Management of latent tuberculous infection in Norway in 2009: a descriptive cross-sectional study.

Tuberculosis (TB) remains one of the infectious diseases with the highest mortality globally. In 2011, it was estimated that there were 8.7 million new cases of TB worldwide.1 The World Health Organization estimates that around one third of the world’s population has latent tuberculous infection (LTBI). Only a minority of immunocompetent persons infected with Mycobacterium tuberculosis will develop active disease.2 However, there is an increased risk for individuals with reduced immunity, particularly among those infected with the human immunodefiency virus (HIV).3,4 Due both to increased immigration from countries with a high TB burden and to the global TB situation, the National Public Institute in Norway recommended in 2003 that the public health service should increase its focus on preventive treatment for LTBI.5 The number of patients receiving preventive treatment in Norway increased from 160 in 2004 to 721 in 2009. All LTBI treatment in Norway is provided by the Public Health Service. Studies indicate that preventive treatment reduces the risk of developing TB by almost 80%, providing that treatment is completed.6,7 However, the treatment dropout rate is high, with completion rates of between 45% and 67%.8–10 Although Norway is a small country, treatment for LTBI is not uniform throughout the country. The purpose of our study was to address the following questions: 1) What are the characteristics of the individuals who receive preventive treatment for LTBI in Norway? 2) How is treatment implemented? 3) How are patients followed up during treatment? and 4) Do we successfully identify those at highest risk of developing active TB and thus can we potentially contribute to reducing the number of TB cases in Norway?