Background:
The complete blood cell count (CBC) with white blood cell (WBC) differential is an essential laboratory test used to screen cancer patients prior to chemotherapy. WBC differential analysis is performed by automated hematology platforms in the clinical laboratory. However, automated results often require manual review if the analysis is associated with instrument flags that indicate the potential for inaccurate results. Review and confirmation of flagged results by laboratory technologists is time consuming and increases test result turnaround time (TAT), thereby prolonging patient appointments. Since chemotherapy administration requires an adequate absolute neutrophil count (ANC), we examined the reliability of the automated ANC in the presence of instrument flags, in outpatients with solid tumor malignancies, to determine if discrete ordering of a "CBC with ANC only" test could be used to replace the traditional CBC with full WBC differential and shorten patient wait times.
Methods:
We performed a retrospective analysis of ANC test results (N=1422) performed for patients with solid tumor malignancies across 5 outpatient sites, over the course of one month. The accuracy of automated ANC results (Sysmex XN) was assessed by comparison to the manual differential using Rumke statistics.
Results:
Of the 1422 CBC with WBC differential results evaluated, 74% (N= 1046) were flagged for manual review. Instrument flags included blasts/abnormal lymphocytes, nucleated red blood cells (NRBC), WBC abnormal scattergram, monocytosis, previous sample with blasts, lymphocytosis, atypical lymphoid cells, eosinophilia, basophilia, and new patients with leukocytosis. Peripheral blood smear review confirmed the automated ANC in 312/1046 (30%) cases. A full manual differential was performed in 734/1046 cases (70%) and confirmed the automated ANC in 604/1046 (58%) cases. Discordant automated and manual ANC results were identified in 130 cases. In the majority of these (N=113), the automated ANC was > 2000/µL, well above chemotherapy administration thresholds, and generally lower than the manual ANC (Figure 1). The automated ANC was ≤ 2000/µL in only 30/1046 (2.9%) flagged WBC differential results.
Conclusion:
These findings support the concept of creating a distinct test order for "CBC with ANC only," when the ANC is required for the initiation of chemotherapy in patients with solid tumors. The data demonstrate that the automated ANC performed by the Sysmex XN can be safely resulted, even in the presence of analyzer flags, when the automated ANC is greater than 2000/µL. This would reduce patient wait times, increase patient satisfaction, as well as conserve laboratory and clinical resources. In our institution, the TAT for an automated and manual ANC is 10-15 minutes and 30-60 minutes, respectively. A reduction in manual differential analysis from 734 to 30 would represent a laboratory labor savings of approximately 2 full time equivalents (FTE). Additional savings are expected based on more efficient management of chemotherapy appointments. Further studies are ongoing to extend this testing algorithm to other outpatient groups such as patients with lymphoma.
No relevant conflicts of interest to declare.
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