Analysis of leucocyte populations with the Coulter S-Plus STKR as a screening tool for haematological abnormalities.
In two institutions at Rome and Florence we evaluated the clinical sensitivity of two Coulter STKR systems using the NCCLS standard H20-T for leucocyte differential count in a patient population with high prevalence of haematologic abnormalities. Reference ranges of normal leucocytes were obtained on 278 adult subjects. On a population of 455 patient specimens, 200 specimens (44%) were flagged by the STKR because of a distributional abnormality, and 122 (27%) because of a morphological abnormality. Percentage of subtotal agreements between the STKR and the reference manual differential count was 85.4%, with 67.5% full and 20.9% partial agreements. Eight specimens that showed a morphological abnormality with the reference manual differential count were classified as normal by the STKR, with a false normal rate of 6.6%. Analysis of the STKR performance for morphological abnormalities showed acceptable sensitivity (82.0%) and rather low specificity (71.5%), low predictive value of positive results (51.3), high predictive value of negative results (91.5%) and efficiency of 74.3%. The main problems of the STKR differential count were a high rate of false monocyte count, and the misidentification of eosinophilias and low-concentration abnormal cells.
d'Onofrio
G
G
Servizio di Ematologia, Università Cattolica del Sacro Cuore, Roma, Italia.
Salvati
A M
AM
Berti
P
P
Cappabianca
M P
MP
Marsili
G
G
Quarantelli
M
M
Zini
G
G
Casini
C
C
De Philippis
C
C
Mango
G
G
D005069:Evaluation Studies as Topic; D006402:Hematologic Diseases / Q000097:blood / Q000175:diagnosis* / Q000453:epidemiology; D006801:Humans; D007958:Leukocyte Count / Q000295:instrumentation*; D008403:Mass Screening / Q000379:methods*; D011237:Predictive Value of Tests; D015995:Prevalence; D012016:Reference Values; D012680:Sensitivity and Specificity