114 Opportunistic Screening of Bone Mineral Density With CT Scans in Chronic Pancreatitis

Abstract

INTRODUCTION: Osteoporosis and fragility fractures have been repeatedly shown to increase morbidity, mortality and socioeconomic costs. Chronic pancreatitis (CP) has multiple shared risk factors and complications that promote an imbalance in bone mineralization and remodeling which ultimately contributes to a high prevalence of metabolic bone disease. However, in the absence of societal guidelines regarding screening, dual-energy x-ray absorptiometry (DEXA) scans are not routinely performed and are not universally covered by insurance. While DEXA scan is the gold standard to assess bone mineral density, a Computed Tomography (CT) L1 vertebral density less than 135 Hounsfield Units (HU) has been validated to diagnose osteoporosis in the general population. The aim of this proof of concept study was to determine if the CT L1 vertebral threshold of 135 HU is also valid as an opportunistic screening cut-point for osteoporosis in chronic pancreatitis patients. METHODS: We selected patients with a definitive diagnosis of CP (according to the American Pancreatic Association guidelines) who were enrolled into The Ohio State Wexner Medical Center Pancreas Disease Biobank. Basic demographic information was abstracted including age, sex, race, BMI, smoking and alcohol history. Pertinent laboratory values and imaging studies, including DEXA scans, were also obtained from these patients. Baseline L1 vertebral HU values on CT scans were determined for BMD assessment (Pickhardt et al, Annals of Internal Medicine 2013). RESULTS: Sixty-four patients with definite CP were identified, including 27 (42%) with a CT and DEXA scan. Of these, 15/27 (56%) had evidence of metabolic bone disease (z-score < −1.5), including 15% with osteoporosis. Mean L1 HU value in those with osteoporosis was 106. There was a statistically significant association between osteoporosis (z score < −2.5) and the CT L1 HU threshold of 135 (P = 0.025, positive likelihood ratio of 8.62, PPV 60%). The L1 HU threshold of 135 had sensitivity of 75% and specificity of 91.3% for osteoporosis and a NPV of 95.45%. CONCLUSION: CT scans performed during routine clinical care of patients with CP may be useful for opportunistic screening for osteoporosis using L1 HU attenuation, especially at a threshold of 135. Larger sample sizes of patients are needed to further develop risk stratification models in CP considering other clinical risk factors.