Drivers determining TB disease screening yield in four European screening programmes: a comparative analysis.

Abstract

The WHO End-TB Strategy emphasises screening for early diagnosis of tuberculosis (TB) in high-risk groups, including migrants. We analysed key drivers of TB yield differences in four large migrant TB screening programmes to inform TB control planning and feasibility of a European approach. We pooled individual TB screening episode data from Italy, the Netherlands, Sweden, and the UK and analysed predictors and interactions for TB case yield using multivariable logistic regression models. Between 2005-2018 in 2,302,260 screening episodes among 2,107,016 migrants to four countries; the programmes identified 1,658 TB cases (yield 72.0 per 100,000; 95% confidence interval, CI68.6-75.6). In logistic regression analysis, we found associations between TB screening yield and age (>55 years odds ratio, OR2.91, CI2.24-3.78), being an asylum seeker (OR3.19, CI1.03-9.83) or on a settlement visa (OR1.78, CI1.57-2.01), close TB contact (OR12.25, 11.73-12.79), and higher TB incidence in the country of origin (CoO). We demonstrated interactions between migrant typology and age, as well as CoO. For asylum seekers, the elevated TB risk remained similar above CoO incidence thresholds of 100 per 100,000. Key determinants of TB yield included close contact, increasing age, incidence in CoO and specific migrant groups including asylum seekers and refugees. For most migrants such as UK students and workers, TB yield significantly increased with levels of incidence in CoO. The high, CoO-independent TB risk in asylum seekers above a 100 per 100,000 threshold could reflect higher transmission and reactivation risk of migration routes; with implications for selecting populations for TB screening.