The clinical-diagnostic role of antistreptolysin O antibodies

The antistreptolysin O antibody (ASLO) test is often requested in a clinical setting with limited evidence for its usefulness. For this reason, the diagnostic scenario in which ASLO plays an evidence-based role and the analytical performance of the test are critically appraised, taking into account the clinical need and the direct medical cost. Little or no scientific evidence was found for the use of ASLO in patients with pharyngitis, post-streptococcal glomerulonephritis and in adults with rheumatoid arthritis. The clinical relevance of ASLO is restricted to paediatrics, where it contributes to fulfil the diagnosis of acute rheumatic fever (ARF) as per Jones criteria. The standardization of current automated ASLO-latex assays is limited. Attention should be paid to inaccurate reference values and many circumstances causing false positive and false negative results. Because of a low prevalence of ARF in the Western world, a high negative predictive value is obtained for the ASLO test (> 99%). In clinical practice, the result of the test is not urgent. To reduce overconsumption, the clinical laboratory should drive the request behaviour of physicians by a strategic lay-out of the application form. The health insurance/government also contributed by introducing a diagnostic rule for reimbursement.