COMPARISON OF MANUAL AND AUTOMATED CELL COUNTS IN EDTA PRESERVED SYNOVIAL-FLUIDS - STORAGE HAS LITTLE INFLUENCE ON THE RESULTS

Objective-To determine the precision and agreement of synovial fluid ( SF) cell counts done manually and with automated counters, and to dete rmine the degree of variability of the counts in SH samples, kept in t he tubes used for routine white blood cell (WBC) counts-which use liqu id EDTA as anticoagulant-at 24 and 48 hours at 4 degrees C, and at roo m temperature, Methods-To determine precision, cell counts were repeat ed 10 times-both manually and by an automated counter-in a SF sample o f low, medium, and high cellularity. The variances were calculated to determine the interobserver variation in two manual (M1,M2) and two au tomated cell counts (C1,C2). The agreement between a manual (M1) and a utomated counter (C1) results, was analysed by the Bland and Altman me thod and the difference against the mean of the two methods was plotte d. Then, the mean difference between the trio methods was estimated an d the standard deviation of the difference, To determine the effects o f storage, SIF samples were kept in a refrigerator at 4 degrees C, and at room temperature; cell counts were done manually (M1) and automati cally (C1) at 24 and 48 hours and the changes analysed by the Bland an d Altman method. The variances were compared using an F test. Results- (1) Precision. With the manual technique, the coefficients of variatio n were 27.9%, 14%, and 10.7% when used for counting the SF with low (2 70), medium (6200), and high cellularities (25 000). With the automate d technique the coefficient of variation were 20%, 3.4%, and 2.9% in t he same SF samples. In the fluids of medium and high cellularity, the variances of the automated cell counts were significatively lower (F t est, p < 0.002) than those of the manual counts. (2) Inter-observer va riation. The variance between C1 and C2 (25 SF) was significatively lo wer (F test, p < 0.002) than that of the manual counts (41 SF). (3) Ag reement between the two techniques (100 SF). For cellularities above 2 000 cells/mm(3), the manual method gave results between +10% to -34% o f the results obtained by the coulter. For cellularities below 2000 ce lls/mm(3), manual cell counts were between +60 to -1280 cells/mm(3) of those obtained by the automated counter. (4) Influence of storage. Th e coulter counts of SF samples preserved at 4 degrees C showed less va riance (F test, p < 0.05) than the manual counts. The worst results we re obtained in manual counts of SF samples kept at room temperature; t hese samples at 48 hours showed a variation between -47% to 42% of the initial results. Conclusions-Automated cell count of the SF offers ad vantages: it gives higher precision and consumes less time. The stabil ity of the samples preserved in the EDTA tubes used for routine WBC co unts is of additional interest,because if delay cannot be avoided, the results of the WBC counts are still accurate at 24 and even at 48 hou rs, at Beast for clinical purposes.