Antistreptolysin O (ASO) test is the commonly requested one by clinicians which reflects the status of post-streptococcal infection. The ASO test would be very useful not only to diagnose acute streptococcal infections, but evaluate the
therapeutic
effect or disease progression. Since 1980s, the assay methods of ASO concentration have been transforming into quantitatively from semi-qunatitive or quantitative methods in order to evaulate patient's condition more accurately. The authors
evaluated
the precision, linearity and correlation of two quantitative ASO assay methods, Array Protein System (Beckman, USA) based on nephelometry and Hitachi-747 (Hitachi, Japan) based on latex agglutination method on 135 sera. The coefficients of
variation of
Array Protein System (X) and Hitachi-747 (Y) were 2.2% (within-run), 2.4% (between -run) and 1.3-6.9% (within-run), 1.4-5.0% (between-run) respectively. The correlation between two quantitative assays was Y=1.1X-104.8(r=0.89). The concordance
rates
of a
qualitative ASO latex Reagents(Kukdong, Japan) compared with Array Protein System and Hitachi-747 were relatively high, 81% and 87% respectively. The concordance rates of a semi-quantitative RapiTex ASL (Behring, Germany) compared with Array
Protein
System and Hitachi-747 were variable, 62% and 95% respectively. More proficency and experience might be necessary in the evaluation and standardization of quantitative ASO assays.
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