2.81–3.56, p <0.001), being single (OR: 1.46 95%CI: 1.20–1.78, p < 0.001), and having health insurance (OR: 1.56 95%CI: 1.29–1.89, p < 0.001). Conclusion: Significant increases in vaccination have been observed in subjects at high risk of infection from 1999–2014. However, approximately 70% of this group remains unvaccinated, especially in HCV positive individuals and IV drug users. Further efforts must be made to educate and immunize subjects that are at high risk of HBV infection. FRI-270 Droplet digital PCR quantitation of HBV cccDNA pool and transcriptional activity in long-term nucleos(t)ide analogue treated patients A. Inchauspé 1,2,3 , Maëlle Locatelli 1,3 , F. Lebosse 3,4 , A. Diederichs 1 , A. Freydier-Berthet 2 , A. Alam 2 , K. Carter 2 , L. Fraisse 2 , M. Bourliere 5 , K. Hamed 6 , Cécile Challier 2 , B. Testoni 1 , F. Zoulim 1,3,7 . 1 CRCL, INSERM U1052, Lyon, France; 2 Sanofi, TA-ID, Marcy l’étoile, France; 3 Université de Lyon 1, Lyon, France; 4 Hospices Civiles de Lyon, Lyon, France; 5 Hopital Saint-Joseph, Marseille, France; 6 Novartis, East Hanover, United States; 7 Hospices Civiles de Lyon, Lyon, France Email: fabien.zoulim@inserm.fr Background and Aims: Nucleos(t)ide anssalogue (NA) therapy for chronic hepatitis B leads to viral suppression in the majority of patients. However, no significant effect on the established pool of covalently closed circular (ccc)DNA has yet been described. cccDNA stably resides in the nucleus of infected hepatocytes and serves as a unique template for pre-genomic RNA (pgRNA), the essential intermediate for full viral replication. Robust data on the effect of long-term (>2 years) NA therapyon intrahepatic cccDNA pool levels are lacking because of technical limitations associated with the sensitivity of cccDNA quantitation in small liver biopsy samples. Method: To address this issue, a droplet digital PCR (ddPCR) assay to absolutely quantify both cccDNA and transcriptional activity (calcu- lated as pgRNA/cccDNA ratio) was set up and applied to 64 liver biopsy samples. Fifty-six samples were obtained from patients treated with telbivudine for 3–5 years, and 8 samples from 4 patients who received mixed NA therapy in the PEGAN study with paired biopsy samples before and after the administration (or not) of add-on 48-week peg-IFN. Results: ddPCR was ten times more sensitive than classic qPCR for cccDNA detection in HepG2-NTCP infected cells. A duplex ddPCR protocol was designed for absolute quantification of pgRNA content and internal normalization using the gusb housekeeping transcript. Among the samples from the 56 telbivudine-treated patients, 70% were negative for cccDNA quantification by classic qPCR. However, ddPCR analysis detected cccDNA in 89% of these qPCR-negative samples. In total, only 11% of NA-treated patient samples had undetectable intrahepatic cccDNA by ddPCR, a percentage compar- able to a matched control group of non-treated patients (12%). Notably, absolute quantitation by ddPCR showed that both cccDNA amount and pgRNA/cccDNA ratio were significantly decreased in samples from NA-treated patients as compared to non-treated patient samples. All of the 8 biopsies derived from the PEGAN patients had undetectable cccDNA levels by qPCR, but ddPCR detected cccDNA in 7 of them. Analysis of cccDNA and pgRNA in matched samples revealed no significant effect of the peg-IFN add-on on both cccDNA amount and activity. Conclusion: This ddPCR protocol extended the limits and precision of cccDNA and pgRNA detection in vivo and demonstrated that liver samples from most long-term NA-treated patients still harbour transcriptionally active cccDNA. FRI-271 Estimated the number of undiagnosed patients and antiviral treatment rate of chronic hepatitis B in the U.S. based on the Truven Health MarketScan Database E. Ogawa 1,2 , D. Jeong 1 , Y.H. Yeo 1 , M. Nguyen 1 . 1 Stanford University Medical Center, Department of Gastroenterology and Hepatology, Palo Alto, United States; 2 Kyushu University Hospital, Department of General Internal Medicine, Fukuoka, Japan Email: mindiehn@stanford.edu Background and Aims: Prior studies suggest that only one-third of chronic hepatitis B (CHB) in the U.S. are aware of theirdiagnosis and only 10–20% or less of diagnosed patients are treated with antiviral therapy. Our goal is to estimate total number of undiagnosed CHB and treatment rate of CHB patients in a large nationwide sample of U.S. population. Method: We used the commercial U.S. Truven Health MarketScan Database (n = 73,644,921; 1/1/2007-12/31/2014) to identify the number of patients with CHB diagnosis (≥1 inpatient or ≥2 outpatient ICD-9-CM codes for CHB). Other study inclusion criteria include continuous insurance and prescription coverage for 6 months prior to the first CHB diagnosis and 6 months after. Then, using the National Health and Nutrition Examination Survey (NHANES) prevalence estimates of HBV infection of 0.3%–0.7%, we estimated the number of undiagnosed CHB patients by subtracting the number of estimated CHB patients by NHANES prevalence in this population of approximately 73 million people with the number of patients who were identified as having CHB in this population sample. We also estimated the proportion of diagnosed CHB patients who received a prescription of any of the FDA-approved anti-HBV medications. Results: In total, we identified 43,765 CHB in this cohort of 73,644,921 during the study period, yielding a prevalence of known or diagnosed CHB of 0.059% (95%CI: 0.059–0.060). The prevalence of diagnosed CHB increased with age and were 0.036% (95%CI: 0.036– 0.037) for the 18–34 age group, 0.069% (95%CI: 0.068–0.070) for the 35–44 group, 0.072% (95%CI: 0.071–0.073) for the 45–54 group, and 0.077% (95%CI: 0.076–0.079) for the 55–64 group. Notably, diagnosed CHB prevalence was higher among HMO insured patients vs. other insurance types: 0.088% (95%CI: 0.086–0.090) vs. 0.056% (95%CI: 0.055–0.057). Based on the NHANES prevalence rate with 0.3–0.7% in HBV infection, the estimated number of undiagnosed patients by sensitivityanalysis was shown in Figure. The overall treatment rate with anti-HBV drugs was 11.5% (95%CI: 11.2–11.8) (5,033/43,765). HBV treatment rate among aged 55–64 (10.7%, 95%CI: 10.1–11.3) group was lower than the aged 35–44 (12.9%, 95%CI: 12.2–13.5) and 45–54 (13.2%, 95%CI: 12.6–13.9) groups. HBV treatment for insured patients with HMO (14.3%, 95%CI: 13.6–15.0) was also higher than thosewith other insurance type (11.0%, 95%CI: 10.6–11.3). POSTERS PRESENTATIONS S481 Journal of Hepatology 2018 vol. 68 | S365–S604