@article {Hern{\'a}ndez-Alvareze000115, author = {Noemi Hern{\'a}ndez-Alvarez and Juan Manuel Pascasio Acevedo and Enrique Quintero and Inmaculada Fern{\'a}ndez V{\'a}zquez and Mar{\'\i}a Garc{\'\i}a-Eliz and Juan de la Revilla Negro and Javier Crespo Garc{\'\i}a and Manuel Hern{\'a}ndez-Guerra}, title = {Effect of season and sunlight on viral kinetics during hepatitis C virus therapy}, volume = {4}, number = {1}, elocation-id = {e000115}, year = {2017}, doi = {10.1136/bmjgast-2016-000115}, publisher = {BMJ Specialist Journals}, abstract = {Background and aims Rapid viral response (RVR) during antiviral treatment for hepatitis C virus (HCV) predicts sustained viral response (SVR). Recently, vitamin D levels have been associated with SVR. As sunlight is the most important source of vitamin D and shows seasonal variation, we evaluated the effect of season on viral kinetics during peginterferon/ribavirin-based therapy for HCV.Methods Consecutive HCV patients treated with peginterferon/ribavirin and boceprevir/ telaprevir (June 2011{\textendash}July 2014) were included. Patients were grouped according to season when therapy was initiated (Season A: May{\textendash}October and Season B: November{\textendash}April) depending on hours of daily sunlight. Multiple logistic regression analysis included factors known to influence SVR to treatment. The dependent variables were undetectable viral load (VL) or VL <=15 UI/mL (VL <=15) at weeks 4, 8 and 12, end of treatment and SVR.Results The study included 930 patients (66.8\% men; median 54 years) treated with telaprevir (n=537) or boceprevir, without (n=481) or with lead-in therapy of peginterferon/ribavirin. Baseline characteristics of patients in Season A (45.3\%, n=421) and Season B groups were similar. Overall, a higher rate of RVR (23.5\% vs 16.1\%, p=0.005) and VL <=15 (51.0\% vs 38.6\%, p<=0.001) was observed in patients starting treatment during Season A versus Season B. By logistic regression analysis, initiating treatment in Season A proved to be an independent predictor of RVR and VL <=15.Conclusions In our setting, seasonality affects viral kinetics in HCV genotype 1 patients treated with peginterferon/ribavirin-based therapy. Our findings support the hypothesis that vitamin D influences viral response to peginterferon/ribavirin-based therapy.}, URL = {https://bmjopengastro.bmj.com/content/4/1/e000115}, eprint = {https://bmjopengastro.bmj.com/content/4/1/e000115.full.pdf}, journal = {BMJ Open Gastroenterology} }