Pancreatic/Biliary.

Abstract

Introduction: Chronic pancreatitis (CP) is a complex syndrome characterized by pancreatic fibrosis (PF), chronic inflammation, and progressive loss of glandular exocrine and endocrine function. The lack of a practical “gold standard” in the diagnosis of CP is a challenge, as direct biopsy of the pancreas to evaluate histology may not be feasible. Endoscopic pancreatic functional tests (ePFTs) can be used to predict PF, a key histologic component of CP. To construct a diagnostic tool based on Fagan’s nomogram for calculating post-test probability of pancreatic fibrosis (PF) utilizing the ePFT in subjects with and without known risk factors for CP. Methods: Exhaustive literature was conducted for review of PF data in surgical histology and autopsy studies. Step 1: Prevalence of PF in histopathology studies of subjects with and without major risk factors (smoking, alcohol abuse, neither smoking nor alcohol) was used to determine pre-test probability of PF. No data was available for subjects with both smoking and alcohol use. Step 2: Positive and negative likelihood ratios (LR) for secretin ePFT detection of PF were calculated based on sensitivity and specificity in literature using histopathology as gold standard (Table 1). Step 3: Fagan’s nomogram (Bayesian analysis) was used to determine the post-test probability of PF incorporating pre-test probability (risk factors) and positive/negative LR of ePFT.Table 1: Test Characteristics of ePFTResults: Based on histologic gold standards, a Fagan’s nomogram was constructed to estimate post-test probability of PF based on pre-test risk factors (smokers, alcoholics, and controls) and ePFT results (Table 2).Table 2: Posttest Pprobability of Pancreatic FibrosisConclusion: ePFT can assist in the assessment for PF, which is a key component of chronic pancreatitis. A negative ePFT (even in the setting of known CP risk factors) is a useful tool to rule out PF. On the other hand, a positive ePFT can predict PF, but should be interpreted in combination with other testing modalities (i.e., EUS, MRI) and clinical features (abdominal pain, recurrent pancreatitis) for a definitive diagnosis of chronic pancreatitis. While not all patients with PF will have clinical diagnosis of chronic pancreatitis, the presence of fibrosis in addition to other factors (exocrine insufficiency, abdominal pain, diabetes) can assist in the diagnostic evaluation.