RESUMO
Importance: Rifampin-resistant tuberculosis treatment regimens require electrocardiographic (ECG) monitoring due to the use of multiple QTc-prolonging agents. Formal 12-lead ECG devices represent a significant burden in resource-constrained clinics worldwide and a potential barrier to treatment scale-up in some settings. Objective: To evaluate the diagnostic accuracy of a handheld 6-lead ECG device within resource-constrained clinics. Design, Setting, and Participants: This diagnostic study was performed within a multicenter, pragmatic (broad eligibility criteria with no exclusions for randomized participants), phase 3 rifampin-resistant tuberculosis treatment trial (BEAT Tuberculosis [Building Evidence for Advancing New Treatment for Tuberculosis]) in South Africa. A total of 192 consecutive trial participants were assessed, and 191 were recruited for this substudy between January 21, 2021, and March 27, 2023. A low proportion (3 of 432 [0.7%]) of all screened trial participants were excluded due to a QTc interval greater than 450 milliseconds. Triplicate reference standard 12-lead ECG results were human calibrated with readers blinded to 6-lead ECG results. Main Outcomes and Measures: Diagnostic accuracy, repeatability, and feasibility of a 6-lead ECG device. Results: A total of 191 participants (median age, 36 years [IQR, 28-45 years]; 81 female participants [42.4%]; 91 participants [47.6%] living with HIV) with a median of 4 clinic visits (IQR, 3-4 visits) contributed 2070 and 2015 12-lead and 6-lead ECG assessments, respectively. Across 170 participants attending 489 total clinic visits where valid triplicate QTc measurements were available for both devices, the mean 12-lead QTc measurement was 418 milliseconds (range, 321-519 milliseconds), and the mean 6-lead QTc measurement was 422 milliseconds (range, 288-574 milliseconds; proportion of variation explained, R2 = 0.4; P < .001). At a QTc interval threshold of 500 milliseconds, the 6-lead ECG device had a negative predictive value of 99.8% (95% CI, 98.8%-99.9%) and a positive predictive value of 16.7% (95% CI, 0.4%-64.1%). The normal expected range of within-individual variability of the 6-lead ECG device was high (±50.2 milliseconds [coefficient of variation, 6.0%]) relative to the 12-lead ECG device (±22.0 milliseconds [coefficient of variation, 2.7%]). The mean (SD) increase in the 12-lead QTc measurement during treatment was 10.1 (25.8) milliseconds, with 0.8% of clinic visits (4 of 489) having a QTc interval of 500 milliseconds or more. Conclusions and Relevance: This study suggests that simplified, handheld 6-lead ECG devices are effective triage tests that could reduce the need to perform 12-lead ECG monitoring in resource-constrained settings.
Assuntos
Eletrocardiografia , Humanos , Feminino , Masculino , Adulto , Eletrocardiografia/instrumentação , Eletrocardiografia/métodos , África do Sul , Pessoa de Meia-Idade , Síndrome do QT Longo/diagnóstico , Reprodutibilidade dos Testes , Tuberculose Resistente a Múltiplos Medicamentos/tratamento farmacológico , Tuberculose Resistente a Múltiplos Medicamentos/diagnóstico , Região de Recursos LimitadosRESUMO
BACKGROUND: Isoniazid-resistant tuberculosis (Hr-TB) is often overlooked in diagnostic algorithms due to reliance on first-line molecular assays testing only for rifampicin resistance. OBJECTIVES: To determine the prevalence, outcomes and molecular mechanisms associated with Hr-TB in the Eastern Cape, South Africa. METHODS: Between April 2016 and October 2017, sputum samples were collected from patients with rifampin-susceptible TB at baseline and at weeks 7 and 23 of drug-susceptible TB treatment. We performed isoniazid phenotypic and genotypic drug susceptibility testing, FluorotypeMTBDR, Sanger sequencing, targeted next-generation sequencing (tNGS), and whole genome sequencing. RESULTS: We analysed baseline isolates from 766 patients with rifampin-susceptible TB. Of 89 patients (11.7%) found to have Hr-TB, 39 (44%) had canonical katG or inhA promoter mutations; 35 (39%) had non-canonical katG mutations (including 5 with underlying large deletions); 4 (5%) had mutations in other candidate genes associated with isoniazid resistance. For 11 (12.4%), no cause of resistance was found. CONCLUSIONS: Among patients with rifampin-susceptible TB diagnosed using first-line molecular TB assays, there is a high prevalence of Hr-TB. Phenotypic DST remains the gold standard. To improve performance of genetic-based phenotyping tests, all isoniazid resistance associated regions should be included, and such tests should have the ability to identify underlying mutations.