Department of Community Medicine, University of Port Harcourt Teaching Hospital, Rivers State. Email:
Department of Community Medicine, River State University. Email:
West Afr J Med. 2024 Jun 28;41(6):682-690.
Antimicrobial resistance is a growing global public health concern, and multidrug-resistant Tuberculosis is responsible for roughly one-quarter of all antimicrobial-resistant infection-related deaths worldwide. GeneXpert is a rapid, automated molecular test that detects multi-drug-resistant Tuberculosis using Rifampicin as a predictor. The World Health Organization (WHO) in 2010 recommended GeneXpert for national tuberculosis programs in developing countries; however, it has limitations. Indeterminate results for Mycobacterium tuberculosis indicate that the test could not determine whether the bacteria were resistant to Rifampicin. This study used the Shewhart Control Chart, which has action limits, to investigate the causes of indeterminate results.
GeneXpert indeterminate results obtained between January and December 2019 in a tertiary hospital in a low and middle-income country were plotted. The control limits on the Shewhart chart are central, upper, and lower. Points above the upper control limit and successive points occurring in one zone were used to determine whether or not the process was under control.
The resultant p-chart showed five points that were within the control limit, two points above the upper control limit, and five points consecutively in one zone on the plot. The former was characteristic of a stable process, while the latter was indicative of a special course variation respectively. The majority of the laboratory findings indicated an out-of-control signal.
GeneXpert indeterminate results impact patient management by preventing accurate diagnosis and delaying the start of anti-tuberculosis medication. Machine malfunctions, low bacterial load, poor-quality samples, operator errors, or faulty laboratory materials could all be to blame. Regular equipment checks by laboratory personnel, program sponsors, or leadership will be highly beneficial in achieving the desired results and initiating appropriate treatment. A large sample size or a multicenter study, could provide more data and yield more robust findings about nonconforming laboratory processes in diagnosing Rifampicin resistance.
抗菌药物耐药性是一个日益严重的全球公共卫生问题，全球约四分之一的与抗菌药物耐药相关的死亡归因于耐多药结核病。GeneXpert 是一种快速、自动化的分子检测方法，使用利福平作为预测因子来检测耐多药结核病。世界卫生组织（WHO）于 2010 年建议将 GeneXpert 用于发展中国家的国家结核病规划；然而，它存在一些局限性。结核分枝杆菌检测结果不确定表明该检测无法确定细菌是否对利福平耐药。本研究使用具有行动限的休哈特控制图来调查不确定结果的原因。
在一个中低收入国家的一家三级医院，对 2019 年 1 月至 12 月间获得的 GeneXpert 不确定结果进行了绘图。休哈特图的控制限包括中心限、上限和下限。位于上限控制限之上的点和连续出现在一个区域中的点用于确定过程是否处于控制之下。
所得的 p 图显示，有五个点在控制限内，两个点在上限控制限之上，五个点连续出现在一个区域中。前者是过程稳定的特征，后者则表示特殊过程变化。大多数实验室结果表明存在失控信号。
GeneXpert 不确定结果通过阻止准确诊断和延迟抗结核药物的开始使用，影响患者的管理。可能的原因包括机器故障、细菌负荷低、样本质量差、操作人员错误或实验室材料故障等。实验室人员、项目赞助者或领导层定期进行设备检查将非常有益，可以达到预期结果并启动适当的治疗。较大的样本量或多中心研究可以提供更多数据，并对诊断利福平耐药性的非规范实验室过程产生更稳健的发现。
