Risk factors for acquired multidrug resistant tuberculosis (MDR TB) are well described but less is known about characteristics that increase risk of primary MDR TB. Moreover, whether diabetes increases the risk of primary MDR TB or is associated with delays in culture conversion remains unclear. We aimed to 1) assess risk factors for primary MDR TB, including diabetes, and 2) determine if diabetes reduced the rate of sputum culture conversion in patients with primary MDR TB.
From 2011-2014 we conducted a prospective cohort study at the National Center for TB and Lung Disease in Tbilisi, Georgia. Adult (≥ 35 years) patients with primary TB (defined as no retreatment cases) were eligible. MDR TB was defined as resistance to at least rifampicin and isoniazid. We measured hemoglobin A1c (HbA1c) within 60 days of treatment start; patients with HbA1c ≥6.5% were defined to have diabetes. Polytomous regression was used to estimate the association of patient characteristics with drug resistance. Cox regression was used to compare the hazard rate of sputum culture conversion in patients with and without diabetes.
Among 318 patients, 268 had drug susceptibility test results. Primary MDR TB was prevalent in 19.4% (52/268) and 13.4% (36/268) had diabetes. In adjusted analyses, lower socioeconomic status (aOR 2.9 95%CI 1.3-6.4), diabetes (aOR 2.7 95%CI 1.0-6.9), and cavitary lung disease (aOR 2.5 95%CI 1.2-5.3) were associated with primary MDR TB. Among 52 patients with primary MDR TB, 44 (84.6%) converted sputum cultures to negative and median conversion time was 61 days (IQR 31-92). Median time to conversion in MDR TB patients with diabetes was 87 days (IQR 35-99) vs. 38 (IQR 31-84) in patients without diabetes (p=0.07). The hazard rate of sputum culture conversion was significantly lower among patients with diabetes (aHR 0.4 95%CI 0.2-1.0) and among smokers (aHR 0.2 95%CI 0.1-0.6).
We found diabetes to be associated with an increased risk of primary MDR TB; both diabetes and smoking were associated with a decreased rate of sputum culture conversion. Our results suggest screening MDR TB patients for diabetes and determining tobacco use at the beginning of MDR TB treatment may identify patients who are at risk for delayed culture conversion.
R. R. Kempker, None
N. Gandhi, None
L. Darchia, None
N. Tukvadze, None
H. Blumberg, None
M. Magee, None