Optimising risk-based screening strategies for tuberculosis infection in Wales: a retrospective cross-sectional study
1
Division of Population Medicine, Cardiff University, Cardiff, United Kingdom
2
Communicable Disease Surveillance Centre, Public Health Wales, Cardiff, United Kingdom
3
Centre for Trials Research, Cardiff University, Cardiff, United Kingdom
4
Division of Infection and Immunity, Cardiff University, Cardiff, United Kingdom
5
School of Medicine, Cardiff University, Cardiff, United Kingdom
6
Department of Infectious Diseases, Cardiff and Vale University Health Board, Cardiff, United Kingdom
7
Department of Respiratory Medicine, Aneurin Bevan University Health Board, Newport, United Kingdom
Popul. Med. 2026;8(Supplement Supplement 1):
ABSTRACT
BACKGROUND:
In low-incidence settings, tuberculosis (TB) cases are increasingly concentrated within specific populations, primarily from reactivation of TB infection. Characterising screening patterns for infection is essential for optimising prevention strategies.
METHODS:
Retrospective, cross-sectional analysis of interferon-gamma release assays (IGRAs) requested in Wales (United Kingdom) between January 2019 and December 2023. Screening groups were categorised by exposure and reactivation risks: (i) planned immunosuppression with biologic therapies (anti-TNF vs non-anti-TNF), (ii) high exposure risk (new entrants, workers from high-incidence countries, and inclusion health groups), and (iii) close contacts of TB disease. The primary outcome was IGRA positivity. Associations were examined using logistic regression with natural cubic splines for non-linear relationships. Screening efficiency was estimated using the number-needed-to-screen (NNS). TB disease cases and prior IGRA history were reviewed for missed opportunities.
RESULTS:
Among 15804 participants, IGRA positivity was 8.7%, varying by subgroup: 2.4% (pre-biologics), 14.3% (high exposure risk), and 12.4% (close contacts). Compared with pre-biologics, the odds of positivity were significantly higher among high-exposure risk (aOR 5.61, 95% CI 4.45-7.09) and close contacts (5.28, 4.11-6.79). Independent predictors included older age (non-linear), male sex (1.47, 1.30-1.67), and travel to or from a high-incidence country (2.60, 2.16-3.21). The median age of IGRA-positive individuals was 57 years (pre-biologics), 35 years (high exposure risk), and 39 years (contacts). Among positive pre-biologics, 43.0% were aged 65 years or older. Screening efficiency was lowest within pre-biologic pathways. Of 1402 participants with a positive IGRA, 63.0% initiated TB preventive therapy, 87.0% completed it, and 4.8% experienced adverse drug reactions.
CONCLUSIONS:
Substantial variation in screening yields among different risk groups in Wales supports targeted resource allocation: prioritising new entrants from high-incidence countries, inclusion health groups, close contacts, and adopting a risk-stratified approach to patients starting biologic therapies. Implementing this approach could optimise TB prevention strategies in other low-incidence settings.
In low-incidence settings, tuberculosis (TB) cases are increasingly concentrated within specific populations, primarily from reactivation of TB infection. Characterising screening patterns for infection is essential for optimising prevention strategies.
METHODS:
Retrospective, cross-sectional analysis of interferon-gamma release assays (IGRAs) requested in Wales (United Kingdom) between January 2019 and December 2023. Screening groups were categorised by exposure and reactivation risks: (i) planned immunosuppression with biologic therapies (anti-TNF vs non-anti-TNF), (ii) high exposure risk (new entrants, workers from high-incidence countries, and inclusion health groups), and (iii) close contacts of TB disease. The primary outcome was IGRA positivity. Associations were examined using logistic regression with natural cubic splines for non-linear relationships. Screening efficiency was estimated using the number-needed-to-screen (NNS). TB disease cases and prior IGRA history were reviewed for missed opportunities.
RESULTS:
Among 15804 participants, IGRA positivity was 8.7%, varying by subgroup: 2.4% (pre-biologics), 14.3% (high exposure risk), and 12.4% (close contacts). Compared with pre-biologics, the odds of positivity were significantly higher among high-exposure risk (aOR 5.61, 95% CI 4.45-7.09) and close contacts (5.28, 4.11-6.79). Independent predictors included older age (non-linear), male sex (1.47, 1.30-1.67), and travel to or from a high-incidence country (2.60, 2.16-3.21). The median age of IGRA-positive individuals was 57 years (pre-biologics), 35 years (high exposure risk), and 39 years (contacts). Among positive pre-biologics, 43.0% were aged 65 years or older. Screening efficiency was lowest within pre-biologic pathways. Of 1402 participants with a positive IGRA, 63.0% initiated TB preventive therapy, 87.0% completed it, and 4.8% experienced adverse drug reactions.
CONCLUSIONS:
Substantial variation in screening yields among different risk groups in Wales supports targeted resource allocation: prioritising new entrants from high-incidence countries, inclusion health groups, close contacts, and adopting a risk-stratified approach to patients starting biologic therapies. Implementing this approach could optimise TB prevention strategies in other low-incidence settings.
| eISSN: | 2654-1459 |
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