This study marks the inaugural examination of GNRI and its association with negative consequences in elderly individuals after cardiac surgery. The outcomes of the multivariate analysis underscored the predictive roles of gender, prolonged mechanical ventilation, serum creatinine, and GNRI < 98g/dL in determining adverse outcomes among elderly cardiac surgery patients. Furthermore, our findings revealed a noteworthy correlation between nutritional risk and the escalation in hospital and ICU stays.
In this study, 68.3% of patients were identified to have nutritional risk based on the GNRI score, and those with nutritional risk exhibited significantly higher adverse outcomes compared to those without nutritional risk. However, GNRI did not show a significant association with in-hospital mortality in our study (P > 0.05). Notably, Peng JC et al15 found a 28.6% prevalence of severe malnutrition assessed by GNRI in elderly intensive care patients. In their study, patients in the risk group experienced elevated rates of ICU mortality, hospital mortality, and prolonged ICU and hospital stays. Malnutrition, implicated in compromised immune function and heightened inflammation, contributes to unfavorable disease outcomes and increased complication risks. The unique nutritional and metabolic characteristics of elderly heart patients render them susceptible to related complications. Contrary to our findings, Nakamura T et al16 demonstrated a higher incidence of adverse events in male heart failure patients with low GNRI compared to female patients. A study on brittle hip fractures in the elderly identified older age, male gender, lower GNRI score, comorbidities, and lower BI as primary risk factors17. Interestingly, our study diverges from these results, as women emerged as predictors of poor prognosis, linked to poorer short-term postoperative outcomes in various cardiovascular surgical procedures18. The study conducted by Fernandez-Zamora MD et al.19 identified prolonged mechanical ventilation as a predictor of prognosis after cardiac surgery. Mechanical ventilation post-cardiac surgery presents challenges, with airway inflammation and infection potentially triggering systemic inflammatory response syndromes, thereby amplifying adverse outcomes. Supporting our study's conclusions, research20 indicated that serum creatinine impacts major renal adverse events in cardiac surgery patients. Even without apparent acute kidney injury, patients undergoing cardiac surgery may experience a decline in function.
GNRI emerges as a promising index, surpassing the predictive efficacy of individual assessments using albumin or BMI alone21. Its popularity in clinical nutrition assessment has surged in recent years, attributed to its convenience and accessibility22. Clinically, GNRI has been linked to the occurrence of various cardiovascular diseases23. Patients undergoing cardiac surgery experience heightened trauma compared to those undergoing other surgical procedures. The increased surgical trauma, coupled with the adoption of cardiopulmonary bypass, renders cardiac surgery patients more susceptible to complications stemming from the systemic inflammatory response syndrome. As malnutrition progresses in these patients, postoperative immunity diminishes, necessitating additional nutritional support24,25. In the study by Zhang Q et al.26, for every one-unit increase in the preoperative Geriatric Nutritional Risk Index (GNRI) score, the postoperative mortality in gastric cancer patients decreased by 5.6%. Consistent with our findings, research indicates that malnutrition adversely affects physical function and strongly correlates with adverse events, prolonged hospital stays27, and increased mortality28, The comprehensive nature of GNRI as an assessment tool is underscored by its ability to capture multifaceted aspects contributing to postoperative outcomes.
Few previous investigations have delved into the association between the Geriatric Nutritional Risk Index (GNRI) and unfavorable outcomes in patients with cardiovascular conditions. For instance, in a transcatheter aortic valve implantation study29, the investigation into postoperative nutritional status and one-year all-cause mortality revealed meta-results suggesting a heightened risk of cardiovascular mortality with lower GNRI. The impact on hospital outcomes, however, remained unclear. Li Y et al.14 conducted a study demonstrating GNRI as a dependable indicator for predicting in-hospital mortality in patients within the cardiac intensive care unit (CICU). Furthermore, individuals at a higher risk of malnutrition experienced significantly prolonged hospitalization and CICU stays. Subsequent studies have reaffirmed this association, establishing a link between GNRI, extended hospital stays, and adverse outcomes30. Despite its established association in various settings, the prognostic value of GNRI in cardiac surgery has received limited attention in prior research. Our study contributes by indicating that GNRI can indeed predict the prognostic value of cardiac surgery in the elderly. Receiver Operating Characteristic (ROC) curve analysis identified an optimal threshold value of 97.53 g/dL, showcasing potential sensitivity in predicting adverse outcomes. The inverse correlation observed as GNRI increases suggests that clinicians might enhance patient outcomes through more proactive treatment and improved care strategies. These results highlight the GNRI's potential as a valuable instrument for risk assessment in cardiac surgery, urging additional investigation and validation in more diverse populations31,32.
Presently, numerous studies on malnutrition rely on questionnaire-based survey tools33. However, applying these tools to older populations may be constrained by recall bias and communication challenges, potentially leading to inaccurate assessments. The Geriatric Nutritional Risk Index (GNRI) addresses these limitations inherent in survey-based approaches. Clinical routine detection conveniently utilizes serum albumin, height, and weight, with these indicators being easily obtainable. Serum albumin, in particular, serves a crucial physiological role in maintaining colloid osmotic pressure and acting as a carrier for various exogenous and endogenous substances. It serves as an indicator that reflects both overall nutrition and the severity of underlying diseases. Given that the metabolic process of the elderly primarily involves catabolism, necessitating more proteins to compensate for tissue protein consumption34, the decline in serum albumin may indicate a potential inflammatory response in cardiovascular disease. In comparison to other nutritional indicators, GNRI is regarded as a more precise predictor of outcomes related to nutrition in the elderly population. Future research should focus on comparing GNRI with alternative assessment tools to identify patients suitable for cardiac surgery. Additionally, incorporating anthropometric assessments and exploring more detailed or simplified assessment methods will further enhance the utility and reliability of GNRI in clinical practice.
Limitations: This study solely evaluated the initial GNRI in elderly patients undergoing cardiac surgery, neglecting to document and analyze dynamic changes in GNRI over time. This investigation is confined to a retrospective design confined to a single center with restricted sample size, warranting a multicenter study for broader population validation of the current findings.
Conclusion: GNRI emerges as a straightforward and readily measurable tool in clinical practice, playing a crucial role in predicting adverse outcomes among elderly cardiac surgery patients. Furthermore, the study establishes a noteworthy correlation between the length of hospital stay and ICU stay in patients with nutritional risk. GNRI serves as a valuable tool for identifying individuals with an unfavorable prognosis who could benefit from early nutritional intervention. To substantiate the significance of these crucial findings, further exploration through prospective studies is essential.