Associated factors for tuberculosis recurrence in Taiwan: a nationwide nested case-control study from 1998 to 2010

The contribution of human immunodeficiency virus (HIV) co-infection to tuberculosis (TB) recurrence is well established worldwide. We conducted this study to investigate associated factors for recurrent TB in Taiwan, which has a relatively low prevalence of HIV.

A case-control study nested within a nationwide population-based cohort was performed using the Taiwan National Health Insurance (NHI) database from 1998 to 2010. Patients with notified TB were identified according to diagnosis codes and prescriptions of anti-TB drugs for more than 60 days. Recurrent TB was defined as cases being retreated for more than 60 days and 6 months after the end of previous TB episode. Four controls were randomly selected from cohort and matched to each case by observational period within a calendar year. Socio-demographic variables and comorbidities were evaluated as factors associated with TB recurrence.

There were totally 760 patients being investigated (608 controls and 152 cases). During an average 5.12 years of follow-up, 3.76% of all developed recurrent TB and the incidence of TB recurrence was 734 per 100,000 person-years. About half of recurrence (55%) was notified within three years of follow-up, and most (86%) recurrences were intrapulmonary. Independent associated factors for TB recurrence included: male (odds ratio, OR: 2.23, 95% confidence interval, CI: 1.40-3.53), diabetes mellitus (DM) (OR: 1.51, 95% CI: 1.02-2.13), chronic obstructive pulmonary disease (COPD) (OR: 1.59, 95% CI: 1.08-2.36) and lower socio-economic status (p=0.001 between groups).

Despite low prevalence of HIV in the Taiwanese population, the incidence of recurrent TB among Taiwanese was not less than that of other countries. Identification of subgroups such as male gender, low economic status, DM and COPD should be a high priority in TB control programs.