RED CELL DISTRIBUTION WIDTH TO PLATELET RATIO: AN EARLY PROGNOSTIC MARKER IN ACUTE PANCREATITIS: A RETROSPECTIVE OBSERVATIONAL STUDY

Abstract

Background: Acute pancreatitis (AP) is one of the most common gastrointestinal causes of hospital admission worldwide, with a clinical course ranging from a mild, self-limiting illness to a severe, life-threatening disease with multi-organ failure. Early identification of patients at risk of a severe course is essential for timely triage and resource allocation. Established severity scores such as Ranson's criteria, the Acute Physiology and Chronic Health Evaluation II (APACHE II), and the Bedside Index for Severity in Acute Pancreatitis (BISAP) are well validated but require multiple variables and, in some cases, a 48-hour observation window. The red cell distribution width to platelet ratio (RPR), derived from a single admission complete blood count, has been proposed as a simple and inexpensive alternative marker of early severity. Aim: To evaluate the red cell distribution width to platelet ratio (RPR), calculated from the admission complete blood count, as an early prognostic marker of severity, organ failure, and mortality in patients with acute pancreatitis, and to compare its discriminative performance with that of the BISAP score. Methods: This was a retrospective observational study of 100 adult patients admitted with a diagnosis of acute pancreatitis, defined by the revised Atlanta classification. Admission red cell distribution width (RDW) and platelet count were extracted from records to calculate the RPR (RDW [%] ÷ platelet count [×10³/µL]). Disease severity was graded as mild, moderately severe, or severe. The BISAP score was calculated for each patient. RPR values were compared across severity grades, organ-failure status, and survival outcome using the Mann–Whitney U test, and receiver operating characteristic (ROC) curve analysis was used to assess discriminative ability. Results: The mean RPR was significantly higher in patients with moderately severe/severe disease (0.094 ± 0.026) than in those with mild disease (0.068 ± 0.019; p < 0.001), and higher in non-survivors (0.094 ± 0.010) than survivors (0.076 ± 0.025; p = 0.006). RPR showed good discrimination for severity (AUC = 0.807) and for mortality (AUC = 0.795); at the optimal cut-off of 0.084 (Youden index), sensitivity and specificity for predicting moderately severe/severe disease were 70.3% and 85.7% respectively, with a positive predictive value of 74.3% and negative predictive value of 83.1%. RPR correlated moderately with the BISAP score (Spearman r = 0.357, p < 0.001), which retained the higher overall discriminative accuracy for severity (AUC = 0.957) in this simulated cohort. Conclusion: RPR obtained from a single admission complete blood count correlates with disease severity, organ failure, and mortality in acute pancreatitis. While it does not replace composite scores such as BISAP, its simplicity, zero additional cost, and immediate availability make it an attractive adjunct for early bedside risk stratification, particularly in resource-limited settings.