia were related to increased 1-year and 3-year mortality in critically ill patients with comorbid COPD, which provides a new reference for the control strategy of correcting serum sodium levels.