Mammographic follow-up before and during the COVID-19 pandemic.

122 Background: Mammography adapted during the COVID-19 pandemic to accommodate social-distancing guidelines and minimize risk of exposure, but it is unclear how these accommodations potentially provoked existing inefficiencies or illuminated opportunities to redress them. The goal of this study was to compare rates of (1) diagnostic follow-up after a BIRADS 0 (i.e., incomplete) screening mammogram and (2) biopsy following a BIRADS 4 or 5 (i.e., biopsy recommended) diagnostic mammogram before and after onset of the pandemic. Methods: We included women ≥18y who underwent a BIRADS 0 screening mammogram and/or BIRADS 4-5 diagnostic mammogram at our institution from 3/15/19-3/15/21. Given seasonal variation in care receipt, pre-COVID (3/15/2019-3/15/20) and COVID (3/15/20-3/15/21) time periods were compared at a quarterly level. Case-mix adjusted associations between time-to-follow-up and COVID vs pre-COVID quarters (Q1-4) were estimated using multivariate Cox proportional hazards models. Results: We identified 17,918 women (Asian: 985, Black: 4054, Hispanic: 840, White: 11,302) who received a total of 14,388 BIRADS 0 screening and 6410 BIRADS 4 or 5 diagnostic mammograms. There were far fewer diagnostic mammograms in COVID Q1 vs pre-COVID Q1 (Table), and they were more likely to be followed up with biopsy (HR 1.21 [95% CI 1.03-1.44], p = 0.023). COVID Q3 (HR 0.92 [95% CI 0.86-0.98], p = 0.002) and Q4 (HR 0.88 [95% CI 0.83-0.95], p < 0.001) screens were less likely to be followed up with diagnostic mammograms but volumes were higher vs the respective pre-COVID quarters (Table). However, COVID Q3 patients with BIRADS 4 or 5 mammograms were 18% more likely to undergo biopsy than their pre-COVID Q3 counterparts (HR 1.18 [95% CI 1.07-1.31], p < 0.0001, Table) despite higher COVID volumes. Conclusions: Early in the pandemic, patients were more likely to receive mammographic follow-up, potentially due to lower patient volumes and enforced strategies for more efficient, less time-intensive care delivery. These gains were lost with regards to diagnostic follow-up for screening mammograms but maintained with regards to performing biopsies. As volumes return to or surpass pre-pandemic levels, health systems must work to identify and preserve operational efficiencies gained during the early pandemic.[Table: see text]