Automatic Laboratory-Initiated Reflex Testing to Identify Patients ...

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Coagulation and Transfusion Medicine / LABORATORY-INITIATED REFLEX TESTING FOR AIHA
Automatic Laboratory-Initiated Reflex Testing to Identify
Patients With Autoimmune Hemolytic Anemia
Paul Froom, MD, Alexander Neck, MD, Michaela Shir, MS, Rosa Haavis, and Mira Barak, PhD
Key Words: Normocytic; Anemia; Laboratory; Workup
DOI: 10.1309/CFEECW31UYLHUJQG
Abstract
The clinical usefulness of automatic laboratoryinitiated
testing of patients with recent-onset
normocytic anemia to diagnose autoimmune hemolytic
anemia (AIHA) is uncertain. During a 28-month period,
we performed 784,185 CBC counts. Patients without a
history of anemia had reticulocyte count testing if
hemoglobin values were less than 10 g/dL (

Froom et al / LABORATORY-INITIATED REFLEX TESTING FOR AIHA
abnormal test results are compared with previous results if
present in the database.
In all patients without a history of anemia, we performed
a reticulocyte count if the hemoglobin value was less than 10
g/dL (

❚Table 1❚
Univariate Analysis *
led to considerable savings by decreasing physician visits.
Cost-effectiveness, however, can be calculated only by determining
the number of additional physician follow-up visits for
patients who are not tested automatically.
Negative consequences of automatic laboratory testing
include redundant testing in approximately 20% of the
patients with a positive direct antiglobulin test result, with previous
positive test results in the hospital or from other areas in
Israel. This might be prevented by improved computer integration
of test results from other sources. Also, 87.7% of
patients with elevated reticulocyte counts did not have a positive
direct antiglobulin test result, and not all with a positive
direct antiglobulin test result were treated. In these patients,
additional test results outside the reference range could lead to
negative consequences, including patient anxiety. Also, the
effect of the test results on subsequent testing and treatment in
patients without autoimmune hemolytic anemia needs to be
studied because the added testing might have had positive or
negative effects on patient care.
We were unable to find clinical or CBC count variables
that aid in limiting direct antiglobulin testing. Neither
absolute reticulocyte counts nor corrected absolute reticulocyte
counts were better than the more familiar uncorrected
reticulocyte test.
The cutoff for the degree of anemia needed to initiate a
reticulocyte count is uncertain. It is possible that patients with
a hemoglobin value of 10 g/dL (100 g/L) or more also might
benefit from such testing. Further studies are warranted to
substantiate our findings and to determine the proper cutoff
for automatic direct antiglobulin testing.
Extrapolation of our results to other settings should be
done with caution. The upper end of the reference interval for
reticulocytes in our laboratory is 1.9% (0.019) but has been
reported variously to be 2.7% (0.027), 3 1.8% (0.018), 3 1.6%
(0.016), 4 1.25% (0.013), 5 2.16% (0.022), 6 1.79% (0.018), 6
1.55% (0.016), 6 2.24% (0.022), 6 1.44% (0.014), 6 1.85%
(0.019), 7 2.3% (0.023), 7 and 1.6% (0.016), 8 depending in
© American Society for Clinical Pathology
Coagulation and Transfusion Medicine / ORIGINAL ARTICLE
Direct Antiglobulin Test Results
Variable Positive (n = 52) Negative (n = 372) P
Age (y) 60 ± 20 52 ± 25 .025
Female 35 (67.3) 244 (65.6) .807
Reticulocyte count, % of RBCs (proportion of RBCs) 6.5 ± 5.5 (0.065 ± 0.055) 4.7 ± 2.7 (0.047 ± 0.027)

Froom et al / LABORATORY-INITIATED REFLEX TESTING FOR AIHA
Conclusion
The laboratory initiation of the workup ensured recommended
medical practices, probably saved physician visits,
and, in some patients, led to more timely diagnosis and appropriate
treatment. Our findings support the use of reflex laboratory-initiated
testing in patients with normocytic anemia.
Further studies are warranted to determine whether our findings
can be extrapolated to other settings.
From the Central Laboratory of Haifa and Western Galilee, Clalit
Health Services, Nesher, Israel.
Address reprint requests to Dr Froom: Hematology
Laboratories, Central Laboratory of Haifa and Western Galilee,
Clalit Health Services, Nesher, Israel.
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