Seven-year retrospective study understanding the latent TB infection treatment cascade of care among adults in a low incidence country

Abstract

Background: Prevention of TB is paramount to achieving elimination targets as recommended by the World Health Organization's action framework for low incidence countries striving to eliminate TB. Although the rates of TB in Canada are low, understanding the latent TB infection (LTBI) cascade is paramount to identifying gaps in care and treatment barriers, thereby increasing the effectiveness of preventive strategies. The purpose of this study was to examine the LTBI cascade of care and identify barriers to treatment completion in adults referred from primary care to a regional tertiary care TB clinic in Ottawa, Canada.

Methods: Electronic medical records between January 2010 and December 2016 were reviewed retrospectively and an LTBI cascade of care was constructed from The Ottawa Hospital TB clinic and surrounding primary care clinics. A cohort of 2207 patients with untreated LTBI was used to ascertain the associations between demographic and clinical factors for both treatment non-initiation and non-completion using log-binomial univariable and multivariable regression models.

Results: Of 2207 patients with untreated LTBI who were seen in the clinic during the study period, 1771 (80.2%) were offered treatment, 1203 (67.9% of those offered) started treatment, and 795 (66.1% of those started) completed treatment. In multivariable analysis, non-initiation of treatment was associated with older age (adjusted risk ratio [aRR] 1.06 per 5-year increase, 95% CI: 1.03-1.08) and female gender (aRR 1.28, 95% CI: 1.11-1.47). Non completion of treatment was associated with referral from the TB Clinic back to the primary care team following initial consult (aRR 1.62, 95% CI: 1.35-1.94) and treatment with the standard of 9 months of Isoniazid (9H) compared to 4 months of Rifampin (4R) (aRR 1.45, 95% CI:1.20-1.74).

Conclusions: LTBI treatment completion was significantly decreased among patients who were referred back to primary care from the TB clinic. The 4R regimen resulted in more people completing LTBI treatment compared to 9H in keeping with a recently published RCT. Improved education, communication, and collaboration between tertiary care TB clinics and primary care teams may improve treatment completion rates and address the TB burden in low incidence communities in Canada.

Keywords: Cascade of care; Latent tuberculosis infection.

Fig. 1

LTBI cascade of care at the Ottawa Hospital TB Clinic – January 1, 2010 to November 30, 2016. Percentages in the left-hand column represent the percentage of patients remaining in the cascade compared to the previous step in the cascade. ¹Patients that started one treatment course during the study period and did not complete the course and started a second treatment course during the study period. ²Individuals who initially accepted treatment but never received a prescription and subsequently declined treatment or were lost to follow up

Fig. 2

LTBI cascade of care at the Ottawa Hospital TB Clinic – January 1, 2010 to November 30, 2016 for the TB clinic and primary care clinics.Details about reasons for losses within the cascade of care are outlined in Table 2. Percentages represent the percentage of patients remaining in the cascade compared to the previous step in the cascade. ¹The patient and the primary care team decided against treatment recommendations that were offered at the TB Clinic

Fig. 3

LTBI cascade of care at the Ottawa Hospital TB Clinic – January 1, 2010 to November 30, 2016.Percentages represent the percentage of patients remaining in the cascade compared the number of individuals screened for LTBI treatment

Fig. 4

Information obtained from the primary care team on LTBI Treatment (n = 272).Information from the primary care team on individuals who were offered latent tuberculosis treatment at the Ottawa TB Clinic and subsequently followed for the duration of the treatment by their primary care team. Reasons treatment was not offered, not accepted, not started and not completed is captured in the Fig. 1