Low Mortality and High Morbidity in Severe Acute Pancreatitis Without Organ Failure: A Case for Revising the Atlanta Classification to Include "Moderately Severe Acute Pancreatitis"

OBJECTIVES: Organ failure (OF) is a main cause of death in severe acute pancreatitis (SAP). Our primary aim was to evaluate the morbidity and mortality of patients admitted with SAP with no OF (NOF), single OF (SOF), and multiple (>= 2) OF (MOF). METHODS: Medical records of 207 consecutive patients admitted with SAP to the Mayo Clinic between 1992 and 2001 were reviewed. OF was defined according to the Atlanta classification and patients were categorized in the three groups-NOF, SOF, and MOF. Primary outcomes were in-hospital mortality, duration of hospitalization, need for the intensive care unit (ICU), and the mean length of stay in the ICU. RESULTS: OF occurred in 108 patients (52%). Gastrointestinal bleeding occurred in 18%, respiratory failure in 36 %, hypotension in 28%, and renal failure in 26 %. Compared to patients with MOF, patients with NOF had shorter hospitalizations (28 vs. 55 days, P=0.02), less need for ICU care (50 % vs. 90%, P=0.001), shorter time in the ICU ( 5 vs. 34 days, P < 0.05), and decreased in hospital mortality (2% vs. 46 %, P < 0.01). Odds ratios evaluating the risk of in-hospital mortality for subjects with any OF was 28 (7-186), 10 (2-69) for patients with SOF, and 64 (15-464) for patients with MOF. CONCLUSIONS: Patients with SAP and NOF have prolonged hospitalizations but low mortality. The Atlanta classification should be revised to include a patient group defined as "moderately severe acute pancreatitis "that identifies those patients currently classified as SAP without OF.