TABLE 2

Methods and definitions

Methods
 The basis for this framework is the post-2015 global TB strategy, which was approved by the World Health  Assembly in May 2014 [8]. The framework [17] is grounded in existing WHO guidelines related to TB care,  prevention and control [18]. A narrative review of WHO policy documents and guidelines, as well as  published literature, was undertaken. A writing group was established, which developed a draft in a  framework-drafting meeting in Geneva in April 2014. It was then circulated to 32 country representatives  and 22 additional representatives of research institutions and technical agencies, nongovernmental and civil  society organisations that were invited to a global consultation meeting in Rome, on July 4–5, 2014 [19].
Data sources
 Data on TB epidemiology and health systems context described in the framework draw on four data  sources: 1) the WHO global TB database [20], 2) a published survey of TB policies in the European Union  countries [14], 3) other published research, and 4) a survey conducted among all countries invited to the  Global Consultation. The latter survey included questions concerning elements of TB epidemiology that  are not routinely reported to the WHO but are available in national surveillance datasets (to various  extent), as well as questions about existing policy and practice with regard to specific TB care and  control interventions.
Low-incidence countries
 In this framework, low-incidence countries are defined as those with a TB notification rate of <100  notified TB cases (all forms) per million population. This definition has been previously proposed [10],  while others have suggested alternative thresholds, such as <200 per million [3] or <160 per million [21].  The <100 per million threshold is the same as the global incidence rate target for 2035, which  corresponds to the goal of the post-2015 global TB strategy to “end the global TB epidemic” (table 1).  However, this framework is not only relevant for countries that meet this particular low-incidence  criterion. The principles and proposed actions are similar for other countries that are approaching the  low-incidence threshold.
Pre-elimination and elimination
 Pre-elimination is defined as <10 notified TB cases (all forms) per million population and year. This is the  same as proposed by Clancy et al. [10] in 1991. Elimination of TB as a public health problem is defined  as less than one notified TB case (all forms) per million population and year. For the European region,  TB elimination was previously defined as less than one sputum-smear-positive case per million, and  thus focused on the most infectious TB cases only [22]. However, the European Centre for Disease  Prevention and Control has proposed a definition that includes all forms of TB [11]. Similarly, the US  Centres for Disease Control and Prevention defines elimination in the USA as less than one case of TB,  all forms, per million population [11, 12].
Notification rate versus true incidence rate
 These definitions use TB notification rate rather than estimated incidence, given that health systems as  well as TB surveillance systems are of generally high quality in low-incidence countries and therefore  the gap between notification rate of new and relapse cases and true incidence rate is small [1].  Nevertheless, TB notification rates should always be evaluated in the context of the coverage of TB  surveillance systems, specifically the likelihood of significant under-detection and/or under-reporting  of TB. WHO guidance is available for this purpose [23, 24].
  • TB: tuberculosis; WHO: World Health Organization.