汗液电导率检测对儿童囊性纤维化的诊断价值分析

Value of sweat conductivity testing in the diagnosis of cystic fibrosis in children

目的评估汗液电导率检测对中国儿童囊性纤维化(CF)的诊断价值。方法回顾性研究,收集2014年5月至2018年6月在首都医科大学附属北京儿童医院呼吸二科确诊的45例CF患儿(CF组)和200例患肺部疾病的非CF患儿(非CF组)的汗液,进行汗液电导率检测,通过Pearson χ2检验比较两组之间的差异,并绘制受试者工作特征曲线计算汗液电导率诊断或排除CF的最佳临界值。分析6岁以上CF患儿肺功能参数(第1秒用力呼气量、用力肺活量、用力呼气流量取75%肺活量时的呼气流速),分两组(80~120 mmol/L和>120 mmol/L)比较汗液电导率水平与肺功能的关系。结果CF组年龄为9(7,12)岁,男19例(42%),女26例(58%);非CF组年龄8(5,11)岁,男106例(53%),女94例(47%)。汗液电导率检测结果显示:CF组汗液电导率108(99,122)mmol/L明显高于非CF组43(36,52)mmol/L(χ^2=207,P<0.01);以80 mmol/L作为诊断CF的临界值,灵敏度93.33%,特异度98.50%;受试者工作特征曲线显示诊断CF的最佳临界值为83.5 mmol/L,灵敏度93.3%,特异度100%,曲线下面积为0.993(95%置信区间为0.985~1.000);排除CF的最佳临界值为63.5 mmol/L,灵敏度97.80%,特异度90.5%。汗液电导率的水平和肺功能下降程度无相关性。结论汗液电导率检测可以用于中国儿童CF的筛查,当数值超过80 mmol/L,应考虑CF可能。

Objective To assess the diagnostic value of sweat conductivity testing in Chinese children with cystic fibrosis (CF). MethodsThis is a retrospective study. Sweat conductivity tests were conducted in 45 CF children (CF group) and 200 non-CF children (non-CF group) diagnosed with other chronic pulmonary diseases at the No. 2 Department of Respiratory Medicine, Beijing Children′s Hospital from May 2014 to June 2018. Pearson′s chi-square test was used to assess the differences between CF and non-CF groups. A receiver operating characteristic curve was constructed to calculate the best cut-off value to diagnose or rule out CF. The pulmonary function parameters (forced expiratory volume in the first second, forced vital capacity,forced expiratory flows at 75% of exhaled vital capacity) of CF children over 6 years old were analyzed. The relationship between sweat conductivity and pulmonary function was compared between the two groups (80-120mmol/L vs.>120mmol/L). Results The age of CF group was 9 (7,12) years old, 19 males (42%) and 26 females(58%);the age of non-CF group was 8 (5,11) years old, 106 males (53%) and 94 females(47%). The results of sweat conductivity test showed that sweat conductivity in CF group 108(99, 122) mmol/L was significantly higher than that in non-CF group 43(36, 52) mmol/L (χ^2=207, P<0.01). A cut-off value of 80 mmol/L for CF diagnosis showed a sensitivity of 93.3% and a specificity of 98.5%. The receiver operating characteristic curve analysis suggested the best conductivity cut-off value for the diagnosis of CF was at 83.5 mmol/L,with a sensitivity of 93.3% and a specificity of 100%,and an area under the curve of 0.993 (95% confidence interval 0.985-1.000). The best conductivity cut-off value to rule out CF diagnosis was at 63.5 mmol/L,with a sensitivity of 97.8% and a specificity of 90.5%. There was no correlation between the level of sweat conductivity and the extent of pulmonary function decline. Conclusions Sweat conductivity testing can be used for the screening of CF in Chinese children. A diagnosis of CF should be considered if the value is greater than 80 mmol/L.