From the Centre for International Health, Department of Preventive and Social Medicine, University of Otago, Dunedin, New Zealand.
Institute of Environmental Science and Research, Wellington, New Zealand.
Pediatr Infect Dis J. 2019 Jan;38(1):e1-e6. doi: 10.1097/INF.0000000000002190.
Globally, there is wide variation in streptococcal titer upper limits of normal (ULN) for antistreptolysin O (ASO) and anti-deoxyribonuclease B (ADB) used as an evidence of recent group A streptococcal infection to diagnose acute rheumatic fever (ARF).
We audited ASO and ADB titers among individuals with ARF in New Zealand (NZ) and in Australia's Northern Territory. We summarized streptococcal titers by different ARF clinical manifestations, assessed application of locally recommended serology guidelines where NZ uses high ULN cut-offs and calculated the proportion of cases fulfilling alternative serologic diagnostic criteria.
From January 2013 to December 2015, group A streptococcal serology results were available for 350 patients diagnosed with ARF in NZ and 182 patients in Northern Territory. Median peak streptococcal titers were similar in both settings. Among NZ cases, 267/350 (76.3%) met NZ serologic diagnostic criteria, whereas 329/350 (94.0%) met Australian criteria. By applying Australian ULN titer cut-off criteria to NZ cases, excluding chorea, ARF definite cases would increase by 17.6% representing 47 cases.
ASO and ADB values were similar in these settings. Use of high ULN cut-offs potentially undercounts definite and probable ARF diagnoses. We recommend NZ and other high-burden settings to use globally accepted, age-specific, lower serologic cut-offs to avoid misclassification of ARF.
全球范围内，抗链球菌溶血素 O（ASO）和抗脱氧核糖核酸酶 B（ADB）的链球菌效价上限（ULN）用于诊断急性风湿热（ARF）的近期 A 组链球菌感染存在很大差异。
我们对新西兰（NZ）和澳大利亚北领地的 ARF 患者的 ASO 和 ADB 滴度进行了审核。我们根据不同的 ARF 临床表现总结了链球菌滴度，评估了 NZ 使用高 ULN 截止值的情况下当地推荐的血清学指南的应用，并计算了符合替代血清学诊断标准的病例比例。
2013 年 1 月至 2015 年 12 月，有 350 例 NZ 确诊的 ARF 患者和 182 例北领地患者的 A 组链球菌血清学结果可供分析。两种情况下的中位峰值链球菌滴度相似。在 NZ 病例中，267/350（76.3%）符合 NZ 血清学诊断标准，而 329/350（94.0%）符合澳大利亚标准。按照澳大利亚 ULN 滴度截止值标准应用于 NZ 病例，排除舞蹈病后，ARF 确诊病例将增加 17.6%，达到 47 例。
这些情况下 ASO 和 ADB 值相似。使用高 ULN 截止值可能会低估明确和可能的 ARF 诊断。我们建议 NZ 和其他高负担地区使用全球认可的、年龄特异性的、较低的血清学截止值，以避免 ARF 的误诊。
