Discussion
The present study investigated the long-term prognostic value of malnutrition assessed by the CONUT score in CAS patients and the results indicated a higher prevalence of all-cause death and stroke in malnourished patients compared to patients with normal nutrition.
The CONUT score was first described by Ignacio de Ulı´barri et al as an objective parameter reflecting malnutrition in hospitalized patients (13). In recent studies, the association of the CONUT score with clinical poor outcomes has been demonstrated in various cardiovascular diseases. Takahashi et al. reported that high CONUT score was associated with adverse outcomes in patients with ACS and also showed its prognostic value in ACS patients (15). Nochioka et al. showed that malnutrition assessed by the CONUT score was associated with adverse cardiac events in patients with chronic heart failure (17). Kunimura et al. demonstrated that the combined use of BMI and CONUT score in stable CAD was associated with MACE (18). In some other studies, the CONUT score was shown to be an independent strong predictor of adverse cardiovascular events and foot events in PAD patients (19). Additionally, it was also reported to be associated with increased prevalence of all-cause death in patients with ST elevation myocardial infarction (STEMI) (20).
To date, numerous nutritional indicators such as serum albumin, total cholesterol, Mini Nutritional Assessment (MNA), Subjective Global Assessment (SGA), and Geriatric Nutritional Risk Index (GNRI) have been reported (21-23). Of these, MNA and SGA are dependent on the physician’s subjective observations. Nevertheless, an evaluation performed with only one nutritional indicator may be affected by various factors and may not provide sufficient information. Therefore, in this study, we used PNI in addition to the CONUT score. PNI, which is calculated on serum albumin level and total lymphocyte count, is an objective nutritional indicator reflecting the immune-nutritional status of individuals. Decreased albumin and lymphocyte response in acute diseases reflect poor immune-nutritional status. On the other hand, PNI is mainly used as a parameter reflecting the immune-nutritional status of patients planned for gastrointestinal surgery to assess the risk of perioperative surgery (24,25). In our study, a PNI score of ≤40 was associated with a shorter survival time.
In the literature, CAS patients have been evaluated with biochemical parameters as well. Of these, NLR has been shown to be associated with in-stent restenosis in CAS patients (26). Additionally, CRP and B-type natriuretic peptide (BNP) have been demonstrated to have a prognostic value in CAS patients undergoing carotid surgery (27).
Both the studies in the literature and our study indicated that malnutrition is associated with mortality. Accordingly, the CONUT score, which is an objective and easily applicable scoring system, can be a useful nutritional indicator in predicting adverse events in CAS patients and, as a novel indicator, can contribute to the prediction of adverse events such as long-term mortality and stroke in the CAS patients, in addition to traditional parameters.
The study had several limitations. First, it was a single-center retrospective study and had a relatively small sample size. Second, the CONUT scores were not assessed after hospital discharge and thus the effect of changes in post-discharge CONUT scores on clinical outcomes could not be evaluated. Third, malnutrition was assessed only by using the CONUT score and PNI, and other nutritional indicators such as MNA, SGA, and GNRI were not used.
In conclusion, malnutrition assessed by the CONUT score was associated with poor prognosis in patients with CAS. The CONUT score is a useful tool for risk stratification of patients with CAS.