In this study, we found that the Cr/Alb ratio is a novel but promising, easy-to-measure, reproducible, non-invasive prognostic score that can be used for the prediction of the effect of debridement in AP patients.
AP is an emergency gastrointestinal condition, characterized by a rapid onset and poor prognoses, with mortality values of up to 40%. As AP often causes severe systemic inflammation and necrosis in the abdomen, debridement plays an important role in its treatment. However, the effect of surgery is not satisfactory owing to the complexity of pancreatic or peri-pancreatic infections, multiple organ attack, and violent systemic inflammation, due to which a large proportion of patients experience numerous post-operative complications, re-operation or even death. Therefore, it is important to evaluate patients’ prognoses before surgery. Previous studies showed that CRP, Cr, and Alb had definite implications for systemic inflammatory response-related conditions such as AP[20, 21]; however, their predictive value, when used alone, is not satisfactory. Therefore, some studies combined those parameters for an enhanced prediction effect[14, 22].
In our study, of all the admission and pre-operation Cr/Alb and CRP/Alb values, the admission Cr/Alb showed the best performance in several analyses, including the distribution analysis and correlation analysis, and had the best predictive value. An admission Cr/Alb cut-off ≥ 3.43 could predict worse prognoses in AP patients, including a more severe heart rate and respiratory rate, impaired levels of blood urea nitrogen, Cr, Alb, white blood cells and platelets, APACHE II score, post-operative electrolyte disorders, respiratory failure, hemorrhage, shock, renal failure, re-operation rate, and mortality. In the logistic regression analysis, the admission Cr/Alb was independently correlated with the APACHE II score, renal failure and re-operation. Above all, our research suggests that the admission Cr/Alb has the potential to predict AP-related prognoses as a simpler alternative to the APACHE II score.
The development of AP is often accompanied by systemic inflammation, sepsis, and multiple organ failure. Therefore, the prognoses of AP are closely related to the severity of inflammation, nutrition intake, negative nitrogen balance, and functional reserve. Of the various tests, CRP, Cr and Alb are the most relevant examinations. CRP is synthesized by the liver and responds to inflammation within a few hours. Owing to its short half-life and high sensitivity, it is often used for the detection and assessment of inflammation[7, 25, 26]. Alb is a negative acute phase reactant synthesized by the liver, and its expression decreases during inflammatory reactions. In previous studies, Alb was shown to be related negatively to the severity of inflammation, disease prognoses, and mortality in AP[20, 27]. Cr is an amino acid derivative produced by the metabolism of muscle tissues. It is filtered through the kidney and its levels are raised significantly in systemic inflammatory diseases. An increase in the Cr level 48 hours after admission is considered a marker of pancreatic necrosis, hypovolemia and renal insufficiency. According to Wilkman et al., increased Cr levels are independent risk factors for 90-day mortality in AP patients. Lipinski et al. also reported that higher Cr values at admission and after 48 hours were associated with a higher incidence of mortality.
In our study, Cr/Alb showed better performance than CRP/Alb. CRP level fluctuations are more intensive in AP and may lead to measurement-related difficulties and inaccuracies in severity evaluation. In comparison, Cr level trends are more stable, lending them more credibility for use as predictors. Cr has the ability to reflect the potential of functional reserve, comprising protein decomposition metabolism and renal function, in the sustenance of the inflammation attack. Besides, Alb reflects a body’s protein reserve more accurately. In summary, Cr and Alb could assess the degree of inflammatory response, catabolism, and fundamental status. The combination of the two markers could indicate the severity and prognoses of AP more reliably and accurately.
This study is the first to compare admission and preoperative Cr/Alb and CRP/Alb values in the assessment of AP. For surgeons, our study provides a simpler and more feasible tool for the evaluation of the basic state of AP patients before surgery-related decision-making. For ward managers, the Cr/Alb value could aid in the identification of high-risk patients in advance and remind medical staff to strengthen the degree of ward care targeted at those patients. As the Cr/Alb value could distinguish mild AP from its severe form, our results can be used by hospitals and health policymakers in the formulation of more efficient gradient treatment strategies for AP.
Our study has several limitations. First, its retrospective design may have led to a certain selection bias. Second, the study included only 140 cases enrolled from a single center, leading to insufficient reliability. Third, this study focused only on AP patients with debridement. In the future, we will include patients with non-surgical treatment for further investigation.
In conclusion, as a clinical scoring system with high accuracy and simplicity, the admission Cr/Alb value was superior in the assessment of the severity of AP with debridement. With the confirmation of our results in larger-scale investigations in the future, Cr/Alb has the potential to improve the quality of the AP risk scoring system and prognostic prediction.