Normal saline versus Ringer’s solution and critical-illness mortality in acute pancreatitis: a nationwide inpatient database study

Abstract Background Fluid resuscitation is fundamental in acute pancreatitis (AP) treatment. However, the optimal choice between normal saline (NS) and Ringer's solution (RS), and its impact on mortality in critically ill patients, remains controversial. This retrospective cohort study, utilizing a national Japanese inpatient database, investigates this question. Methods Using the Japanese Diagnosis Procedure Combination database between July 2010 and March 2021, we identified adult patients hospitalized in intensive care units (ICU) or high-dependency care units (HDU) for AP who survived at least three days and received sufficient fluid resuscitation (≥ [10 ml/kg/hr*1 h + 1 ml/kg/hr*71 h] ml) within three days of admission including emergency room infusions. Patients were classified into groups based on the predominant fluid type received: the NS group (> 80% normal saline) and the RS group (> 80% Ringer's solution). Propensity score matching was employed to reduce potential confounding factors and facilitate a balanced comparison of in-hospital mortality between the two groups. Results Our analysis included 8710 patients with AP. Of these, 657 (7.5%) received predominantly NS, and 8053 (92.5%) received predominantly RS. Propensity score matching yielded 578 well-balanced pairs for comparison. The NS group demonstrated significantly higher in-hospital mortality than the RS group (12.8% [474/578] vs. 8.5% [49/578]; risk difference, 4.3%; 95% confidence interval, 0.3% to 8.3%). Conclusions In patients admitted to ICU or HDU with AP receiving adequate fluid resuscitation, RS can be a preferred infusion treatment compared to NS.