Do "Virtual" and "Outpatient" Public Health Tuberculosis Clinics Perform Equally Well? A Program-Wide Evaluation in Alberta, Canada

The prevalence, risk factors, and public health consequences of peripheral lymph node-associated clinical and subclinical pulmonary tuberculosis

OBJECTIVES

Relatively little is known about the prevalence, risk factors, and public health consequences of peripheral lymph node (PLN)-associated pulmonary tuberculosis (PTB).

METHODS

We developed a 10-year (2010-2019) population-based cohort of PLNTB patients in Canada. We used systematically collected primary source data and expert reader chest radiograph interpretations in a multivariable logistic regression to determine associations between sputum culture positivity and demographic, clinical, and radiographic features. Public health risks were estimated among contacts of PLNTB patients.

RESULTS

There were 306 patients with PLNTB, among whom 283 (92.5%) were 15-64 years of age, 159 (52.0%) were female, and 293 (95.8%) were foreign-born. Respiratory symptoms were present in 21.6%, and abnormal chest radiograph in 23.2%. Sputum culture positivity ranged from 12.9% in patients with no symptoms and normal lung parenchyma to 66.7% in patients with both. Respiratory symptoms, abnormal lung parenchyma, and HIV-coinfection (borderline) were independent predictors of sputum culture positivity (odds ratio [OR] 2.24 [95% confidence interval [CI] 1.15-4.39], P = 0.01, OR 4.78 [95% CI 2.41-9.48], P < 0.001, and OR 2.54 [95% CI 0.99-6.52], P = 0.05), respectively. Among contacts of sputum culture-positive PLNTB patients, one secondary case and 16 new infections were identified.

CONCLUSION

Isochronous PTB is common in PLNTB patients. Routine screening of PLNTB patients for PTB is strongly recommended.

Introduction of short course treatment for latent tuberculosis infection at a primary care facility for refugees in Winnipeg, Canada: A mixed methods evaluation

Background

The World Health Organization (WHO) End TB strategy document 'Toward tuberculosis elimination: an action framework for low incidence countries'-like Canada- identifies screening and treatment of latent tuberculosis infection (LTBI) for groups at increased risk for TB disease as a priority, including newcomers from endemic countries. In 2015, the clients-centered model offered at a primary care facility for refugees, BridgeCare Clinic, Winnipeg, Canada was evaluated. The model included LTBI screening, assessment, and treatment, and originally offered 9-months of isoniazid as treatment. This mixed methods evaluation investigates LTBI program outcomes since the introduction of two short-course treatment regimens: 4-months of rifampin, and 3-months of isoniazid and rifapentine.

Methods

This study combined a retrospective analysis of program administrative data with structured interviews of clinic staff. We included LTBI treatment eligibility, the treatment regimen offered, treatment initiation, and completed treatment from January 1, 2015 to August 6, 2020.

Results

Seven hundred and one people were screened, and infection rates varied from 34.1% in 2015 to 53.3% in 2020. Most people living with LTBI came from high TB burden countries in Africa and South-East Asia WHO regions and were younger than 45 years old. Treatment eligibility increased 9% (75% in 2015 to 86% in 2016-2020) and most people diagnosed with LTBI took the short course treatments offered. There was an increase of 14.5% in treatment initiation (75.6 vs. 90.1%), and an increase of 8% in treatment completion (82.4 vs. 90.4%) after short-course regimens were introduced. The final model showed that the treatment regimen tends to affect the frequency of treatment completion, but there are other factors that influence this outcome, in this population. With the new treatments, BridgeCare Clinic achieved the 90% of treatment coverage, and the 90% treatment completion rate targets recommended in the End TB Strategy. Qualitative interviews with clinic staff further affirm the higher acceptability of the new treatments.

Conclusion

While these results are limited to government-sponsored refugees in Winnipeg, they highlight the acceptability and value of short-course LTBI treatment as a possibility for reaching End TB targets in primary care settings.

Exploration of inter-jurisdictional TB programming and mobility in a Canadian First Nation community

Background

Colonially imposed jurisdictional boundaries that have little meaning to Indigenous peoples in Canada may confound tuberculosis (TB) prevention and care activities. This study explores how inter-jurisdictional mobility and the current accommodation of mobility through policies and programming sustain a regional TB epidemic in northwestern Saskatchewan, and northeastern Alberta.

Methods

A qualitative instrumental case study was performed using a community based participatory approach. Semi-structured interviews were conducted with First Nations peoples from a high-incidence community in Canada including community-based healthcare workers. These interview data are presented in the context of a multi-level document analysis of TB program guidelines.

Results

The location of the community, and related lack of access to employment, services and care, necessitates mobility across jurisdictional boundaries. There are currently no formal federal or provincial guidelines in place to accommodate highly mobile patients and clients within and across provincial TB prevention and care programs. As a result, locally developed community-based protocols, and related ad-hoc strategies ensure continuity of care.

Conclusion

Indigenous peoples living in remote communities face unique push/pull factors that motivate mobility. When these motivations exist in communities with increased risk of contagion by communicable infectious diseases such as TB, public health risks extend into increasingly large areas with competing jurisdictional authority. Such mobility poses several threats to TB elimination. We have identified a gap in TB services to systematically accommodate mobility, with specific implications for Indigenous peoples and reconciliation. We recommend clearly defined communication paths and inter-jurisdictional coordination to ensure maintenance of care for mobile populations.

eHealth in TB clinical management

BACKGROUND: The constant expansion of internet and mobile technologies has created new opportunities in the field of eHealth, or the digital delivery of healthcare services. This TB meta-analysis aims to examine eHealth and its impact on TB clinical management in order to formulate recommendations for further development.METHODS: A systematic search was performed using the Preferred Reporting Items for Systematic Reviews and Meta-Analyses framework in PubMed and Embase of articles published up to April 2021. Screening, extraction and quality assessment were performed by two independent researchers. Studies evaluating an internet and/or mobile-based eHealth intervention with an impact on TB clinical management were included. Outcomes were organised following the five domains described in the WHO "Recommendations on Digital Interventions for Health System Strengthening" guideline.RESULTS: Search strategy yielded 3,873 studies, and 89 full texts were finally included. eHealth tended to enhance screening, diagnosis and treatment indicators, while being cost-effective and acceptable to users. The main challenges concern hardware malfunction and software misuse.CONCLUSION: This study offers a broad overview of the innovative field of eHealth applications in TB. Different studies implementing eHealth solutions consistently reported on benefits, but also on specific challenges. eHealth is a promising field of research and could enhance clinical management of TB.

The Radiographic and Mycobacteriologic Correlates of Subclinical Pulmonary TB in Canada: A Retrospective Cohort Study

BACKGROUND

Very little is known about subclinical pulmonary TB (PTB), a recently described intermediate state, in high-income countries.

RESEARCH QUESTION

What is the prevalence of subclinical PTB in Canada? What are its diagnostic chest radiography features? What is the relationship between those features and time to culture positivity, and what is the association between DNA fingerprint clustering, a measure of local transmission, and radiographic or other features in the foreign-born?

STUDY DESIGN AND METHODS

We used primary source data to identify a 16-year retrospective cohort of patients with PTB. Demographic and mycobacteriologic features in patients with subclinical and clinical disease were compared, and the reason for assessment of patients with subclinical disease was described. Diagnostic chest radiographs in patients with subclinical disease were read by two independent readers and were arbitrated by a third reader. Linear regression was used to compute time to culture positivity (in days) in relationship to the change in chest radiograph findings from normal or minimally abnormal to moderately or far advanced, adjusted for age and sex and stratified by reason for assessment. Multivariate logistic regression was used in foreign-born patients with subclinical disease to determine associations between DNA fingerprint clustering of Mycobacterium TB isolates and age, sex, chest radiograph features, and time since arrival.

RESULTS

We identified 1,656 patients with PTB, 347 of whom (21%) were subclinical. Compared with patients with clinical disease, patients with subclinical disease were more likely to be foreign-born (90.2% vs 79.6%) and to demonstrate negative smear results (88.2% vs 43.5%). The median time to culture-positivity was 18 days (interquartile range [IQR], 14-25 days) vs 12 days (IQR, 7-17 days). Most patients with PTB (75.2%) were identified during active case finding. Parenchymal disease was absent or minimal on chest radiography in 86.4% of patients. More advanced disease on chest radiography was associated with shorter times to culture positivity in nonstratified (by 3.3 days) and stratified (by 4.5-5.8 days) analysis (active case-finding groups). DNA fingerprint clustering was associated with male sex and a longer time between arrival and diagnosis.

INTERPRETATION

Subclinical patients with PTB constitute a substantial and heterogeneous minority of patients with PTB in high-income countries. DNA fingerprint clustering is consistent with some, albeit limited, local transmission.

Local Transmission Plays No Important Role in the Occurrence of Multidrug-Resistant Tuberculosis in Immigrants to Canada: An In-depth Epidemiologic Analysis

BACKGROUND

Multidrug-resistant (MDR) tuberculosis has increased among migrants in Canada. The cause(s) of this increase is unknown.

METHODS

We performed a retrospective cohort study in a Canadian province with substantially increased immigration between 1982-2001 and 2002-2019. The proportion of MDR tuberculosis among migrants arriving from high MDR (HMDR) tuberculosis burden countries during these 2 periods was used to estimate the proportion of cases due to immigration versus change in proportion in the country of birth. Epidemiologic, spatiotemporal, and drug resistance pattern data were used to confirm local transmission.

RESULTS

Fifty-two of 3514 (1.48%) foreign-born culture-positive tuberculosis patients had MDR tuberculosis: 8 (0.6%) in 1982-2001 and 44 (2.0%) in 2002-2019. Between time periods, the proportion of MDR tuberculosis among migrants with tuberculosis from HMDR tuberculosis countries increased from 1.11% to 3.62%, P = .003; 31.6% attributable to recent immigration and 68.4% to a higher proportion of MDR tuberculosis in cases arrived from HMDR tuberculosis countries. No cases of MDR tuberculosis were attributable to local transmission.

CONCLUSIONS

In stark contrast to HMDR tuberculosis countries, local transmission plays no important role in the occurrence of MDR tuberculosis in Canada. Improved tuberculosis programming in HMDR tuberculosis countries is urgently needed.

Cohort profile: St. Michael's Hospital Tuberculosis Database (SMH-TB), a retrospective cohort of electronic health record data and variables extracted using natural language processing

Background

Tuberculosis (TB) is a major cause of death worldwide. TB research draws heavily on clinical cohorts which can be generated using electronic health records (EHR), but granular information extracted from unstructured EHR data is limited. The St. Michael’s Hospital TB database (SMH-TB) was established to address gaps in EHR-derived TB clinical cohorts and provide researchers and clinicians with detailed, granular data related to TB management and treatment.

Methods

We collected and validated multiple layers of EHR data from the TB outpatient clinic at St. Michael’s Hospital, Toronto, Ontario, Canada to generate the SMH-TB database. SMH-TB contains structured data directly from the EHR, and variables generated using natural language processing (NLP) by extracting relevant information from free-text within clinic, radiology, and other notes. NLP performance was assessed using recall, precision and F₁ score averaged across variable labels. We present characteristics of the cohort population using binomial proportions and 95% confidence intervals (CI), with and without adjusting for NLP misclassification errors.

Results

SMH-TB currently contains retrospective patient data spanning 2011 to 2018, for a total of 3298 patients (N = 3237 with at least 1 associated dictation). Performance of TB diagnosis and medication NLP rulesets surpasses 93% in recall, precision and F₁ metrics, indicating good generalizability. We estimated 20% (95% CI: 18.4–21.2%) were diagnosed with active TB and 46% (95% CI: 43.8–47.2%) were diagnosed with latent TB. After adjusting for potential misclassification, the proportion of patients diagnosed with active and latent TB was 18% (95% CI: 16.8–19.7%) and 40% (95% CI: 37.8–41.6%) respectively

Conclusion

SMH-TB is a unique database that includes a breadth of structured data derived from structured and unstructured EHR data by using NLP rulesets. The data are available for a variety of research applications, such as clinical epidemiology, quality improvement and mathematical modeling studies.

Prompt recognition of infectious pulmonary tuberculosis is critical to achieving elimination goals: a retrospective cohort study

INTRODUCTION

All pulmonary tuberculosis (PTB) cases are presumed to be infectious to some degree. This spectrum of infectiousness is independently described by both the acid-fast bacilli smear and radiographic findings. Smear-positive patients with chest radiographic findings that are typical for adult-type PTB are believed to be most infectious.

HYPOTHESIS

Characterisation of the presumed most infectious PTB case is possible by reference to readily available clinical features and laboratory results.

METHODS

Retrospective cohort study of adult, culture-positive PTB cases (151 smear-positive; 162 smear-negative) diagnosed between 1 January 2013 and 30 April 2017 in Canada. We describe cases according to demographic, clinical and laboratory features. We use multivariable multinomial logistic regression to estimate the relative risk ratio (RRR) with 95% CI of features associated with an outcome of smear-positive PTB, characterised by 'typical' chest radiograph findings.

RESULTS

Being Canadian-born, symptomatic, having a subacute duration of symptoms and broad-spectrum antibiotic prescriptions were all more commonly associated with smear-positive than smear-negative disease (36% vs 20%; 95% vs 63%; 88% vs 54%; and 59% vs 28%, respectively). After combining smear status and radiographic features, we show that smear-positive patients with typical chest radiographs were younger, had a longer duration of symptoms (RRR 2.41; 95% CI 1.01 to 5.74 and 2.93; 95% CI 1.20 to 7.11, respectively) and were less likely to be foreign-born, or have a moderate to high-risk factor for reactivation (RRR 0.40; 95% CI 0.17 to 0.92 and 0.18; 95% CI 0.04 to 0.71, respectively) compared with smear-negative patients with atypical chest radiograph findings.

CONCLUSION

A clear picture of the presumed most infectious PTB case emerges from available historical and laboratory information; vigilance for this presentation by front-line providers will support elimination strategies aimed at reducing transmission.

A clinical audit and cost analysis of latent TB management at a tertiary referral centre in Ireland

INTRODUCTION

It is estimated that 24.8% of the world's population has latent TB. The World Health Organization's (WHO) End TB Strategy states that the systematic identification and management of LTBI in groups of people at high risk of reactivation is an essential part of TB elimination in low-incidence countries.

AIM

Our aims were to evaluate the effectiveness of LTBI management at our tertiary referral outpatient department (OPD) and to identify how our service could be improved.

METHODS

We included all patients seen in the infectious diseases outpatient service who were referred querying a diagnosis of latent TB. Patients had to have attended the outpatient clinic at least once in the 6 months from 1 July 2018 to 31 December 2018. Patients who were referred for assessment of possible active TB were not included in. A retrospective review of each patient's electronic record was performed by two auditors.

RESULTS

Twenty-five patients reviewed in our TB clinic were referred querying a diagnosis of LTBI. Twenty-two of 25 (88%) were diagnosed with LTBI; 21/25 (84%) were offered treatment. All patients offered treatment accepted treatment. Seventeen of 21 (81%) patients completed treatment. The mean cost per patient seen in the clinic was €1378.66. The mean cost per LTBI successfully treated was €2027.45. No patient had a raised ALT detected. There were no other adverse events.

CONCLUSION

Our TB clinic is effective in the assessment and safe management of latent TB in accordance with national guidelines. Interventions for improvement are the creation of referral guidelines and a referral proforma and exploring alternative clinic models.

Back to Basics: Giant Challenges to Addressing Isaac's "Geriatric Giants" Post COVID-19 Crisis

The COVID-19 pandemic, being the greatest challenge to our healthcare system for over a century, has its greatest impact on older patients. This subgroup has higher morbidity and mortality than younger age groups. Superimposed on this, the major preventative intervention resulting in social isolation has negative consequences. Prof. Bernard Isaacs described the "Geriatric Giant Symptoms" in 1965 and encouraged the development of interventions for immobility, instability, incontinence and impaired intellect/memory with careful management of these symptoms resulting in better outcomes for older patients including reduced admissions to Nursing Homes and mortality. The author's explore the impact of the current pandemic and, most particularly its aftermath on the provision of such interventions. In the context of a major economic crisis, resources for highly effective interventions such as joint replacement surgery, urological interventions, cataract surgery will be all be limited after this crisis. Moreover delayed access to day patient services with suboptimal access to assessments for conditions such as cognitive decline and falls as well as social care will likewise militate against addressing the "Geriatric Giant Symptoms". Thus the "Founding Fathers" of Geriatric Medicine including Prof Isaacs would be justifiably concerned regarding our ability to deliver interventions to address the "Geriatric Giant Symptoms". Current leaders in geriatric medicine, healthcare workers, funders and providers as well as advocacy groups must redouble their efforts to ensure gains made in management of older patients over 2 generations are not lost in the aftermath of this pandemic.

Molecular Epidemiology of Tuberculosis in British Columbia, Canada: A 10-Year Retrospective Study

Background

Understanding regional molecular epidemiology allows for the development of more efficient tuberculosis prevention strategies in low-incidence settings.

Methods

We analyzed 24-locus mycobacterial interspersed repetitive-unit–variable-number tandem repeat (MIRU-VNTR) genotyping for 2290 Mycobacterium tuberculosis clinical isolates collected in the province of British Columbia (BC), Canada, in 2005–2014. Laboratory data for each isolate were linked to case-level clinical and demographic data. These data were used to describe the molecular epidemiology of tuberculosis across the province.

Results

We detected >1500 distinct genotypes across the 4 major M. tuberculosis lineages, reflecting BC’s diverse population. Disease site and clustering rates varied across lineages, and MIRU-VNTR was used to group the 2290 isolates into 189 clusters (2–70 isolates per cluster), with an overall clustering rate of 42.4% and an estimated local transmission rate of 34.1%. Risk factors for clustering varied between Canadian-born and foreign-born individuals; the former had increased odds (odds ratio, 7.8; 95% confidence interval [CI], 6.2–9.6) of belonging to a genotypic cluster, although nearly one-quarter of clusters included both Canadian- and foreign-born persons. Large clusters (≥10 cases) occurred more frequently within the M. tuberculosis Euro-American lineage, and individual-level risk factors associated with belonging to a large cluster included being Canadian born (adjusted odds ratio, 3.3; 95% CI, 2.3–4.8), residing in a rural area (2.3; 1.2–4.5), and illicit drug use (2.0; 1.2–3.4).

Conclusions

Although tuberculosis in BC largely arises through reactivation of latent tuberculosis in foreign-born persons, locally transmitted infections occur in discrete populations with distinct disease and risk factor profiles, representing groups for targeted interventions.

Tuberculosis among northern Manitoba First Nations, 2008-2012: program performance on- and off-reserve

OBJECTIVES

The objectives of this study were to: (1) report tuberculosis (TB) program performance for northern First Nations in the province of Manitoba; (2) present methods for TB program performance measurement using routinely collected surveillance data; and (3) advance dialogue on performance measurement of Canadian TB programs.

METHODS

Data on a retrospective cohort of people diagnosed with TB in Manitoba between January 1, 2008 and December 31, 2010, and their contacts, were extracted from the Manitoba TB Registry. Performance measures based on US-CDC were analyzed. Adjusted probability ratios (aPR) and 95% confidence intervals (CIs) were reported with comparisons between on-/off-reserve First Nations, adjusted for age, sex, and treatment history.

RESULTS

A cohort of n = 149 people diagnosed with TB and n = 3560 contacts were identified. Comparisons off-/on-reserve: Treatment completion (aPR = 1.03; 95% CI 0.995-1.07); early detection (aPR = 0.87; 95% CI 0.57-1.33); HIV testing and reporting (aPR = 0.42; 95% CI 0.21-0.83); pediatric TB (age < 15 years) (aPR = 1.20; 95% CI 0.47-3.06); retreatment for TB (aPR = 0.93; 95% CI 0.89-0.97); contact elicitation (aPR = 0.94; 95% CI 0.84-1.05); contact assessment (aPR = 0.69; 95% CI 0.50-0.94). Pediatric (ages < 15 years) TB incidence in northern Manitoba was 37.1 per 100,000/year.

CONCLUSION

TB program performance varies depending on residence in a reserve or non-reserve community. Action is urgently needed to address TB program performance in terms of contact investigation and HIV testing/reporting for First Nations off-reserve and to address high rates of pediatric TB in northern Manitoba. First Nations collaboration and models of care should be considered both on- and off-reserve to improve TB program performance.

Is there a fundamental flaw in Canada's post-arrival immigrant surveillance system for tuberculosis?

BACKGROUND

New immigrants to Canada with a history of tuberculosis or evidence of old healed tuberculosis on chest radiograph are referred to public health authorities for medical surveillance. This ostensible public health protection measure identifies a subgroup of patients (referrals) who are at very low risk (compared to non-referrals) of transmission.

METHODS

To assess whether earlier diagnosis or a different phenotypic expression of disease explains this difference, we systematically reconstructed the immigration and transmission histories from a well-defined cohort of recently-arrived referral and non-referral pulmonary tuberculosis cases in Canada. Incident case chest radiographs in all cases and sequential past radiographs in referrals were re-read by three experts. Change in disease severity from pre-immigration radiograph to incident radiograph was the primary, and transmission of tuberculosis, the secondary, outcome.

RESULTS

There were 174 cohort cases; 61 (35.1%) referrals and 113 (64.9%) non-referrals. Compared to non-referrals, referrals were less likely to be symptomatic (26% vs. 80%), smear-positive (15% vs. 50%), or to have cavitation (0% vs. 35%) or extensive disease (15% vs. 59%) on chest radiograph. After adjustment for referral status, time between films, country-of-birth, age and co-morbidities, referrals were less likely to have substantial changes on chest radiograph; OR 0.058 (95% CI 0.018-0.199). All secondary cases and 82% of tuberculin skin test conversions occurred in contacts of non-referrals.

CONCLUSIONS

Phenotypically different disease, and not earlier diagnosis, explains the difference in transmission risk between referrals and non-referrals. Screening, and treating high-risk non-referrals for latent tuberculosis is necessary to eliminate tuberculosis in Canada.

Would program performance indicators and a nationally coordinated response accelerate the elimination of tuberculosis in Canada?

Twenty years ago, a National Consensus Conference on Tuberculosis (TB) recommended that the provinces and territories of Canada jointly declare a commitment to TB elimination with national coordination and assured funding, executed by a committee of federal and provincial/territorial representatives. Canada has committed to the global TB elimination targets set forth by the World Health Organization but lacks a coordinated response. In particular, with the exception of one published and implemented by Indigenous Services Canada, there has been no national monitoring and performance framework. Herein, we provide a commentary on the importance, to TB elimination in Canada, of developing such a framework. We invite a debate about whether more can and should be done to monitor and report for action at every jurisdictional level. Of utmost importance will be the need to achieve consensus from stakeholders about what is measured, among whom, how often, who collects and processes data, and how to respond to the successes and failures those data indicate. Insofar, as performance targets are well defined and implemented, national progress towards tuberculosis elimination should accelerate.

Towards the elimination of paediatric tuberculosis in high-income, immigrant-receiving countries: a 25-year conventional and molecular epidemiological case study

The epidemiology of tuberculosis (TB) in high-income countries is increasingly dictated by immigration. The influence of this trend on paediatric TB and TB elimination are not well defined.

We undertook a 25-year conventional and molecular epidemiologic study of paediatric TB in Alberta, one of four major immigrant-receiving provinces in Canada. All isolates of Mycobacterium tuberculosis were DNA fingerprinted using standard methodology.

Between 1990 and 2014, 176 children aged 0–14 years were diagnosed with TB. Foreign-born children or Canadian-born children of foreign-born parents accounted for an increasingly large proportion of total cases during the study period (from 32.1% to 89.5%). Of the 78 culture-positive cases, 35 (44.9%) had a putative source case identified by conventional epidemiology, with 34 (97.1%) having a concordant molecular profile. Of the remaining 43 culture-positive cases, molecular profiling identified spatially and temporally related sources in six cases (14.0%). These six children, along with four other children whose source cases were discovered through reverse-contact tracing, had a high morbidity and mortality.

The increasing burden of paediatric TB in both foreign-born children and Canadian-born children of foreign-born parents calls for more timely diagnosis of source cases and more targeted screening for latent TB infection.

Conventional and molecular epidemiology can inform paediatric TB elimination strategy in high-income countrieshttp://ow.ly/mwbn30iY1WF

Performance of centralized versus decentralized tuberculosis treatment services in Southern Brazil, 2006-2015

Background

Tuberculosis (TB) control programs face the challenges of decreasing incidence, mortality rates, and drug resistance while increasing treatment adherence. The Brazilian TB control program recommended the decentralization of patient care as a strategy for combating the disease. This study evaluated the performance of this policy in an area with high default rates, comparing epidemiological and operational indicators between two similar municipalities.

Methods

This study analyzed epidemiological and operational indicators on new cases of pulmonary tuberculosis reported in the Brazilian Notifiable Diseases Information System between 2006 and 2015. In addition, to characterize differences between the populations of the two studied municipalities, a prospective cohort study was conducted between 2014 and 2015, in which patients with new cases of culture-confirmed pulmonary tuberculosis were interviewed and monitored until the disease outcome. A descriptive analysis, the chi-square test, and a Poisson regression model were employed to compare TB treatment outcomes and health care indicators between the municipalities.

Results

Two thousand three hundred nine cases were evaluated, of which 207 patients were interviewed. Over the 2006–2015 period, TB incidence per 100,000 population in the municipality with decentralized care was significantly higher (39%, 95% CI 27–49%) in comparison to that of the municipality with centralized care. TB treatment default rate (45%, 95% CI 12–90%) was also higher in the municipality with decentralized care. During the two-year follow-up, significant differences were found between patients in centralized care and those in decentralized care regarding treatment success (84.5 vs. 66.1%), treatment default (10.7 vs. 25.8%), illicit drug use (27.7 vs. 45.9%), and homelessness (3.6 vs. 12.9%). The operational indicators revealed that the proportion of control smear tests, medical imaging, and HIV tests were all significantly higher in the centralized care. However, a significantly higher proportion of patients started treatment in the early stages of the disease in the municipality with decentralized care.

Conclusions

These data showed a low success rate in TB treatment in both municipalities. Decentralization of TB care, alone, did not improve the main epidemiological and operational indicators related to disease control when compared to centralized care. Full implementation of strategies already recommended is needed to improve TB treatment success rates.

Predicting pulmonary tuberculosis in immigrants: a retrospective cohort study

Our objective was to investigate whether pulmonary tuberculosis (PTB) can be predicted from features of a targeted medical history and basic laboratory investigations in immigrants.

A retrospective cohort of 391 foreign-born adults referred to the Edmonton Tuberculosis Clinic (Edmonton, AB, Canada) was studied using multiple logistic regression analysis to predict PTB. Seven characteristics of disease were used as explanatory variables. Cross-validation assessed performance. Each predictor was tested on two outcomes: “culture-positive” and “smear-positive”. Receiver operating characteristic (ROC) curves were generated and the area under the ROC curve (AUC) was quantified.

Symptoms, subacute duration of symptoms, risk factors for reactivation of latent TB infection and anaemia were all associated with a positive culture (adjusted OR 1.79, 2.24, 1.72 and 2.28, respectively; p<0.05). Symptoms, inappropriate prescription of broad-spectrum antibiotics and a “typical” chest radiograph were associated with smear-positive PTB (adjusted OR 2.91, 1.55 and 12.34, respectively; p<0.05). ROC curve analysis was used to test each model, yielding AUC=0.91 for the outcome “culture-positive” disease and AUC=0.94 for the outcome “smear-positive” disease.

PTB among the foreign-born can be predicted from a targeted medical history and basic laboratory investigations, raising the threshold of suspicion in settings where the disease is relatively rare.

In high-income, low tuberculosis incidence countries, certain clinical characteristics should raise the threshold of suspicion to confirm a timely diagnosishttp://ow.ly/bRDZ30iPurz

Effectiveness of Canada's tuberculosis surveillance strategy in identifying immigrants at risk of developing and transmitting tuberculosis: a population-based retrospective cohort study

BACKGROUND

In Canada, tuberculosis disproportionately affects the foreign-born population. The national tuberculosis medical surveillance programme aims to prevent these cases. Individuals referred for further in-country surveillance (referrals) have a history of active tuberculosis or have features of old, healed tuberculosis on chest radiograph; those not referred (non-referrals) do not undergo surveillance. We aimed to examine the risk of transmission arising from referrals versus non-referrals.

METHODS

We did this population-based retrospective cohort study of foreign-born migrants (aged 15-64 years) to Alberta, Canada, between Jan 1, 2002, and Dec 31, 2013. We obtained information about year of arrival and country of citizenship from Immigration, Refugees and Citizenship Canada, and data for tuberculosis cases and their contacts from the Alberta Tuberculosis Registry. The outcome of interest was culture-positive pulmonary tuberculosis. We compared the incidence of pulmonary tuberculosis and the odds of transmission among referrals versus non-referrals. By use of conventional and molecular epidemiological techniques, we defined transmission as either a secondary case or a tuberculin skin-test (TST) conversion among close contacts. We used multivariate logistic regression to determine the independent association between referral for tuberculosis surveillance and transmission.

FINDINGS

Between 2002 and 2013, there were 223 225 foreign-born migrants to Alberta, of whom 5500 (2%) were referrals and 217 657 (98%) were non-referrals. 3805 (69%) referrals and 115 226 (53%) non-referrals were from countries with a tuberculosis incidence of more than 150 per 100 000 populations, or sub-Saharan Africa. 234 foreign-born individuals were diagnosed with culture-positive pulmonary tuberculosis between Jan 1, 2004, and Dec 31, 2013. The incidence of culture-positive pulmonary disease was nine times higher in referrals (n=50) than all non-referrals (n=184; incidence rate ratio 9·1, 95% CI 6·7-12·5) and five times higher in referrals than non-referrals from high-risk countries (n=167; 5·0, 3·6-6·8). 71 total transmission events arose from the individuals with culture-positive pulmonary tuberculosis-three (4%) from referrals and 68 (96%) from non-referrals. No secondary cases were attributable to a referral source case, whereas 18 secondary cases were attributable to 11 different non-referral source cases. Three TST conversions were attributable to three different referral source cases compared with 50 conversions from 31 different non-referral source cases. That is, three (6%) referrals transmitted tuberculosis compared with 42 (22%) non-referrals (adjusted odds ratio of 0·19, 95% CI 0·054-0·66; p=0·009).

INTERPRETATION

Despite a much higher incidence of pulmonary tuberculosis in referrals than non-referrals, referrals were 80% less likely to transmit tuberculosis. Rather than a focus on referrals, Canada could consider screening and treatment of latent tuberculosis in all migrants from high-risk countries-a group that accounted for 100% of secondary cases.

FUNDING

Canadian Institutes of Health Research.