Factors associated with extended treatment among tuberculosis patients at risk of relapse in California

SETTING: California, United States. OBJECTIVE: To determine the frequency of tuberculosis (TB) patients at risk for relapse who received at least 9 months of anti-tuberculosis treatment (extended treatment) and to identify factors associated with not receiving extended treatment. DESIGN: We analyzed characteristics of culture-confirmed pulmonary TB patients reported to the California TB Registry during 2004-2009. Patients with cavities on initial chest radiograph and delayed culture conversion ((>=. 70 days) were at 'high risk of relapse', and anti-tuberculosis treatment of >= 270 days was 'extended treatment'. We used a generalized linear model to identify independent risk factors for absence of extended treatment in the high risk of relapse group. RESULTS: Among 5680 TB patients, 483 (8.5%) were at high risk of relapse: 372 (77%) received extended treatment but 111 (23%) did not. Factors associated with absence of extended treatment included negative sputum smears (adjusted prevalence ratio [aPR] 2.62, 95%CI 1.69-4.05), residence in three specific counties (aPR 1.71, 95%CI 1.19-2.46) and Black race (aPR 1.56, 95 %CI 1.03-2.38). CONCLUSIONS: Nearly a quarter of TB patients at high risk of relapse did not receive extended treatment. Increased efforts are needed to ensure that all patients who may benefit from extended anti-tuberculosis treatment receive it.