Dr. Thomas Bauer and colleagues from the Cleveland Clinic previously reported in part on their experience with validation of whole slide imaging for primary diagnosis in surgical pathology at the Digital Pathology Association meeting in October of 2011.
The study authors determined, based on an a prior power study that estimated 450 cases would be needed to demonstrate noninferiority, based on a null hypothesis: “The true difference in major discrepancies between whole slide imaging (WSI) and microscope slide review is greater than 4%”.
In other words, asking the question “Is WSI inferior to the light microscope?” based on some assumptions with over 600 cases reviewed with some limitations as to case/specimen type, case mix, etc…
The authors hypothesized that WSI review was noninferior to microscope slide review. It would be considered noninferior if major discrepancies with WSI review were not more than 4% when compared with microscope slide review. Put another way, “the null hypothesis that we hoped to reject stated that the true difference in major discrepancies between WSI and microscope slide reviews was greater than 4%”.”
Their paper describes in detail nature of the healthcare system their practice serves, definitions of “major” and “minor” discrepancies, concordance, study design and distinction of “cases” versus “parts”.
The results and conclusions, based on their study design and assumptions, showed diagnostic review by WSI was not inferior to microscope slide review.
As the authors mention in their comments, I think this represents the first study to perform an a prior power study to estimate sample size needed to determine noninferiority of WSI diagnosis.
Additionally, I think this is encouraging news concerning use of digital pathology/WSI for primary diagnosis for pathologists and patients alike.