Yield of tuberculosis contact investigations in Amsterdam: opportunities for improvement

We aimed to determine the coverage and yield of tuberculosis contact investigation, and compliance with guidelines, and to identify opportunities for improvement. Data were extracted from records on contacts of pulmonary tuberculosis patients at the Public Health Service (Amsterdam, the Netherlands) from 2008 to 2011. Additional data were obtained from the national tuberculosis register. Among 3743 contacts of 235 pulmonary tuberculosis index patients, 2337 (62%) were screened for latent tuberculosis infection (LTBI). Those less likely to be screened for LTBI included contacts of sputum smear-negative index patients (adjusted odds ratio (a0R) 0.6, 95% CI 0.4-0.9) and bacille Calmette Guerin (BCG)-vaccinated contacts (aOR 0.06, 95% CI 0.04-0.09). Among BCG-vaccinated contacts, the proportion screened increased from 9% in 2008 to 43% in 2011 (p-value for trend <0.001). LTBI diagnosis among contacts screened was associated with non-Dutch nationality (aOR 2.8, 95% CI 1.9-4.1) and being a close contact (aOR 4.0, 95% CI 1.9-8.3). Of the 254 contacts with LTBI diagnosis, 142 (56%) started preventive treatment. Starting treatment was associated with Dutch nationality (aOR 2.6, 95% CI 1.2-5.4) and being a close contact (aOR 10.5, 95% CI 1.5-70.7). Treatment completion was achieved by 129 (91%) of the 142 contacts who started treatment. Two areas for improvement were identified: further expanding LTBI screening, particularly among BCG-vaccinated contacts and contacts of sputum smear-negative index patients, and expanding preventive treatment among contacts with LTBI.