Fig 2. The age- and sex-adjusted incidence of tuberculosis in Alberta, 1989–2013: The age- and sex-adjusted incidence of TB in Alberta over the 25 years 1989–2013 was estimated in three population groups: Registered or Status Indians (SI), the foreign-born (FB) and Canadian-born ‘Others’ (CBO).

The population estimates used in the analysis were derived from Canadian censuses conducted in 1986, 1991, 1996, 2001, and 2006. [5] After 2006 the long form of the Canadian census, which had previously estimated the foreign-born population by age and sex, was discontinued. However, it was noted that in 2001 and 2006 the proportion of the population, other than Status Indians, that was foreign-born by 5-year age and sex grouping, was relatively constant. Accordingly, the foreign-born population in 2011 was calculated on the basis of the proportions in 2006. Inter-censal estimates were estimated using linear interpolations between censuses; estimates from 2012 and 2013 were obtained by linear extrapolation. Adjustment of rates was carried out using the direct method with the total Alberta population as the reference population. The three-clinic model began in 1999; see red arrow.