[1992] Evaluating Peripheral Blood Lymphocytosis: Improving Efficiency While Maintaining Quality

Adam S Morgan, Victor Tseng, Catherine P Leith, David T Yang. University of Wisconsin, Madison, WI; Emory University, Atlanta, GA

Background: Peripheral smear review is a critical adjunct to automated CBC analysis when abnormalities are identified. Smear review is a large contributor to overall laboratory cost and productivity. An absolute lymphocyte count (ALC) >5000/uL is the consensus guideline for review of lymphocytosis. We hypothesize that evidence based adjustment of ALC and age discriminators will decrease the workload without compromising patient care.
Design: 1100 CBCs with ALCs >5000/uL analyzed in the core hematology laboratory for a two year period (2008-9) were included. Health records were reviewed and patients were categorized into diagnostic groups based on strictly defined follow-up criteria. 401 patients with new onset lymphocytosis who met criteria for reactive lymphocytosis (82%) or lymphoproliferative disorder (18%) were identified. Receiver operating characteristic (ROC) curve analysis was used to establish optimal ALC and age cut-offs for this group.
Results: As an initial screening discriminator between benign and disease populations, ALC has an ROC area under the curve (AUC) of 0.725 indicating a moderate degree of overlap between these two groups. Selecting cases with ALC >10,000/uL for review enriched the proportion of lymphoproliferative cases in the review pool (specificity = 90%) but decreased sensitivity (sensitivity = 52%). For this group of cases with ALC between 5,000 and 10,000/uL, age could be utilized as a disease discriminator, with an ROC AUC of 0.886.

Selecting patients >50 years old in this group for review efficiently captured the disease population with a sensitivity and specificity of 93% and 62%, respectively. Implementing these review criteria would have excluded 60/401 cases (15%) from review, including three lymphoproliferative cases, none of which have required treatment to date.
Conclusions: To our knowledge, this is the first retrospective cohort study evaluating all patients with newly discovered lymphocytosis, not just patients who underwent flow cytometry, for predictors of lymphoproliferative disorders. Our findings suggest that modifying the typical 5000/uL ALC smear review threshold through retrospective analysis of institutional data can reduce the laboratory workload without compromising quality.
Category: Quality Assurance

Tuesday, March 5, 2013 9:30 AM

Poster Session III # 303, Tuesday Morning


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