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

California, United States.

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.

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.

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).

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.