State University of New York at Buffalo, School of Pharmacy and Pharmaceutical Science, Buffalo, New York 14260, USA.
Pharmacoeconomics. 2010;28(7):567-75. doi: 10.2165/11533020-000000000-00000.
Patients hospitalized with Staphylococcus aureus bacteraemia have an unacceptably high mortality rate. Literature available to date has shown that timely selection of the most appropriate antibacterial may reduce mortality. One tool that may help with this selection is a polymerase chain reaction (PCR) assay that distinguishes methicillin (meticillin)-resistant S. aureus (MRSA) from methicillin-susceptible S. aureus (MSSA) in less than 1 hour. To date, no information is available evaluating the impact of this PCR technique on clinical or economic outcomes.
To evaluate the effect of a rapid PCR assay on mortality and economics compared with traditional empiric therapy, using a literature-derived model.
A literature search for peer-reviewed European (EU) and US publications regarding treatment regimens, outcomes and costs was conducted. Information detailing the rates of infection, as well as the specificity and sensitivity of a rapid PCR assay (Xpert MRSA/SA Blood Culture PCR) were obtained from the peer-reviewed literature. Sensitivity analysis varied the prevalence rate of MRSA from 5% to 80%, while threshold analysis was applied to the cost of the PCR test. Hospital and testing resource consumption were valued with direct medical costs, adjusted to year 2009 values. Adjusted life-years were determined using US and WHO life tables. The cost-effectiveness ratio was defined as the cost per life-year saved. Incremental cost-effectiveness ratios (ICERs) were calculated to determine the additional cost necessary to produce additional effectiveness. All analyses were performed using TreeAge Software (2008).
The mean mortality rates were 23% for patients receiving empiric vancomycin subsequently switched to semi-synthetic penicillin (SSP) for MSSA, 36% for patients receiving empiric vancomycin treatment for MRSA, 59% for patients receiving empiric SSP subsequently switched to vancomycin for MRSA and 12% for patients receiving empiric SSP for MSSA. Furthermore, with an MRSA prevalence of 30%, the numbers of patients needed to test in order to save one life were 14 and 16 compared with empiric vancomycin and SSP, respectively. The absolute mortality difference for MRSA prevalence rates of 80% and 5% favoured the PCR testing group at 2% and 10%, respectively, compared with empiric vancomycin and 18% and 1%, respectively, compared with empiric SSP. In the EU, the cost-effectiveness ratios for empiric vancomycin- and SSP-treated patients were Euro 695 and Euro 687 per life-year saved, respectively, compared with Euro 636 per life-year saved for rapid PCR testing. In the US, the cost-effectiveness ratio was $US 898 per life-year saved for empiric vancomycin and $US 820 per life-year saved for rapid PCR testing. ICERs demonstrated dominance of the PCR test in all instances. Threshold analysis revealed that PCR testing would be less costly overall, even at greatly inflated assay prices.
Rapid PCR testing for MRSA appears to have the potential to reduce mortality rates while being less costly than empiric therapy in the EU and US, across a wide range of MRSA prevalence rates and PCR test costs.
金黄色葡萄球菌菌血症住院患者的死亡率高得令人无法接受。迄今为止的文献表明，及时选择最合适的抗菌药物可能会降低死亡率。一种可能有助于这种选择的工具是聚合酶链反应（PCR）检测，可以在不到 1 小时的时间内区分耐甲氧西林金黄色葡萄球菌（MRSA）和甲氧西林敏感金黄色葡萄球菌（MSSA）。迄今为止，尚无关于该 PCR 技术对临床或经济结果的影响的信息。
使用文献衍生模型评估快速 PCR 检测与传统经验性治疗相比在死亡率和经济学方面的效果。
对欧洲（EU）和美国有关治疗方案、结果和成本的同行评议出版物进行了文献检索。从同行评议文献中获得了有关感染率以及快速 PCR 检测（Xpert MRSA/SA 血培养 PCR）的特异性和敏感性的详细信息。敏感性分析将 MRSA 的流行率从 5%变化到 80%，而阈值分析则应用于 PCR 检测的成本。使用直接医疗成本对医院和检测资源消耗进行估值，并调整为 2009 年的价值。使用美国和世界卫生组织的生命表确定调整后的生命年。成本效益比定义为每节省一个生命年的成本。使用 TreeAge 软件（2008 年）进行了增量成本效益比（ICER）的计算，以确定产生额外效果所需的额外成本。
接受经验性万古霉素治疗后转为半合成青霉素（SSP）治疗 MSSA 的患者死亡率为 23%，接受经验性万古霉素治疗 MRSA 的患者死亡率为 36%，接受经验性万古霉素治疗后转为万古霉素治疗 MRSA 的患者死亡率为 59%，接受经验性 SSP 治疗 MSSA 的患者死亡率为 12%。此外，当 MRSA 的流行率为 30%时，为了挽救一个生命，需要检测的患者人数分别为 14 和 16 例，与经验性万古霉素和 SSP 相比。对于 MRSA 流行率为 80%和 5%的情况，与经验性万古霉素相比，PCR 检测组的绝对死亡率差异分别为 2%和 10%，与经验性 SSP 相比，分别为 18%和 1%。在欧盟，经验性万古霉素和 SSP 治疗患者的成本效益比分别为每挽救一个生命年节省 695 欧元和 687 欧元，而快速 PCR 检测每挽救一个生命年节省 636 欧元。在美国，经验性万古霉素的成本效益比为每挽救一个生命年节省 898 美元，而快速 PCR 检测的成本效益比为每挽救一个生命年节省 820 美元。增量成本效益比表明在所有情况下 PCR 检测都具有优势。阈值分析表明，即使在 PCR 检测价格大幅上涨的情况下，PCR 检测的总体成本也会更低。
快速 PCR 检测 MRSA 似乎有可能降低死亡率，并且在欧盟和美国，在广泛的 MRSA 流行率和 PCR 检测成本范围内，比经验性治疗更具成本效益。
