title: Population-level impact of active tuberculosis case finding in an Asian megacity.
abstract: BACKGROUND
  The potential population-level impact of private-sector initiatives for tuberculosis (TB) case finding in Southeast Asia remains uncertain. In 2011, the Indus Hospital TB Control Program in Karachi, Pakistan, undertook an aggressive case-finding campaign that doubled notification rates, providing an opportunity to investigate potential population-level effects.
  
  
  METHODS
  We constructed an age-structured compartmental model of TB in the intervention area. We fit the model using field and literature data, assuming that TB incidence equaled the estimated nationwide incidence in Pakistan (primary analysis), or 1.5 times greater (high-incidence scenario). We modeled the intervention as an increase in the rate of formal-sector TB diagnosis and evaluated the potential impact of sustaining this rate for five years.
  
  
  RESULTS
  In the primary analysis, the five-year intervention averted 24% (95% uncertainty range, UR: 18-30%) of five-year cumulative TB cases and 52% (95% UR: 45-57%) of cumulative TB deaths. Corresponding reductions in the high-incidence scenario were 12% (95% UR: 8-17%) and 27% (95% UR: 21-34%), although the absolute number of lives saved was higher. At the end of five years, TB notification rates in the primary analysis were below their 2010 baseline, incidence had dropped by 45%, and annual mortality had fallen by 72%. About half of the cumulative impact on incidence and mortality could be achieved with a one-year intervention.
  
  
  CONCLUSIONS
  Sustained, multifaceted, and innovative approaches to TB case-finding in Asian megacities can have substantial community-wide epidemiological impact.
authors.affiliation: Department of Epidemiology, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland, United States of America ; Center for Tuberculosis Research, Johns Hopkins University, Baltimore, Maryland, United States of America.
authors.forename: David W
authors.initials: DW
authors.lastname: Dowdy
authors.forename: Ismat
authors.initials: I
authors.lastname: Lotia
authors.forename: Andrew S
authors.initials: AS
authors.lastname: Azman
authors.forename: Jacob
authors.initials: J
authors.lastname: Creswell
authors.forename: Suvanand
authors.initials: S
authors.lastname: Sahu
authors.forename: Aamir J
authors.initials: AJ
authors.lastname: Khan
mesh_terms: D000293:Adolescent; D000328:Adult; D002648:Child; D002675:Child, Preschool; D002947:Cities; D006801:Humans; D015994:Incidence; D007223:Infant; D007231:Infant, Newborn; D008875:Middle Aged; D009026:Mortality; D009169:Mycobacterium tuberculosis; D010154:Pakistan / Q000453:epidemiology; D011159:Population Surveillance; D015995:Prevalence; D014376:Tuberculosis / Q000175:diagnosis / Q000453:epidemiology* / Q000635:transmission; D055815:Young Adult