Risk factors for multidrug resistant tuberculosis in Europe: a systematic review.

BACKGROUND The resurgence of tuberculosis (TB) in western countries has been attributed to the HIV epidemic, immigration, and drug resistance. Multidrug resistant tuberculosis (MDR-TB) is caused by the transmission of multidrug resistant Mycobacterium tuberculosis strains in new cases, or by the selection of single drug resistant strains induced by previous treatment. The aim of this report is to determine risk factors for MDR-TB in Europe. METHODS A systematic review was conducted of published reports of risk factors associated with MDR-TB in Europe. Meta-analysis, meta-regression, and sub-grouping were used to pool risk estimates of MDR-TB and to analyse associations with age, sex, immigrant status, HIV status, occurrence year, study design, and area of Europe. RESULTS Twenty nine papers were eligible for the review from 123 identified in the search. The pooled risk of MDR-TB was 10.23 times higher in previously treated than in never treated cases, with wide heterogeneity between studies. Study design and geographical area were associated with MDR-TB risk estimates in previously treated patients; the risk estimates were higher in cohort studies carried out in western Europe (RR 12.63; 95% CI 8.20 to 19.45) than in eastern Europe (RR 8.53; 95% CI 6.57 to 11.06). National estimates were possible for six countries. MDR-TB cases were more likely to be foreign born (odds ratio (OR) 2.46; 95% CI 1.86 to 3.24), younger than 65 years (OR 2.53; 95% CI 1.74 to 4.83), male (OR 1.38; 95% CI 1.16 to 1.65), and HIV positive (OR 3.52; 95% CI 2.48 to 5.01). CONCLUSIONS Previous treatment was the strongest determinant of MDR-TB in Europe. Detailed study of the reasons for inadequate treatment could improve control strategies. The risk of MDR-TB in foreign born people needs to be re-evaluated, taking into account any previous treatment.