Quality of tuberculosis diagnostic laboratories in Ethiopia assessed through External Quality Assessment components: a systematic review

Reliable tuberculosis (TB) diagnosis is central to TB control programs, particularly in high-burden countries such as Ethiopia. External Quality Assessment (EQA) is a core component of laboratory quality assurance, encompassing blinded rechecking, panel testing, and on-site evaluation. This systematic review aimed to evaluate the quality of tuberculosis diagnostic laboratories in Ethiopia through EQA components and to synthesize evidence on laboratory performance, error patterns, and associated factors. A systematic review of published studies conducted in Ethiopia was performed. Seventeen original articles published between 2005 and 2025 were included. All studies assessed TB diagnostic laboratory quality using one or more EQA components. Data were extracted on study characteristics, EQA methods, performance indicators (sensitivity, specificity, agreement), error rates, and determinants of quality. A narrative synthesis approach was employed. Seventeen studies (n = 17) conducted between 2005 and 2025 met the inclusion criteria. EQA methods included blinded rechecking (n = 15), panel testing (n = 13), and on-site evaluation (n = 12). Reported sensitivity ranged from 83.5% to 96.6%, and specificity from 92.9% to 99.7%. Agreement between peripheral and reference laboratories was consistently high (κ = 0.60–0.97). Major errors, particularly high false negatives, were reported in several regions and were associated with poor smear quality, lack of internal quality control, inadequate training, reagent shortages, and absence of regular EQA participation. Decentralized and sustained EQA implementation demonstrated measurable improvements in laboratory performance over time. External Quality Assessment has substantially improved the quality of TB diagnostic laboratories in Ethiopia; however, persistent technical, infrastructural, and human resource gaps remain. Strengthening EQA coverage, integrating internal quality control, and continuous capacity building are essential to ensure reliable TB diagnosis and support national TB control efforts. Not applicable.