Executive Summary: Tuberculosis in Canada 2012

Executive Summary

Introduction

The federal Health Portfolio works to address tuberculosis (TB) in Canada. The Health Portfolio includes the Public Health Agency of Canada (the “Agency”), Health Canada, and the Canadian Institutes for Health Research. It works in partnership to address TB with provincial and territorial governments and other federal departments and agencies.

One of the Agency’s key responsibilities is monitoring active TB disease through a national surveillance system, which is a collaborative effort with the provincial and territorial ministries of health. The Agency uses TB surveillance data and reports to monitor progress towards achieving Canada’s goal of preventing and controlling the transmission of TB, as outlined in Tuberculosis Prevention and Control in Canada - A Federal Framework for Action.^{Footnote 1}

Methods

In Canada, active TB disease is monitored at the national level using the Canadian Tuberculosis Reporting System (CTBRS), a case-based surveillance system that maintains selected non-nominal data on people diagnosed with active TB disease. Provincial and territorial public health authorities voluntarily submit data on TB cases that meet the case definition for national-level surveillance to the CTBRS annually.

This report presents descriptive results from the CTBRS, primarily for the years 2010, 2011, and 2012.  Specifically, this report presents updated data and previously unpublished data on the overall number of reported active TB cases and corresponding incidence rates in Canada, by select demographic and clinical characteristics, for the years 2010, 2011, and 2012. Treatment outcome data are presented for the years 2009 through 2011. This report focuses on 2012, the most recent reporting year for which data are available. Select data from 2010 and 2011 are also highlighted, as are important trends over time.

In this report, the term “incidence rate” refers to individuals newly diagnosed with active TB disease (new and re-treatment cases) in each reporting year, per 100,000 population. Rates are expressed as the number of cases reported each calendar year per 100,000 population. No statistical procedures were used for comparative analyses in this report, nor were any statistical techniques applied to account for missing data.

Results

New and re-treatment cases for 2010, 2011, and 2012

From 2002 to 2012, both the number of reported TB cases and the incidence rates have remained relatively unchanged. From 2010 to 2012, 4,890 new active and re-treatment TB cases were reported to the CTBRS: 1,587 in 2010, 1,618 in 2011, and 1,685 in 2012. In 2010 and 2011, the incidence rate remained unchanged at 4.7 per 100,000 population. In 2012 the incidence rate rose to 4.8 per 100,000 population. Of the 1,685 cases reported in 2012, 1,570 (93%) were new active TB cases and 91 (5%) were re-treatment cases. There were 24 (2%) reported cases for which the history of previous TB treatment was unknown.

In 2010, 2011 and 2012, all provinces and territories reported at least one case of TB. In 2012, the three largest provinces, British Columbia, Ontario, and Quebec, continued to account for the majority (69%) of all reported cases. However, Nunavut, which represents 0.1% of the Canadian population, reported 5% of all cases and had the highest incidence rate of any province or territory in Canada, at 234.4 per 100,000 population.

Across all three reporting years, males accounted for a larger percentage of reported cases than females. In 2012, males accounted for 983 (58%) of the 1,685 reported cases; 702 (42%) cases  were females. In 2012, the incidence rate for males was 5.7 per 100,000 population versus 4.0 per 100,000 population for females.

In 2012, 18% of all cases were 25 to 34 years old, representing the largest number of cases within any one age group. However, the highest incidence rate was for those aged 75 and older, at 9.1 per 100,000 population. Considering age and sex together, the largest burden of TB was observed for males aged 75 years and older, with an incidence rate of 14.5 per 100,000 population.

From 2010 to 2012, Canadian-born Aboriginal people and foreign-born individuals continued to be disproportionately represented among reported cases of TB. In 2012, the foreign-born population, which represented 24% of the total Canadian population, accounted for 65% of all reported cases (n=1,100), with a corresponding incidence rate of 13.4 per 100,000 population.  In 2012, Canadian-born Aboriginal people made up 4% of the total Canadian population but accounted for 22% (n=379) of reported cases, with a corresponding incidence rate of 29.2 per 100,000 population. Among Canadian-born Aboriginal cases, almost half were Inuit (42%, n=160), and the incidence rate for the Inuit was the highest of any population group in Canada at 262.2 per 100,000 population. Canadian-born non-Aboriginal people accounted for the lowest percentage of reported cases at 10% (n=173) with a corresponding incidence rate of 0.7 per 100,000 population.

Of the cases reported in 2012, 77% were diagnosed with respiratory TB and 23% with non-respiratory TB. Pulmonary TB, which includes TB of the lungs and conducting airways, accounted for 67% of reported cases in 2012. TB of the peripheral lymph nodes was the second-most frequently reported disease site, accounting for an additional 12% of all reported cases.  Compared to Canadian-born non-Aboriginal and Canadian-born Aboriginal cases, a higher percentage of foreign-born cases were diagnosed with TB of the peripheral lymph nodes.

In 2012, drug-sensitivity results were reported for 1,326 of the 1,367 (97%) culture-positive TB cases. Among cases with known drug-sensitivity results, 130 (10%) were resistant to at least one anti-tuberculosis drug at the time of diagnosis, the vast majority of which (92%) were monoresistant. From 2010 to 2012, 36 multidrug-resistant TB (MDR-TB) cases were reported: 13 in 2010, 15 in 2011, and eight in 2012. All MDR-TB cases were foreign-born. In Canada, one case of extensively drug-resistant TB (XDR-TB) was reported in 2010, in 2011, and in 2012.

In 2012, HIV status (positive or negative) was reported for 42% (n=715) of all cases. Of these, 8% (n=57) were HIV-positive.

Treatment outcomes for 2009, 2010, and 2011

No major differences in outcomes were reported for individuals diagnosed with TB from 2009 to 2011. Of the 1,445 cases reported in 2011 for which treatment outcome data were available, 1,251 (86%) were reportedly cured or had completed treatment, 140 (10%) died before or during treatment, 31 (2%) had moved outside of Canada before completing treatment, seven (0.5%) absconded or were lost to follow-up, and four (0.3%) cases stopped treatment due to an adverse reaction. Treatment was reported as ongoing for 14 (0.9%) cases.

Treatment delivery mode (directly observed therapy (DOT) vs. daily self-administered or other) was reported for 1,427 (88%) of the 1,618 cases reported in 2011. Of these, 906 (63%) were on DOT and 479 (34%) were on a daily self-administered regimen. Of the cases for which treatment outcome was reported, 88% of cases on DOT and 91% of cases on a daily self-administered regimen were reportedly cured or had completed treatment.

Of the 140 cases reported to have died, the cause of death was reported as TB for 35 (25%) cases; for 69 (49%) cases TB contributed to but was not the underlying cause of death. Sixty-six percent of the individuals who died were males and 78% were individuals aged 55 and older. One male paediatric (< 1 year of age) death was reported, and TB was reported as the cause of death for this case.

Conclusion

From 2002 to 2012, the profile of TB in Canada remained relatively unchanged. Foreign-born individuals, especially those born in countries recognized as high-burden TB countries, continued to be over-represented in the total number of reported cases. However, the burden of TB disease, as measured by the annual incidence rate, remains highest in the Canadian-born Aboriginal population.