Cohort profile: the Comparative Outcomes And Service Utilization Trends (COAST) Study among people living with and without HIV in British Columbia, Canada

Risk of Multiple Sclerosis in People Living with HIV: An International Cohort Study

OBJECTIVE

There has been interest in a possible negative association between HIV and multiple sclerosis (MS). We aimed to compare the risk of MS in a cohort of individuals living with HIV to that in the general population.

METHODS

Population-based health data were accessed for 2 cohorts of HIV-positive persons from Sweden and British Columbia, Canada. Incident MS was identified using MS registries or a validated algorithm applied to administrative data. Individuals with HIV were followed from 1 year after the first clinical evidence of HIV or the first date of complete administrative health data (Canada = April 1, 1992 and Sweden = January 1, 2001) until the earliest of incident MS, emigration, death, or study end (Canada = March 31, 2020 and Sweden = December 31, 2018). The observed MS incidence rate in the HIV-positive cohort was compared to the expected age-, sex-, calendar year-, income-specific, and region of birth-specific rates in a randomly selected sample of >20% of each general population. The standardized incidence ratio (SIR) for MS following the first antiretroviral therapy exposure ("ART-exposed") was also calculated.

RESULTS

The combined Sweden-Canada cohort included 29,163 (75% men) HIV-positive persons. During 242,248 person-years of follow-up, 14 incident MS cases were observed in the HIV-positive cohort, whereas 26.19 cases were expected. The SIR for MS in the HIV-positive population was 0.53 (95% confidence interval [CI] = 0.32-0.90). The SIR for MS following the first ART exposure was 0.55 (95% CI = 0.31-0.96).

INTERPRETATION

This international population-based study demonstrated a lower risk of MS among HIV-positive individuals, and HIV-positive ART-exposed individuals. These findings provide support for further exploration into the relationship among HIV, ART, and MS. ANN NEUROL 2024;95:487-494.

Disability-adjusted life years associated with chronic comorbidities among people living with and without HIV: Estimating health burden in British Columbia, Canada

Life span of people living with HIV (PLWH) has increased dramatically with the advent of modern antiretroviral therapy. As a result, comorbidities have emerged as a significant concern in this population. To describe the burden of chronic comorbidities among PLWH and HIV-negative individuals in British Columbia (BC), Canada, we estimated disability-adjusted life years (DALYs) related to these comorbidities. Based on a population-based cohort in BC, antiretroviral-treated adult PLWH and 1:4 age-sex-matched HIV-negative controls were followed for ≥1 year during 2001-2012. DALYs combined years of life lost to premature mortality (YLLs) and due to disability (YLDs), and were estimated following the Global Burden of Diseases' approaches. DALYs associated with non-AIDS-defining cancers, diabetes, osteoarthritis, hypertension, dementia, cardiovascular (CVD), kidney, liver and chronic obstructive pulmonary diseases were each measured for 2008-2012. Among PLWH, DALYs attributed to non-AIDS-related cancers were also estimated for 2013-2020. We observed that at baseline, our matched cohort consisted of 82% males with a median age of 40 years (25th-75th percentiles: 34-47). During 2008-2012, 7042 PLWH and 30,640 HIV-negative individuals were alive, where PLWH experienced a twofold higher DALYs associated with chronic comorbidities (770.2 years/1000 people [95% credible intervals: 710.2, 831.6] vs. 359.0 [336.0, 382.2]). Non-AIDS-defining cancers and CVD contributed the highest DALYs in both populations, driven by YLLs rather than YLDs. Among PLWH, we estimated increasing DALYs attributable to non-AIDS-defining cancers with 91.7 years/1000 people (77.4, 106.0) in 2013 vs. 97.6 (81.0, 115.2) in 2020. In this study, we showed that PLWH experience a disproportionate burden of chronic comorbidities compared to HIV-negative individuals. The observed disparities may relate to differential health behaviors, residual HIV-related inflammation, and ART-related toxicities. As aging shapes future healthcare needs, our findings highlight the need to enhance prevention and management of comorbidities as part of HIV care.

The impact of lookback windows on the prevalence and incidence of chronic diseases among people living with HIV: an exploration in administrative health data in Canada

BACKGROUND

We described the impact of different lengths of lookback window (LW), a retrospective time period to observe diagnoses in administrative data, on the prevalence and incidence of eight chronic diseases.

METHODS

Our study populations included people living with HIV (N = 5151) and 1:5 age-sex-matched HIV-negative individuals (N = 25,755) in British Columbia, Canada, with complete follow-up between 1996 and 2012. We measured period prevalence and incidence of diseases in 2012 using LWs ranging from 1 to 16 years. Cases were deemed prevalent if identified in 2012 or within a defined LW, and incident if newly identified in 2012 with no previous cases detected within a defined LW. Chronic disease cases were ascertained using published case-finding algorithms applied to population-based provincial administrative health datasets.

RESULTS

Overall, using cases identified by the full 16-year LW as the reference, LWs ≥8 years and ≥ 4 years reduced the proportion of misclassified prevalent and incidence cases of most diseases to < 20%, respectively. The impact of LWs varied across diseases and populations.

CONCLUSIONS

This study underscored the importance of carefully choosing LWs and demonstrated data-driven approaches that may inform these choices. To improve comparability of prevalence and incidence estimates across different settings, we recommend transparent reporting of the rationale and limitations of chosen LWs.

Disparities in multimorbidity and mortality among people living with and without HIV across British Columbia's health regions: a population-based cohort study

OBJECTIVES

Longer survival has increased the likelihood of antiretroviral-treated people living with HIV (PLWH) developing age-associated comorbidities. We compared the burden of multimorbidity and all-cause mortality across HIV status in British Columbia (BC), and assessed the longitudinal effect of multimorbidity on all-cause mortality among PLWH.

METHODS

Antiretroviral-treated PLWH aged ≥19 years and 1:4 age-sex-matched HIV-negative individuals from a population-based cohort were followed for ≥1 year during 2001-2012. Diagnoses of seven age-associated comorbidities were identified from provincial administrative databases and grouped into 0, 1, 2, and ≥3 comorbidities. Multimorbidity prevalence and age-standardized mortality rates (ASMRs) in both populations were stratified by BC's health regions. Marginal structural models were used to estimate the effect of multimorbidity on mortality among PLWH, adjusted for time-varying confounders affected by prior multimorbidity.

RESULTS

Among 8031 PLWH and 32,124 HIV-negative individuals, 25% versus 11% developed multimorbidity, and 23.53 deaths/1000 person-years (95% confidence interval [95% CI]: 22.02-25.13) versus 3.04 (2.81-3.29) were observed, respectively. PLWH in Northern region had the highest ASMR, but those in South Vancouver Island experienced the greatest difference in mortality compared with HIV-negative individuals. Among PLWH, compared with those with zero comorbidities, adjusted hazard ratios for those with 1, 2, and ≥3 comorbidities were 3.36 (95% CI: 2.86-3.95), 6.92 (5.75-8.33), and 12.87 (10.45-15.85), respectively.

CONCLUSION

PLWH across BC's health regions experience excess multimorbidity and associated mortality. We highlight health disparities which are key when planning the distribution of healthcare resources across BC, and provide evidence for improved HIV care models integrating prevention and management of chronic diseases.

Indigenizing our research: indigenous community leadership in HIV epidemiology research

The use of data intensive health research has allowed for greater understandings of population health. When conducting data intensive health research, engaging and involving the community is essential for conducting meaningful research that is responsive to the public's needs. Particularly, when engaging Indigenous communities in research, there is a need to understand historical and ongoing impacts of colonialism and recognize the strengths in Indigenous Peoples' knowledges and experiences while supporting Indigenous leadership and self-determination in research. This article describes the approach our research team/organization used to engage and involve Indigenous people living with HIV in three research projects using large, linked datasets and looking at HIV outcomes of Indigenous populations in Canada. The foundation of these projects was simultaneously: 1) supporting Indigenous people living with HIV to be involved as research team members, 2) developing research questions to answer with available datasets, and 3) integrating Indigenous and Western ways of knowing. We have identified important considerations and suggestions for engaging and involving Indigenous communities and individuals in the generation of research ideas and analysis of linked data using community-based participatory research approaches through our work. These include engaging stakeholders at the start of the project and involving them throughout the research process, honouring Indigenous ways of knowing, the land, and local protocols and traditions, prioritizing Indigenous voices, promoting co-learning and building capacity, and focusing on developing longitudinal relationships. We describe keys to success and learnings that emerged. Importantly, the methodology practiced and presented in this manuscript is not  a qualitative study design whereby research subjects are surveyed about their experiences or beliefs. Rather, the study approach described herein is about engaging people with living experience to co-lead as researchers. Our approach supported Indigenous people to share research that addresses their research priorities and responds to issues relevant to Indigenous Peoples and communities.

Incidence of diabetes mellitus among people living with and without HIV in British Columbia, Canada between 2001 and 2013: a longitudinal population-based cohort study

INTRODUCTION

People living with HIV (PLHIV) are increasingly at risk of age-related comorbidities such as diabetes mellitus (DM). While DM is associated with elevated mortality and morbidity, understanding of DM among PLHIV is limited. We assessed the incidence of DM among people living with and without HIV in British Columbia (BC), Canada, during 2001-2013.

METHODS

We used longitudinal data from a population-based cohort study linking clinical data and administrative health data. We included PLHIV who were antiretroviral therapy (ART) naïve at baseline, and 1:5 age-sex-matched persons without HIV. All participants had ≥5 years of historic data pre-baseline and ≥1 year(s) of follow-up. DM was identified using the BC Ministry of Health's definitions applied to hospitalisation, physician billing and drug dispensation datasets. Incident DM was identified using a 5-year run-in period. In addition to unadjusted incidence rates (IRs), we estimated adjusted incidence rate ratios (IRR) using Poisson regression and assessed annual trends in DM IRs per 1000 person years (PYs) between 2001 and 2013.

RESULTS

A total of 129 PLHIV and 636 individuals without HIV developed DM over 17 529 PYs and 88,672 PYs, respectively. The unadjusted IRs of DM per 1000 PYs were 7.4 (95% CI 6.2 to 8.8) among PLHIV and 7.2 (95% CI 6.6 to 7.8) for individuals without HIV. After adjustment for confounding, HIV serostatus was not associated with DM incidence (adjusted IRR: 1.03, 95% CI 0.83 to 1.27). DM incidence did not increase over time among PLHIV (Kendall trend test: p=0.9369), but it increased among persons without HIV between 2001 and 2013 (p=0.0136).

CONCLUSIONS

After adjustment, HIV serostatus was not associated with incidence of DM, between 2001 and 2013. Future studies should investigate the impact of ART on mitigating the potential risk of DM among PLHIV.

Development of a computable phenotype to identify a transgender sample for health research purposes: a feasibility study in a large linked provincial healthcare administrative cohort in British Columbia, Canada

OBJECTIVES

Innovative methods are needed for identification of transgender people in administrative records for health research purposes. This study investigated the feasibility of using transgender-specific healthcare utilisation in a Canadian population-based health records database to develop a computable phenotype (CP) and identify the proportion of transgender people within the HIV-positive population as a public health priority.

DESIGN

The Comparative Outcomes and Service Utilization Trends (COAST) Study cohort comprises a data linkage between two provincial data sources: The British Columbia (BC) Centre for Excellence in HIV/AIDS Drug Treatment Program, which coordinates HIV treatment dispensation across BC and Population Data BC, a provincial data repository holding individual, longitudinal data for all BC residents (1996-2013).

SETTING

British Columbia, Canada.

PARTICIPANTS

COAST participants include 13 907 BC residents living with HIV (≥19 years of age) and a 10% random sample comparison group of the HIV-negative general population (514 952 individuals).

PRIMARY AND SECONDARY OUTCOME MEASURES

Healthcare records were used to identify transgender people via a CP algorithm (diagnosis codes+androgen blocker/hormone prescriptions), to examine related diagnoses and prescription concordance and to validate the CP using an independent provider-reported transgender status measure. Demographics and chronic illness burden were also characterised for the transgender sample.

RESULTS

The best-performing CP identified 137 HIV-negative and 51 HIV-positive transgender people (total 188). In validity analyses, the best-performing CP had low sensitivity (27.5%, 95% CI: 17.8% to 39.8%), high specificity (99.8%, 95% CI: 99.6% to 99.8%), low agreement using Kappa statistics (0.3, 95% CI: 0.2 to 0.5) and moderate positive predictive value (43.2%, 95% CI: 28.7% to 58.9%). There was high concordance between exogenous sex hormone use and transgender-specific diagnoses.

CONCLUSIONS

The development of a validated CP opens up new opportunities for identifying transgender people for inclusion in population-based health research using administrative health data, and offers the potential for much-needed and heretofore unavailable evidence on health status, including HIV status, and the healthcare use and needs of transgender people.

Research using population-based administration data integrated with longitudinal data in child protection settings: A systematic review

INTRODUCTION

Over the past decade there has been a marked growth in the use of linked population administrative data for child protection research. This is the first systematic review of studies to report on research design and statistical methods used where population-based administrative data is integrated with longitudinal data in child protection settings.

METHODS

The systematic review was conducted according to Preferred Reporting Items for Systematic Review and Meta-Analyses (PRISMA) statement. The electronic databases Medline (Ovid), PsycINFO, Embase, ERIC, and CINAHL were systematically searched in November 2019 to identify all the relevant studies. The protocol for this review was registered and published with Open Science Framework (Registration DOI: 10.17605/OSF.IO/96PX8).

RESULTS

The review identified 30 studies reporting on child maltreatment, mental health, drug and alcohol abuse and education. The quality of almost all studies was strong, however the studies rated poorly on the reporting of data linkage methods. The statistical analysis methods described failed to take into account mediating factors which may have an indirect effect on the outcomes of interest and there was lack of utilisation of multi-level analysis.

CONCLUSION

We recommend reporting of data linkage processes through following recommended and standardised data linkage processes, which can be achieved through greater co-ordination among data providers and researchers.

Excess burden of age-associated comorbidities among people living with HIV in British Columbia, Canada: a population-based cohort study

OBJECTIVES

As people living with HIV (PLWH) live longer, morbidity and mortality from non-AIDS comorbidities have emerged as major concerns. Our objective was to compare prevalence trends and age at diagnosis of nine chronic age-associated comorbidities between individuals living with and without HIV.

DESIGN AND SETTING

This population-based cohort study used longitudinal cohort data from all diagnosed antiretroviral-treated PLWH and 1:4 age-sex-matched HIV-negative individuals in British Columbia, Canada.

PARTICIPANTS

The study included 8031 antiretroviral-treated PLWH and 32 124 HIV-negative controls (median age 40 years, 82% men). Eligible participants were ≥19 years old and followed for ≥1 year during 2000 to 2012.

PRIMARY AND SECONDARY OUTCOME MEASURES

The presence of non-AIDS-defining cancers, diabetes, osteoarthritis, hypertension, Alzheimer's and/or non-HIV-related dementia, cardiovascular, kidney, liver and lung diseases were identified from provincial administrative databases. Beta regression assessed annual age-sex-standardised prevalence trends and Kruskal-Wallis tests compared the age at diagnosis of comorbidities stratified by rate of healthcare encounters.

RESULTS

Across study period, the prevalence of all chronic age-associated comorbidities, except hypertension, were higher among PLWH compared with their community-based HIV-negative counterparts; as much as 10 times higher for liver diseases (25.3% vs 2.1%, p value<0.0001). On stratification by healthcare encounter rates, PLWH experienced most chronic age-associated significantly earlier than HIV-negative controls, as early as 21 years earlier for Alzheimer's and/or dementia.

CONCLUSIONS

PLWH experienced higher prevalence and earlier age at diagnosis of non-AIDS comorbidities than their HIV-negative controls. These results stress the need for optimised screening for comorbidities at earlier ages among PLWH, and a comprehensive HIV care model that integrates prevention and treatment of chronic age-associated conditions. Additionally, the robust methodology developed in this study, which addresses concerns on the use of administrative health data to measure prevalence and incidence, is reproducible to other settings.

Influence of the definition of rurality on geographic differences in HIV outcomes in British Columbia: a retrospective cohort analysis

BACKGROUND

Improving rural health is often identified as a priority area for research and policy in Canada. We examined how findings on HIV outcomes (virologic suppression) can vary depending on the definition of rurality used.

METHODS

We performed retrospective cohort analyses using the Comparative Outcomes and Service Utilization Trends study population-based cohort of adults (age ≥ 19 yr) living with HIV in British Columbia between Apr. 1, 2012, and Mar. 31, 2013. We performed univariate logistic regression analyses using the following geographic variables to predict HIV virologic suppression: rurality defined by forward sortation area, by Statistical Area Classification and by health authority. We mapped suppression using geographic information systems.

RESULTS

Virologic suppression was observed in 5605 (65.2%) of 8598 participants. In univariate analysis, rurality defined by Statistical Area Classification (odds ratio [OR] 0.73, 95% confidence interval [CI] 0.65-0.82), but not by forward sortation area, was associated with lower odds of suppression. When we examined suppression by health authority, Northern Health had the lowest odds of suppression (OR 0.46, 95% CI 0.36-0.58 compared to Vancouver Coastal Health). Geographic information systems mapping showed poorer suppression in northern areas.

INTERPRETATION

Health outcome findings can vary depending on the definition of the geographic variable. When including geographic variables, researchers should carefully consider variable definitions and whether other classification systems, such as north-south, are more appropriate than rurality for their analysis.

Comparison of Clinical Outcomes of Persons Living With HIV by Enrollment Status in Washington, DC: Evaluation of a Large Longitudinal HIV Cohort Study

Background

HIV cohort studies have been used to assess health outcomes and inform the care and treatment of people living with HIV disease. However, there may be similarities and differences between cohort participants and the general population from which they are drawn.

Objective

The objective of this analysis was to compare people living with HIV who have and have not been enrolled in the DC Cohort study and assess whether participants are a representative citywide sample of people living with HIV in the District of Columbia (DC).

Methods

Data from the DC Health (DCDOH) HIV surveillance system and the DC Cohort study were matched to identify people living with HIV who were DC residents and had consented for the study by the end of 2016. Analysis was performed to identify differences between DC Cohort and noncohort participants by demographics and comorbid conditions. HIV disease stage, receipt of care, and viral suppression were evaluated. Adjusted logistic regression assessed correlates of health outcomes between the two groups.

Results

There were 12,964 known people living with HIV in DC at the end of 2016, of which 40.1% were DC Cohort participants. Compared with nonparticipants, participants were less likely to be male (68.0% vs 74.9%, P<.001) but more likely to be black (82.3% vs 69.5%, P<.001) and have a heterosexual contact HIV transmission risk (30.3% vs 25.9%, P<.001). DC Cohort participants were also more likely to have ever been diagnosed with stage 3 HIV disease (59.6% vs 47.0%, P<.001), have a CD4 <200 cells/µL in 2017 (6.2% vs 4.6%, P<.001), be retained in any HIV care in 2017 (72.9% vs 59.4%, P<.001), and be virally suppressed in 2017. After adjusting for demographics, DC Cohort participants were significantly more likely to have received care in 2017 (adjusted odds ratio 1.8, 95% CI 1.70-2.00) and to have ever been virally suppressed (adjusted odds ratio 1.3, 95% CI 1.20-1.40).

Conclusions

These data have important implications when assessing the representativeness of patients enrolled in clinic-based cohorts compared with the DC-area general HIV population. As participants continue to enroll in the DC Cohort study, ongoing assessment of representativeness will be required.

Incidence of select chronic comorbidities among a population-based cohort of HIV-positive individuals receiving highly active antiretroviral therapy

Objective: To characterize the incidence of select chronic comorbidities in the era of modern (pre-integrase-inhibitor) highly active antiretroviral therapy (HAART) in British Columbia, Canada. Methods: We used data from the Comparative Outcomes And Service Utilization Trends (COAST) study, a population-based cohort study of people living with HIV (PLWH), to determine incidence rates of six key chronic diseases among PLWH receiving HAART in BC from 2000 to 2012. The selected diseases included cardiovascular disease (CVD), diabetes mellitus (DM), hypertension (HTN), asthma/chronic obstructive pulmonary disease (COPD), chronic kidney disease (CKD) and chronic liver disease (CLD) defined using ICD-9 and -10 codes. Disease incidence was determined by number of new cases per year. We used Poisson regression to measure trends in incidence rates. Results: The study sample (n = 10,210) was predominantly male (83%), white (72%) and younger than 50 years of age at HAART initiation (88%). Incidence rates of HTN per 1000 person-years (PY) increased significantly between 2000 and 2012, after adjusting for age, sex, baseline-weighted Charlson Comorbidity Index, CD4 cell count and viral load (p < .001); incidence rates of CKD and CLD decreased significantly over time (p < .001). Unadjusted incidence rates of DM increased over time (p < .01), but remained stable in the adjusted model. Incidence rate patterns for CVD and COPD/asthma were stable over the study period. Conclusions: Population-level increases in incidence rates for HTN, and decreases for CLD and CKD, were observed among PLWH on modern (pre-integrase-inhibitor) HAART from 2000 to 2012. Overall, the increasing incidence of several of these chronic comorbidities in our study suggests that further efforts are needed to maximize the potential for healthy aging among PLWH receiving modern (pre-integrase-inhibitor) HAART.

HIV, schizophrenia, and all-cause mortality: A population-based cohort study of individuals accessing universal medical care from 1998 to 2012 in British Columbia, Canada

Schizophrenia is a severe mental illness with important implications for morbidity and mortality. This population-based cohort study examined the impact of schizophrenia diagnoses on all-cause mortality among a sample of people living with HIV (PLHIV) and a 10% random sample of individuals living without HIV (HIV-) in British Columbia (BC), through a data linkage between the BC Centre for Excellence in HIV/AIDS and Population Data BC's data holdings. Schizophrenia diagnoses were identified via International Classification of Diseases version 9 and version 10 codes. Age- and sex-adjusted all-cause mortality rates from January 1st, 1998 to December 31st, 2012 were calculated. Multivariable logistic models assessed (1) HIV status and mortality among individuals diagnosed with schizophrenia, (2) schizophrenia diagnosis and mortality among PLHIV, and (3) correlates of mortality among PLHIV concurrently diagnosed with schizophrenia (HIV+/SZO+). From 1998 to 2012, 6.3% of those with HIV had a schizophrenia diagnosis, compared to 1.1% of those without HIV. While significant declines in mortality rates were observed throughout the study period, mortality rates were highest among HIV+/SZO+. After adjustment for substance use disorder and age at baseline, HIV+/SZO+ had a 2.64 times greater odds of mortality (95% confidence interval [CI] = 2.14-3.25) compared to HIV-/SZO+. For PLHIV, a schizophrenia diagnosis was not associated with mortality after controlling for potential confounders (adjusted odds ratio [aOR] = 0.90, 95%CI = 0.74-1.09). Among HIV+/SZO+, age, history of injection drug use, ever having an AIDS-defining illness, and never being on anti-psychotic medication or accessing psychiatric services were associated with mortality. Efforts should be made to identify and link to care individuals disproportionately affected by schizophrenia and excess mortality, including those living with HIV.