Division of Global HIV/AIDS, Center for Global Health, US Centers for Disease Control and Prevention (CDC), 1600 Clifton Road NE, MS A-04, Atlanta, GA, 30329-4027, USA.
Division of Global HIV/AIDS, Center for Global Health, US Centers for Disease Control and Prevention (CDC), National Institute of Public Health, #80, 289 Samdach Penn Nouth St. (289), Phnom Penh, Cambodia.
Appl Health Econ Health Policy. 2018 Aug;16(4):537-548. doi: 10.1007/s40258-018-0397-3.
The Xpert MTB/RIF (Xpert) test has been shown to be effective and cost-effective for diagnosing tuberculosis (TB) under conditions with high HIV prevalence and HIV-TB co-infection but less is known about Xpert's cost in low HIV prevalence settings. Cambodia, a country with low HIV prevalence (0.7%), high TB burden, and low multidrug-resistant (MDR) TB burden (1.4% of new TB cases, 11% of retreatment cases) introduced Xpert into its TB diagnostic algorithms for people living with HIV (PLHIV) and people with presumptive MDR TB in 2012. The study objective was to estimate these algorithms' costs pre- and post-Xpert introduction in four provinces of Cambodia.
Using a retrospective, ingredients-based microcosting approach, primary cost data on personnel, equipment, maintenance, supplies, and specimen transport were collected at four sites through observation, records review, and key informant consultations.
Across the sample facilities, the cost per Xpert test was US$33.88-US$37.11, clinical exam cost US$1.22-US$1.84, chest X-ray cost US$2.02-US$2.14, fluorescent microscopy (FM) smear cost US$1.56-US$1.93, Ziehl-Neelsen (ZN) smear cost US$1.26, liquid culture test cost US$11.63-US$22.83, follow-on work-up for positive culture results and Mycobacterium tuberculosis complex (MTB) identification cost US$11.50-US$14.72, and drug susceptibility testing (DST) cost US$44.26. Specimen transport added US$1.39-US$5.21 per sample. Assuming clinician adherence to the algorithms and perfect test accuracy, the normative cost per patient correctly diagnosed under the post-Xpert algorithms would be US$25-US$29 more per PLHIV and US$34-US$37 more per person with presumptive MDR TB (US$41 more per PLHIV when accounting for variable test sensitivity and specificity).
Xpert test unit costs could be reduced through lower cartridge prices, longer usable life of GeneXpert (Cepheid, USA) instruments, and increased test volumes; however, epidemiological and test eligibility conditions in Cambodia limit the number of specimens received at laboratories, leading to sub-optimal utilization of current instruments. Improvements to patient referral and specimen transport could increase test volumes and reduce Xpert test unit costs in this setting.
Xpert MTB/RIF（Xpert）检测已被证明在高 HIV 流行率和 HIV-TB 合并感染的情况下，对诊断结核病（TB）是有效且具有成本效益的，但对于 HIV 低流行率环境下 Xpert 的成本知之甚少。柬埔寨是一个 HIV 流行率低（0.7%）、结核病负担重且耐多药（MDR）结核病负担低（新结核病病例的 1.4%，复治病例的 11%）的国家，于 2012 年将 Xpert 纳入其 HIV 感染者（PLHIV）和疑似 MDR-TB 患者的结核病诊断算法中。本研究的目的是在柬埔寨的四个省中，在引入 Xpert 前后估计这些算法的成本。
采用回顾性、基于成分的微观成本法，通过观察、记录审查和关键知情人咨询，在四个地点收集人员、设备、维护、用品和标本运输方面的主要成本数据。
在整个样本设施中，每个 Xpert 检测的成本为 33.88-37.11 美元，临床检查成本为 1.22-1.84 美元，胸部 X 光检查成本为 2.02-2.14 美元，荧光显微镜（FM）涂片成本为 1.56-1.93 美元，齐-尼二氏（ZN）涂片成本为 1.26 美元，液体培养试验成本为 11.63-22.83 美元，针对阳性培养结果和结核分枝杆菌复合群（MTB）鉴定的后续工作成本为 11.50-14.72 美元，药物敏感性试验（DST）成本为 44.26 美元。标本运输每例样本增加 1.39-5.21 美元。假设临床医生遵守这些算法，并且检测具有完美的准确性，那么根据 Xpert 后算法，每位正确诊断的 PLHIV 和疑似 MDR-TB 患者的规范成本将分别增加 25-29 美元和 34-37 美元（考虑到可变的检测灵敏度和特异性时，PLHIV 的成本增加 41 美元）。
可以通过降低试剂盒价格、延长 GeneXpert（Cepheid，美国）仪器的可用寿命和增加检测量来降低 Xpert 检测的单位成本；然而，柬埔寨的流行病学和检测资格条件限制了实验室收到的标本数量，导致当前仪器的利用率不足。改进患者转诊和标本运输可以增加检测量，并降低该环境下 Xpert 检测的单位成本。
