Fernanda Mattos de Souza

Comparison of Interferon-γ Release Assay to Two Cut-Off Points of Tuberculin Skin Test to Detect Latent Mycobacterium tuberculosis Infection in Primary Health Care Workers

Background An interferon-γ release assay, QuantiFERON-TB (QFT) test, has been introduced an alternative test for the diagnosis of latent Mycobacterium tuberculosis infection (LTBI). Here, we compared the performance of QFT with tuberculin skin test (TST) measured at two different cut-off points among primary health care work (HCW) in Brazil. Methods A cross-sectional study was carried out among HCWs in four Brazilian cities with a known history of high incidence of TB. Results of the QFT were compared to TST results based on both ≥5 mm and ≥10 mm as cut-off points. Results We enrolled 632 HCWs. When the cut-off value of ≥10 mm was used, agreement between QFT and TST was 69% (k = 0.31), and when the cut-off of ≥5 mm was chosen, the agreement was 57% (k = 0.22). We investigated possible factors of discordance of TST vs QFT. Compared to the TST−/QFT− group, risk factors for discordance in the TST+/QFT− group with TST cut-off of ≥5 mm included age between 41–45 years [OR = 2.70; CI 95%: 1.32–5.51] and 46–64 years [OR = 2.04; CI 95%: 1.05–3.93], BCG scar [OR = 2.72; CI 95%: 1.40–5.25], and having worked only in primary health care [OR = 2.30; CI 95%: 1.09–4.86]. On the other hand, for the cut-off of ≥10 mm, BCG scar [OR = 2.26; CI 95%: 1.03–4.91], being a household contact of a TB patient [OR = 1.72; CI 95%: 1.01–2.92] and having had a previous TST [OR = 1.66; CI 95%: 1.05–2.62], were significantly associated with the TST+/QFT− group. No statistically significant associations were found among the TST−/QFT+ discordant group with either TST cut-off value. Conclusions Although we identified BCG vaccination to contribute to the discordance at both TST cut-off measures, the current Brazilian recommendation for the initiation of LTBI treatment, based on information gathered from medical history, TST, chest radiograph and physical examination, should not be changed.

Prevalência e fatores associados à infecção pelo Mycobacterium tuberculosis entre agentes comunitários de saúde no Brasil, usando-se a prova tuberculínica

Este artigo tem por objetivo determinar a prevalencia e os fatores associados a infeccao latente pelo Mycobacterium tuberculosis entre agentes comunitarios de saude (ACS), usando dois pontos de corte da prova tuberculinica 5mm e 10mm. Trata-se de estudo transversal, com dados coletados sobre sexo, idade, cicatriz de BCG, prova tuberculinica (PT) anterior, tempo que trabalha na profissao de ACS, atuar em unidade basica de saude (UBS), ter tido contato intradomiciliar com tuberculose (TB), usar alcool, ser fumante e apresentar comorbidades. Para controle de variaveis de confusao e estimativa da medida de efeito (OR), foi empregada a regressao logistica. Aplicou-se PT, com leitura apos 48-72 horas. As prevalencias foram de 57,88% e 37,3%, respectivamente, para 5mm e 10mm. Manteve-se associada a positividade para o ponto de corte de 10mm a condicao de trabalhar em UBS com Programa de Controle de Tuberculose (PCT) implementado e ja ter tido contato intradomiciliar com TB. Ja para o ponto de corte de 5mm, trabalhar em UBS com PCT e implementado. Sao necessarias acoes de conscientizacao nos municipios e fortalecimento das acoes de educacao permanente sobre a tematica.This article aimed to determine the prevalence of latent Mycobacterium tuberculosis infection and associated factors in community health workers (CHW) in Brazil, using two cutoff points for the tuberculin skin test (5mm and 10mm). This was a cross-sectional study with data on gender, age, BCG scar, working in a primary care unit (PCU), having a household contact with tuberculosis (TB), alcohol consumption, previous tuberculin skin test (TST), smoking, time on the job as CHW, and comorbidities. Logistic regression was used to estimate odds ratios (OR) and to control for confounding. TST was applied and read after 48-72 hours. Prevalence rates were 57.88% and 37.3%, respectively, for the 5mm and 10mm TST cutoffs. Variables that remained associated with positive TST using the 10mm cutoff were working in a primary care unit that had implemented a Tuberculosis Control Program (TCP) and history of household contact with TB. Variables associated with the 5mm cutoff were working in a primary care unit with a TCP. Necessary actions at the local level include awareness-raising and strengthening of continuing education.

Prevalence of infection with Mycobacterium tuberculosis and associated factors in community health workers in Brazil based on the tuberculin skin test

Este artigo tem por objetivo determinar a prevalencia e os fatores associados a infeccao latente pelo Mycobacterium tuberculosis entre agentes comunitarios de saude (ACS), usando dois pontos de corte da prova tuberculinica 5mm e 10mm. Trata-se de estudo transversal, com dados coletados sobre sexo, idade, cicatriz de BCG, prova tuberculinica (PT) anterior, tempo que trabalha na profissao de ACS, atuar em unidade basica de saude (UBS), ter tido contato intradomiciliar com tuberculose (TB), usar alcool, ser fumante e apresentar comorbidades. Para controle de variaveis de confusao e estimativa da medida de efeito (OR), foi empregada a regressao logistica. Aplicou-se PT, com leitura apos 48-72 horas. As prevalencias foram de 57,88% e 37,3%, respectivamente, para 5mm e 10mm. Manteve-se associada a positividade para o ponto de corte de 10mm a condicao de trabalhar em UBS com Programa de Controle de Tuberculose (PCT) implementado e ja ter tido contato intradomiciliar com TB. Ja para o ponto de corte de 5mm, trabalhar em UBS com PCT e implementado. Sao necessarias acoes de conscientizacao nos municipios e fortalecimento das acoes de educacao permanente sobre a tematica.This article aimed to determine the prevalence of latent Mycobacterium tuberculosis infection and associated factors in community health workers (CHW) in Brazil, using two cutoff points for the tuberculin skin test (5mm and 10mm). This was a cross-sectional study with data on gender, age, BCG scar, working in a primary care unit (PCU), having a household contact with tuberculosis (TB), alcohol consumption, previous tuberculin skin test (TST), smoking, time on the job as CHW, and comorbidities. Logistic regression was used to estimate odds ratios (OR) and to control for confounding. TST was applied and read after 48-72 hours. Prevalence rates were 57.88% and 37.3%, respectively, for the 5mm and 10mm TST cutoffs. Variables that remained associated with positive TST using the 10mm cutoff were working in a primary care unit that had implemented a Tuberculosis Control Program (TCP) and history of household contact with TB. Variables associated with the 5mm cutoff were working in a primary care unit with a TCP. Necessary actions at the local level include awareness-raising and strengthening of continuing education.

Prevalencia y factores asociados a la infección porMycobacterium tuberculosis, usando la prueba tuberculina entre los agentes comunitarios de salud en Brasil

Este artigo tem por objetivo determinar a prevalencia e os fatores associados a infeccao latente pelo Mycobacterium tuberculosis entre agentes comunitarios de saude (ACS), usando dois pontos de corte da prova tuberculinica 5mm e 10mm. Trata-se de estudo transversal, com dados coletados sobre sexo, idade, cicatriz de BCG, prova tuberculinica (PT) anterior, tempo que trabalha na profissao de ACS, atuar em unidade basica de saude (UBS), ter tido contato intradomiciliar com tuberculose (TB), usar alcool, ser fumante e apresentar comorbidades. Para controle de variaveis de confusao e estimativa da medida de efeito (OR), foi empregada a regressao logistica. Aplicou-se PT, com leitura apos 48-72 horas. As prevalencias foram de 57,88% e 37,3%, respectivamente, para 5mm e 10mm. Manteve-se associada a positividade para o ponto de corte de 10mm a condicao de trabalhar em UBS com Programa de Controle de Tuberculose (PCT) implementado e ja ter tido contato intradomiciliar com TB. Ja para o ponto de corte de 5mm, trabalhar em UBS com PCT e implementado. Sao necessarias acoes de conscientizacao nos municipios e fortalecimento das acoes de educacao permanente sobre a tematica.This article aimed to determine the prevalence of latent Mycobacterium tuberculosis infection and associated factors in community health workers (CHW) in Brazil, using two cutoff points for the tuberculin skin test (5mm and 10mm). This was a cross-sectional study with data on gender, age, BCG scar, working in a primary care unit (PCU), having a household contact with tuberculosis (TB), alcohol consumption, previous tuberculin skin test (TST), smoking, time on the job as CHW, and comorbidities. Logistic regression was used to estimate odds ratios (OR) and to control for confounding. TST was applied and read after 48-72 hours. Prevalence rates were 57.88% and 37.3%, respectively, for the 5mm and 10mm TST cutoffs. Variables that remained associated with positive TST using the 10mm cutoff were working in a primary care unit that had implemented a Tuberculosis Control Program (TCP) and history of household contact with TB. Variables associated with the 5mm cutoff were working in a primary care unit with a TCP. Necessary actions at the local level include awareness-raising and strengthening of continuing education.