Prediction of Upper Limits of Normal Values of Anti Streptolysin ‘O’ Titres in Normal Healthy School Going Children of 6–16 Years

Abstract

Antistreptolysin O test, an internationally gold standard test is widely used in detection of group A streptococcal infections and their sequelae at global level. An observational study was conducted at Bengaluru city during 2015-16. A total 454 children were randomly selected from the different schools in Bangalore city. As per the results, the sex ratio was 1:1(Male 230/454, Female 224/454) with mean age 12.58±2.63 years. The titre mean ASO value was 275.93±248.73 IU, median value was 202 IU. The average cut of ASO value was 256.53IU with good specificity (95.0%), sensitivity (88.05%), PPV (85.33%), NPV (68.93%); AUC was 0.93. The resulted findings was found to be statistically significant (P<0.01) and also this mean value will help for detection of streptococcal infections at population level (p<0.01). Majority of the cases were suffering from acute rheumatic fever (80%). Test algorithms was formulated by ROC analysis, the results showed that, the AUC of non-suppurative sequelae of Group-A streptococcal (GAS) infection of the throat (63.0%). The summing of the results concludes that, the ASO is a gold standard for the investigation of the disease progression at early stage (streptococcal and rheumatic fever). This present study will help to clinician’s for diagnose streptococcal infection at greater accuracy.