Comparative Evaluation of Rapid and Conventional Diagnostic Tests for Tuberculosis Detection

Thesis Abstract

Tuberculosis (TB) continues to pose a significant public health challenge globally, particularly in resource-limited settings where timely and accurate diagnosis remains critical for effective disease management and control. Despite the availability of traditional conventional diagnostic methods such as sputum microscopy and culture, these techniques are often limited by their lengthy processing times, varying sensitivity, and the requirement for specialized laboratory infrastructure. Rapid diagnostic tests, including molecular assays like GeneXpert MTB/RIF and lateral flow immunoassays, have emerged as promising alternatives, offering potential improvements in diagnostic speed and accuracy. This study aims to critically evaluate and compare the performance, cost-effectiveness, and operational feasibility of rapid versus conventional diagnostic tests for TB detection within clinical settings. The specific objectives include assessing the sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of selected rapid tests in comparison with conventional methods; analyzing the turnaround time for each diagnostic approach; evaluating the cost implications and resource requirements associated with implementation; and determining patient and healthcare worker satisfaction levels with each testing modality. The study employed a cross-sectional analytical research design, integrating quantitative and qualitative methodologies. The research was conducted at three tertiary healthcare facilities, targeting a population of 1,200 patients presenting with suspected pulmonary TB over a six-month period. A stratified random sampling technique was used to select 400 participants, ensuring representativeness across age, gender, and clinical presentation categories. Data collection instruments comprised structured clinical data forms, laboratory testing sheets, and patient/healthcare worker satisfaction questionnaires. Laboratory tests included acid-fast bacilli (AFB) smear microscopy, culture on Lowenstein-Jensen media, and the GeneXpert MTB/RIF assay, with sequential testing performed on each patient specimen. The validation of data collection instruments involved pre-testing and calibration procedures, ensuring high reliability (Cronbach's alpha > 0.85) and validity. Data were analyzed using SPSS version 26.0. Descriptive statistics summarized demographic and clinical characteristics. Diagnostic performance metrics—sensitivity, specificity, PPV, and NPV—were calculated with 95% confidence intervals. Comparative analysis of turnaround times employed ANOVA, while cost analysis involved comprehensive cost-effectiveness modeling and cost-benefit analyses. Cohen’s kappa coefficient assessed agreement between diagnostic methods. Qualitative data from satisfaction surveys were analyzed thematically. The study hypothesized that rapid diagnostic tests yield superior sensitivity and comparable specificity relative to conventional techniques and are associated with shorter turnaround times and lower overall costs. Expected findings indicate that molecular tests, particularly GeneXpert MTB/RIF, demonstrate higher sensitivity (expected range 85–95%) compared to sputum microscopy (expected range 50–70%), with specificity exceeding 90%. Rapid tests are anticipated to significantly reduce diagnostic turnaround times from an average of 48 hours (culture) to less than two hours (GeneXpert), enabling faster clinical decision-making. Cost analysis is projected to favor rapid tests in high-burden, resource-limited settings by reducing personnel and reagent costs associated with culture, despite higher initial device procurement expenditure. The study’s anticipated contribution lies in providing empirical evidence to inform policy decisions related to TB diagnostics, emphasizing the balance between accuracy, speed, and cost-effectiveness. This research will contribute to the existing body of knowledge by delineating the operational advantages and limitations of rapid diagnostic tests in real-world healthcare contexts. The main conclusion underscores that integrating rapid molecular diagnostics into TB control programs enhances early detection, improves patient management, and potentially reduces disease transmission. Recommendations include advocating for broader adoption of GeneXpert MTB/RIF in resource-constrained settings, developing tailored implementation strategies to address infrastructural challenges, and conducting further longitudinal studies to evaluate the impact of rapid diagnostics on TB treatment outcomes and epidemiology. The findings aim to guide stakeholders—health policymakers, clinicians, and laboratory scientists—in optimizing TB diagnostic algorithms to achieve timely diagnosis, cost efficiency, and improved patient care outcomes.