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Free Content Reliability of the MODS assay decentralisation process in three health regions in Peru

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OBJECTIVE: To deliver rapid isoniazid (INH) and rifampicin (RMP) drug susceptibility testing (DST) close to the patient, we designed a decentralisation process for the microscopic observation drug susceptibility (MODS) assay in Peru and evaluated its reliability.

METHODS: After 2 weeks of training, laboratory staff processed ≥120 consecutive sputum samples each in three regional laboratories. Samples were processed in parallel with MODS testing at an expert laboratory. Blinded paired results were independently analysed by the Instituto Nacional de Salud (INS) according to pre-determined criteria: concordance for culture, DST against INH and RMP and diagnosis of multidrug-resistant tuberculosis (MDR-TB) ≥ 95%, McNemar's P > 0.05, kappa index (κ) ≥ 0.75 and contamination 1–4%. Sensitivity and specificity for MDR-TB were calculated.

RESULTS: The accreditation process for Callao (126 samples, 79.4% smear-positive), Lima Sur (n = 130, 84%) and Arequipa (n = 126, 80%) took respectively 94, 97 and 173 days. Pre-determined criteria in all regional laboratories were above expected values. The sensitivity and specificity for detecting MDR-TB in regional laboratories were >95%, except for sensitivity in Lima Sur, which was 91.7%. Contamination was 1.0–2.3%. Mean delay to positive MODS results was 9.9–12.9 days.

CONCLUSION: Technology transfer of MODS was reliable, effective and fast, enabling the INS to accredit regional laboratories swiftly.
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Keywords: MDR-TB; MODS assay; Peru; decentralisation

Document Type: Regular Paper

Affiliations: 1: Centro Nacional de Salud Pública, Instituto Nacional de Salud de Perú, Lima, Peru 2: Laboratorio Regional, Dirección Regional de Salud Callao–Ministerio de Salud, Callao, Peru 3: Laboratorio Regional, Dirección de Salud Lima Sur–Ministerio de Salud, Lima, Peru 4: Laboratorio Regional, Gerencia Regional de Salud de Arequipa, Arequipa, Peru 5: Universidad Peruana Cayetano Heredia, Lima, Peru 6: Estrategia Sanitaria Nacional de Prevención y Control de la Tuberculosis, Lima, Peru 7: Universidad Peruana Cayetano Heredia, Lima, Peru; and London School of Hygiene & Tropical Medicine, London, UK

Publication date: 2011-02-01

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  • The International Journal of Tuberculosis and Lung Disease publishes articles on all aspects of lung health, including public health-related issues such as training programmes, cost-benefit analysis, legislation, epidemiology, intervention studies and health systems research. The IJTLD is dedicated to the continuing education of physicians and health personnel and the dissemination of information on tuberculosis and lung health world-wide.

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