Sustainability and impact of an intervention to improve initiation of tuberculosis preventive treatment: results from a follow-up study of the ACT4 randomized trial

Background

In a cluster randomized trial (clinicaltrials.gov: NCT02810678) a flexible but comprehensive health system intervention significantly increased the number of household contacts (HHC) identified and started on tuberculosis preventive treatment (TPT). A follow-up study was conducted one year later to test the hypotheses that these effects were sustained, and were reproducible with a simplified intervention.

Methods

We conducted a follow-up study from May 1, 2018 until April 30, 2019, as part of a multinational cluster randomized trial. Eight sites in 4 countries that had received the intervention in the original trial received no further intervention; eight other sites in the same countries that had not received the intervention (control sites in the original trial) now received a simplified version of the intervention. This consisted of repeated local evaluation of the Cascade of care for TB infection, and stakeholder decision making. The number of HHC identified and starting TPT were repeatedly measured at all 16 sites and expressed as rates per 100 newly diagnosed index TB patients. The sustained effect of the original intervention was estimated by comparing these rates after the intervention in the original trial with the last 6 months of the follow-up study. The reproducibility was estimated by comparing the pre-post intervention changes in rates at sites receiving the original intervention with the pre-post changes in rates at sites receiving the later, simplified intervention.

Findings

With regard to the sustained impact of the original intervention, compared to the original post-intervention period, the number of HHC identified and treated per 100 newly diagnosed TB patients was 10 more (95% confidence interval: 84 fewer to 105 more), and 1 fewer (95% CI: 22 fewer to 20 more) respectively up to 14 months after the end of the original intervention. With regard to the reproducibility of the simplified intervention, at sites that had initially served as control sites, the number of HHC identified and treated per 100 TB patients increased by 33 (95% CI: -32, 97), and 16 (-69, 100) from 3 months before, to up to 6 months after receiving a streamlined intervention, although differences were larger, and significant if the post-intervention results were compared to all pre-intervention periods.

Interpretation

Up to one year after it ended, a health system intervention resulted in sustained increases in the number of HHC identified and starting TPT. A simplified version of the intervention was associated with non-significant increases in the identification and treatment of HHC. Inferences are limited by potential bias due to other temporal effects, and the small number of study sites.

Funding

Funded by the Canadian Institutes of Health Research (Grant number 143350).

Human resource implications of expanding latent tuberculosis patient care activities

Introduction

The World Health Organization (WHO) declared increasing services for latent tuberculosis infection (LTBI) a priority to eliminate tuberculosis (TB) by 2035. Yet, there is little information about thehuman resource needs required to implement LTBI treatment scale-up. Our study aimed to estimate the change in healthcare workers (HCW) time spent on different patient care activities, following an intervention to strengthen LTBI services.

Methods

We conducted a time and motion (TAM) study, observing HCW throughout a typical workday before and after the intervention (Evaluation and Strengthening phases, respectively) at 24 health facilities in five countries. The precise time spent on pre-specified categories of work activities was recorded. Time spent on direct patient care was subcategorized as relating to one of three conditions: LTBI, active or suspected TB, and non-TB (i.e., patients with any other medical condition). A linear mixed model (LMM) was fit to estimate the change in HCW time following the intervention.

Results

A total of 140 and 143 HCW participated in the TAMs during the Evaluation and Strengthening phases, respectively. Results from intervention facilities showed an increase of 9% (95% CI: 3%, 15%) in the proportion of HCW time spent on LTBI-related services, but with a corresponding change of -11% (95% CI: -21%, -1%) on active TB services. There was no change in the proportion of time spent on LTBI care in control facilities; this remained low in both phases of the study.

Discussion

Our findings suggest that additional HCW personnel will be required for expansion of LTBI services to ensure that this expansion does not reduce the time available for care of active TB patients.

Risk of Tuberculosis Disease in People With Chronic Kidney Disease Without Kidney Failure: A Systematic Review and Meta-analysis

BACKGROUND

Kidney failure is an established risk factor for tuberculosis (TB), but little is known about TB risk in people with chronic kidney disease (CKD) who have not initiated kidney replacement therapy (CKD without kidney failure). Our primary objective was to estimate the pooled relative risk of TB disease in people with CKD stages 3-5 without kidney failure compared with people without CKD. Our secondary objectives were to estimate the pooled relative risk of TB disease for all stages of CKD without kidney failure (stages 1-5) and by each CKD stage.

METHODS

This review was prospectively registered (PROSPERO CRD42022342499). We systematically searched MEDLINE, Embase, and Cochrane databases for studies published between 1970 and 2022. We included original observational research estimating TB risk among people with CKD without kidney failure. Random-effects meta-analysis was performed to obtain the pooled relative risk.

RESULTS

Of the 6915 unique articles identified, data from 5 studies were included. The estimated pooled risk of TB was 57% higher in people with CKD stages 3-5 than in people without CKD (adjusted hazard ratio: 1.57; 95% CI: 1.22-2.03; I2 = 88%). When stratified by CKD stage, the pooled rate of TB was highest in stages 4-5 (incidence rate ratio: 3.63; 95% CI: 2.25-5.86; I2 = 89%).

CONCLUSIONS

People with CKD without kidney failure have an increased relative risk of TB. Further research and modeling are required to understand the risks, benefits, and CKD cutoffs for screening people for TB with CKD prior to kidney replacement therapy.

Distinct healthcare utilization profiles of high healthcare use tuberculosis survivors: A latent class analysis

BACKGROUND

Recent data have demonstrated that healthcare use after treatment for respiratory tuberculosis (TB) remains elevated in the years following treatment completion. However, it remains unclear which TB survivors are high healthcare users and whether any variation exists within this population. Thus, the primary objective of this study was to identify distinct profiles of high healthcare-use TB survivors to help inform post-treatment support and care.

METHODS

Using linked health administrative data from British Columbia, Canada, we identified foreign-born individuals who completed treatment for incident respiratory TB between 1990 and 2019. We defined high healthcare-use TB survivors as those in the top 10% of annual emergency department visits, hospital admissions, or general practitioner visits among the study population during the five-year period immediately following TB treatment completion. We then used latent class analysis to categorize the identified high healthcare-use TB survivors into subgroups.

RESULTS

Of the 1,240 people who completed treatment for respiratory TB, 258 (20.8%) people were identified as high post- TB healthcare users. Latent class analysis results in a 2-class solution. Class 1 (n = 196; 76.0%) included older individuals (median age 71.0; IQR 59.8, 79.0) with a higher probability of pre-existing hypertension and diabetes (41.3% and 33.2%, respectively). Class 2 (n = 62; 24.0%) comprised of younger individuals (median age 31.0; IQR 27.0, 41.0) with a high probability (61.3%) of immigrating to Canada within five years of their TB diagnosis and a low probability (11.3%) of moderate to high continuity of primary care.

DISCUSSION

Our findings suggest that foreign-born high healthcare-use TB survivors in a high-resource setting may be categorized into distinct profiles to help guide the development of person-centred care strategies targeting the long-term health impacts TB survivors face.

Healthcare Utilization After Respiratory Tuberculosis: A Controlled Interrupted Time Series Analysis

BACKGROUND

Despite data suggesting elevated morbidity and mortality among people who have survived tuberculosis disease, the impact of respiratory tuberculosis on healthcare utilization in the years following diagnosis and treatment remains unclear.

METHODS

Using linked health administrative data from British Columbia, Canada, we identified foreign-born individuals treated for respiratory tuberculosis between 1990 and 2019. We matched each person with up to four people without a tuberculosis diagnosis from the same source cohort using propensity score matching. Then, using a controlled interrupted time series analysis, we measured outpatient physician encounters and inpatient hospital admissions in the 5 years following respiratory tuberculosis diagnosis and treatment.

RESULTS

We matched 1216 individuals treated for respiratory tuberculosis to 4864 non-tuberculosis controls. Immediately following the tuberculosis diagnostic and treatment period, the monthly rate of outpatient encounters in the tuberculosis group was 34.0% (95% confidence interval [CI]: 30.7%, 37.2%) higher than expected, and this trend was sustained for the duration of the post-tuberculosis period. The excess utilization represented an additional 12.2 (95% CI: 10.6, 14.9) outpatient encounters per person over the post-tuberculosis period, with respiratory morbidity a large contributor to the excess healthcare utilization. Results were similar for hospital admissions, with an additional 0.4 (95% CI: .3, .5) hospital admissions per person over the post-tuberculosis period.

CONCLUSIONS

Respiratory tuberculosis appears to have long-term impacts on healthcare utilization beyond treatment. These findings underscore the need for screening, assessment, and treatment of post-tuberculosis sequelae, as it may provide an opportunity to improve health and reduce resource use.

Role of latent tuberculosis infection on elevated risk of cardiovascular disease: a population-based cohort study of immigrants in British Columbia, Canada, 1985-2019

We investigated cardiovascular disease (CVD) risk associated with latent tuberculosis infection (LTBI) (Aim-1) and LTBI therapy (Aim-2) in British Columbia, a low-tuberculosis-incidence setting. 49,197 participants had valid LTBI test results. Cox proportional hazards model was fitted, adjusting for potential confounders. Compared with the participants who tested LTBI negative, LTBI positive was associated with an 8% higher CVD risk in complete case data (adjusted hazard ratio (HR): 1.08, 95% CI: 0.99-1.18), a statistically significant 11% higher risk when missing confounder values were imputed using multiple imputation (HR: 1.11, 95% CI: 1.02-1.20), and 10% higher risk when additional proxy variables supplementing known unmeasured confounders were incorporated in the highdimensional disease risk score technique to reduce residual confounding (HR: 1.10, 95% CI: 1.01-1.20). Also, compared with participants who tested negative, CVD risk was 27% higher among people who were LTBI positive but incomplete LTBI therapy (HR: 1.27, 95% CI: 1.04-1.55), whereas the risk was similar in people who completed LTBI therapy (HR: 1.04, 95% CI: 0.87-1.24). Findings were consistent in different sensitivity analyses. We concluded that LTBI is associated with an increased CVD risk in low-tuberculosis-incidence settings, with a higher risk associated with incomplete LTBI therapy and attenuated risk when therapy is completed.

Ethical challenges in the treatment of non-refugee migrants with tuberculosis in Canada

While attention to the ethical issues that migrants face in accessing tuberculosis care has increased in the last few years, most of the attention has focused on challenges that refugees face when emigrating. Less attention has been given to ethical challenges that arise in the context of providing tuberculosis treatment and care to non-refugee migrants in high-income countries (HIC), particularly those that do not face immediate danger or violence. In this paper, we analyze some of the ethical challenges associated with treating migrants with tuberculosis in the Canadian context. In particular, we will discuss (i) inter- and intra-jurisdictional issues that challenge quotidian public health governance structures, and (ii) the ethical imperative for the Canadian government and its provinces to clearly differentiate access to healthcare from a person's immigration status to help overcome power imbalances that may exist between public health workers and their clients. The arguments presented herein could potentially apply to other HIC with some form of universal health coverage.

Epidemiology, clinical features and outcomes of incident tuberculosis in children in Canada in 2013-2016: results of a national surveillance study

PURPOSE

Childhood tuberculosis disease is difficult to diagnose and manage and is an under-recognised cause of morbidity and mortality. Reported data from Canada do not focus on childhood tuberculosis or capture key epidemiologic, clinical and microbiologic details. The purpose of this study was to assess demographics, presentation and clinical features of childhood tuberculosis in Canada.

METHODS

We conducted prospective surveillance from 2013 to 2016 of over 2700 paediatricians plus vertical tuberculosis programmes for incident tuberculosis disease in children younger than 15 years in Canada using the Canadian Paediatric Surveillance Program (CPSP).

RESULTS

In total, 200 cases are included in this study. Tuberculosis was intrathoracic in 183 patients of whom 86% had exclusively intrathoracic involvement. Central nervous system tuberculosis occurred in 16 cases (8%). Fifty-one per cent of cases were hospitalised and 11 (5.5%) admitted to an intensive care unit. Adverse drug reactions were reported in 9% of cases. The source case, most often a first-degree relative, was known in 73% of cases. Fifty-eight per cent of reported cases were Canadian-born Indigenous children. Estimated study rates of reported cases (per 100 000 children per year) were 1.2 overall, 8.6 for all Indigenous children and 54.3 for Inuit children.

CONCLUSION

Childhood tuberculosis may cause significant morbidity and resource utilisation. Key geographies and groups have very high incidence rates. Elimination of childhood tuberculosis in Canada will require well-resourced community-based efforts that focus on these highest risk groups.

Safety and Efficacy of Rifampin or Isoniazid Among People With Mycobacterium tuberculosis Infection and Living With Human Immunodeficiency Virus or Other Health Conditions: Post Hoc Analysis of 2 Randomized Trials

BACKGROUND

The safety and efficacy of rifampin among people living with human immunodeficiency virus (PLHIV) or other health conditions is uncertain. We assessed completion, safety, and efficacy of 4 months of rifampin vs 9 months of isoniazid among PLHIV or other health conditions.

METHODS

We conducted post hoc analysis of 2 randomized trials that included 6859 adult participants with Mycobacterium tuberculosis infection. Participants were randomized 1:1 to 10 mg/kg/d rifampin or 5 mg/kg/d isoniazid. We report completion, drug-related adverse events (AE), and active tuberculosis incidence among people living with HIV; with renal failure or receiving immunosuppressants; using drugs or with hepatitis; with diabetes mellitus; consuming >1 alcoholic drink per week or current/former smokers; and with no health condition.

RESULTS

Overall, 270 (3.9%) people were living with HIV (135 receiving antiretroviral therapy), 2012 (29.3%) had another health condition, and 4577 (66.8%) had no condition. Rifampin was more often or similarly completed to isoniazid in all populations. AEs were less common with rifampin than isoniazid among PLHIV (risk difference, -2.1%; 95% confidence interval [CI], -5.9 to 1.6). This was consistent for others except people with renal failure or on immunosuppressants (2.1%; 95% CI, -7.2 to 11.3). Tuberculosis incidence was similar among people receiving rifampin or isoniazid. Among participants receiving rifampin living with HIV, incidence was comparable to those with no health condition (rate difference, 4.1 per 1000 person-years; 95% CI, -6.4 to 14.7).

CONCLUSIONS

Rifampin appears to be safe and as effective as isoniazid across many populations with health conditions, including HIV.

CLINICAL TRIALS REGISTRATION

NCT00170209; NCT00931736.

Evaluation of the implementation process of the mobile health platform 'WelTel' in six sites in East Africa and Canada using the modified consolidated framework for implementation research (mCFIR)

BACKGROUND

Health systems globally are investing in integrating secure messaging platforms for virtual care in clinical practice. Implementation science is essential for adoption, scale-up, spread and maintenance of complex evidence-based solutions in clinics with evolving priorities. In response, the mobile Health (mHealth) Research Group modified the existing consolidated framework for implementation research (CFIR) to evaluate implementation of virtual health tools in clinical settings. WelTel® is an evidence-based digital health platform widely deployed in various geographical and health contexts. The objective is to identify the facilitators and barriers for implementing WelTel and to assess the application of the mCFIR tool in facilitating focus groups in different geographical and health settings.

METHODS

Both qualitative and descriptive quantitative approaches were employed. Six mCFIR sessions were held in three countries with 51 key stakeholders. The mCFIR tool consists of 5 Domains and 25 constructs and was distributed through Qualtrics Experience Management (XM). "Performance" and "Importance" scores were valued on a scale of 0 to 10 (Mean ± SD). Descriptive analysis was conducted using R computing software. NVivo 12 Pro software was used to analyze mCFIR responses and to generate themes from the participants' input.

RESULTS

We observed a parallel trend in the scores of Importance and Performance. Of the five Domains, Domain 4 (End-user Characteristics) and Domain 3 (Inner Settings) scored highest in Importance (8.9 ± 0.5 and 8.6 ± 0.6, respectively) and Performance (7.6 ± 0.7 and 7.2 ± 1.3, respectively) for all sites. Domain 2 (Outer Setting) scored the lowest in both Importance and Performance for all sites (7.6 ± 0.4 and 5.6 ± 1.8). The thematic analysis produced the following themes: for areas of strengths, the themes brought up were timely diagnosis and response, cost-effectiveness, and user-friendliness. As for areas for improvement, the themes discussed were training, phone accessibility, stakeholder engagement, and literacy.

CONCLUSION

The mCFIR tool allowed for a comprehensive understanding of the barriers and facilitators to the implementation, reach, and scale-up of digital health tools. Amongst several important findings, we observed the value of bringing the perspectives of both end users (HCPs and patients) to the table across Domains.

TRIAL REGISTRATION

NCT02603536 - November 11, 2015: WelTelOAKTREE: Text Messaging to Support Patients With HIV/AIDS in British Columbia (WelTelOAKTREE). NCT01549457 - March 9, 2012: TB mHealth Study-Use of Cell Phones to Improve Compliance in Patients on LTBI Treatment.

Using Whole-genome Sequencing to Determine the Timing of Secondary Tuberculosis in British Columbia, Canada

Combined with epidemiological data, whole-genome sequencing (WGS) can help better resolve individual tuberculosis (TB) transmission events to a degree not possible with traditional genotyping. We combine WGS data with patient-level data to calculate the timing of secondary TB among contacts of people diagnosed with active TB in British Columbia, Canada.

Tuberculosis-associated depression: a population-based cohort study of people immigrating to British Columbia, Canada, 1985-2015

PURPOSE

To estimate the risk of tuberculosis (TB)-associated depression. A second aim was to estimate the extent to which any increased risk of depression among TB patients may be mediated by the length of hospital length stay (LOS) METHODS: Retrospective cohort study of linked healthcare claims and public health surveillance data. Our primary outcome, time-to-depression, was analyzed using Cox proportional hazards (PH) regressions. Causal mediation analysis was used to estimate the natural direct and indirect effect of TB mediated by hospital LOS.

RESULTS

Among 755,836 participants (52.2% female, median age=35 years, median follow-up=8.75 years), 2295 were diagnosed with TB (exposure), and 128,963 were diagnosed with depression (outcome). We observed a covariate-adjusted hazard ratio (aHR) of 1.24 (95% CI, 1.14-1.34) for depression by TB. The total effect of TB on depression was decomposed into a natural direct effect of TB of aHR=1.11 (95% CI, 1.02-1.21) and an indirect effect through hospital LOS of aHR=1.11 (95% CI, 1.10-1.12), indicating that TB's total effect was mediated by 50% (95% CI, 35-82%) through hospital LOS.

CONCLUSIONS

TB patients had a 24% higher risk of developing depression. TB's effect was mediated substantially by hospital LOS, requiring further study. Depression screening among TB patients is warranted.

Effectiveness and cost-effectiveness of a health systems intervention for latent tuberculosis infection management (ACT4): a cluster-randomised trial

BACKGROUND

Reaching the UN General Assembly High-Level Meeting on Tuberculosis target of providing tuberculosis preventive treatment to at least 30 million people by 2022, including 4 million children under the age of 5 years and 20 million other household contacts, will require major efforts to strengthen health systems. The aim of this study was to evaluate the effectiveness and cost-effectiveness of a health systems intervention to strengthen management for latent tuberculosis infection (LTBI) in household contacts of confirmed tuberculosis cases.

METHODS

ACT4 was a cluster-randomised, open-label trial involving 24 health facilities in Benin, Canada, Ghana, Indonesia, and Vietnam randomly assigned to either a three-phase intervention (LTBI programme evaluation, local decision making, and strengthening activities) or control (standard LTBI care). Tuberculin and isoniazid were provided to control and intervention sites if not routinely available. Randomisation was stratified by country and restricted to ensure balance of index patients with tuberculosis by arm and country. The primary outcome was the number of household contacts who initiated tuberculosis preventive treatment at each health facility within 4 months of the diagnosis of the index case, recorded in the first or last 6 months of our 20-month study. To ease interpretation, this number was standardised per 100 newly diagnosed index patients with tuberculosis. Analysis was by intention to treat. Masking of staff at the coordinating centre and sites was not possible; however, those analysing data were masked to assignment of intervention or control. An economic analysis of the intervention was done in parallel with the trial. ACT4 is registered at ClinicalTrials.gov, NCT02810678.

FINDINGS

The study was done between Aug 1, 2016, and March 31, 2019. During the first 6 months of the study the crude overall proportion of household contacts initiating tuberculosis preventive treatment out of those eligible at intervention sites was 0·21. After the implementation of programme strengthening activities, the proportion initiating tuberculosis preventive treatment increased to 0·35. Overall, the number of household contacts initiating tuberculosis preventive treatment per 100 index patients with tuberculosis increased between study phases in intervention sites (adjusted rate difference 60, 95% CI 4 to 116), while control sites showed no statistically significant change (-12, -33 to 10). There was a difference in rate differences of 72 (95% CI 10 to 134) contacts per 100 index patients with tuberculosis initiating preventive treatment associated with the intervention. The total cost for the intervention, plus LTBI clinical care per additional contact initiating treatment was estimated to be CA$1348 (range 724 to 9708).

INTERPRETATION

A strategy of standardised evaluation, local decision making, and implementation of health systems strengthening activities can provide a mechanism for scale-up of tuberculosis prevention, particularly in low-income and middle-income countries.

FUNDING

Canadian Institutes of Health Research.

Risk of active tuberculosis in migrants diagnosed with cancer: a retrospective cohort study in British Columbia, Canada

OBJECTIVES

To describe the association between types of cancer and active tuberculosis (TB) risk in migrants. Additionally, in order to better inform latent TB infection (LTBI) screening protocols, we assessed proportion of active TB cases potentially preventable through LTBI screening and treatment in migrants with cancer.

DESIGN

Population-based, retrospective cohort study.

SETTING

British Columbia (BC), Canada.

PARTICIPANTS

1 000 764 individuals who immigrated to Canada from 1985 to 2012 and established residency in BC at any point up to 2015.

PRIMARY AND SECONDARY OUTCOME MEASURES

Using linked health administrative databases and disease registries, data on demographics, comorbidities, cancer type, TB exposure and active TB diagnosis were extracted. Primary outcomes included: time to first active TB diagnoses, and risks of active TB following cancer diagnoses which were estimated using Cox extended hazard regression models. Potentially preventable TB was defined as active TB diagnosed >6 months postcancer diagnoses.

RESULTS

Active TB risk was increased in migrants with cancer ((HR (95% CI)) 2.5 (2.0 to 3.1)), after adjustment for age, sex, TB incidence in country of origin, immigration classification, contact status and comorbidities. Highest risk was observed with lung cancer (HR 11.2 (7.4 to 16.9)) and sarcoma (HR 8.1 (3.3 to 19.5)), followed by leukaemia (HR 5.6 (3.1 to 10.2)), lymphoma (HR 4.9 (2.7 to 8.7)) and gastrointestinal cancers (HR 2.7 (1.7 to 4.4)). The majority (65.9%) of active TB cases were diagnosed >6 months postcancer diagnosis.

CONCLUSION

Specific cancers increase active TB risk to varying degrees in the migrant population of BC, with approximately two-thirds of active TB cases identified as potentially preventable.

Post-tuberculosis airway disease: A population-based cohort study of people immigrating to British Columbia, Canada, 1985-2015

BACKGROUND

Current epidemiological evidence of post-TB airway disease is largely cross-sectional and derived from high-TB-incidence settings. We present the first cohort study of post-TB airway disease in a low-TB-incidence setting.

AIMS

(1) analyze the risk of airway disease by respiratory TB, (2) assess potential unmeasured confounding between TB and airway disease, and (3) investigate TB effect measure modification.

METHODS

A population-based cohort study using healthcare claims data for immigrants to British Columbia (BC), Canada, 1985-2015. Airway disease included chronic airway obstruction, asthma, bronchitis, bronchiolitis, and emphysema. Respiratory TB was defined from TB registry data. Cox proportional hazards (PH) regressions were used to analyze time-to-airway disease by respiratory TB. Sensitivity analyses included varying definitions of TB and airway disease. Potential unmeasured confounding by smoking was evaluated by E-value and hybrid least absolute shrinkage and selection operator (LASSO)-high-dimensional propensity score (hdPS).

FINDINGS

In our cohort (N = 1 005 328; n_TB=1141) there were 116 840 incident cases of airway disease during our 30-year study period (10.43 per 1,000 person-years of follow-up), with cumulative incidence of 42·5% among respiratory TB patients compared with 11·6% among non-TB controls. The covariate-adjusted hazard ratio (aHR) for airway disease by respiratory TB was 2·08 (95% CI: 1·91-2·28) with E-value=3·58. The LASSO-hdPS analysis produced aHR=2·26 (95% CI: 2·07-2·47).

INTERPRETATION

A twofold higher risk of airway disease was observed among immigrants diagnosed with respiratory TB, compared with non-TB controls, in a low-TB-incidence setting. Unmeasured confounding is unlikely to explain this relationship. Models of post-TB care are needed.

FUNDING

Canadian Institutes of Health Research.

Post-tuberculosis mortality risk among immigrants to British Columbia, Canada, 1985-2015: a time-dependent Cox regression analysis of linked immigration, public health, and vital statistics data

OBJECTIVE

To compare non-tuberculosis (non-TB)-cause mortality risk overall and cause-specific mortality risks within the immigrant population of British Columbia (BC) with and without TB diagnosis through time-dependent Cox regressions.

METHODS

All people immigrating to BC during 1985-2015 (N = 1,030,873) were included with n = 2435 TB patients, and the remaining as non-TB controls. Outcomes were time-to-mortality for all non-TB causes, respiratory diseases, cardiovascular diseases, cancers, and injuries/poisonings, and were ascertained using ICD-coded vital statistics data. Cox regressions were used, with a time-varying exposure variable for TB diagnosis.

RESULTS

The non-TB-cause mortality hazard ratio (HR) was 4.01 (95% CI 3.57-4.51) with covariate-adjusted HR of 1.69 (95% CI 1.50-1.91). Cause-specific covariate-adjusted mortality risk was elevated for respiratory diseases (aHR = 2.96; 95% CI 2.18-4.00), cardiovascular diseases (aHR = 1.63; 95% CI 1.32-2.02), cancers (aHR = 1.40; 95% CI 1.13-1.75), and injuries/poisonings (aHR = 1.85; 95% CI 1.25-2.72).

CONCLUSIONS

In any given year, if an immigrant to BC was diagnosed with TB, their risk of non-TB mortality was 69% higher than if they were not diagnosed with TB. Healthcare providers should consider multiple potential threats to the long-term health of TB patients during and after TB treatment. TB guidelines in high-income settings should address TB survivor health.

Estimated Impact of World Health Organization Latent Tuberculosis Screening Guidelines in a Region With a Low Tuberculosis Incidence: Retrospective Cohort Study

BACKGROUND

Latent tuberculosis infection (LTBI) screening and treatment is a key component of the World Health Organization (WHO) EndTB Strategy, but the impact of LTBI screening and treatment at a population level is unclear. We aimed to estimate the impact of LTBI screening and treatment in a population of migrants to British Columbia (BC), Canada.

METHODS

This retrospective cohort included all individuals (N = 1 080 908) who immigrated to Canada as permanent residents between 1985 and 2012 and were residents in BC at any time up to 2013. Multiple administrative databases were linked to identify people with risk factors who met the WHO strong recommendations for screening: people with tuberculosis (TB) contact, with human immunodeficiency virus, on dialysis, with tumor necrosis factor-alpha inhibitors, who had an organ/haematological transplant, or with silicosis. Additional TB risk factors included immunosuppressive medications, cancer, diabetes, and migration from a country with a high TB burden. We defined active TB as preventable if diagnosed ≥6 months after a risk factor diagnosis. We estimated the number of preventable TB cases, given optimal LTBI screening and treatment, based on these risk factors.

RESULTS

There were 16 085 people (1.5%) identified with WHO strong risk factors. Of the 2814 people with active TB, 118 (4.2%) were considered preventable through screening with WHO risk factors. Less than half (49.4%) were considered preventable with expanded screening to include people migrating from countries with high TB burdens, people who had been prescribed immunosuppressive medications, or people with diabetes or cancer.

CONCLUSIONS

The application of WHO LTBI strong recommendations for screening would have minimally impacted the TB incidence in this population. Further high-risk groups must be identified to develop an effective LTBI screening and treatment strategy for low-incidence regions.

Latent Tuberculosis Therapy Outcomes in Dialysis Patients: A Retrospective Cohort

RATIONALE & OBJECTIVES

Maintenance dialysis patients are at an increased risk for active tuberculosis (TB). In 2012, British Columbia, Canada, began systematically screening maintenance dialysis patients for latent TB infection (LTBI) and treating people with evidence of LTBI when appropriate. We examined LTBI treatment outcomes and compared treatment outcomes before and after rollout of the systematic screening program.

STUDY DESIGN

Retrospective cohort study.

SETTING & PARTICIPANTS

The study comprised 365 people in British Columbia, Canada, initiating at least 90 days of dialysis from January 1, 2001, to May 31, 2017, and starting LTBI therapy: 290 (79.5%) people in the recent cohort and 75 (20.5%) in the historical cohort. People starting LTBI therapy from January 1, 2012, onward were classified as the recent cohort, whereas people starting LTBI therapy before January 1, 2012, were classified as the historical cohort.

EXPOSURE

Systematic LTBI screening and therapy.

OUTCOMES

Proportion of people who experience grade 3 to 5 adverse events (AEs) or any grade rash and end-of-treatment outcomes.

ANALYTICAL APPROACH

Outcomes were reported using descriptive statistics. 2-sample test of proportions using χ² distribution was used to test for statistical significance between the recent and historical cohorts.

RESULTS

298 (81.6%) people successfully completed LTBI therapy. The proportion of people experiencing a grade 3 to 4 AE or any grade rash was 21.1%. Most AEs were related to gastrointestinal events, general malaise, or pruritus that resulted in regimen changes. 2 (0.5%) people were hospitalized for AEs related to LTBI therapy. No significant difference was found between the recent and historical cohorts in all outcomes of interest. No grade 5 AEs (deaths) were attributed to LTBI therapy.

LIMITATIONS

Retrospective data and generalizability outside low-TB-burden settings.

CONCLUSIONS

Our findings suggest that a high proportion of people receiving maintenance dialysis can complete LTBI therapy. The rate of grade 3 to 4 AEs was high and associated with frequent medication changes during therapy. LTBI therapy in maintenance dialysis may be safe but requires close monitoring.

Effectiveness of Latent TB Screening and Treatment in People Initiating Dialysis in British Columbia, Canada

Background:

People undergoing chronic dialysis are at an increased risk of active tuberculosis (TB). In 2012, the Canadian province of British Columbia began systematically screening people initiating dialysis for latent TB using interferon-gamma release assay (IGRA), and treating when appropriate.

Objective:

The objective of this study was to compare active TB rate in people who initiated dialysis and were screened using an IGRA compared with those not screened during the same period.

Design:

Retrospective cohort study.

Setting:

British Columbia (BC), a Canadian province of 5.0 million people with an active TB incidence of 5.1 per 100 000 population.

Participants:

All people in BC who initiated at least 90 days of dialysis between January 2012 and May 2017 were included in the study. People were excluded if they were <18 years of age or had a prior history of active TB diagnosis or treatment for latent TB.

Methods:

A retrospective cohort was created of British Columbians who initiated dialysis between 2012 and 2017. Individuals were stratified into a screened and nonscreened group. Multivariable Cox regression was used to determine the association between latent TB screening and the development of active TB. The primary outcome was incident active TB, either microbiologically confirmed or clinically diagnosed.

Results:

Of the 3190 people included in the study, 1790 (56.1%) were screened, of which 152 (8.5%) initiated latent TB treatment postscreening. During follow-up, incident active TB was diagnosed in 6 (0.3%) of the 1790 people screened, compared with 11 (0.8%) of the 1400 people who received no screening. In multivariable analysis, latent TB screening and treatment was associated with a significant reduction in the rate of active TB (adjusted hazard ratio = 0.3, 95% confidence interval = 0.1-0.8; P < .01).

Limitations:

This was an observational retrospective study and the potential for unmeasured confounding should be carefully assessed.

Conclusions:

These findings suggest that systematically screening and treating people initiating dialysis can significantly decrease the rate of active TB in this high-risk population. Given the importance of screening high-risk groups, the results from this analysis could inform scale-up of TB screening in dialysis programs in other low incidence regions. Trial registration is not applicable as this was a retrospective cohort analysis and not a randomized trial.

Cost-effectiveness of Latent Tuberculosis Infection Screening before Immigration to Low-Incidence Countries

Prospective migrants to countries where the incidence of tuberculosis (TB) is low (low-incidence countries) receive TB screening; however, screening for latent TB infection (LTBI) before immigration is rare. We evaluated the cost-effectiveness of mandated and sponsored preimmigration LTBI screening for migrants to low-incidence countries. We used discrete event simulation to model preimmigration LTBI screening coupled with postarrival follow-up and treatment for those who test positive. Preimmigration interferon-gamma release assay screening and postarrival rifampin treatment was preferred in deterministic analysis. We calculated cost per quality-adjusted life-year gained for migrants from countries with different TB incidences. Our analysis provides evidence of the cost-effectiveness of preimmigration LTBI screening for migrants to low-incidence countries. Coupled with research on sustainability, acceptability, and program implementation, these results can inform policy decisions.

Demographic predictors of active tuberculosis in people migrating to British Columbia, Canada: a retrospective cohort study

BACKGROUND

Canadian tuberculosis (TB) guidelines recommend targeting postlanding screening for and treatment of latent tuberculosis infection (LTBI) in people migrating to Canada who are at increased risk for TB reactivation. Our objectives were to calculate robust longitudinal estimates of TB incidence in a cohort of people migrating to British Columbia, Canada, over a 29-year period, and to identify groups at highest risk of developing TB based on demographic characteristics at time of landing.

METHODS

We included all individuals (n = 1 080 908) who became permanent residents of Canada between Jan. 1, 1985, and Dec. 31, 2012, and were resident in BC at any time between 1985 and 2013. Multiple administrative databases were linked to the provincial TB registry. We used recursive partitioning models to identify populations with high TB yield.

RESULTS

Active TB was diagnosed in 2814 individuals (incidence rate 24.2/100 000 person-years). Demographic factors (live-in caregiver, family, refugee immigration classes; higher TB incidence in country of birth; and older age) were strong predictors of TB incidence in BC, with elevated rates continuing many years after entry into the cohort. Recursive partitioning identified refugees 18-64 years of age from countries with a TB incidence greater than 224/100 000 population as a high-yield group, with 1% developing TB within the first 10 years.

INTERPRETATION

These findings support recommendations in Canadian guidelines to target postlanding screening for and treatment of LTBI in adult refugees from high-incidence countries. Because high-yield populations can be identified at entry via demographic data, screening at this point may be practical and high-impact, particularly if the LTBI care cascade can be optimized.

The problem with defining foreign birth as a risk factor in tuberculosis epidemiology studies

OBJECTIVE

To examine how stratifying persons born outside Canada according to tuberculosis (TB) incidence in their birth country and other demographic factors refines our understanding of TB epidemiology and local TB transmission.

BACKGROUND

Population-level TB surveillance programs and research studies in low incidence settings often report all persons born outside the country in which the study is conducted as "foreign-born"-a single label for a highly diverse population with variable TB risks. This may mask important TB epidemiologic trends and not accurately reflect local transmission patterns.

METHODS

We used population-level data from two large cohorts in British Columbia (BC), Canada: an immigration cohort (n = 337,492 permanent residents to BC) and a genotyping cohort (n = 2290 culture-confirmed active TB cases). We stratified active TB case counts, incidence rates, and genotypic clustering (an indicator of TB transmission) in BC by birth country TB incidence, age at immigration, and years since arrival.

RESULTS

Persons from high-incidence countries had a 12-fold higher TB incidence than those emigrating from low-incidence settings. Estimates of local transmission, as captured by genotyping, versus reactivation of latent TB infection acquired outside Canada varied when data were stratified by birthplace TB incidence, as did patient-level characteristics of individuals in each group, such as age and years between immigration and diagnosis.

CONCLUSION

Categorizing persons beyond simply "foreign-born", particularly in the context of TB epidemiologic and molecular data, is needed for a more accurate understanding of TB rates and patterns of transmission.

Preventing Tuberculosis in a Low Incidence Setting: Evaluation of a Multi-lingual, Online, Educational Video on Latent Tuberculosis

Treating latent tuberculosis infection (LTBI) in those at risk is an important yet challenging cornerstone of TB elimination. We evaluated a culturally-tailored, multi-lingual, 4.5-min, health promotional video on LTBI. Mixed methods study assessed use of the video with web-analytics, acceptability of content through interviews and survey questions, and compared knowledge scores in viewers and non-viewers using a survey. The video was viewed 6999 times in six languages over 1 year. Of 1598 survey respondents, 193 viewers had a mean knowledge score of 59%, compared to 38% in non-viewers. Eighty-four percent of viewers rated the video as helpful. When controlling for other factors, viewing the video was associated with a 1.04 (95% CI 0.85-1.26) or a 21% increase in a knowledge score. Qualitative data suggested the video was acceptable and may facilitate behavior change. This online, educational video shows promise as a tool to supplement clinical care.

Universal genotyping reveals province-level differences in the molecular epidemiology of tuberculosis

OBJECTIVES

Compare the molecular epidemiology of tuberculosis (TB) between two large Canadian provinces-Ontario and British Columbia (BC)-to identify genotypic clusters within and across both provinces, allowing for an improved understanding of genotype data and providing context to more accurately identify clusters representing local transmission.

DESIGN

We compared 24-locus Mycobacterial Interspersed Repetitive Units-Variable Number of Tandem Repeats (MIRU-VNTR) genotyping for 3,314 Ontario and 1,602 BC clinical Mycobacterium tuberculosis isolates collected from 2008 through 2014. Laboratory data for each isolate was linked to case-level records to obtain clinical and demographic data.

RESULTS

The demographic characteristics of persons with TB varied between provinces, most notably in the proportion of persons born outside Canada, which was reflected in the large number of unique genotypes (n = 3,461). The proportion of clustered isolates was significantly higher in BC. Substantial clustering amongst non-Lineage 4 TB strains was observed within and across the provinces. Only two large clusters (≥10 cases/cluster) representing within province transmission had interprovincial genotype matches.

CONCLUSION

We recommend expanding analysis of shared genotypes to include neighbouring jurisdictions, and implementing whole genome sequencing to improve identification of TB transmission, recognize outbreaks, and monitor changing trends in TB epidemiology.

Enhancing the public health impact of latent tuberculosis infection diagnosis and treatment (ACT4): protocol for a cluster randomised trial

INTRODUCTION

Treatment of latent tuberculosis (TB) infection (LTBI) is an important component of the End-TB strategy. However, the number of individuals who successfully complete LTBI treatment remains low as there are losses at all steps in the LTBI 'cascade-of-care'. The reasons for these losses are variable and highly dependent on the setting. We have planned a trial of a standardised public health approach to strengthen the management of household contacts (HHCs) of newly diagnosed patients with pulmonary TB. Assessing costs related to approach is a secondary objective of the study.

METHODS AND ANALYSIS

A cluster randomised trial will be conducted in 24 randomisation units (health facilities or groups of health facilities) in five countries. In Phase 1, at intervention sites, we will conduct a standardised assessment of the current LTBI programme, with a focus on cascade-of-care endpoints. Standardised open-ended questionnaires on practices, knowledge, attitudes and beliefs regarding TB prevention are then administered to key patient groups and healthcare workers. At each site, local stake-holders will review study findings and select solutions based on their acceptability, cost and effectiveness. In Phase 2, intervention clinics will implement the selected solutions, along with contact measurement registries and regular in-service LTBI management training. Control sites will continue their usual LTBI care with no explicit evaluation, strengthening or training activities. The primary study outcome is the number of HHC initiating LTBI treatment per newly diagnosed active TB patient, within 3 months of diagnosis of the index patient. An intention-to-treat analysis will be performed, using a Poisson regression approach.

ETHICS AND DISSEMINATION

Ethics approval from the MUHC ethical review board (ERB) was obtained in November 2015. During the study standardised tools will be developed and made publicly available. Key study findings and novel methodologic contributions will be detailed in publications and other dissemination activities.

TRIAL REGISTRATION NUMBER

NCT02810678; Pre-Results.

Screening for Latent Tuberculosis Infection in Migrants With CKD: A Cost-effectiveness Analysis

RATIONALE & OBJECTIVE

In countries with a low tuberculosis (TB) incidence, TB disproportionately affects populations born abroad. TB persists in these populations through reactivation of latent TB infection (LTBI) acquired before immigration. Those with chronic kidney disease (CKD) are at increased risk for reactivation and may benefit from LTBI screening and treatment.

STUDY DESIGN

Health administrative data from British Columbia, Canada, were used to inform a cost-effectiveness analysis evaluating LTBI screening in those diagnosed with stage 4 or 5 CKD not requiring dialysis (late-stage CKD) and those who began dialysis therapy.

SETTING & POPULATION

Permanent residents establishing residency in British Columbia, Canada, between 1985 and 2012 who had late-stage CKD diagnosed or began dialysis therapy.

INTERVENTIONS

Screening with the tuberculin skin test or interferon-gamma release assay (IGRA) compared to no LTBI screening at the time of late-stage CKD diagnosis and time of dialysis therapy initiation. Treatment for those who tested positive was isoniazid for 9 months.

OUTCOMES

Costs (2016 Can $), TB cases, and quality-adjusted life-years (QALYs). The incremental cost-effectiveness ratio for QALYs gained was calculated.

MODEL, PERSPECTIVE, & TIMEFRAME

Discrete event simulation model using a health care system perspective, 1.5% discount rate, and 5-year time horizon.

RESULTS

Screening with IGRA was superior to the tuberculin skin test in all situations. Screening with IGRA was less expensive and resulted in better outcomes compared to no screening in those initiating dialysis therapy from countries with an elevated TB incidence. In individuals with late-stage CKD, screening with IGRA was only cost-effective in those 60 years or older (cost per QALY gained, <$48,000) from countries with an elevated TB incidence.

LIMITATIONS

This study has limitations in generalizability to different epidemiologic settings and in modeling complicated clinical decisions.

CONCLUSIONS

LTBI screening should be considered in non-Canadian-born residents initiating dialysis therapy and those with late stage CKD who are older.

Genotyping and Whole-Genome Sequencing to Identify Tuberculosis Transmission to Pediatric Patients in British Columbia, Canada, 2005-2014

Background

Tuberculosis (TB) in children is often an indicator of recent transmission. Genotyping and whole-genome sequencing (WGS) can enhance pediatric TB investigations by confirming or refuting transmission events.

Methods

Mycobacterium tuberculosis isolates from all pediatric patients <18 years with culture-confirmed TB in British Columbia (BC) from 2005 to 2014 (n = 49) were genotyped by Mycobacterial Interspersed Repetitive Units-Variable Number Tandem Repeat (MIRU-VNTR) and compared with adult isolates. Genotypically clustered cases underwent WGS. Clinical, demographic, and contact data were reviewed for each case.

Results

Twenty-three children were Canadian-born, 7 to Canadian-born parents (CBP) and 16 to foreign-born parents (FBP). Of the 26 foreign-born children, all were born in Asia (81%) or Africa (19%). Using molecular and epidemiological data, we determined that 15 children had acquired their infection within BC, and household transmission explained all 7 Canadian-born (FBP) children that acquired TB locally. In contrast, 6 of 7 Canadian-born (CBP) children were exposed via a non-household community source. Eight Canadian-born (FBP) children acquired their infections through travel to their parents' place of birth. All but 1 of the foreign-born children acquired their infection outside of BC.

Conclusions

Genotyping and genomic data reveal that drivers of pediatric transmission vary according to a child's age, birthplace, and their parents' place of birth.

Four Months of Rifampin or Nine Months of Isoniazid for Latent Tuberculosis in Adults

BACKGROUND

A 9-month regimen of isoniazid can prevent active tuberculosis in persons with latent tuberculosis infection. However, the regimen has been associated with poor adherence rates and with toxic effects.

METHODS

In an open-label trial conducted in nine countries, we randomly assigned adults with latent tuberculosis infection to receive treatment with a 4-month regimen of rifampin or a 9-month regimen of isoniazid for the prevention of confirmed active tuberculosis within 28 months after randomization. Noninferiority and potential superiority were assessed. Secondary outcomes included clinically diagnosed active tuberculosis, adverse events of grades 3 to 5, and completion of the treatment regimen. Outcomes were adjudicated by independent review panels.

RESULTS

Among the 3443 patients in the rifampin group, confirmed active tuberculosis developed in 4 and clinically diagnosed active tuberculosis developed in 4 during 7732 person-years of follow-up, as compared with 4 and 5 patients, respectively, among 3416 patients in the isoniazid group during 7652 person-years of follow-up. The rate differences (rifampin minus isoniazid) were less than 0.01 cases per 100 person-years (95% confidence interval [CI], -0.14 to 0.16) for confirmed active tuberculosis and less than 0.01 cases per 100 person-years (95% CI, -0.23 to 0.22) for confirmed or clinically diagnosed tuberculosis. The upper boundaries of the 95% confidence interval for the rate differences of the confirmed cases and for the confirmed or clinically diagnosed cases of tuberculosis were less than the prespecified noninferiority margin of 0.75 percentage points in cumulative incidence; the rifampin regimen was not superior to the isoniazid regimen. The difference in the treatment-completion rates was 15.1 percentage points (95% CI, 12.7 to 17.4). The rate differences for adverse events of grade 3 to 5 occurring within 146 days (120% of the 4-month planned duration of the rifampin regimen) were -1.1 percentage points (95% CI, -1.9 to -0.4) for all events and -1.2 percentage points (95% CI, -1.7 to -0.7) for hepatotoxic events.

CONCLUSIONS

The 4-month regimen of rifampin was not inferior to the 9-month regimen of isoniazid for the prevention of active tuberculosis and was associated with a higher rate of treatment completion and better safety. (Funded by the Canadian Institutes of Health Research and the Australian National Health and Medical Research Council; ClinicalTrials.gov number, NCT00931736 .).

Cost-effectiveness of post-landing latent tuberculosis infection control strategies in new migrants to Canada

BACKGROUND

The majority of tuberculosis in migrants to Canada occurs due to reactivation of latent TB infection. Risk of tuberculosis in those with latent tuberculosis infection can be significantly reduced with treatment. Presently, only 2.4% of new migrants are flagged for post-landing surveillance, which may include latent tuberculosis infection screening; no other migrants receive routine latent tuberculosis infection screening. To aid in reducing the tuberculosis burden in new migrants to Canada, we determined the cost-effectiveness of using different latent tuberculosis infection interventions in migrants under post-arrival surveillance and in all new migrants.

METHODS

A discrete event simulation model was developed that focused on a Canadian permanent resident cohort after arrival in Canada, utilizing a ten-year time horizon, healthcare system perspective, and 1.5% discount rate. Latent tuberculosis infection interventions were evaluated in the population under surveillance (N = 6100) and the total cohort (N = 260,600). In all evaluations, six different screening and treatment combinations were compared to the base case of tuberculin skin test screening followed by isoniazid treatment only in the population under surveillance. Quality adjusted life years, incident tuberculosis cases, and costs were recorded for each intervention and incremental cost-effectiveness ratios were calculated in relation to the base case.

RESULTS

In the population under surveillance (N = 6100), using an interferon-gamma release assay followed by rifampin was dominant compared to the base case, preventing 4.90 cases of tuberculosis, a 4.9% reduction, adding 4.0 quality adjusted life years, and saving $353,013 over the ensuing ten-years. Latent tuberculosis infection screening in the total population (N = 260,600) was not cost-effective when compared to the base case, however could potentially prevent 21.8% of incident tuberculosis cases.

CONCLUSIONS

Screening new migrants under surveillance with an interferon-gamma release assay and treating with rifampin is cost saving, but will not significantly impact TB incidence. Universal latent tuberculosis infection screening and treatment is cost-prohibitive. Research into using risk factors to target screening post-landing may provide alternate solutions.

Treatment outcomes for isoniazid-resistant tuberculosis under program conditions in British Columbia, Canada

Background

Every year, over 1 million people develop isoniazid (INH) resistant tuberculosis (TB). Yet, the optimal treatment regimen remains unclear. Given increasing prevalence, the clinical efficacy of regimens used by physicians is of interest. This study aims to examine treatment outcomes of INH resistant TB patients, treated under programmatic conditions in British Columbia, Canada.

Methods

Medical charts were retrospectively reviewed for cases of culture-confirmed INH mono-resistant TB reported to the BC Centre for Disease Control (BCCDC) from 2002 to 2014. Treatment regimens, patient and strain characteristics, and clinical outcomes were analysed.

Results

One hundred sixty five cases of INH mono-resistant TB were included in analysis and over 30 different treatment regimens were prescribed. Median treatment duration was 10.5 months (IQR 9–12 months) and treatment was extended beyond 12 months for 26 patients (15.8%). Fifty six patients (22.6%) experienced an adverse event that resulted in a drug regimen modification. Overall, 140 patients (84.8%) had a successful treatment outcome while 12 (7.2%) had an unsuccessful treatment outcome of failure (n = 2; 1.2%), relapse (n = 4; 2.4%) or all cause mortality (n = 6; 3.6%).

Conclusion

Our treatment outcomes, while consistent with findings reported from other studies in high resource settings, raise concerns about current recommendations for INH resistant TB treatment. Only a small proportion of patients completed the recommended treatment regimens. High quality studies to confirm the effectiveness of standardized regimens are urgently needed, with special consideration given to trials utilizing fluoroquinolones.

A syndemic approach to assess the effect of substance use and social disparities on the evolution of HIV/HCV infections in British Columbia

BACKGROUND

Co-occurrence of social conditions and infections may affect HIV/HCV disease risk and progression. We examined the changes in relationship of these social conditions and infections on HIV and hepatitis C virus (HCV) infections over time in British Columbia during 1990-2013.

METHODS

The BC Hepatitis Testers Cohort (BC-HTC) includes ~1.5 million individuals tested for HIV or HCV, or reported as a case of HCV, HIV, HBV, or tuberculosis linked to administrative healthcare databases. We classified HCV and HIV infection status into five combinations: HIV-/HCV-, HIV+monoinfected, HIV-/HCV+seroconverters, HIV-/HCV+prevalent, and HIV+/HCV+.

RESULTS

Of 1.37 million eligible individuals, 4.1% were HIV-/HCV+prevalent, 0.5% HIV+monoinfected, 0.3% HIV+/HCV+ co-infected and 0.5% HIV-/HCV+seroconverters. Overall, HIV+monoinfected individuals lived in urban areas (92%), had low injection drug use (IDU) (4%), problematic alcohol use (4%) and were materially more privileged than other groups. HIV+/HCV+ co-infected and HIV-/HCV+seroconverters were materially most deprived (37%, 32%), had higher IDU (28%, 49%), problematic alcohol use (14%, 17%) and major mental illnesses (12%, 21%). IDU, opioid substitution therapy, and material deprivation increased in HIV-/HCV+seroconverters over time. In multivariable multinomial regression models, over time, the odds of IDU declined among HIV-/HCV+prevalent and HIV+monoinfected individuals but not in HIV-/HCV+seroconverters. Declines in odds of problematic alcohol use were observed in HIV-/HCV+seroconverters and coinfected individuals over time.

CONCLUSIONS

These results highlight need for designing prevention, care and support services for HIV and HCV infected populations based on the evolving syndemics of infections and social conditions which vary across groups.

Predicting tuberculosis risk in the foreign-born population of British Columbia, Canada: study protocol for a retrospective population-based cohort study

INTRODUCTION

Improved understanding of risk factors for developing active tuberculosis (TB) will better inform decisions about diagnostic testing and treatment for latent TB infection (LTBI) in migrant populations in low-incidence regions. We aim to examine TB risk factors among the foreign-born population in British Columbia (BC), Canada, and to create and validate a clinically relevant multivariate risk score to predict active TB.

METHODS AND ANALYSIS

This retrospective population-based cohort study will include all foreign-born individuals who acquired permanent resident status in Canada between 1 January 1985 and 31 December 2013 and acquired healthcare coverage in BC at any point during this period. Multiple administrative databases and disease registries will be linked, including a National Immigration Database, BC Provincial Health Insurance Registration, physician billings, hospitalisations, drugs dispensed from community pharmacies, vital statistics, HIV testing and notifications, cancer, chronic kidney disease and dialysis treatment, and all TB and LTBI testing and treatment data in BC. Extended proportional hazards regression will be used to estimate risk factors for TB and to create a prognostic TB risk score.

ETHICS AND DISSEMINATION

Ethical approval for this study has been obtained from the University of British Columbia Clinical Ethics Review Board. Once completed, study findings will be presented at conferences and published in peer-reviewed journals. An online TB risk score calculator will also be created.

Tuberculosis and chronic kidney disease: an emerging global syndemic

The link between chronic kidney disease (CKD) and tuberculosis (TB) has been known for more than 40 years, but the interaction between these 2 diseases is still poorly understood. Dialysis and renal transplant patients appear to be at a higher risk of TB, in part related to immunosuppression along with socioeconomic, demographic, and comorbid factors. Meanwhile, TB screening and diagnostic test performance is suboptimal in the CKD population, and there is limited evidence to guide protocols. Given the increasing prevalence of CKD in TB endemic areas, a merging of CKD and TB epidemics could have significant public health implications, especially in low- to middle-income countries such as India and China, that are experiencing rapid increases in CKD prevalence and account for more than one-third of global TB prevalence. To begin addressing TB-CKD, a clear understanding of the relationship between these 2 conditions needs to be established, and consistent, evidence-based screening and treatment guidelines need to be developed.

Knowledge and Perceptions of Latent Tuberculosis Infection among Chinese Immigrants in a Canadian Urban Centre

Background. Since most tuberculosis (TB) cases in immigrants to British Columbia (BC), Canada, develop from latent TB infection (LTBI), treating immigrants for LTBI can contribute to the eradication of TB. However, adherence to LTBI treatment is a challenge that is influenced by knowledge and perceptions. This research explores Chinese immigrants' knowledge and perceptions towards LTBI in Greater Vancouver. Methods. This mixed methods study included a cross-sectional patient survey at BC's Provincial TB clinics and two focus group discussions (FGDs) with Chinese immigrants. Data from FGDs were coded and analyzed in Simplified Chinese. Codes, themes, and selected quotes were then translated into English. Results. The survey identified a mean basic knowledge score: 40.0% (95% CI: 38.3%, 41.7%). FGDs confirmed that Chinese immigrants' knowledge of LTBI was low, and they confused it with TB disease to the extent of experiencing LTBI associated stigma. Participants also expressed difficulties navigating the health system which impeded testing and treatment of LTBI. Online videos were the preferred format for receiving health information. Conclusion. We identified striking gaps in knowledge surrounding an LTBI diagnosis. Concerns of stigma may influence acceptance and adherence of LTBI treatment in Chinese immigrants. Integrating these findings into routine health care is recommended.

Chest radiography for active tuberculosis case finding in the homeless: a systematic review and meta-analysis

SETTING

In low-incidence regions, tuberculosis (TB) often affects vulnerable populations. Guidelines recommend active case finding (ACF) in homeless populations, but there is no consensus on a preferred screening method.

OBJECTIVE

We performed a systematic review and meta-analysis to evaluate the use of chest X-ray (CXR) screening in ACF for TB in homeless populations.

DESIGN

Articles were identified through EMBASE, Medline and the Cochrane Library. Studies using symptom screens, CXRs, sputum sweeps, tuberculin skin tests and/or interferon-gamma release assays to detect active TB in homeless populations were sought. Data were extracted using a standardised method by two reviewers and validated with an objective tool.

RESULTS

Sixteen studies addressing CXR screening of homeless populations for active TB in low-incidence regions were analysed. The pooled prevalence of active TB in the 16 study cohorts was 931 per 100 000 population screened (95%CI 565-1534) and 782/100 000 CXR performed (95%CI 566-1079). Six of seven longitudinal screening programs reported a reduction in regional TB incidence after implementation of the CXR-based ACF programme.

CONCLUSION

Our data suggest that CXR screening is a good tool for ACF in homeless populations in low-incidence regions.

Longitudinal clinical findings and outcome among patients with Cryptococcus gattii infection in British Columbia

BACKGROUND

Cryptococcus gattii (Cg) infection emerged in British Columbia in 1999. A longitudinal, clinical description of patients has not been reported.

METHODS

Medical records were reviewed for Cg patients identified through surveillance (1999-2007). Risk factors for Cg mortality were explored using multivariate Cox regression; longitudinal patterns in serum cryptococcal antigen (SCrAg) titers and the probability of chest cryptococcomas over time were estimated using cubic B-splines in mixed-effects regression models.

RESULTS

Among 152 patients, 111 (73.0%) were culture confirmed. Isolated lung infection was present in 105 (69.1%) patients; 47 (30.9%) had central nervous system infection, with or without lung involvement. Malignancy was the provisional diagnosis in 64 (42.1%) patients. Underlying diseases were present in 91 (59.9%) patients; 23 (15.1%) were immunocompromised, and 23 (15.1%) had asymptomatic disease. There were only 2 (1.8%) culture positive relapses, both within 12 months of follow-up. The estimated median time to resolution of lung cryptococcomas and decline in SCrAg titer to <1:8 was 2.8 and 2.9 years, respectively. Cg-related and all-cause mortality among culture-confirmed cases at 12 months' follow-up was 23.3% and 27.2%, respectively. Cg-related mortality was associated with age >50 years (hazard ratio [HR], 15.6; 95% confidence interval [CI], 1.9-130.5) and immunocompromise (HR, 5.8; CI, 1.5-21.6). All Cg-related mortality occurred among culture-positive cases within 1 year of diagnosis.

CONCLUSIONS

Cryptococcomas and serum antigenemia were slow to resolve. However, late onset of failed therapy or relapse was uncommon, suggesting that delayed resolution of these findings does not require prolongation of treatment beyond that recommended by guidelines.

Treatment outcomes from community-based drug resistant tuberculosis treatment programs: a systematic review and meta-analysis

BACKGROUND

There is increasing evidence that community-based treatment of drug resistant tuberculosis (DRTB) is a feasible and cost-effective alternative to centralized, hospital-based care. Although several large programs have reported favourable outcomes from community-based treatment, to date there has been no systematic assessment of community-based DRTB treatment program outcomes. The objective of this study was to synthesize available evidence on treatment outcomes from community based multi-drug resistant (MDRTB) and extensively drug resistant tuberculosis (XDRTB) treatment programs.

METHODS

We performed a systematic review and meta-analysis of the published literature to examine treatment outcomes from community-based MDRTB and XDRTB treatment programs. Studies reporting outcomes from programs using community-based treatment strategies and reporting outcomes consistent with WHO guidelines were included for analysis. Treatment outcomes, including treatment success, default, failure, and death were pooled for analysis. Meta-regression was performed to examine for associations between treatment outcomes and program or patient factors.

RESULTS

Overall 10 studies reporting outcomes on 1288 DRTB patients were included for analysis. Of this population, 65% [95% CI 59-71%] of patients had a successful outcome, 15% [95% CI 12-19%] defaulted, 13% [95% CI 9-18%] died, and 6% [95% CI 3-11%] failed treatment for a total of 35% [95% CI 29-41%] with unsuccessful treatment outcome. Meta-regression failed to identify any factors associated with treatment success, including study year, age of participants, HIV prevalence, XDRTB prevalence, treatment regimen, directly observed therapy (DOT) location or DOT provider.

CONCLUSIONS

Outcomes of community-based MDRTB and XDRTB treatment outcomes appear similar to overall treatment outcomes published in three systematic reviews on MDRTB therapy. Work is needed to delineate program characteristics associated with improved treatment outcomes.

Tuberculosis in HIV-infected persons in British Columbia during the HAART era

OBJECTIVE

Prior to the introduction of highly active antiretroviral therapy (HAART), active tuberculosis (TB) was a major contributor to HIV-related morbidity and mortality in Canada and other low-incidence regions. We performed this study to examine TB incidence, clinical manifestations and screening uptake in HIV-infected TB patients during the era of HAART therapy.

METHODS

We performed a retrospective study on all HIV-infected TB patients in British Columbia over a 10-year period (2003-2012). Demographic and clinical characteristics were extracted along with screening and treatment outcomes. Trends in provincial TB incidence, HIV testing and HAART prevalence were also examined.

RESULTS

In total, 2,839 TB cases were identified in BC during this period, including 129 HIV-infected TB patients. Surprisingly, only 64 HIV-infected TB patients (50%) had a documented screening tuberculin skin test (TST) prior to TB diagnosis. Of the 39 HIV-infected TB patients with prior TST positivity, 38 (97.4%) had not completed a course of isoniazid preventive therapy. TB incidence decreased significantly in the HIV-infected population of BC over the study period, from 1.9 to 0.5 TB cases per 1,000 HIV-infected individuals (p<0.001).

CONCLUSION

The incidence of HIV-TB decreased significantly over the past decade despite suboptimal latent TB infection screening and prevention practices. This decrease in TB incidence is likely attributable to the increased uptake of HAART. Consideration should be given to intensifying prevention efforts to accelerate TB elimination in HIV-infected populations in low-incidence regions.

Modern contact investigation methods for enhancing tuberculosis control in aboriginal communities

The Aboriginal communities in Canada are challenged by a disproportionate burden of TB infection and disease. Contact investigation (CI) guidelines exist but these strategies do not take into account the unique social structure of different populations. Because of the limitations of traditional CI, new approaches are under investigation and include the use of social network analysis, geographic information systems and genomics, in addition to the widespread use of genotyping to better understand TB transmission. Guidelines for the routine use of network methods and other novel methodologies for TB CI and outbreak investigation do not exist despite the gathering evidence that these approaches can positively impact TB control efforts, even in Aboriginal communities. The feasibility and efficacy of these novel approaches to CI in Aboriginal communities requires further investigation. The successful integration of these novel methodologies will require community involvement, capacity building and ongoing support at every level. The outcome will not only be the systematic collection, analysis, and interpretation of CI data in high-burden communities to assess transmission but the prioritization of contacts who are candidates for treatment of LTBI which will break the cycle of transmission. Ultimately, the measure of success will be a clear and sustained decline in TB incidence in Aboriginal communities.

Is the delay in diagnosis of pulmonary tuberculosis related to exposure to fluoroquinolones or any antibiotic?

BACKGROUND

Delays in diagnosis of tuberculosis (TB) have been associated with previous use of antibiotics, and in particular fluoroquinolones (FQ), for suspected pulmonary infections.

METHODS

We conducted a population-based cohort study with 2232 patients who had active TB between 1997 and 2006 (records obtained from the British Columbia Linked Health Databases). Patients with a record of an initial health care contact preceding the diagnosis of TB were identified for inclusion. Health care delay was defined as the time between initial health care contact and the initiation of anti-tuberculosis medication, and was compared between patients prescribed antibiotics and those not exposed to any antibiotics.

RESULTS

A total of 1544 patients were included. After adjusting for covariates, average health care delay for patients exposed to antibiotics was found to be significantly greater, by a factor of 2.10 (95%CI 1.80-2.44), with a median delay of 41 days in the antibiotic group compared to 14 days in the non-antibiotic group. Sex, age, foreign-born status and socio-economic status were non-significant factors. Health care delay increased with the number of antibiotic courses received, but not with the type of antibiotic.

CONCLUSIONS

Previous treatment with any antibiotic, and not only a FQ, is associated with a delay in TB diagnosis.

Whole-genome sequencing and social-network analysis of a tuberculosis outbreak

BACKGROUND

An outbreak of tuberculosis occurred over a 3-year period in a medium-size community in British Columbia, Canada. The results of mycobacterial interspersed repetitive unit-variable-number tandem-repeat (MIRU-VNTR) genotyping suggested the outbreak was clonal. Traditional contact tracing did not identify a source. We used whole-genome sequencing and social-network analysis in an effort to describe the outbreak dynamics at a higher resolution.

METHODS

We sequenced the complete genomes of 32 Mycobacterium tuberculosis outbreak isolates and 4 historical isolates (from the same region but sampled before the outbreak) with matching genotypes, using short-read sequencing. Epidemiologic and genomic data were overlaid on a social network constructed by means of interviews with patients to determine the origins and transmission dynamics of the outbreak.

RESULTS

Whole-genome data revealed two genetically distinct lineages of M. tuberculosis with identical MIRU-VNTR genotypes, suggesting two concomitant outbreaks. Integration of social-network and phylogenetic analyses revealed several transmission events, including those involving "superspreaders." Both lineages descended from a common ancestor and had been detected in the community before the outbreak, suggesting a social, rather than genetic, trigger. Further epidemiologic investigation revealed that the onset of the outbreak coincided with a recorded increase in crack cocaine use in the community.

CONCLUSIONS

Through integration of large-scale bacterial whole-genome sequencing and social-network analysis, we show that a socioenvironmental factor--most likely increased crack cocaine use--triggered the simultaneous expansion of two extant lineages of M. tuberculosis that was sustained by key members of a high-risk social network. Genotyping and contact tracing alone did not capture the true dynamics of the outbreak. (Funded by Genome British Columbia and others.).

A mutation in Mycobacterium tuberculosis rpoB gene confers rifampin resistance in three HIV-TB cases

Rifampin is a key component of standard short-course first-line therapy against Mycobacterium tuberculosis (MTB). Rifampin monoresistant MTB, previously a rare phenomenon, is now being reported at increasing rates worldwide. We report a mutation in the rpoB region leading to low level rifampin monoresistance in a cluster of HIV-positive patients. All rifampin monoresistant isolates identified from 2004 to 2006 underwent susceptibility confirmation, sequencing of rpoB and genotyping. Three patients were found to have a previously undocumented 3 base pair insertion at codon 525 in the rpoB region. The earliest initial case was infected with fully susceptible MTB. Disease relapse occurred 7 months later with a genotypically identical MTB isolate, showing acquired rifampin monoresistance. MTB isolates from 2 subsequent patients showed primary rifampin monoresistance with an identical genotype to the index case. Patients with rifampin monoresistant MTB tend to have poorer outcomes than those with fully susceptible strains. Risk factors for the development of rifampin monoresistance include co-morbid HIV infection and previously treated tuberculosis. HIV infection has been associated with malabsorption of anti-tuberculous medications leading to sub-therapeutic levels of administered drugs. These factors may have played a role in the development of this previously undocumented mutation.

Genetic variations of NAT2 and CYP2E1 and isoniazid hepatotoxicity in a diverse population

AIMS

TB is a serious global public health problem. Isoniazid, a key drug used to treat latent TB, can cause hepatotoxicity in some patients. This pilot study investigated the effects of genetic variation in NAT2 and CYP2E1 on isoniazid-induced hepatotoxicity in TB contacts in British Columbia, Canada.

MATERIALS & METHODS

DNA re-sequencing was used to establish the spectrum of genetic variation in the exons, promoter and conserved regions of NAT2 in all subjects. For CYP2E1, the CYP2E1*1C polymorphism was genotyped by PCR-RFLP. Association tests of NAT2 variants and haplotypes, as well acetylator types were performed.

RESULTS

We enrolled 170 subjects on isoniazid treatment (23 cases and 147 controls). Systematic re-sequencing of NAT2 revealed 18 known and 10 novel variants.

CONCLUSION

No single genetic variant of NAT2 and CYP2E1 showed a significant association with isoniazid-induced hepatotoxicity in this highly heterogeneous population. There was evidence of a trend for increasing hepatotoxicity risk across the rapid, intermediate and slow acetylator groups (p = 0.08).

Risk of tuberculosis in screened subjects without known risk factors for active disease

SETTING

Tuberculosis (TB) referral clinic in Vancouver, British Columbia, Canada.

BACKGROUND

Screening for and treatment of latent TB infection (LTBI) in at-risk populations are the cornerstone of TB control in low-incidence countries. Persons at low risk often undergo the tuberculin skin test (TST) for reasons other than contact. Little information exists on the actual risk of TB in this population.

OBJECTIVE

To determine the risk of TB in screened subjects without known risk factors.

DESIGN

Retrospective descriptive analysis of demographics, TST reaction size and TB disease occurrence in 98333 low-risk subjects screened from 1990 to 2002.

RESULTS

The average annual disease rate was 0.4 per 100000 population (cumulative rate 7.4/100000) from 1990 to 2006, and TB was diagnosed only in the foreign-born. Risk of TB in the foreign-born increased with larger TST reaction size (P < 0.03). Completion of treatment for LTBI was not documented for any of the subsequent active TB cases.

CONCLUSION

In a low-risk screened population, active TB disease was found only in the foreign-born. Treatment of LTBI is not recommended in persons with a positive TST and no additional risk factors. Local screening programs should focus on populations with confirmed risk factors for disease.

Investigation of suspected laboratory cross-contamination: interpretation of single smear-negative, positive cultures for Mycobacterium tuberculosis

Restriction fragment length polymorphism (RFLP) analysis can be used to assess genetic relatedness of Mycobacterium tuberculosis isolates. This study reports a collaborative investigation of false-positive cultures for M. tuberculosis, suspected when the DNA fingerprint from an index case matched an epidemiologically improbable source case. RFLP analysis matched fingerprints in ten of 16 cases of suspected laboratory contamination to four separate smear-positive sources that were processed on the same day in the same laboratory. All single smear-negative, positive cultures processed on the same day as smear-positive specimens should be reviewed on a case-by-case basis to identify possible false-positive cultures.

BCG vaccination and the prevalence of latent tuberculosis infection in an aboriginal population

SETTING

Estimations of prevalence of latent tuberculous infection (LTBI) are confounded by factors known to influence the results of the tuberculin skin test (TST) such as age, contact history and bacille Calmette-Guerin (BCG) vaccination. Appropriate interpretation of TST results is necessary to ensure LTBI treatment for those at greatest risk.

OBJECTIVE

To document the prevalence of LTBI in Aboriginal people living on a reserve in British Columbia (BC) and to determine the influence of BCG.

DESIGN

A population-based, retrospective descriptive analysis of all epidemiological data collected for the on-reserve Aboriginal programme in BC (1951-1996).

RESULTS

Of 17615 persons who received a TST during the study period, 42% had received BCG. During the study period, an average of 2517 TSTs were completed per year (SD = 1228) among persons with an average age of 26 years (SD = 16). Among all subjects, the average prevalence of LTBI was 25% (95 %CI 24-25). The presence of BCG (OR = 3.1, 95%CI 2.8-3.4) and multiple BCGs (OR = 10.2, 95%CI 7.7-13.6) were both associated with a positive TST. A positive TST was also associated with a shorter duration in years between the most recent BCG and the TST.

CONCLUSION

The average prevalence of LTBI in a sequential sample of Aboriginal people living on a reserve in BC was estimated at 25%. BCG, especially in multiple doses, increased the likelihood of a positive TST.

The Lack of Association Between Bacille Calmette-Guerin Vaccination and Clustering of Aboriginals with Tuberculosis in Western Canada

BACKGROUND: Tuberculosis (TB) remains a major health problem for Aboriginal people in Canada, with high rates of clustering of active TB cases. Bacille Calmette-Guérin (BCG) vaccination has been used as a preventive measure against TB in this high-risk population.

OBJECTIVE: The study was designed to determine if BCG vaccination in Aboriginal people influenced recent TB transmission through an analysis of the clustering of TB cases.

METHODS: A retrospective analysis of all culture-positive Mycobacterium tuberculosis cases in Aboriginal people in western Canada (1995 to 1997) was performed. Isolates were analyzed using standard methodology for restriction fragment length polymorphism and spoligotyping.

RESULTS: Of 256 culture-positive Aboriginal TB cases, BCG status was confirmed in 216 (84%) cases; 34% had been vaccinated with BCG, 57% were male and 56% were living on-reserve. Patients who had been vaccinated with BCG were younger than unvaccinated individuals (mean age 32.4±1.65 years versus 45.0±1.8 years, P<0.0001). Clustering was found in 62% of cases: 59% of non-BCG vaccinated cases were clustered versus 68% of those vaccinated with BCG (P=0.16). Younger patients (younger than 60 years of age) were more likely to be clustered in the univariate analysis (P<0.01). When age, sex, province, and HIV and reserve status were controlled for, BCG vaccination was not associated with clustering (OR 1.3, 95% CI 0.7 to 2.6).

CONCLUSIONS: BCG vaccinated Aboriginal people were no less likely to have active TB from recently transmitted disease. BCG vaccination appears to have limited value in preventing clustering of TB cases within this high-risk community.