Short summary

World Health Organization estimate 1/4 of the world population to be infected with Mycobacterium tuberculosis. Prevalence of latent tuberculosis, infected but not ill, is unknown in Denmark.

Rationale

The World Health Organization estimates that one-fourth of the world population has latent tuberculosis infection (LTBI). To success the End TB Strategy announced by The World Health Organization in 2014 management of LTBI in high-income counties with an estimated TB rate of less than 100 per 100.000, such as Denmark, is important.

The prevalence of LTBI is unknown in Denmark. Few studies with small sample sizes have investigated the rate of LTBI among high-risk populations living in Denmark like socially marginalised citizens, homeless, and immigrants from high incidence areas. In these studies the prevalence of LTBI was 13% to 19%.

In Denmark, patients with autoimmune diseases are screened for LTBI with interferon gamma release tests before initiating biologic drugs. These patients are not expected to have increased risk for TB exposure but are at increased risk of developing active TB due to immunosuppressive treatment with biologic drugs. We assume that the estimated prevalence of LTBI in this group will represent the prevalence of LTBI in the background population.

Description of the cohort

All patients from 2005 to 2018 diagnosed with immune-mediated inflammatory bowl diseases and inflammatory rheumatic disease: Crohn's disease , Ulcerative colitis, inflammatory bowel disease, rheumatoid arthritis, juvenile arthritis, psoriasis arthritis and spondyloarthropaty.

Data and biological material

Civil Registration numbers Register: Demographics, immigrant status.The National Laboratory Registry/ The International Reference Laboratory of Mycobacteriology (IRLM), Statens Serum Institut/Department of Clinical Microbiology at Odense University Hospital, Slagelse Hospital, and Rigshospitalet: Interferon Gamma release Assay (IGRA) results.

National prescription registry: Anatomical Therapeutic Chemical Classification (ATC) codes for glucocorticoids, synthetic and biologiscal disease-modifying antirheumatic drugs (sDMARDs and bDMARDs).

The Danish National Patient Register: ICD10 codes for inflammatory bowl and rheumatic disease.

Collaborating researchers and departments

International Reference Laboratory of Mycobacteriology, Statens Serum Institut

• Troels Lillebæk

Lungemedinsk Afdeling, Sygehus Lillebælt

• Ole Hilberg

Department of Pulmonology, Aarhus University Hospital

• Andreas Fløe Hvass

Research Unit for Infectious Diseases, University of Southern Denmark

• Stephanie Bjerrum

Department of Infectious Diseases, University Hospital Herlev Gentofte

• Bente Nørgård

Department of Clinical Microbiology, Odense University Hospital

• Sofie Skovmand Rasmussen
• Department of Infectious Diseases, Aarhus University Hospital
• Christian Wejse