van Cleeff M R A, Kivihya-Ndugga L E, Meme H, Odhiambo J A, Klatser P R
KNCV Tuberculosis Foundation, The Hague, The Netherlands.
BMC Infect Dis. 2005 Dec 12;5:111. doi: 10.1186/1471-2334-5-111.
The objective of this study was to establish 1) the performance of chest X-ray (CXR) in all suspects of tuberculosis (TB), as well as smear-negative TB suspects and 2) to compare the cost-effectiveness of the routine diagnostic pathway using Ziehl-Neelsen (ZN) sputum microscopy followed by CXR if case of negative sputum result (ZN followed by CXR) with an alternative pathway using CXR as a screening tool (CXR followed by ZN).
From TB suspects attending a chest clinic in Nairobi, Kenya, three sputum specimens were examined for ZN and culture (Lowenstein Jensen). Culture was used as gold standard. From each suspect a CXR was made using a four point scoring system: i: no pathology, ii: pathology not consistent for TB, iii: pathology consistent for TB and iv: pathology highly consistent for TB. The combined score i + ii was labeled as "no TB" and the combined score iii + iv was labeled as "TB". Films were re-read by a reference radiologist. HIV test was performed on those who consented. Laboratory and CXR costs were used to compare for cost-effectiveness.
Of the 1,389 suspects enrolled, for 998 (72%) data on smear, culture and CXR was complete. 714 films were re-read, showing a 89% agreement (kappa value = 0.75 s.e.0.037) for the combined scores "TB" or "no-TB". The sensitivity/specificity of the CXR score "TB" among smear-negative suspects was 80%/67%. Using chest CXR as a screening tool in all suspects, sensitivity/specificity of the score "any pathology" was 92%, respectively 63%. The cost per correctly diagnosed case was for the routine process 8.72 dollars, compared to 9.27 dollars using CXR as screening tool. When costs of treatment were included, CXR followed by ZN became more cost-effective.
The diagnostic pathway ZN followed by CXR was more cost-effective as compared to CXR followed by ZN. When cost of treatment was also considered CXR followed by ZN became more cost-effective. The low specificity of chest X-ray remains a subject of concern. Depending whether CXR was performed on all suspects or on smear-negative suspects only, 22%-45% of patients labeled as "TB" had a negative culture. The introduction of a well-defined scoring system, clinical conferences and a system of CXR quality control can contribute to improved diagnostic performance.
本研究的目的是确定1）胸部X线检查（CXR）在所有结核病（TB）疑似患者以及痰涂片阴性的TB疑似患者中的表现，以及2）比较常规诊断途径（采用萋-尼氏（ZN）痰涂片显微镜检查，若痰检结果为阴性则进行CXR检查（ZN检查后进行CXR检查））与另一种以CXR作为筛查工具的途径（CXR检查后进行ZN检查）的成本效益。
从肯尼亚内罗毕一家胸部诊所的TB疑似患者中，采集三份痰标本进行ZN检查和培养（罗氏培养基）。培养结果用作金标准。为每位疑似患者进行CXR检查，并使用四点评分系统：i：无病变，ii：病变与TB不符，iii：病变与TB相符，iv：病变高度符合TB。综合评分i + ii标记为“非TB”，综合评分iii + iv标记为“TB”。由一位参考放射科医生重新阅读胸片。对同意的患者进行HIV检测。使用实验室和CXR检查的成本来比较成本效益。
在纳入的1389名疑似患者中，998名（72%）的痰涂片、培养和CXR检查数据完整。重新阅读了714份胸片，“TB”或“非TB”综合评分的一致性为89%（kappa值 = 0.75，标准误0.037）。痰涂片阴性疑似患者中CXR评分“TB”的敏感性/特异性为80%/67%。在所有疑似患者中使用胸部CXR作为筛查工具，评分“有任何病变”的敏感性/特异性分别为92%和63%。常规流程每正确诊断一例的成本为8.72美元，而使用CXR作为筛查工具时为9.27美元。当纳入治疗成本时，CXR检查后进行ZN检查变得更具成本效益。
与CXR检查后进行ZN检查相比，ZN检查后进行CXR检查的诊断途径更具成本效益。当考虑治疗成本时，CXR检查后进行ZN检查变得更具成本效益。胸部X线检查的低特异性仍然是一个令人担忧的问题。根据CXR检查是针对所有疑似患者还是仅针对痰涂片阴性的疑似患者进行，22%-45%被标记为“TB”的患者培养结果为阴性。引入明确的评分系统、临床会诊和CXR质量控制体系有助于提高诊断性能。
