Treatment completion in latent tuberculosis infection at specialist tuberculosis units in Spain

SETTING: Treatment of latent tuberculosis infection (LTBI) is essential for tuberculosis (TB) control in low-prevalence countries. However, the long treatment duration and adverse events frequently result in suboptimal treatment completion. OBJECTIVE: To determine completion rates of LTBI treatment and to identify risk factors for non-completion of treatment. DESIGN: Retrospective, observational cohort study. METHODS: All non-human immunodeficiency virus infected adults who started treatment for LTBI at two specialist TB units in Spain between January 2004 and March 2007 were included. Those who discontinued treatment due to toxicity were excluded. RESULTS: Of 599 people who started on treatment, 484 (80.8%, 95%CI 77.5-83.8) completed it. Age <36 years (OR 0.33, 95%CI 0.30-0.76, P = 0.001), male sex (OR 0.58, 95%CI 0.37-0.92, P = 0.02), immigrant status <5 years of residence (OR 0.21, 95%CI 0.12-0.37, P < 0.001) and the presence of social risk factors (OR 0.21, 95 /0C1 0.11-0.39, P < 0.001) were associated with lower rates of treatment completion. Short treatment regimens were not associated with better treatment completion compared with isoniazid for 6-9 months (OR 0.89, 95%CI 0.45-1.80, P = 0.76). CONCLUSIONS: Overall, completion rates of LTBI treatment in specialist TB units arc good. Nevertheless, counselling should be strengthened and new strategies to enhance adherence should be sought for recent immigrants and for people in unfavourable social situations.