Methods: In this retrospective study, we systematically quantified the risk of TB progression in 20 LTBI patients in the TNFα group and 74 LTBI immunocompetent controls seen at Saint Louis University hospital from 2010 to 2015 using a validated online calculator, TSTin3D.com. The calculator generates an individual’s cumulative risk of progression to active TB based on demographic information, TST/IGRA results and presence of TB progression risk factors. We then compared risk factor prevalence and treatment completion rates in the two groups.
Results: A higher proportion (75%) of TNFα group were seen because of recent TST/IGRA conversion from negative to positive, compared to 17.5% in the control group. The TNFα group also had a decreased prevalence of diabetes, smoking, and renal failure. The median cumulative risk of progression to active TB was 17.25% in the TNFα group and 5.87% in the control group. Although the overall LTBI treatment completion rates in our cohort were highest for 3 months INH + RFP (75%) compared to 9 months of INH (56%) or 4 months of Rifampin (54%), only 25% of TNFα group patients were prescribed INH+RFP. However, 70% of patients were able to successfully complete LTBI therapy in the TNFα group.
Conclusion: TSTin3D.com was able to confirm and quantify the fact that patients with LTBI on TNFα antagonist therapy have a higher median cumulative risk of TB progression compared to immunocompetent controls. Overall, patients were more likely to complete a full course of 3 months of INH+RFP but only 25% of the TNFα group received this treatment. We are currently implementing the use of this calculator in the Infectious Diseases clinic to determine whether quantification of risk will affect prescribing practice among clinicians to increase successful treatment completion rates in patients with LTBI.
S. Chatterjee, None