Abstract
Objective
Contrast-induced acute kidney injury (CI-AKI) is a significant complication in acute coronary syndrome (ACS) patients undergoing percutaneous coronary intervention (PCI). This study evaluates the predictive value of the Naples prognostic score (NPS) and controlling nutritional status (CONUT) score for CI-AKI risk.
Method
The data of 520 ACS patients who underwent PCI between January 2019 and December 2022 were retrospectively analyzed. Patients were stratified by NPS and CONUT scores, based on blood markers including serum albumin, cholesterol, and inflammatory cell counts. CI-AKI was defined as an acute post-contrast renal function decline. Logistic regression and ROC analyses assessed the predictive value of NPS and CONUT scores.
Results
CI-AKI occurred in 142 (27.3%) patients. Higher NPS and CONUT scores were significantly associated with increased CI-AKI risk (p<0.001). Multivariate analysis identified NPS and CONUT as independent predictors of CI-AKI (odds ratio: 0.060, p=0.002; odds ratio: 0.442, p=0.008). ROC analysis showed high predictive accuracy (AUC: 0.950 for NPS; AUC: 0.930 for CONUT).
Conclusion
NPS and CONUT scores effectively predict CI-AKI risk in ACS patients undergoing PCI. Their routine use may enhance risk stratification and preventive strategies.
Introduction
Contrast-induced acute kidney injury (CI-AKI) is characterized by a rapid decline in renal function that manifests subsequent to the administration of contrast media during diagnostic or interventional procedures (1). This pathological condition poses a considerable clinical obstacle, particularly in individuals diagnosed with acute coronary syndrome (ACS) who are subjected to percutaneous coronary intervention (PCI) (2). The incidence of CI-AKI results in prolonged hospitalization, increased healthcare costs, and correlates with heightened risks of morbidity and mortality (3, 4). Conventional risk determinants for CI-AKI include pre-existing renal dysfunction, diabetes mellitus, and administration of substantial quantities of contrast agents (5-7). Preliminary evaluation of risk in individuals with ACS undergoing PCI has significant clinical relevance.
Inadequate or unbalanced nutrition, classified as malnutrition, has been correlated with unfavorable prognoses in conditions such as heart failure (HF), ACS, and various malignancies (8-10). Malnutrition and systemic inflammation are interrelated, and elevated inflammatory biomarkers are frequently observed during nutritional deficiency (11). Systemic inflammation is associated with increased concentrations of circulating biomarkers, including interleukin-6 (IL-6), C-reactive protein, and tumor necrosis factor-alpha (TNF-α) (12). Moreover, previous research has validated the relationship between inflammation-associated parameters and CI-AKI (13, 14).
The Naples prognostic score (NPS) and controlling nutritional status (CONUT) scores were initially established as pivotal prognostic instruments for individuals diagnosed with malignancies; however, they have also been demonstrated to correlate with adverse outcomes in patients presenting with ACS and HF (15, 16). Both scoring systems can be readily computed utilizing various biomarkers, including serum albumin concentration, total cholesterol levels, lymphocyte enumeration, neutrophil-to-lymphocyte ratio (NLR), and lymphocyte-to-monocyte ratio (LMR), which collectively reflect the inflammatory and nutritional status of the patient (17).
This study aimed to determine whether NPS and CONUT scores independently predict CI-AKI in ACS patients undergoing PCI. By incorporating inflammatory and nutritional assessments, the goal was to enhance early risk stratification. Our findings suggest that higher scores are associated with increased CI-AKI risk and may support individualized prevention strategies in clinical care.
Materials and Methods
Study Design and Population
A retrospective cohort study was conducted between January 2019 and December 2022. A total of 584 patients diagnosed with ACS and treated with PCI using contrast media were assessed. Individuals aged ≥18 years with a confirmed diagnosis of ACS who received contrast agents during PCI were included (18). Patients with epidermal growth factor receptor (eGFR) <30 mL/min/1.73 m², infectious diseases, active malignancy, cardiogenic shock, or pregnancy were excluded. Renal disease was defined as chronic kidney disease stage 4 or higher, corresponding to an eGFR <30 mL/min/1.73 m². In addition, 64 patients were excluded because of incomplete data (n=16), renal disease (n=17), cardiogenic shock (n=12), systemic infection (n=9), hepatic disorders (n=5), or malignancy (n=5), resulting in a final cohort of 520 patients (Figure 1).
This article contains human participants, so Institutional Review Board approval was required for this research article and was obtained from the İstanbul Medipol Mega Hospital’s Local Ethical Committee (E-10840098-202.3.02-6647, date: 24.10.2024, number: 986).
Data Collection
Venous blood specimens were obtained prior to PCI at the time of admission by using conventional methods. Hematological parameters were measured within 30 minutes using an automated hematology system (BC-6800 Plus, Mindray, Shenzhen, China). The NLR and LMR were computed based on these indicators, whereas the established scoring framework derived the NPS (Table 1). The subjects were categorized into three separate cohorts predicated on their NPS: Group 0 (NPS score of 0), group 1 (NPS score of 1-2), and group 2 (NPS score of 3-4). The CONUT score, representative of nutritional status, was computed utilizing the serum albumin concentration, total cholesterol level, and lymphocyte enumeration (spanning from 0 to 12). CONUT scores categorized as 0-1, 2-4, and ≥5 correspond to normal nutritional status (group 0), mild nutritional deficiency (group 1), and moderate-to-severe malnutrition (group 2), respectively (19).
Procedures
All patients received dual antiplatelet therapy consisting of aspirin (300 mg loading dose, followed by 100 mg daily), combined with either prasugrel (60 mg loading, 10 mg maintenance), ticagrelor (180 mg loading, 90 mg twice daily), or clopidogrel (600 mg loading, 75 mg maintenance). An intravenous dose of 5,000 IU of unfractionated heparin was administered in line with European clinical guidelines (18). In addition, patients were initiated on beta-blockers, ACE inhibitors, and high-intensity statin therapy unless contraindications were present, consistent with international recommendations. Upon admission, two-dimensional echocardiography was performed as part of the routine cardiovascular assessment. PCI procedures were carried out via femoral or radial artery access using 6-7 Fr sheaths under standard interventional protocols.
Statistical Analysis
All statistical methodologies were executed utilizing IBM SPSS Statistics software (version 21.0; SPSS Inc., Chicago, IL, USA). The normal distribution of continuous variables was analyzed using the Shapiro-Wilk test. Data demonstrating a normal distribution were articulated as mean ± standard deviation, whereas non-normally distributed variables were outlined as median values along with interquartile ranges (IQR, 25th-75th percentiles). Between-group discrepancies were scrutinized employing either the independent samples t-test or Mann-Whitney U test, contingent upon data distribution. Categorical data were delineated as frequencies (percentages) and compared utilizing Pearson’s chi-square test or Fisher’s exact test when deemed appropriate. The discriminatory efficacy of NPS and CONUT scores for forecasting CI-AKI was examined through receiver operating characteristic (ROC) curve analysis, with area under the curve (AUC) values computed distinctly for each. To ascertain independent predictors of CI-AKI, multivariable logistic regression analysis was executed employing a stepwise backward elimination methodology. Findings were expressed as odds ratios (OR) accompanied by 95% confidence intervals (CI). A p-value <0.05 (two-tailed) was adjudged statistically significant.
Results
A cohort of 520 patients was included in the investigation, of whom 142 (27.3%) manifested CI-AKI after PCI. Baseline characteristics showed CI-AKI patients were older (62.1 vs. 58.5 years, p=0.003), had more hypertension (63.4% vs. 50.3%, p=0.008), and had lower left ventricular ejection fraction(43.6% vs. 45.8%, p=0.012). Significant differences were also noted in systolic blood pressure (127.0 vs. 131.1 mmHg, p=0.048) and contrast volume used (203.3 vs. 182.2 mL, p=0.032) (Table 1). CI-AKI patients exhibited lower hemoglobin (13.2 vs. 14.2 g/dL, p<0.001) and lymphocyte counts (1.7 vs. 2.4, p<0.001), along with higher white blood cell (11.9 vs. 10.8, p=0.004) and neutrophil counts (9.4 vs. 7.6, p<0.001). Baseline creatinine levels were elevated (0.99 vs. 0.85 mg/dL, p<0.001), while total cholesterol (154.4 vs. 194.3 mg/dL, p<0.001) and LDL cholesterol (95.9 vs. 112.9 mg/dL, p<0.001) were lower. There was a significant difference in NPS and CONUT scores between patients with and without CI-AKI. In the NPS, 94.4% of the patients with CI-AKI were in group 2, compared to only 8.7% of those without CI-AKI (p<0.001). Similarly, 38% of patients with CI-AKI had moderate-to-severe CONUT scores, while only 0.3% of those without CI-AKI were in this category (p<0.001) (Table 2).
Independent determinants of CI-AKI were determined using multivariate logistic regression analysis. Age was significant, with older patients showing a higher risk (OR: 0.832; 95% CI: 0.712-0.972; p=0.021), likely due to declining renal function with age. Baseline creatinine (OR: 0.001; 95% CI: 0.000-0.855; p=0.045) and lower GFR (OR: 0.868; 95% CI: 0.787-0.957; p=0.005) also emerged as significant predictors, emphasizing the role of renal function. A higher NPS significantly increased the risk of CI-AKI (OR: 0.060, 95% CI: 0.010-0.344, p=0.002). CONUT score similarly predicted CI-AKI (OR: 0.442; 95% CI: 0.242-0.805, p=0.008) (Table 3).
ROC analysis demonstrated excellent predictive accuracy for NPS (AUC: 0.950; 95% CI: 0.927-0.972) and CONUT scores (AUC: 0.930; 95% CI: 0.902-0.956), highlighting their utility in stratifying the risk of CI-AKI. These findings support their potential use in clinical decision-making (Figure 2).
Discussion
This investigation elucidated that NPS and CONUT indices serve as autonomous prognosticators of CI-AKI in individuals undergoing PCI following ACS. Our results underscore the pivotal significance of nutritional and inflammatory conditions in renal outcomes among these individuals, indicating that nutritional deficiency and systemic inflammation markedly elevate the likelihood of CI-AKI.
Prior examinations have illustrated that undernutrition constitutes a considerable risk determinant for unfavorable outcomes in individuals with cardiovascular ailments, particularly in subjects subjected to invasive procedures, such as PCI (20-22). Undernutrition has been correlated with deteriorated outcomes, encompassing CI-AKI, especially in individuals undergoing PCI (23). The CONUT score has been consistently correlated with elevated mortality and poorer clinical outcomes in patients with ACS. Our investigation corroborates these observations by demonstrating that individuals with heightened CONUT scores are at a markedly increased risk of developing CI-AKI. The underlying mechanisms may include reduced albumin levels, which lower oncotic pressure and compromise renal perfusion, and decreased lymphocyte counts, which reflect a weakened immune response and a state of systemic inflammation (1, 23, 24). The exact mechanism linking CONUT score to CI-AKI development is not yet fully understood; however, its individual components have been consistently associated with kidney damage. Among these, serum albumin, the highest component in the CONUT score, plays a vital role. Research has suggested that diminished serum albumin concentration functions as a notable prognostic marker for both acute renal impairment and mortality subsequent to cardiac interventions. A comprehensive meta-analysis elucidated that decreased albumin levels independently forecasted adverse outcomes in individuals undergoing cardiac surgical procedures or coronary interventions (25). Another investigation fortified its predictive significance by demonstrating that patients undergoing PCI who developed CI-AKI exhibited significantly lower serum albumin concentrations compared to those who did not (26).
Although elevated cholesterol levels have historically been identified as a significant cardiovascular risk determinant within the broader population, diminished cholesterol concentrations in individuals exhibiting renal impairment have been correlated with unfavorable clinical outcomes (27). One study showed that survival rates in AKI patients were significantly better in those with cholesterol levels above 150 mg/dL than in those with cholesterol levels below (28). Supplementary investigations have demonstrated that consistently diminished total cholesterol concentrations are significantly correlated with inferior survival prognoses in individuals suffering from chronic renal impairment (29). Another noteworthy facet of the CONUT score, the lymphocyte enumeration, serves as a parameter of immune functionality and systemic inflammation, which are crucial in the etiology of CI-AKI. Empirical research has demonstrated that diminished lymphocyte counts correlate with unfavorable prognosis in individuals diagnosed with coronary artery disease (30). Moreover, an elevated NLR, signifying an intensified inflammatory response, has been associated with an augmented risk of CI-AKI in individuals undergoing PCI (31). These findings suggest that the CONUT score not only encompasses nutritional deficiencies, but also represents the magnitude of the inflammatory load, thereby establishing it as a pivotal instrument for the early detection of patients predisposed to CI-AKI.
Inflammatory reactions and heightened prothrombotic states are fundamentally implicated in the pathogenesis of CI-AKI. Biomarkers that signify these inflammatory reactions may be pivotal for the detection of CI-AKI. The pathogenesis of CI-AKI is markedly linked with inflammatory mechanisms, featuring pro-inflammatory cytokines, including IL-6 and TNF-α, which are acknowledged as factors contributing to the exacerbation of renal endothelial dysfunction and impairment of renal autoregulation (32, 33). Many studies have demonstrated a substantial correlation between inflammatory processes and AKI.
NPS is a novel scoring system designed to simultaneously evaluate inflammation and malnutrition. Initially introduced by Galizia et al. (34), it has been widely employed in assessing cancer prognosis, including gastric and esophageal squamous cell carcinoma. For example, a 2021 study demonstrated that NPS could independently predict survival in patients undergoing surgery for gastric cancer (35). Similarly, this scoring system has also been validated as an independent prognostic indicator in individuals undergoing surgical treatment for esophageal squamous cell carcinoma (36).
In cardiology, NPS has been recognized as a reliable indicator of in-hospital mortality in individuals with HF and has been linked to unfavorable outcomes in various chronic conditions (15). Among its components, NLR has been notably associated with long-term clinical endpoints such as infarct size, mortality, and prognosis in ACS (37). Additionally, NLR has demonstrated predictive value for CI-AKI in ACS patients undergoing PCI. Likewise, LMR has been identified as an independent predictor of CI-AKI in this population (38).
Unlike the CONUT score, which primarily assesses nutritional status, NPS comprehensively evaluates the inflammatory process. In accordance with preceding investigations, our results elucidated that individuals with elevated NPS values, signifying a heightened inflammatory load, are at a considerably increased susceptibility to CI-AKI. Elevated concentrations of inflammatory indicators have persistently been associated with poorer renal outcomes in subjects undergoing PCI, underscoring the pivotal role of inflammation in the pathogenesis of CI-AKI (39).
Our study highlights that nutritional and inflammatory markers independently predict CI-AKI risk and traditional factors, such as age, diabetes, and baseline renal function (40). While these conventional factors remain relevant, our findings suggest that incorporating nutritional and inflammatory assessments could provide more comprehensive risk stratification. Patients identified as high-risk based on NPS or CONUT scores could benefit from targeted preventive strategies such as aggressive hydration, minimizing contrast exposure, or nutritional interventions. Recent investigations have examined the capacity of preprocedural dietary assistance in diminishing the prevalence of CI-AKI, yielding encouraging outcomes.
In our cohort, the overall elevated HbA1c and glucose levels likely reflect the high prevalence of diabetes mellitus and the occurrence of acute stress hyperglycemia in patients presenting with ACS. Although mean glucose levels were significantly higher in the CI-AKI group in univariate analysis, they were not identified as independent predictors in multivariate logistic regression analysis. Stress hyperglycemia represents a neuroendocrine and inflammatory response to acute illness, leading to increased catecholamine and cortisol release, insulin resistance, and enhanced oxidative stress. These mechanisms may contribute to renal microvascular injury and functional impairment, thereby increasing susceptibility to CI-AKI regardless of baseline glycemic status (41).
Furthermore, amalgamating the NPS and CONUT indices into standard clinical praxis presents pragmatic benefits. Both indices are comparatively straightforward to compute utilizing routine hematological assessments and can be effortlessly integrated into extant risk prognostication frameworks. This would enable medical practitioners to discern patients at heightened risk with greater efficacy and execute prompt interventions to alleviate the likelihood of CI-AKI. The incorporation of these indices into established risk frameworks, such as the Mehran risk score, could further augment the precision of CI-AKI forecasting and refine clinical decision-making.
Study Limitations
Notwithstanding the advantages of our examination, which encompassed a relatively considerable sample size and the application of multivariate analysis to alleviate the impact of confounding variables, it is crucial to acknowledge several constraints. Primarily, the retrospective framework of the inquiry obstructs the capacity to establish causal connections between malnutrition, inflammation, and CI-AKI. Prospective studies are vital to authenticate these observations and to evaluate the efficacy of interventions aimed at enhancing nutritional status and diminishing inflammation. Furthermore, our study was restricted to a unique institution, which might limit the external validity of the outcomes to a heterogeneous population. Subsequent inquiries should strive to replicate these results in a more comprehensive multicenter framework.
Conclusion
In this study, evaluating the predictive power of NPS and CONUT scores in predicting the development of contrast nephropathy in patients with ACS undergoing PCI is a clinically important contribution. These scores offer a novel approach to risk stratification by incorporating nutritional and inflammatory statuses, which are increasingly recognized as important determinants of clinical outcomes. The routine use of these scores may guide preventive strategies and improve patient outcomes. Prospective studies are needed to confirm these results and to assess whether nutritional or anti-inflammatory strategies can help reduce the risk of CI-AKI.