Comparison of manual and automated cell counts in EDTA preserved synovial fluids. Storage has little influence on the results

• Published in: Annals of the rheumatic diseases 1997-10, Vol.56 (10), p.622-626
• Main Authors: Salinas, María, Rosas, José, Iborra, José, Manero, Herminia, Pascual, Eliseo
• Format: Article
• Language: English
• Subjects: Agreements; Automation; Biological and medical sciences; Blood Preservation; cell count; Concise Reports; cytology; Edetic Acid; Electronic Data Processing; Fluids; Humans; Investigative techniques, diagnostic techniques (general aspects); Lymphocyte Count - methods; Medical sciences; Methods; Observer Variation; Osteoarticular system. Muscles; Pathology. Cytology. Biochemistry. Spectrometry. Miscellaneous investigative techniques; Reproducibility of Results; Sensitivity and Specificity; synovial fluid; Synovial Fluid - immunology; Temperature; Zinc
• ISSN: 0003-4967; 1468-2060
• DOI: 10.1136/ard.56.10.622

OBJECTIVE To determine the precision and agreement of synovial fluid (SF) cell counts done manually and with automated counters, and to determine the degree of variability of the counts in SF samples, kept in the tubes used for routine white blood cell (WBC) counts—which use liquid EDTA as anticoagulant—at 24 and 48 hours at 4°C, and at room temperature. METHODS To determine precision, cell counts were repeated 10 times—both manually and by an automated counter—in a SF sample of low, medium, and high cellularity. The variances were calculated to determine the interobserver variation in two manual (M1,M2) and two automated cell counts (C1,C2). The agreement between a manual (M1) and automated counter (C1) results, was analysed by the Bland and Altman method and the difference against the mean of the two methods was plotted. Then, the mean difference between the two methods was estimated and the standard deviation of the difference. To determine the effects of storage, SF samples were kept in a refrigerator at 4°C, and at room temperature; cell counts were done manually (M1) and automatically (C1) at 24 and 48 hours and the changes analysed by the Bland and Altman method. The variances were compared using an F test. RESULTS (1) Precision. With the manual technique, the coefficients of variation were 27.9%, 14%, and 10.7% when used for counting the SF with low (270), medium (6200), and high cellularities (25 000). With the automated technique the coefficients of variation were 20%, 3.4%, and 2.9% in the same SF samples. In the fluids of medium and high cellularity, the variances of the automated cell counts were significatively lower (F test, p