Development and validation of an app-based cell counter for use in the clinical laboratory setting.
BACKGROUND
For decades cellular differentials have been generated exclusively on analog tabletop cell counters. With the advent of tablet computers, digital cell counters - in the form of mobile applications ("apps") - now represent an alternative to analog devices. However, app-based counters have not been widely adopted by clinical laboratories, perhaps owing to a presumed decrease in count accuracy related to the lack of tactile feedback inherent in a touchscreen interface. We herein provide the first systematic evidence that digital cell counters function similarly to standard tabletop units.


METHODS
We developed an app-based cell counter optimized for use in the clinical laboratory setting. Paired counts of 188 peripheral blood smears and 62 bone marrow aspirate smears were performed using our app-based counter and a standard analog device. Differences between paired data sets were analyzed using the correlation coefficient, Student's t-test for paired samples and Bland-Altman plots.


RESULTS
All counts showed excellent agreement across all users and touch screen devices. With the exception of peripheral blood basophils (r = 0.684), differentials generated for the measured cell categories within the paired data sets were highly correlated (all r ≥ 0.899). Results of paired t-tests did not reach statistical significance for any cell type (all P > 0.05), and Bland-Altman plots showed a narrow spread of the difference about the mean without evidence of significant outliers.


CONCLUSIONS
Our analysis suggests that no systematic differences exist between cellular differentials obtained via app-based or tabletop counters and that agreement between these two methods is excellent.
Department of Pathology and Laboratory Medicine, The University of California, San Francisco Medical Center, San Francisco, CA 94143-0102, California, USA.
Alexander C
AC
Thurman
Department of Pathology and Laboratory Medicine, The University of California, San Francisco Medical Center, San Francisco, CA 94143-0102, California, USA.
Jessica L
JL
Davis
Department of Pathology and Laboratory Medicine, The University of California, San Francisco School of Medicine, San Franacisco, CA 94117, California, USA.
Max
M
Jan
Department of Epidemiology and Biostatistics, The University of California, San Francisco, San Francisco, CA 94107-1762, California, USA.
Charles E
CE
McCulloch
Department of Pathology and Laboratory Medicine, The University of California, San Francisco Medical Center, San Francisco, CA 94143-0102, California, USA.
Benjamin D
BD
Buelow
App; apps; cell counter; digital; mobile; tablet; validation