AP Discrepancy Rates - College of American Pathologists

ut this has not been thoroughly studied in pathology laboratories.
Some leading patient safety researchers, such as Resar
et al, 32 have argued that error prevention programs should
target errors that have an effect on patient outcome, rather
than all errors. These Q-Probes study data show that the
majority of anatomic pathology discrepancies do not result
in harm, similar to the data reported in nonpathology
fields. 1 Determining the effect of a pathology error on patient
outcome is challenging because of contact and temporal
barriers between pathology and clinical care. Thorough
medical record review generally is not performed
after a pathology error has occurred, and health care systems
invariably lack personnel trained in the intricacies of
the triad of pathology reporting, patient safety, and assessing
patient outcomes. Grzybicki et al 27 reported that
even with data from medical record review, pathologists
showed poor agreement in determining if harm actually
occurred. We used pathologist self-assessment to determine
error severity, and acknowledging the biases inherent
in this process, we found that 16.6% of all errors resulted
in some form of patient harm. This indicates that
1.1% of all anatomic pathology cases that underwent secondary
review were associated with a harmful significant
event. Because secondary review processes tend to be varied
across institutions, the probability is high that a relatively
large percentage of pathology errors resulting in
harm go undetected.
Statistical significance testing did not show that any
body site was most likely to be associated with an error.
However, some organs (eg, female genital tract and breast)
tended to have higher associations with a discrepancy resulting
in clinical harm compared with other organs. Using
medical chart review to determine clinical follow-up
of errors detected through cytologic-histologic correlation,
Clary et al 6 reported that the most common cytology specimens
associated with harm were pulmonary and breast
specimens. In a study examining errors associated with
malpractice claims, Troxel and Sabella 15 also identified
that diagnostic errors in breast cytology specimens were
associated with harm; in addition, they identified other
organ or specimen types, such as prostate needle biopsies,
Papanicolaou tests, and melanocytic skin lesions, as being
associated with errors resulting in harm. In this Q-Probes
study, discrepancies detected in cytology specimens were
more likely (compared with surgical pathology specimens)
to have a 2-step change in diagnosis, and this
change often meant that the original diagnosis was either
a false-negative or false-positive diagnosis. These types of
errors are more likely to have a clinical effect than other
types of errors. 2 Harm was more likely to be associated
with cases reviewed at the behest of a clinician and cases
sent for extradepartmental review.
Although researchers have studied anatomic pathology
diagnostic variability, the relationship of variability and
error is not sufficiently addressed in the pathology literature.
Strictly speaking, variability is a form of error, and
secondary case review is simply a means to unearth differences
in diagnosis or errors. In practice, some pathologists
would like to maintain that ‘‘true’’ diagnostic errors
are errors that most reasonable pathologists would agree
are errors. However, establishing the ‘‘true’’ diagnosis is a
complex and controversial task (eg, do we use a panel of
practicing pathologists or experts?) that has not been well
studied in anatomic pathology. Our study did not address
methods of establishing the accuracy of the original and
review diagnoses. However, some methods of secondary
review were performed with knowledge of clinical outcome,
which, although biasing the review pathologist
(compared with the original pathologist, who lacked this
bias), provides a window on the actual effect of the diagnosis.
This Q-Probes study recorded errors other than interpretive
errors. Typographic errors and changes in patient
information infrequently result in harm, but when harm
occurs, it may be severe, with far-reaching consequences
(eg, switching of patient specimens). Pathology laboratories
place checks in the system in order to limit these error
types, although these safeguards are generally not formally
shared across laboratories. The frequency of marked
harm as a result of these errors is known only through
small studies or anecdotally, 9,33,34 resulting in a lack of
widespread system learning. Our study was not detailed
enough to drill down into these error types.
The lack of report clarity is an example of error that is
difficult to quantify and falls within the realm of communication
error. Poor communication is an important
source of error in clinical medicine and may result in severe
harm 35 ; Dovey et al 25 reported that 5.8% of family
practice errors were a result of miscommunication. Report
clarity is subjective, and Powsner et al 28 reported that surgeons
misunderstood 30% of pathology reports. As expected,
in this Q-Probes study, pathologists believed that
the majority of reports were clear, and less than 1% were
perceived as markedly unclear. This confirms the conclusion
by Powsner et al 28 that a communication gap exists
between pathologists and clinicians. The fact that clinicians
request that a certain percentage of cases be reviewed
underscores a potential communication problem
but shows as well a functioning means of detecting error.
Conclusions
Using secondary pathologist review, the mean anatomic
pathology diagnostic discrepancy frequency was 6.7%.
More than 1% of all reviewed anatomic pathology cases
may be associated with an error associated with patient
harm.
The College of American Pathologists provided financial support.
The statistical reviewer was Molly Walsh, PhD, College of
American Pathologists.
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Arch Pathol Lab Med—Vol 129, April 2005 Patient Safety in Anatomic Pathology—Raab et al 465