An audit of the implementation of the international consensus group's guidelines on reporting of blood films

Efficient assessment of peripheral blood lymphocytosis in adults: developing new thresholds for blood smear review by pathologists

BACKGROUND

Peripheral smear review is a critical, but labor intensive adjunct for evaluation of lymphocytosis. Standard practice based on consensus guidelines is to review cases with absolute lymphocyte count (ALC) >5×109/L. We hypothesize that identifying cases for review by applying appropriately adjusted ALC and age discriminators will decrease laboratory workload without compromising patient care.

METHODS

1170 complete blood counts with ALCs >5×109/L analyzed in the core laboratory during a 2-year period were included. Patients were categorized into diagnostic groups based on follow-up criteria. A total of 402 patients with new onset lymphocytosis who met criteria for reactive lymphocytosis (82%) or lymphoproliferative disorder (18%) were used to establish optimal ALC and age thresholds from receiver operating characteristic (ROC) curve analysis.

RESULTS

ALC as a discriminator for neoplastic lymphocytosis had an ROC area under the curve (AUC) of 0.732. Selecting cases with ALC >10×109/L enriched the proportion of neoplastic cases in the review pool (90% specificity); however, many cases with ALC below this threshold were also neoplastic (52% sensitivity). For cases with ALC between 5 and 10×109/L, age as a discriminator had an ROC AUC of 0.886. Selecting patients >50 years old in this group for review captured the neoplastic cases while excluding the reactive cases (93% sensitivity, 62% specificity). When applied to a validation cohort, the predictive performance of the thresholds was maintained while reducing smears reviewed by 50%.

CONCLUSIONS

We show that modifying the standard 5×109/L ALC smear review threshold through retrospective analysis of institutional data can reduce laboratory workload without compromising quality.

Are the review criteria for automated complete blood counts of the International Society of Laboratory Hematology suitable for all hematology laboratories?

OBJECTIVE

to verify whether the review criteria for automated blood counts suggested by the International Consensus Group for Hematology Review of the International Society for Laboratory Hematology are suitable for the Hematology Laboratory of Hospital de Clinicas, Universidade Federal do Paraná.

METHODS

initially, the review criteria of the International Society for Laboratory Hematology were adapted due to limitations in the Institution's electronic hospital records and interfacing systems. The adapted review criteria were tested using 1977 samples. After this first assessment, an additional 180 inpatient samples were analyzed to evaluate the screening criteria of the review criteria in conjunction with positive smear findings established by the institution. The performance of the review criteria was verified by determining false positive, false negative, true positive and true negative rates, sensitivity, specificity, positive predictive value, negative predictive value, microscopic review rate and efficiency.

RESULTS

initial analysis showed false negatives=6.73%, false positives=23.27%, microscopic review rate=46.03% and efficiency=70.0%. An evaluation of the screening criteria adapted from the review criteria together with the positive smear findings of the institution showed false negatives=15.5%, false positives=10.5%, microscopic review rate=37.3% and efficiency=73.8%. In both situations the safety limit (false negative <5%) recommended by the review criteria was exceeded.

CONCLUSIONS

the review criteria adapted from the International Society for Laboratory Hematology are neither suitable nor safe for use in the hematology laboratory of the Hospital de Clinicas. This implies a need to develop and validate institution-specific review criteria in order to decrease false negative results to an acceptable and safe rate for patients.