Population impact of factors associated with prevalent pulmonary tuberculosis in Tanzania.

SETTING

Tanzania has an estimated tuberculosis (TB) prevalence of 295 per 100 000 adult population. There is currently no nationally representative information on factors associated with TB in Tanzania.

OBJECTIVE

To determine the demographic and clinical factors associated with bacteriologically confirmed TB in the adult general population of Tanzania.

DESIGN

A case-control study nested in a nationally representative TB prevalence survey. All patients with bacteriologically confirmed pulmonary TB (PTB) constituted cases and a representative sample of people without bacteriologically confirmed PTB constituted controls. We calculated adjusted odds ratios (aORs) to identify factors associated with TB.

RESULTS

Age groups 25-34 years (aOR 3.7, 95%CI 1.5-8.8) and 55-64 years (aOR 2.5, 95%CI 1.1-5.5), male sex (aOR 1.6, 95%CI 1.1-2.3) and low body mass index (BMI) (aOR 1.7, 95%CI 1.1-2.8) were significantly associated with TB. Association with human immunodeficiency virus (HIV) and diabetes mellitus (DM) was not statistically significant. The population attributable fraction (PAF) was 2% (95%CI -2 to 5) for DM and 3% (95%CI -2 to 8) for HIV.

CONCLUSION

Being in an older age group, being male and having a low BMI were associated with bacteriologically confirmed PTB. On the population level, classic risk factors for TB have no major effect on prevalent TB from which future transmission may occur.