Using faecal elastase-1 to screen for chronic pancreatitis in patients admitted with acute pancreatitis

Background: Patients presenting with acute pancreatitis may have co-existing chronic pancreatitis, the accurate diagnosis of which would potentially guide appropriate management. Gold standard tests are often invasive, costly or time-consuming, but the faecal elastase-1 assay has been shown to be comparatively accurate for moderate and severe exocrine deficiency. This study aimed to evaluate fecal elastase-1 concentration [FE-1] against clinical criteria for chronicity in an acute setting. Patients and methods: [FE-1] was performed on patients admitted with acute onset of epigastric pain and a serum lipase at least three times the upper limit of normal. Clinical diagnosis of chronic pancreatitis was defined by the presence of specific clinical, pathological or radiological criteria. A [FE-1] value of <200 µg/g was similarly considered indicative of chronic exocrine insufficiency. Thus a 2×2 table comparing [FE-1] and clinical diagnosis was constructed. Results: After exclusion of liquid stool specimens, 105 stool specimens from 87 patients were suitable for [FE-1] determination. [FE-1] was evaluated against the clinical diagnosis of chronic pancreatitis, initially for the whole sample, and then after exclusion of cases of moderate and severe acute pancreatitis (Ranson score >2). The latter analysis, based on an exocrine insufficiency threshold of 200 µg/g, yielded a sensitivity of 79.5%, specificity of 98.0%, positive predictive value of 96.9% and negative predictive value of 86.0%. Conclusion: [FE-1] is an accurate screening tool for underlying chronic exocrine insufficiency when taken in the course of a hospital admission for mild acute pancreatitis.