PDF(Pubmed)
Abstract：
BACKGROUND: The aim of this study was to determine performance indicators of thick blood smears of 50 µl (TBS-50), following the Standards for the Reporting of Diagnostic Accuracy Studies-Bayesian Latent Class Model (STARD-BLCM) guidelines. TBS-50 was compared with two common parasitological techniques-direct examination of 10 µl blood and a leukoconcentration of 5 ml-for the diagnosis of microfilaremic loiasis.
METHODS: The study population was recruited among patients of the Department of Parasitology-Mycology-Tropical Medicine over a period of 1 year. Age, sex, symptoms, and eosinophilia variables were recorded from laboratory registers and medical files. Direct examination of 10 µl of blood, TBS-50, and the leukoconcentration technique with 5 ml of blood were performed for each patient. The classical formula and BLCM were used to determine the diagnostic accuracy of the three techniques as well as the prevalence of microfilaremic loiasis. Three models were built within the framework of BLCM-the BLCM model I and alternative models II and III-for sensitivity analysis.
RESULTS: In total, 191 patients consented to be included. The direct blood examination and TBS-50 yielded comparable qualitative and quantitative results. Hence, they are reported together. The prevalence of Loa loa microfilaremia was 9.4% (95% CI 5.7-14.5; n = 18/191) with direct blood examination/TBS-50 and 12.6% [8.2-18.1] (n = 24/191) for leukoconcentration. Comparing TBS-50 with the leukoconcentration method using the classical formula, the sensitivity was 75.0% [53.3-90.2], specificity was 100.0% [97.8-100.0], the positive predictive value was 100.0% [81.5-100.0], and the negative predictive value was 96.5% [92.6-98.7]. The prevalence of microfilaremic loiasis was estimated at 9.7% [6.2-13.7] using BLCM model I. The outputs of BLCM model I showed sensitivity of 78.9% [65.3-90.3], specificity of 100.0% [99.3-100.0], a positive predictive value of 99.1% [87.2-100.0], and a negative predictive value of 93.0% [87.3-97.7] for direct blood examination/TBS-50.
CONCLUSIONS: TBS-50 demonstrates low sensitivity relative to two other techniques. In one in five cases, the result will be falsely declared negative using these methods. However, this method can be deployed with limited funds.
METHODS: The study population was recruited among patients of the Department of Parasitology-Mycology-Tropical Medicine over a period of 1 year. Age, sex, symptoms, and eosinophilia variables were recorded from laboratory registers and medical files. Direct examination of 10 µl of blood, TBS-50, and the leukoconcentration technique with 5 ml of blood were performed for each patient. The classical formula and BLCM were used to determine the diagnostic accuracy of the three techniques as well as the prevalence of microfilaremic loiasis. Three models were built within the framework of BLCM-the BLCM model I and alternative models II and III-for sensitivity analysis.
RESULTS: In total, 191 patients consented to be included. The direct blood examination and TBS-50 yielded comparable qualitative and quantitative results. Hence, they are reported together. The prevalence of Loa loa microfilaremia was 9.4% (95% CI 5.7-14.5; n = 18/191) with direct blood examination/TBS-50 and 12.6% [8.2-18.1] (n = 24/191) for leukoconcentration. Comparing TBS-50 with the leukoconcentration method using the classical formula, the sensitivity was 75.0% [53.3-90.2], specificity was 100.0% [97.8-100.0], the positive predictive value was 100.0% [81.5-100.0], and the negative predictive value was 96.5% [92.6-98.7]. The prevalence of microfilaremic loiasis was estimated at 9.7% [6.2-13.7] using BLCM model I. The outputs of BLCM model I showed sensitivity of 78.9% [65.3-90.3], specificity of 100.0% [99.3-100.0], a positive predictive value of 99.1% [87.2-100.0], and a negative predictive value of 93.0% [87.3-97.7] for direct blood examination/TBS-50.
CONCLUSIONS: TBS-50 demonstrates low sensitivity relative to two other techniques. In one in five cases, the result will be falsely declared negative using these methods. However, this method can be deployed with limited funds.
摘要：
背景：这项研究的目的是确定50μl（TBS-50）的厚血涂片的性能指标，遵循诊断准确性研究报告标准-贝叶斯潜在类别模型(STARD-BLCM)指南。将TBS-50与两种常见的寄生虫学技术-直接检查10μl血液和5ml的白细胞浓度-进行了比较，以诊断微丝病。
方法：研究人群是在寄生虫-真菌学-热带医学系1年的患者中招募的。年龄,性别,症状,和嗜酸性粒细胞增多症变量从实验室登记簿和医疗档案中记录.直接检查10μl血液，对每位患者进行TBS-50和5ml血液的白细胞浓缩技术。经典公式和BLCM用于确定这三种技术的诊断准确性以及微丝病的患病率。在BLCM的框架内建立了三个模型-BLCM模型I和替代模型II和III-用于敏感性分析。
结果：总计，191名患者同意纳入。直接血液检查和TBS-50产生了可比的定性和定量结果。因此，他们一起报告。Loaloa微丝血症的患病率为9.4％（95％CI5.7-14.5；n=18/191），采用直接血液检查/TBS-50，白细胞浓度为12.6％[8.2-18.1]（n=24/191）。将TBS-50与使用经典公式的白细胞浓缩方法进行比较，灵敏度为75.0%[53.3-90.2]，特异性为100.0%[97.8-100.0]，阳性预测值为100.0%[81.5-100.0]，阴性预测值为96.5%[92.6-98.7]。使用BLCM模型I估计微丝病的患病率为9.7％[6.2-13.7]。BLCM模型I的输出显示灵敏度为78.9％[65.3-90.3]，特异性为100.0%[99.3-100.0]，阳性预测值为99.1%[87.2-100.0]，直接血液检查/TBS-50的阴性预测值为93.0％[87.3-97.7]。
结论：TBS-50相对于其他两种技术显示出低灵敏度。在五分之一的案例中，使用这些方法，结果将被错误地声明为否定。然而,这种方法可以用有限的资金来部署。
方法：研究人群是在寄生虫-真菌学-热带医学系1年的患者中招募的。年龄,性别,症状,和嗜酸性粒细胞增多症变量从实验室登记簿和医疗档案中记录.直接检查10μl血液，对每位患者进行TBS-50和5ml血液的白细胞浓缩技术。经典公式和BLCM用于确定这三种技术的诊断准确性以及微丝病的患病率。在BLCM的框架内建立了三个模型-BLCM模型I和替代模型II和III-用于敏感性分析。
结果：总计，191名患者同意纳入。直接血液检查和TBS-50产生了可比的定性和定量结果。因此，他们一起报告。Loaloa微丝血症的患病率为9.4％（95％CI5.7-14.5；n=18/191），采用直接血液检查/TBS-50，白细胞浓度为12.6％[8.2-18.1]（n=24/191）。将TBS-50与使用经典公式的白细胞浓缩方法进行比较，灵敏度为75.0%[53.3-90.2]，特异性为100.0%[97.8-100.0]，阳性预测值为100.0%[81.5-100.0]，阴性预测值为96.5%[92.6-98.7]。使用BLCM模型I估计微丝病的患病率为9.7％[6.2-13.7]。BLCM模型I的输出显示灵敏度为78.9％[65.3-90.3]，特异性为100.0%[99.3-100.0]，阳性预测值为99.1%[87.2-100.0]，直接血液检查/TBS-50的阴性预测值为93.0％[87.3-97.7]。
结论：TBS-50相对于其他两种技术显示出低灵敏度。在五分之一的案例中，使用这些方法，结果将被错误地声明为否定。然而,这种方法可以用有限的资金来部署。
