Departamento de Clínica Médica, Faculdade de Ciências Médicas, Universidade Estadual de Campinas, Campinas, SP, Brazil.
Rev Soc Bras Med Trop. 2011 Jul-Aug;44(4):405-11. doi: 10.1590/s0037-86822011005000048. Epub 2011 Jul 22.
The case definition of influenza-like illness (ILI) is a powerful epidemiological tool during influenza epidemics.
A prospective cohort study was conducted to evaluate the impact of two definitions used as epidemiological tools, in adults and children, during the influenza A H1N1 epidemic. Patients were included if they had upper respiratory samples tested for influenza by real-time reverse transcriptase polymerase chain reaction during two periods, using the ILI definition (coughing + temperature ≤ 38ºC) in period 1, and the definition of severe acute respiratory infection (ARS) (coughing + temperature ≤ 38ºC and dyspnoea) in period 2.
The study included 366 adults and 147 children, covering 243 cases of ILI and 270 cases of ARS. Laboratory confirmed cases of influenza were higher in adults (50%) than in children (21.6%) ( p < 0.0001) and influenza infection was more prevalent in the ILI definition (53%) than ARS (24.4%) (p < 0.0001). Adults reported more chills and myalgia than children (p = 0.0001). Oseltamivir was administered in 58% and 46% of adults and children with influenza A H1N1, respectively. The influenza A H1N1 case fatality rate was 7% in adults and 8.3% in children. The mean time from onset of illness until antiviral administration was 4 days.
The modification of ILI to ARS definition resulted in less accuracy in influenza diagnosis and did not improve the appropriate time and use of antiviral medication.
流感样疾病（ILI）的病例定义是流感流行期间一种强大的流行病学工具。
一项前瞻性队列研究评估了两种定义作为流行病学工具在成人和儿童中的应用，这两种定义在甲型 H1N1 流感流行期间使用，分别为第 1 期的 ILI 定义（咳嗽+体温≤38°C）和第 2 期的严重急性呼吸道感染（SARI）定义（咳嗽+体温≤38°C 和呼吸困难）。如果患者在上呼吸道样本通过实时逆转录聚合酶链反应检测到流感病毒，他们将被纳入研究。
该研究共纳入 366 名成人和 147 名儿童，涵盖 243 例 ILI 和 270 例 SARI。实验室确诊的流感病例在成人（50%）中高于儿童（21.6%）（p<0.0001），ILI 定义（53%）中流感感染的发生率高于 SARI（24.4%）（p<0.0001）。成人比儿童更常报告寒战和肌痛（p=0.0001）。在成人和儿童中，分别有 58%和 46%的甲型 H1N1 流感患者使用了奥司他韦。成人的甲型 H1N1 流感病死率为 7%，儿童为 8.3%。从发病到开始使用抗病毒药物的平均时间为 4 天。
将 ILI 改为 SARI 定义会降低流感诊断的准确性，且不能改善抗病毒药物的合理使用和使用时机。
