Risk factors for and timing of presumptive recurrent TB

<sec><title>INTRODUCTION</title>Understanding factors associated with increased risk for tuberculosis (TB) recurrence is essential in lowering the TB burden. We aimed to quantify the burden, risk factors, and timing of TB presumptive recurrence.</sec><sec><title>METHODS</title>We analyzed test results from 2013 to 2017 in the South African National Health Laboratory Service's database. We defined a person's TB episode to start with their first positive TB test. In the absence of treatment outcome data, we assumed the episode concluded 6 months later for rifampicin-susceptible TB (RS-TB) and 18 months later for rifampicin-resistant TB (RR-TB), provided that at least one negative smear or culture test was recorded within this period. We defined a presumptive recurrent TB episode to start with a positive TB test after the completion of a prior episode. We calculated recurrence measures stratified by various demographics and RR-TB status.</sec><sec><title>RESULTS</title>Of 574,316 people with RS-TB, 4.7% experienced at least one presumptive recurrent TB episode. Higher local TB notification rates, HIV coinfection, and males experienced higher recurrence rates. Most (89.4%) of the first RS-TB recurrences occurred within a year of the initial episode.</sec><sec><title>CONCLUSION</title>Our findings of when and among whom recurrent TB is more likely to occur can be used to assist early interventions and inform impact on patient care.</sec>.