Results: Tuberculosis in Canada 2012 – Section II : Treatment Outcomes for 2009, 2010, and 2011

Results

Section II – Treatment Outcomes for 2009, 2010, and 2011

Treatment outcome, drug regimen, treatment mode, and treatment adherence

Partial or complete outcome data were available for 1,634 (99%) of the 1,655 cases reported in 2009, for 1,562 (98%) of the 1,587 cases reported in 2010, and for 1,445 (89%) of the 1,618 cases reported in 2011 (Table 22-1, Table 22-2, and Table 22-3).

There were no major differences in outcomes reported for individuals diagnosed with TB during the three-year period from 2009 to 2011. Treatment outcome details for 2011, the most recent year for which data are available, are described below.

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 out of Canada before completing treatment, seven (0.5%) had absconded or were lost to follow-up, and four cases (0.3%) had discontinued treatment due to an adverse reaction (Table 22-3). Treatment was reported as ongoing for 14 (0.9%) cases and as “other” for 12 (0.8%) cases. Of these 12 cases, eight were reported to have declined further medication following several months of treatment. No further information was available for the remaining four cases. Finally, outcomes for cases reported in 2011 remain unreported for 159 (10%) cases, which is high compared to corresponding figures in 2009 (n=15) and 2010 (n=14). Of the 159 cases in 2011 for which outcomes remained unreported, 135 were reported by Quebec. Changes made at the end of 2012 to the way treatment outcome variables are reported (i.e. from paper forms to electronic transmission) are believed to account for the decrease in response rates; it is hoped that reporting via an updated provincial registration system will improve on these variables over time.

Data on the final medication regimen used to treat the case for more than one month was reported for 906 (56%) of all cases reported in 2011. Of these, 94% were reported to have received a drug regimen that included three or more drugs (Table 23-3).

Information on drug compliance was available for 83% of cases reported in 2011. Of these, compliance was reported as 80% or higher for the vast majority of cases (Table 24).

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 (Table 25). 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 (Figure 17; Table 25).

Figure 17: Treatment outcome by major mode of treatment – Canada: 2011

Enlarge Figure 17

Acquired drug resistance

Acquired drug resistance occurs when patients whose initial drug-susceptible TB infection subsequently becomes drug-resistant as a result of inadequate, inappropriate, or irregular treatment, or, more commonly, because of non-adherence to the drug regimen. The prevalence of acquired drug resistance in Canada remains low.

In 2011, there were five reported cases with acquired drug resistance. Of these, four were new cases and one was a re-treatment case. All cases were monoresistant: two to INH, one to RMP, one to PZA, and one to EMB. All five cases with acquired resistance were foreign-born (data not shown).

Deaths

Based on available treatment outcome data, of the 140 cases reported to have died in 2011, the cause of death was reported as:

• TB for 35 (25%) cases;
• TB contributed to but was not the underlying cause of death for 69 (49%) cases; and
• TB was an incidental finding and did not contribute to death for 29 (21%) cases (Table 26).

Note: The cause of death was not reported for the remaining 7 (5%) cases.

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 in 2011, and TB was reported as the cause of death (Table 27).