Cohort analysis of asylum seekers in Oslo, Norway, 1987-1995: effectiveness of screening at entry and TB incidence in subsequent years.

Methods: Municipalities of Baerum and Oslo, Norway.

Objective: To examine the effectiveness of tuberculosis (TB) screening in asylum seekers 1987-1995, and to describe TB incidence rates after arrival.

Methods: Register-based, retrospective cohort study of 19912 asylum seekers with a mean follow-up of 6.3 years.

Results: Seventy-six persons were diagnosed with TB, of whom 43 (57%) had pulmonary TB. Twenty-two cases (17 pulmonary) were found through screening at entry. Eleven persons had abnormal mass miniature X-rays (MMRs), but had inadequate follow-up and were diagnosed later through passive case finding. MMR itself had a sensitivity of 96% and a specificity of 98% for pulmonary TB, diagnosed within 1 year after arrival. TB prevalence at entry was 110/100000; for Somalis it was 577/100000. Incidence rates were stable in the total cohort after arrival, whereas rates for extra-pulmonary TB in Somalis increased.

Conclusions: Screening on entry should continue, but follow-up of abnormal MMRs must be improved. There should be more emphasis on treatment of latent infection.