Incidence of Typical Neutrophil Count With Fy(a‐b‐) Status Among Hematology Referrals for Neutropenia at an Urban Safety‐Net Hospital

Background: Duffy‐null associated neutrophil count (DANC) causes neutropenia without clinical sequelae. 25%–50% of people of African ancestry in the United States are thought to have Fy(a‐b‐) status and are often erroneously identified as having pathologically low neutrophil counts. Results: We performed a retrospective chart review of new neutropenia referrals to the Hematology Clinic at Boston Medical Center (BMC) to evaluate diagnostic patterns for Fy(a‐b‐) status. 103 new referrals for neutropenia were made from 1/2020 to 2/2022, of which 78 were included for further analysis. DANC was the etiology for low neutrophil count in 64.1%, 82% of whom were African American or Black or were born in an African or Caribbean country. 66% of these patients underwent confirmatory blood bank testing, and 97% of patients tested were confirmed to have Fy(a‐b‐) status. The average cost of a laboratory visit for patients with typical neutrophil count with Fy(a‐b‐) status was on average lower, but not negligible, than those without ($363.82 vs. $737.93; p < 0.005). These patients were also statistically less likely to have a follow‐up appointment ( p = 0.039). Conclusions: Expanded use of serological Fy(a,b) antigen testing for patients with chronic, asymptomatic neutropenia could reduce the cost of care and referrals to the hematology clinic.