Overall 5% of patients discontinued treatment by 4 weeks. Among 592 patients with week 4 data, HCV RNA was UD in 75.0%, <50 IU/mL in 15.0%, 50-99 in 3.5%, 100-999 in 5.1% and ≥1000 in 1.4%. ALD patients were less likely to have UD HCV RNA (68.3%

vs 84.5%, p<0.0001; OR 0.47 95%CI 0.30-0.73, p=0.001) as were those on SR (67.5% SR, 73.4% SS/R, 84.0% SPR, p=0.0002; OR 0.32 95%CI 0.18-0.55 compared to SPR, p<0.0001). No association was found between age, sex, race/ethnicity, GT, prior treatment, HIV or transplant status and UD week 4 HCV RNA. In 347 patients with ALD, prior treatment (OR 0.59 95%CI 0.36-0.95, p=0.03), age>65 years (OR 0.38 95%CI 0.15-0.94 compared to <55, p=0.04), and SR regimen (OR 0.37 95%CI 0.19-0.69 PF 2341066 compared to SPR, p=0.002) were independent predictors of reduced likelihood of UD week 4 HCV RNA. In 245 patients without ALD, GT1 or 4 (OR 0.22 95%CI 0.05-0.84 compared to GT2, p=0.03)

and SR regimen (OR 0.15 95%CI 0.04-0.53 compared to SPR, p=0.003) were independent predictors of reduced likelihood of UD week 4 HCV RNA. Conclusion: In a large real-world cohort of patients treated with SOF-based regimens, 90% had undetectable or very low level HCV RNA at week 4 of treatment. ALD and use of SR was associated with a greater likelihood of detectable week 4 HCV RNA. The impact of low level viremia at week 4 on sustained virologic response is yet to be determined. Disclosures: The following people have nothing to disclose: Lisa PS341 I. Backus, Pamela S. Belperio, Troy A. Shahoumian, Larry A. Mole Objectives: Sofosbuvir (SOF) is the first nucleotide polymerase inhibitor with pan-genotypic

activity and a high barrier to resistance. Efficacy and safety have been demonstrated in five phase III clinical trials of SOF administered with either ribavirin (R) or a combination of pegylated interferon alfa selleck chemical and ribavirin (PR). SOF is also the first all-oral 24-week option available for patients unsuitable for interferon (UI). This analysis evaluated the cost-effectiveness of SOF in treatment-naïve (TN) genotype (GT) 1/4/5/6 and GT 2 and 3 patients who are TN, treatment-experienced (TE), interferon eligible (IE) and UI, in the UK. Methods: A Markov model followed a cohort of 10,000 patients over lifetime, with approximately 20% initiating treatment at the compensated cirrhotic stage. SOF/PR for 12 weeks was compared to telaprevir, boceprevir, PR and no treatment (NT); SOF/PR achieved 90% cure rates with only 12 weeks of treatment with no adverse drug reactions above those for PR. For patients UI SOF/RBV for either 12 or 24 weeks was compared to NT. The analysis took the perspective of the National Health Service. Results: SOF, including interferon-free regimens, was shown to be cost-effective across all genotypes (£17,981/ QALY).