Risk Factors for Tuberculosis (TB) Among Household Contacts of Patients With Smear-Positive TB in 8 Provinces of Vietnam: A Nested Case-Control Study

• Published in: Clinical infectious diseases Vol. 73; no. 9; pp. e3358 - e3364
• Main Authors: Velen, Kavindhran, Nhung, Nguyen Viet, Anh, Nguyen Thu, Cuong, Pham Duc, Hoa, Nguyen Binh, Cuong, Nguyen Kim, Dung, Nguyen Huy, Sy, Dinh Ngoc, Britton, Warwick John, Marks, Guy Barrington, Fox, Greg James
• Format: Journal Article
• Language: English
• Published: US Oxford University Press 02-11-2021
• Subjects: contact investigation; household; active case finding; tuberculosis
• ISSN: 1058-4838; 1537-6591
• DOI: 10.1093/cid/ciaa1742

Abstract
Background
Tuberculosis (TB) continues to account for significant morbidity and mortality annually. Household contacts (HHCs) of persons with TB are a key population for targeting prevention and control interventions. We aimed to identify risk factors associated with developing TB among HHCs.
Methods
We conducted a nested case-control study among HHCs in 8 provinces in Vietnam enrolled in a randomized controlled trial of active case finding for TB. Cases were any HHCs diagnosed and registered with TB within the Vietnam National TB Program during 2 years of follow-up. Controls were selected by simple random sampling from the remaining HHCs. Risk factor data were collected at enrollment and during follow-up. A logistic regression model was developed to determine predictors of TB among HHCs.
Results
We selected 1254 HHCs for the analysis: 214 cases and 1040 controls. Underlying characteristics varied between both groups; cases were older, more likely to be male, with a higher proportion of reported previous TB and diabetes. Risk factors associated with a TB diagnosis included being male (adjusted odds ratio [aOR], 1.4; 95% confidence interval [CI], 1.03–2.0), residing in an urban setting (aOR, 1.8; 1.3–2.5), prior TB (aOR, 4.6; 2.5–8.7), history of diabetes (aOR, 3.1; 1.7–5.8), current smoking (aOR, 3.1; 2.2–4.4), and prolonged history of coughing in the index case at enrollment (OR , 1.6; 1.1–2.3).
Conclusions
Household contacts remain an important key population for TB prevention and control. TB programs should ensure effective contact investigations are implemented for household contacts, particularly those with additional risk factors for developing TB.
Among household contacts of source cases in a high-tuberculosisburden setting, risk factors for tuberculosis development related to the household contact (male gender, urban setting, smoking, diabetes, and prior tuberculosis) and their source case (prior tuberculosis and prolonged cough).