Risk factors for recurrent tuberculosis among successfully treated patients in Israel, 1999–2011

Background: Recurrent tuberculosis (TB) is one of the indices used to assess the effectiveness of the National TB Program. Objectives: To estimate the incidence of recurrent TB in Israel and to identify the associated risk factors. Methods: We conducted a retrospective cohort study that included all TB patients who were Israeli citizens and diagnosed between 1999 and 2011 with a treatment outcome recorded as “success.” We compared those who had recurrent TB with those who did not. In addition, a nested case-control study included all those who had recurrent TB with a random sample from this cohort matched by age, gender, and year of TB diagnosis. Results: Of 3515 TB patients diagnosed between 1999 and 2011, 37 (1.05%) had recurrent TB during the follow-up period, with an incidence rate of 1.55 cases per 1000 person-years. Male gender [hazard ratio (HR) 3.2, 95% confidence interval (95%CI) 1.4–7.4], human immunodeficiency virus (HIV) infection (HR 3.9, 95%CI 1.5–10.4), positive sputum culture [odds ratios (OR) 2.7, 95%CI 1.1–6.9], and low adherence to anti-TB treatment (OR 3.2, 95%CI 1.0–10.3) were found to be risk factors for recurrent TB. Conclusions: Male gender, HIV infection, positive sputum culture, and low adherence to anti-TB drugs during the initial TB episode were risk factors for developing recurrent TB.