The problem with defining foreign birth as a risk factor in tuberculosis epidemiology studies

Area of Science:

• Public Health
• Epidemiology
• Infectious Disease Research

Background:

• Population-level tuberculosis (TB) surveillance often labels diverse groups as "foreign-born", potentially obscuring TB epidemiology and local transmission patterns.
• This broad categorization masks variable TB risks among individuals born outside the study country.

Purpose of the Study:

• To analyze how stratifying individuals by TB incidence in their birth country and demographic factors enhances understanding of TB epidemiology.
• To refine the assessment of local TB transmission patterns by moving beyond the "foreign-born" label.

Main Methods:

• Utilized population-level data from immigration and TB genotyping cohorts in British Columbia, Canada.
• Stratified active TB case counts, incidence rates, and genotypic clustering by birth country TB incidence, age at immigration, and years since arrival.

Main Results:

• Individuals from high-incidence countries exhibited a 12-fold higher TB incidence compared to those from low-incidence settings.
• Stratification revealed variations in estimates of local TB transmission versus reactivation of latent TB infection acquired abroad.
• Patient characteristics, including age and time since immigration, differed across stratified groups.

Conclusions:

• A more nuanced categorization of individuals beyond "foreign-born" is essential for accurate TB epidemiology and transmission analysis.
• Detailed stratification using TB incidence and demographic data improves understanding of TB rates and transmission patterns.