Bayesian Evidence Synthesis to Estimate Subnational TB Incidence: An Application in Brazil

Background: Evidence on local disease burden and the completeness of case detection represent important information for TB control programs. We present a new method for estimating subnational TB incidence and the fraction of individuals with incident TB who are diagnosed and treated in Brazil. Methods: We compiled data on TB notifications and TB-related mortality in Brazil, and specified an analytic model approximating incidence as the number of individuals exiting untreated active disease (sum of treatment initiation, death before treatment, and self-cure). We employed a Bayesian inference approach to synthesize data and adjust for known sources of bias. We estimated TB incidence and the fraction of cases treated, for each Brazilian state and the Federal District over 2007-2016. Findings: For 2016, TB incidence was estimated as 41·8 (95% interval: 40·6, 43·8) per 100 000 nationally, and ranged from 13·3 to 82·0 per 100 000 across states. The fraction of cases treated was estimated as 89·3% (84·7%, 92·2%) nationally and ranged 83%-94% across states, with an estimated 8.2 (5.8, 12.2) thousand cases going untreated in 2016. Over 2007-2016, the average annual decline in incidence rates was 1·8% (1·5%, 2·3%) nationally, and -0·4%-10·1% across states. Over this period there was little change in the fraction of cases treated (0·1% average annual rate of increase nationally; -0·3%, 0·6%). Interpretation: Subnational time-series estimates of TB burden and the fraction of cases treated can be derived from routinely-collected data and used to target TB control efforts. Funding Statement: Lemann Brazil Research Fund. Declaration of Interests: Dr. Menzies reports grants from Lemann Brazil Research Fund during the conduct of the study; Ms. Chitwood reports grants from Michael von Clemm Traveling Fellowship Fund during the conduct of the study; all other authors have nothing to disclose. Ethics Approval Statement: The Office of Human Research Administration at Harvard T.H. Chan School of Public Health reviewed the Initial Study Submission (Protocol #: IRB18-0759) and determined that it met the criteria for exemption from ethics board (IRB) review.