Lab Med Online.  2011 Jul;1(3):153-157.

Re-evaluation of the Anti-streptolysin O Test for Systemic Rheumatic Diseases

  • 1Department of Laboratory Medicine, College of Medicine, Hanyang University, Seoul, Korea.


Anti-streptolysin O (ASO) test is usually used to diagnose group A streptococcal infection-related diseases, such as rheumatic fever, reactive arthritis, and various infectious diseases. Despite the recent declining incidence of these diseases, ASO test is still frequently performed as a screening test to diagnose rheumatic diseases. This study re-evaluated the clinical usefulness of ASO test in systemic rheumatic diseases (SRD).
ASO tests was performed in 825 patients between April and October in 2010. ASO levels were compared between SRD and non-SRD groups of patients. The results of ASO, C-reactive protein (CRP), and rheumatoid factor (RF) were compared among 6 subgroups of SRD: rheumatoid arthritis, systemic lupus erythematosus, ankylosing spondylitis, Behcet disease, Sjogren's syndrome and others.
Positive results in ASO test (>200 IU/mL) were observed in 15.3% (126/825) of the patients tested. None of the ASO positive patients was, however, diagnosed with rheumatic fever or reactive arthritis. There were no statistically significant differences in the mean value (P=0.688) or positive rate (P=0.835) of ASO test between SRD and non-SRD groups. Positive rates of ASO test were also not statistically significant different among six subgroups of SRD patients (all P>0.05), whereas those of CRP and RF tests were significantly different.
The usefulness of ASO test is very low for diagnosing SRD, although it is frequently carried out as a screening test. We suggest that ASO test must be performed selectively when diseases from group A streptococcal infection are suspected.


Anti-streptolysin O; Group A streptococcal infections; Systemic rheumatic disease
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