Novel and simple approach to estimating the actual incidence of blood and body fluid exposure

Background: There is no current way to determine the actual blood and body fluid exposure (BBFE) incidence in hospitals. We propose a simple, reliable, and widely available method for the accurate estimation of BBFE. Methods: Data for BBFE for healthcare workers between 2006 and 2015 at Osaka University Hospital were retrospectively extracted from the electronic records. Annual positivity of hepatitis C virus (HCV) antibody in the source individuals and overall patient population were calculated over time. We created an estimation formula focusing on the difference in HCV positivity between the source individuals and overall patient population for the actual number of BBFEs. A linear regression model was used to evaluate the temporal change in the reported and estimated BBFEs. Results: During the study period, 937 BBFEs were reported. HCV positivity between the post-BBFE cohort and overall patient population greatly differed; the incidence ratio ranged from 2.1 to 5.7. The linear regression model revealed that the reported BBFEs did not significantly change during the study period (the slope, 1.315 [95% confidence interval (C.I.):-0.849 to 3.480, p=0.199]). The annual incidence ratio of the estimated and reported BBFEs significantly reduced over time (the slope,-0.287 [95% C.I.:-0.488 to-0.086, p=0.011]), indicating that, although the reported number of BBFEs seemed unchanged, the estimated incidence decreased. Conclusions: We propose a novel and simple approach to estimating the actual incidence of BBFEs in hospitals using the difference in HCV positivity between the post-BBFE cohort and overall patient population.