Abstract
SummaryBackgroundThe epidemiological impact and cost-effectiveness of social protection and biomedical interventions for tuberculosis-affected households might be improved by risk stratification. We therefore derived and externally validated a household-level risk score to predict tuberculosis among contacts of patients with tuberculosis.MethodsIn this prospective cohort study, we recruited tuberculosis-affected households from 15 desert shanty towns in Ventanilla and 17 urban communities in Callao, Lima, Peru. Tuberculosis-affected households included index patients with a new diagnosis of tuberculosis and their contacts who reported being in the same house as the index patient for more than 6 h per week in the 2 weeks preceding index patient diagnosis. Tuberculosis-affected households were not included if the index patient had no eligible contacts or lived alone. We followed contacts until 2018 and defined household tuberculosis, the primary outcome, as any contact having any form of tuberculosis within 3 years. We used logistic regression to identify characteristics of index patients, contacts, and households that were predictive of household tuberculosis, and used these to derive and externally validate a household-level score.FindingsBetween Dec 12, 2007, and Dec 31, 2015, 16 505 contacts from 3 301 households in Ventanilla were included in a derivation cohort. During the 3-year follow-up, tuberculosis occurred in contacts of index patients in 430 (13%, 95% CI 12–14) households. Index patient predictors were pulmonary tuberculosis and sputum smear grade, age, and the maximum number of hours any contact had spent with the index patient while they had any cough. Household predictors were drug use, schooling of the female head of a household, and lower food spending. Contact predictors were if any of the contacts were children, number of lower-weight (body-mass index [BMI] <20·0 kg/m2) adult contacts, number of normal-weight (BMI 20·0–24·9 kg/m2) adult contacts, and number of past or present household members who previously had tuberculosis. In this derivation cohort, the score c statistic was 0·77 and the risk of household tuberculosis in the highest scoring quintile was 31% (95% CI 25–38; 65 of 211) versus 2% (95% CI 0–4; four of 231) in the lowest scoring quintile. We externally validated the risk score in a cohort of 4248 contacts from 924 households in Callao recruited between April 23, 2014, and Dec 31, 2015. During follow-up, tuberculosis occurred in contacts of index patients in 120 (13%, 95% CI 11–15) households. The score c statistic in this cohort was 0·75 and the risk of household tuberculosis in the highest scoring quintile was 28% (95% CI 21–36; 43 of 154) versus 1% (95% CI 0–5; two of 148) in the lowest scoring quintile. The highest-scoring third of households captured around 70% of all tuberculosis among contacts. A simplified risk score including only five variables performed similarly, with only a small reduction in performance.InterpretationThis externally validated score will enable comprehensive biosocial, household-level interventions to be targeted to tuberculosis-affected households that are most likely to benefit.FundingWellcome Trust, Medical Research Council, Department of Health and Social Care, Department for International Development, Joint Global Health Trials consortium, Bill & Melinda Gates Foundation, Innovation for Health and Development.
Highlights
Tuberculosis-affected households have intense tuber culosis transmission, with contacts of index patients with tuberculosis at substantially higher risk of latent tuber culosis infection and tuberculosis disease than other community members.1 the majority of tuberculosis transmission might occur outside the household, comprehensive interventions targeted to tuberculosis-affected households have the potential to reduce the population-level burden of tuberculosis.2–4 Such interventions include tuberculosis screening, surveillance, and preventive treatment for contacts, www.thelancet.com/infection Vol 20 January 2020Research in contextEvidence before this study We searched PubMed, Google Scholar, Web of Science, and Embase databases for studies published between database inception and Jan 1, 2019, that characterised the epidemiology, risk factors, and management of contacts of patients with tuberculosis
We investigated the association between index patient, household, and contact variables and household tuberculosis in univariable logistic regression models, including data from households recruited to the derivation cohort
Between Dec 12, 2007, and Dec 31, 2015, 3661 tuberculosisaffected households in Ventanilla and 1083 in Callao were recruited. 3301 (90%) of 3661 tuberculosis-affected households in Ventanilla were included in the derivation cohort, including 16 505 eligible contacts. 924 (85%) of 1083 of tuberculosis-affected households in Callao were included in the external validation cohort, including 4248 eligible contacts
Summary
Tuberculosis-affected households have intense tuber culosis transmission, with contacts of index patients with tuberculosis at substantially higher risk of latent tuber culosis infection and tuberculosis disease than other community members. the majority of tuberculosis transmission might occur outside the household, comprehensive interventions targeted to tuberculosis-affected households have the potential to reduce the population-level burden of tuberculosis. Such interventions include tuberculosis screening, surveillance, and preventive treatment for contacts, www.thelancet.com/infection Vol 20 January 2020Research in contextEvidence before this study We searched PubMed, Google Scholar, Web of Science, and Embase databases for studies published between database inception and Jan 1, 2019, that characterised the epidemiology, risk factors, and management of contacts of patients with tuberculosis. The majority of tuberculosis transmission might occur outside the household, comprehensive interventions targeted to tuberculosis-affected households have the potential to reduce the population-level burden of tuberculosis.. The majority of tuberculosis transmission might occur outside the household, comprehensive interventions targeted to tuberculosis-affected households have the potential to reduce the population-level burden of tuberculosis.2–4 Such interventions include tuberculosis screening, surveillance, and preventive treatment for contacts, www.thelancet.com/infection Vol 20 January 2020. Despite strong evidence of their value, these interventions are infrequently implemented in many settings because of a lack of programmatic focus on tuberculosis prevention and limited resources To help address this challenge, we previously derived and externally validated a risk score that predicts the risk of tuberculosis among individual adult contacts of patients with laboratory confirmed tuberculosis, independently of baseline latent tuberculosis infection status.
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