Optimal duration of anti-TB treatment in patients with diabetes: nine or six months?

Diabetes mellitus (DM) increases the risk of TB recurrence. This study investigated whether 9-month anti-TB treatment is associated with a lower risk of TB recurrence within 2 years after complete treatment than 6-month treatment in patients with DM with an emphasis on the impact of directly observed therapy, short course (DOTs).

Patients with pulmonary but not extrapulmonary TB receiving treatment of 173 to 277 days between 2002 and 2010 were identified from the National Health Insurance Research Database of Taiwan. Patients with DM were then selected and classified into two groups based on anti-TB treatment duration (9 months vs 6 months). Factors predicting 2-year TB recurrence were explored using Cox regression analysis.

Among 12,688 patients with DM and 43,195 patients without DM, the 2-year TB recurrence rate was 2.20% and 1.38%, respectively (P < .001). Of the patients with DM, recurrence rate decreased from 3.54% to 1.19% after implementation of DOTs (P < .001). A total of 4,506 (35.5%) were classified into 9-month anti-TB treatment group. Although a 9-month anti-TB treatment was associated with a lower recurrence rate (hazard ratio, 0.76 [95% CI, 0.59-0.97]), the benefit disappeared (hazard ratio, 0.69 [95% CI, 0.43-1.11]) under DOTs. Other predictors of recurrence included older age, male sex, malignancy, earlier TB diagnosis year, culture positivity after 2 months of anti-TB treatment, and anti-TB treatment being ≤ 80% consistent with standard regimen.

The 2-year TB recurrence rate is higher in a diabetic population in Taiwan and can be reduced by treatment supervision. Extending the anti-TB treatment by 3 months may also decrease the recurrence rate when treatment is not supervised.