Prevalence and detection of undiagnosed active hepatitis C virus infections in Navarre, Spain, 2017-2019.

BACKGROUND Undiagnosed active hepatitis C virus (HCV) infection remains an obstacle towards its eradication. This study aimed to estimate the prevalence of HCV infection and describe the diagnostic advances in Navarre, Spain. METHODS HCV-infection diagnostic performance was analyzed in Navarre´s primary and specialized healthcare between 2017 and 2019. The prevalence of undiagnosed infections was estimated for patients with programmed surgeries unrelated to HCV infection, who underwent a routine HCV antibody (anti-HCV) determination. HCV-RNA (viral load) was quantified in anti-HCV positive cases. The prevalence was standardized according to the sex and age distribution in the general population. RESULTS From the 63,405 subjects examined for anti-HCV, 84 (five per 100,000 person-years) were diagnosed with an active infection. In primary healthcare, 20,363 patients were analyzed and 47 active infections were detected, i.e. one case for every 433 people tested, implying 56% of all identified active infections. On the other hand, 9,399 surgical patients were analyzed and 120 anti-HCV positive cases were detected (adjusted prevalence: 1.47%; 95% CI: 1.24-1.52). A positive viral load had been determined at any time in 66 cases (0.61%), of which five were undiagnosed active infections (adjusted prevalence: 0.04%; 95% CI: 0.01-0.11). Preoperative screening allowed the detection of one undiagnosed infection per 795 people analyzed aged between 45 to 64 years. CONCLUSIONS Primary healthcare efficiently contributes to the detection of undiagnosed HCV active infections. This may be speeded up by performing population screening, targeting subjects between 45 and 64 years of age.