Low grade squamous intraepithelial lesion, epithelial cell abnormality-adjusted workload, and the ThinPrep imaging system.

Previous studies have shown a negative correlation between screening sensitivity using the ThinPrep Imaging System (TIS) and epithelial cell abnormality (ECA) adjusted workload (ECA rate × actual slides screened/day) at the thresholds of atypical squamous cells of undetermined significance (ASCUS) and high-grade squamous intraepithelial lesion (HSIL). We sought to determine if a similar correlation could be shown at the threshold of low grade squamous intraepithelial lesion (LSIL). Using data in seven manuscripts from the literature that contain sufficient information, the change in screening sensitivity using the TIS compared with manual screening was negatively correlated with ECA adjusted workload (y = -3.75x + 54, R(2) = 0.104). Using the sensitivity of manual screening of 79% for manual screening at a threshold of LSIL from the original TIS trial, 100% sensitivity could be achieved at an ECA adjusted workload of approximately seven slides/day, the same workload that achieves 100% sensitivity at a threshold of ASCUS and slightly higher than the threshold for HSIL. We conclude that the ECA adjusted workload is a valuable method to assess workload for the TIS at the threshold of LSIL. Laboratories using the TIS should restrict workload to seven ECA adjusted slides/day (maximum actual slides/day = 700/ECA percentage).