ASO titre cut-off values for normal children (80% ULN)
| Country | ULN | N | Age range | Technique | Year published | Handling of recent streptococcal infections |
| India (Chandigarh)7 | 239 IU | 200 | 5–15 | Microtitration haemolysin inhibition | 2003 | Medical record review, excluding previous history of recent throat infection. No information provided on length of historical review. |
| USA5 | 240 IU | 1131 | 2–12 | Microtitration haemolysin inhibition | 1997 | 1131 children with acute pharyngitis with positive throat culture for GAS—median time from symptoms to antibody titre 1.77 days, authors presume levels reflect a healthy population, as titres peak later after infection. |
| Fiji11 | 276 IU | 186 | 5–14 | Nephlometric | 2008 | Direct inquiry and medical record review, excluding previous history of RF/RHD/invasive GAS, and last 14 days ST/SS, and fever on day of enrolment. |
| Yemen9 | 276 IU | 404 | 5–15 | ELISA | 2015 | Direct inquiry and echocardiogram, excluding rheumatic heart disease proven on echocardiogram, recent GAS pharyngitis and any evidence of impetigo (including dry, crusted or pustule lesions). No information provided on length of historical review. |
| India (Mumbai)6 | 305 IU | 40 | 5–15 | Microtitration haemolysin inhibition | 2003 | Source of data not specified; excluded use of antibiotic therapy for joint pain, history of joint pain and features suggestive of sore throat in the last 3 months. No information provided on length of historical review for joint pain. |
| Australia (urban)10 | 320 IU | 64 | 4–14 | Microtitration haemolysin inhibition | 2005 | Excluded history of sore throat, pyoderma lesion or other possible disease caused by Streptococcus pyogenes in the preceding month (4 weeks), or was immunocompromised due to illness or immunosuppressive therapy. Source of data not specified. |
| Korea8 | 326 IU | 266 | 7–12 | ELISA | 2005 | Throat cultures and blood samples obtained from 266 healthy children (no signs or symptoms of streptococcal pharyngitis). Samples stratified into three groups: contained S. pyogenes, contained non-group A beta-haemolytic streptococci (BHS) and did not contain BHS. |
| Ethiopia15 | 360 IU | 127 | 5–15 | Latex agglutination | 2018 | Medical records reviewed, excluded those with a recent history of tonsillitis or impetigo. No information provided on length of historical review for tonsillitis. |
| Uganda (this study) | 389 IU | 181 | 5–14 | Nephlometric | 2019 | Direct inquiry and echocardiogram, excluded participants who had a temperature of >38.0°C on the day of enrolment, history of acute rheumatic fever, rheumatic heart disease evidence on echo or invasive GAS disease and a history in the previous 14 days of sore throat or skin sores. |
| Egypt3 | 400 IU | 660 | 5–10 | Latex agglutination | 2011 | Medical history and clinical examination; excluded recent history of tonsillitis or sore throat. No information provided on length of historical review for tonsillitis. |