Asymptomatic and symptomatic recurrence of TB among cured pulmonary TB patients

SUMMARY BACKGROUND Asymptomatic pulmonary TB (PTB), including asymptomatic recurrence, has emerged as a potential contributor to TB transmission. METHODS Participants ≥14 years old from two Indian cohorts with culture-confirmed, drug-sensitive PTB and an outcome of cure were followed up for up to 18 months post treatment completion. We calculated the cumulative incidence and timing of symptomatic TB recurrence and the prevalence of asymptomatic recurrence at two screening time points, and performed Cox-regression analysis. RESULTS Of 713 culture-confirmed PTB and cure, 60 (8%) experienced confirmed TB recurrence (cumulative incidence: 8.7 [95% confidence interval (CI): 6.6–11.2]/100 person-years), including 40 (66.7%) symptomatic and 20 (33.3%) asymptomatic recurrences. At study visits with scheduled sputum testing, 22 of 35 (63%) TB recurrences diagnosed were asymptomatic at the time of diagnosis. Undernutrition was an independent risk factor for overall TB recurrence (adjusted hazard ratio [aHR] 2.1, 95% CI: 1.1–4.0, P = 0.03). Symptomatic recurrences were associated with age > 35 years (aHR 2.5, 95% CI: 1.3–5.0, P = 0.01), while the risk of asymptomatic recurrences was higher in the age-group of 14–35 years (aHR 2.8, 95% CI: 0.8–9.8, P = 0.10). CONCLUSIONS Among cured PTB patients, 8.4% experienced recurrent TB and one third of recurrences were asymptomatic at diagnosis, highlighting a public health concern due to substantial hidden burden of recurrent TB disease in India.