Background: Extra pulmonary tuberculosis appears to be increasing in England and Wales. We examined trends in extra pulmonary tuberculosis and factors associated with these trends.
Methods: We used national tuberculosis surveillance data from 1999-2006 for England and Wales, including demographic, clinical and laboratory information. Trends in the proportion of tuberculosis cases with extra pulmonary disease were investigated using the chi-square trend test and associated factors using logistic regression.
Results: Amongst all tuberculosis cases, the proportion with extra pulmonary disease increased from 48% in 1999 (2,717 cases) to 53% in 2006 (4,205 cases, p<0.001). Regression analysis showed that the rise in extra pulmonary disease was associated with an increase in the proportion of non-UK born cases (odds ratio 2.7 [2.6-2.8]). A more than three-fold increase was observed in the proportion of all tuberculosis cases with miliary tuberculosis from 0.7% of all cases (38 cases) to 2.2% (180 cases, p<0.001). This rise was not associated with changes in place of birth nor in any of the other risk factors identified.
Conclusions: The proportion of cases with extra pulmonary disease has increased over the study period. To a large extent this is due to an increasing proportion of non-UK born cases. Reasons for the rise in miliary tuberculosis require further investigation. Clinicians should have a higher index of clinical suspicion of extra pulmonary tuberculosis in non-UK born cases.