British Columbia Research Articles

Estimating the population size of persons contending with homelessness using electronic health records

Abstract The majority of attempts to enumerate the homeless population rely on point-in-time or shelter counts, which can be costly and inaccurate. As an alternative, we use electronic health records from the Vancouver Island Health Authority, British Columbia, Canada from 2013 to 2022 to identify adults contending with homelessness based on their self-reported housing status. We estimate the annual population size of this population using a flexible open-population capture–recapture model that takes into account (1) the age and gender structure of the population, including aging across detection occasions, (2) annual recruitment into the population, (3) behavioural-response, and (4) apparent survival in the population, including emigration and incorporating known deaths. With this model, we demonstrate how to perform model selection for the inclusion of covariates. We then compare our estimates of annual population size with reported point-in-time counts of homeless populations on Vancouver Island over the same time period, and find that using data extracts from electronic health records gives comparable estimates. We find similarly comparable results using only a subset of interaction data, when using only ER interactions, suggesting that even if cross-continuum data is not available, reasonable estimates of population size can still be found using our method.

Migration, movements, and survival in a partially migratory elk (Cervus canadensis) population

AbstractMigration provides an adaptive strategy to improve fitness by allowing individuals to exploit gradients of resources and changes in predation risk. In recent decades, the extent and prevalence of migration has declined in numerous ungulate species including many populations of elk (Cervus canadensis). Resident elk are often more closely associated with human activity, are more readily involved in agricultural conflicts and may contribute to overgrazing on some ranges. We evaluated migratory trends, survival rates, and causes of mortality in a partially migratory elk population in southeastern British Columbia, Canada, and compared these parameters with data from a 1982–1996 study from the same area. Analysis of 201 animal‐years (n = 78 collared cow elk) between 2016 and 2022 showed a ratio of 52% migratory to 48% resident elk, similar to what was found during the 1982–1996 study (55% migratory to 45% resident; n = 40 cows). Among the migrants, 55% were standard migrants (traveling moderate to longer distances and changing little in elevation), 35% elevational, and 10% mixed/atypical. We detected a 14% yearly switching rate between migratory and resident strategies. We recorded 30 mortalities: 47% from human causes, predominantly elk‐vehicle/train collisions (33% of mortalities), apparent starvation/old age (17%), and predation (17%). Notably, while mortality from natural causes was similar between strategies, human‐caused mortality was nearly twice as high in resident elk. Signs of nutritional stress and lower pregnancy rates indicated potential forage limitations. Migrants had higher average survival rates (0.90) compared to residents (0.83), a shift from the 1982–1996 study that recorded higher resident survival rates (0.98), the same migrant survival rate (0.90), and fewer elk‐vehicle/train collisions. Cow elk in our study made fewer and shorter movements into upper mountain tributaries and greater use of mine properties than observed during the 1982–1996 study. Wildlife managers should consider opportunities to enhance elk forage within traditional high‐elevation summer ranges and mitigations to reduce elk‐vehicle/train collisions. Further research is needed to quantify reproductive success, monitor calf survival, and determine relative forage quality among summering areas between migratory strategies, and determine winter ranges of long‐distant migrants.

Abstract PO4-18-01: International Validation of a Staging Model for de novo Metastatic Breast Cancer

Abstract Background Given the heterogeneity in outcomes for de novo metastatic breast cancer (dnMBC), a staging system was recently developed that refines prognostic estimates for patients presenting with distant metastases (JCO 2023;10:2546). This staging model was developed using the National Cancer Database and stratified patients into 4 subgroups, termed IVA, IVB, IVC, and IVD based on 3-year overall survival (OS): IVA >70%, IVB 50-70%, IVC 25-< 50%, and IVD < 25%; the primary factors affecting higher stage grouping were negative for ER, PR, and HER2 expression and a higher number of involved organ sites. Here, we aim to validate this model using an international data set. Methods Data for dnMBC patients were obtained from the Netherlands Cancer Registry (NCR, hosted by IKNL), Epidemiological Strategy and Medical Economics (ESME) by Unicancer, British Columbia Cancer (BCCan), Instituto Nacional de Cancerología, México (INCan), and Grupo Español de Investigación en Cáncer de Mama (GEICAM); the diagnosis years included varied by organization (range 2002-2021). Stage groups were assigned based on previously published criteria, defined by T-category, grade, ER, PR, HER2, histology, organ system site of metastases (bone-only, brain-only, visceral), and number of organ systems involved. For each cohort, followup time and OS were estimated using the reverse Kapan-Meier and Kaplan-Meier method, respectively. Median rates were estimated across all cohorts by weighting on cohort sample size or number at risk. Cox proportional hazards models were used to estimate the association of stage with OS after adjustment for age at diagnosis (treatment data not available for all cohorts). For the ESME cohort, a subgroup multivariable analysis was used to estimate the association of stage with OS after adjustment for age, local (surgery or radiotherapy) and first line systemic treatments. Results The final validation cohort was comprised of N=11,199 patients from 5 international organizations: n=5063 (45.2%, IKNL), n=4139 (37.0%, ESME), n=774 (6.9%, BCCan), n=757 (6.8%, INCan), and n=466 (4.2% GEICAM). Median followup across all cohorts was 77.5 months (95% CI 74.3-80.2). Median followup (in months) for the IKNL, ESME, BCCan, INCan, and GEICAM cohorts was 45.3 (95% CI 43.6-47.1), 77.5 (95% CI 74.3-80.2), 105.0 (95% CI 95.9-106.5), 93.0 (95% CI 86.5-102.1), and 49.5 (95% CI 46.5-53.4), respectively. Patients were stratified into stage groups: IVA, n=603 (5.4%); IVB, n=5704 (50.9%); IVC, n=3356 (30.0%); IVD, n=1536 (13.7%). For all cohorts combined, the weighted average OS rates consistently decreased with increasing stage group; similar findings were noted for individual cohorts (all p< 0.001; Table). On multivariable subgroup analysis including age at diagnosis, stage group was significantly associated with OS, and the risk of death increased with increasing stage (all p< 0.001; Table). On multivariable subgroup analysis for n=4139 patients (ESME cohort), stage group remained significantly associated with OS [IVA: reference; IVB: HR 1.51 (95% CI 1.17-1.93); IVC: HR 2.11 (95% CI 1.64-2.72); IVD: HR 3.60 (95% CI 2.75-4.70)] after adjusting for age and treatment. Conclusions These findings provide external validation of the previously published staging guidelines for dnMBC. This may guide future revisions of the AJCC staging guidelines for patients with dnMBC and provide patients and providers valuable information in planning therapy and goals of care as they approach the end-of-life. Table. Citation Format: Jennifer Plichta, Samantha Thomas, Sabine Siesling, Linda de Munck, Amélie Lusque, Thomas Grinda, Lovedeep Gondara, Stephen Chia, Paula Cabrera-Galeana, Nancy Reynoso-Noverón, Sara López-Tarruella, Isabel Álvarez López, Stephen Edge, Gabriel Hortobagyi. International Validation of a Staging Model for de novo Metastatic Breast Cancer [abstract]. In: Proceedings of the 2023 San Antonio Breast Cancer Symposium; 2023 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2024;84(9 Suppl):Abstract nr PO4-18-01.

Inappropriate Use of Proton Pump Inhibitor Among Elderly Patients in British Columbia: What are the Long-term Adverse Events?

Proton pump inhibitors (PPIs) are one of the most used classes of drugs. For most indications, PPIs are only recommended up to 8 weeks duration. However, PPI use continues to expand. Regular and prolonged use of PPIs should be avoided because of the risk of adverse events. The main objective of this study was to (1) investigate the extent of PPI usage in people aged 65 or older in the province of British Columbia (BC), Canada, (2) provide an overview of the harms associated with the long-term use of PPIs. We examined utilization trends of the PPIs in BC since the year 2009 using PharmaNet, BC's medication dispensing database where the information is accessible to community pharmacists. We performed a comprehensive literature search for relevant reviews reporting harms associated with long-term use of PPIs. A search was conducted from January 2014 to June 2022. Between 2000 and 2018 BC's population grew by 20%, but the use of PPIs escalated to 257%. Of these older British Columbians, 62% had a cumulative exposure exceeding 2 years and 42% exceeded 5 years. This is alarming because the recommended treatment duration is 4-12 weeks for common indications including reflux esophagitis, and duodenal and gastric ulcers. Only 13.5% were dispensed PPIs for 90 days or less. Patients on long-term PPI therapy should be reassessed. Adverse events of PPI use are common among older adults. We identified over 217 systematic reviews published during the last 8 years of specific harms associated with long-term daily usage of PPIs. These harms include increased risks of death, cardiovascular disease, acute renal injury, chronic kidney disease, dementia, fractures, hypomagnesemia, iron deficiency, vitamin B12 deficiency, enteric infection (including C. difficile), pneumonia, and neoplasia (gastric cancer, carcinoids, and colon cancer), and drug interactions. This study revealed a high prevalence of PPI use among elderly populations in BC, Canada. The overutilization of PPIs is often a result of failure to re-evaluate the need for continuation of therapy. Published studies identified signals of serious harm from long-term PPI exposure. Healthcare providers with patients can reverse the relentless expansion of long-term PPI exposure by discussing the expected benefits and potential harms.

SARS-CoV-2 Transmission in Alberta, British Columbia, and Ontario, Canada, January 2020-January 2022.

We estimated COVID-19 transmission potential and case burden by variant type in Alberta, British Columbia, and Ontario, Canada, during January 23, 2020-January 27, 2022; we also estimated the effectiveness of public health interventions to reduce transmission. We estimated time-varying reproduction number (Rt) over 7-day sliding windows and nonoverlapping time-windows determined by timing of policy changes. We calculated incidence rate ratios (IRRs) for each variant and compared rates to determine differences in burden among provinces. Rt corresponding with emergence of the Delta variant increased in all 3 provinces; British Columbia had the largest increase, 43.85% (95% credible interval [CrI] 40.71%-46.84%). Across the study period, IRR was highest for Omicron (8.74 [95% CrI 8.71-8.77]) and burden highest in Alberta (IRR1.80 [95% CrI 1.79-1.81]). Initiating public health interventions was associated with lower Rt and relaxing restrictions and emergence of new variants associated with increases in Rt.

Impact of screening and doxycycline prevention on the syphilis epidemic among men who have sex with men in British Columbia: a mathematical modelling study

Men who have sex with men (MSM) in British Columbia (BC) are disproportionately affected by infectious syphilis and HIV. In this study, we developed a co-interaction model and evaluated the impact and effectiveness of possible interventions among different MSM subgroups on the syphilis epidemic. We designed a deterministic compartmental model, which stratified MSM by HIV status and HIV pre-exposure prophylaxis (HIV-PrEP) usage into (1) HIV-negative/unaware MSM (HIV-PrEP not recommended, noton HIV-PrEP), (2) HIV-negative/unaware MSM with HIV-PrEP recommended (not on HIV-PrEP), (3)HIV-negative/unaware MSM actively on HIV-PrEP, and (4) MSM diagnosed with HIV. We estimated the effect of scaling up syphilis testing frequency from Status Quo to six-, four-, and three-months, increasing the percentage of MSM using doxycycline prevention (Doxy-P) to 25%, 50%, and 100% of the target level, and a combination of both among subgroups (2)-(4). We also assessed the impact of these interventions on the syphilis incidence rates from 2020 to 2034 in comparison to the Status Quo scenario where no intervention was introduced. Under the Status Quo scenario, with the expansion of the HIV-PrEP program to improve syphilis testing, the syphilis incidence rate was estimated to peak at 16.1 [Credible Interval (CI):14.2-17.9] per 1,000 person-years (PYs) in 2023 and decrease to 6.7 (CI:3.8-10.9) per 1,000 PYs by 2034. The syphilis incidence rate in 2034 was estimated at 0.7 (0.3-1.3) per 1,000 PYs if MSM diagnosed with HIV could be tested every four months, and at 1.5 (0.7-3.0) per 1,000 PYs if HIV-negative/unaware MSM actively on HIV-PrEP could be tested every three months. By achieving 100% of the target coverage of Doxy-P, the syphilis incidence rate was estimated at 1.4 (0.5-3.4) if focusing on MSM diagnosed with HIV, and 2.6 (1.2-5.1) per 1,000 PYs if focusing on HIV-negative/unaware MSM actively on HIV-PrEP. Under the combined interventions, the syphilis incidence rate could be as low as 0.0 (0.0-0.1) and 0.8 (0.3-1.8) per 1,000 PYs, respectively. The HIV-PrEP program in BC plays a crucial role in increasing syphilis testing frequency among high-risk MSM and reducing syphilis transmission among this group. In addition, introducing Doxy-P can be an effective complementary strategy to minimize syphilis incidence, especially among MSM diagnosed with HIV. This work was funded by the Canadian Institutes of Health Research.

Building benchmarking and energy performance: Analysis of social and affordable housing in British Columbia, Canada

This research assesses the energy performance of social and affordable housing by conducting quantitative analysis of 23 community housing buildings in British Columbia (BC) using ENERGY STAR Portfolio Manager. The study sampled community housing buildings, tracked utility bills from 2019 to 2022, and analyzed weather-normalized energy consumption. We find that high-rise buildings in our dataset performed worse compared to other buildings in the dataset and to market housing buildings in BC. We attribute these differences to variability in building characteristics, construction methods, and mechanical systems. Results also show that average energy consumption per dwelling unit in community housing buildings is lower than the BC average, indicating that residents in social and affordable housing use less energy. This could be linked to the lack of amenities in community housing like air conditioning as well as possible efforts taken by residents to reduce utility bills by using less energy. These results demonstrate that it is important to retrofit these buildings for the sake of building and environmental performance but also, and perhaps more critically, to improve the living conditions of those who live in social and affordable housing. Limited understanding of the influence of occupant behaviour on energy performance is a study limitation warranting further study.

British Columbia’s Autism Funding Policies

British Columbia’s Autism Funding Policies

Insights from First Nations, Government and Industry Leaders on Criteria for Successful Impact Benefit Agreements.

Over the past decade, British Columbia, Canada's westernmost province, has begun developing liquified natural gas (LNG) mega projects that can transport Canadian resources to foreign markets across the Pacific region. These projects have gained significant profile due to high-level debates over their environmental, social and economic impacts. While LNG projects are required to undergo environmental impact assessment procedures, there is growing recognition of the need to ensure that positive social, economic and environmental impacts are fairly distributed to local communities. Similar to other extractive industries, many corporations leading the development of these projects engage in negotiations over so-called "impact benefit agreements (IBAs)"-legal agreements between a corporation, a government and/or a community that details how projects can benefit the local community and on what timeline so as to build social license to operate and investor confidence. This contribution details the findings of a qualitative study highlighting the perspectives of First Nations, provincial and federal government, and industry leaders to examine what makes an IBA successful and from whose perspective. The paper provides an introduction to IBA structures and processes, a brief review of the legal context, a qualitative methodology co-developed between academic researchers and Indigenous community leaders, and describes key criteria to inform future successful IBA agreements that create equitable multi-party benefits in an era of Indigenous reconciliation.

Lake surface and downstream river temperature response to the retreat of a lake‐terminating glacier

AbstractGlacier contributions to streamflow moderate summer water temperatures and help keep rivers cool during periods of hot, dry weather. As glaciers retreat, the length of channel exposed to solar radiation above a given point of interest would increase, which should ultimately result in higher water temperatures. However, formation of proglacial lakes may complicate river temperature response to glacier retreat. This study examined river and lake temperature response to the retreat of lake‐terminating Bridge Glacier, British Columbia, using a combination of manual spot and continuous river temperatures at a stream gauge, lake surface temperatures derived from Landsat imagery, and in situ lake temperatures made during a field campaign during summer 2013. Temperature data spanned the period from 1984 to 2022. Lake and river temperatures were relatively constant prior to and during a period of rapid retreat, but exhibited an upward trend following 2012, when iceberg density declined due to an apparent decrease in calving rate, resulting in an increase in lake surface area and river temperature of about 5°C even though the glacier remained lake terminating. In addition to providing the first longitudinal study of water temperature response to the retreat of a lake‐terminating glacier, this study adds to a body of literature that demonstrates that routine spot river temperatures, if collected in a consistent manner over a number of years, can provide valid information about river and stream temperature trends.

Forest Disturbance Thresholds and Cumulative Hydrological Impacts

AbstractForest disturbance threshold is defined as a critical disturbance level (e.g., % of forest cover change) in forested landscapes above which significant hydrological impacts are detected. Determining disturbance thresholds is critically important for supporting forest management to ensure the sustaining of ecological and hydrological functions. However, there are very few quantitative evaluations of forest disturbance thresholds globally. In this study, we applied a well‐tested methodology (the modified double mass curve) to derive the long‐term, continuous hydrological response curves and then to quantify forest disturbance thresholds on annual streamflow in 42 forested watersheds in British Columbia, Canada. The results show that forest disturbance thresholds for significant and cumulative hydrological impacts vary from 7% to 52% of cumulative equivalent clear‐cut area with an average of 17% or from 8% to 52% of disturbed area with an average of 19%. Climate (inter‐annual and intra‐annual) and watershed properties exert critical controls on forest disturbance thresholds. Watersheds with greater snowfall proportions (more annual precipitation falling as snow), more desynchronizations (temporal mismatching) of energy demand and water supply at the intra‐annual scale, less diverse ecosystems, and larger watershed sizes have lower forest disturbance thresholds. Given the present forest disturbance levels in the central interior of British Columbia, about half (53%) of the forested watersheds have already crossed the average disturbance threshold. These results highlight that watershed planning and management using forest disturbance thresholds must carefully consider local climate and watershed properties. The methodology can be effectively and robustly extended elsewhere around the globe.

Factors Influencing the Resilience of Created Tidal Marshes in the Fraser River Estuary, British Columbia

More than 100 tidal marsh creation projects were constructed throughout the Fraser River Estuary, British Columbia, Canada from the 1980s to present. Past studies described and evaluated many of these projects and found varied success, but the underlying factors that determine project outcomes remain uncertain. Combining field sampling, spatial analysis, and statistical modeling of plant communities, we aim to address this knowledge gap by asking what factors influence the resilience of created marshes, as measured by (1) persistence of marsh vegetation, (2) native species dominance, and (3) species richness. We observed marsh recession in 40 of the 78 projects visited, representing 23,666 m2 (9.3%) of the 254,357 m2 of created marsh surveyed. Increases in mean site elevation had a negative effect on percent recessed area, while sites in the north branch of the river and sites further upriver were more prone to recession. From field observations and data interpretation we suggest that wake erosion and Canada Goose (Branta canadensis) herbivory may be drivers behind these losses and warrant further investigation. Dominance of native species declined with distance upriver, though invasive cattail (Typha angustifolia, T. × glauca) defied this trend, dominating outer estuary sites, particularly closed embayments, when present. Native and non-native richness shared similar patterns and were comparable between reference and created marshes, increasing on average with elevation and distance upriver. These findings offer insight into how site design and location influence the outcome of marsh creation projects, and the challenges presented by stressors and environmental change in estuaries.

Navigating Patterns of Oral PrEP Use: A Qualitative Longitudinal Study of Gay, Bisexual, and Queer Men’s Dynamic Practices of Pausing, On-Demand, and Stopping PrEP in Canada

The Canadian HIV pre-exposure prophylaxis (PrEP) guidelines recommend both daily and on-demand dosing for gay, bisexual, and queer men (GBQM), meeting additional risk criteria. However, limited research explored how GBQM implement pausing, on-demand, discontinuation, and resumption of PrEP, including the contextual factors affecting decision-making. Using a relationally situated implementation science framework, we examined how GBQM tailor PrEP use to changing social and sexual circumstances. We conducted 109 longitudinal interviews with current and former PrEP users from Ontario (n=18) and British Columbia (n=20), Canada, at three time points between 2020 and 2022. We identified three dynamic PrEP use trajectories: pausing, on-demand, and stopping. Pausing involved brief breaks followed by a return to daily use during heightened sexual activity. Others followed the 2-1-1 on-demand schedule, while some stopped PrEP with plans to resume if social and sexual circumstances change. During the COVID-19 pandemic, participants paused PrEP when sexual activities decreased, restarting daily use when sexual engagements resumed. Others paused due to relationship changes or sexual inactivity, resuming PrEP in anticipation of sex. On-demand PrEP was adopted to manage side effects or save costs. Some stopped PrEP for sustained periods due to monogamy, private insurance loss, side effects, or low perceived HIV risk. Participants expressed concerns regarding lack of information on these strategies, relying on online sources or peers for guidance. Most participants obtained enough PrEP knowledge to adapt use appropriately. Comprehensive education campaigns on adaptable PrEP use effectiveness and strategies to discontinue and resume PrEP for clinicians, and GBQM should be implemented.

Outcomes with allogeneic stem cell transplant using cryopreserved versus fresh hematopoietic progenitor cell products

BackgroundAllogeneic hematopoietic stem cell transplant (alloHSCT) is a mainstay of treatment for hematologic malignancies such as acute leukemias and aggressive lymphomas. Historically, fresh Hematopoietic Progenitor Cell (HPC) products have been preferred to cryopreserved products (cryo-HPC) due to concerns of loss of stem cell viability and number with the cryopreservation procedure. ObjectiveWe aimed to analyze the outcomes of patients who received cryo-HPCs during the COVID-19 pandemic and compare this against historical cohorts that received fresh HPC. Study DesignA retrospective chart review was conducted on all adult patients who received a peripheral blood alloHSCT in British Columbia, Canada between June 2017 and November 2021. Baseline characteristics, Kaplan-Meier (KM) Overall Survival (OS), engraftment, and incidences of acute and chronic graft versus host disease were compared between patients who received cryo-HPCs and fresh HPCs. Univariable analysis followed by multivariable analysis was performed using a backward stepwise selection procedure to generate predictors of OS, cumulative incidence of relapse (CIR), non-relapse mortality (NRM), and primary and secondary graft failure. Results383 patients were included in the analysis, with cryo-HPC representing 40%. Median viability was higher in the fresh-HPC group at 99.2% (IQR 98.3-99.5) versus cryo-HPCs at 97.0% (96.0, 98.6) (p<0.01). The 12-month actuarial survivals were 77% in the fresh HPC and 75% in the cryo-HPC groups (p=0.21). There were no differences between cryo-HPCs and fresh HPCs on univariable analysis of OS, CIR, or NRM. There was a shorter median time to platelet engraftment in patients receiving fresh HPC at 17 days (IQR 16, 20) versus cryo-HPC at 21 days (IQR 18, 29), p<0.001. There was a shorter median time to neutrophil engraftment in the fresh HPC group at 17 days (IQR 14, 20) versus 20 days (17, 23), p<0.001. Cryo-HPC accounted for 5 out of 6 cases of primary graft failure (p=0.04), and 3 out of five cases of secondary graft failure (p=0.39). There were no significant differences in acute GVHD between the fresh HPC and cryo-HPC groups (p=0.34). The incidence of moderate or severe chronic GVHD was 32% in the fresh-HPC group and 17% in the cryo-HPC group (p<0.001).In multivariable analysis, cryopreservation did not emerge as an independent predictor of OS, CIR, NRM, primary GF or secondary GF. However, viability <90% on arrival at our center was a significant predictor of OS (HR 5.3, 2.3-12.3, p<0.01), primary graft failure (OR 36.3, 5.4-210.2, p<0.01), and secondary graft failure (OR 18.4, 1.7-121.1, p<0.01). ConclusionPatients who received cryo-HPCs had similar OS and relapse rates to those who received fresh-HPCs but typically took 2-3 days longer to achieve engraftment of platelets or neutrophils and were associated increased primary graft failure. However, after accounting for multiple variables, cryopreservation was no longer a significant predictor of survival or engraftment while viability <90% emerged as an important predictor of OS, primary graft failure, and secondary graft failure. If confirmed, this suggests that viability on arrival at the infusion center may be a good quality control indicator used to identify HPC products that may warrant recollection if the risk of graft failure is sufficiently increased.

A switching state-space transmission model for tracking epidemics and assessing interventions

The effective control of infectious diseases relies on accurate assessment of the impact of interventions, which is often hindered by the complex dynamics of the spread of disease. A Beta-Dirichlet switching state-space transmission model is proposed to track underlying dynamics of disease and evaluate the effectiveness of interventions simultaneously. As time evolves, the switching mechanism introduced in the susceptible-exposed-infected-recovered (SEIR) model is able to capture the timing and magnitude of changes in the transmission rate due to the effectiveness of control measures. The implementation of this model is based on a particle Markov Chain Monte Carlo algorithm, which can estimate the time evolution of SEIR states, switching states, and high-dimensional parameters efficiently. The efficacy of the proposed model and estimation procedure are demonstrated through simulation studies. With a real-world application to British Columbia's COVID-19 outbreak, the proposed switching state-space transmission model quantifies the reduction of transmission rate following interventions. The proposed model provides a promising tool to inform public health policies aimed at studying the underlying dynamics and evaluating the effectiveness of interventions during the spread of the disease.

A Review of Pacific Salmon Hatcheries in British Columbia, Canada, and Interactions With Natural Populations

Pacific salmon Oncorhynchus spp. hatcheries in British Columbia (BC) have been the major activity of the Salmonid Enhancement Program since 1977. However, the present diminished abundance of Pacific salmon and loss of fisheries in BC called for a review of hatchery effectiveness. The Pacific Salmon Foundation conducted a review resulting in 15 reports publicly available on the Pacific Salmon Foundation marine science website. The review includes evaluations of effectiveness of hatchery production, evidence of interactions with natural salmon populations (including rebuilding natural populations with hatchery‐produced salmon), and future opportunities via genomics. Beyond the estimation of juvenile production and contribution to catches and spawning escapements, the ability to assess effectiveness was limited. The assessments of interactions provided a few examples of positive outcomes, but most were negative. The lack of comparative assessments in purely wild populations seriously limits interpretations of hatchery–wild interactions. Future evaluations of the hatchery effectiveness require more quantitative and integrated assessments of hatchery and wild salmon, open data sharing for public review or research, and related studies could benefit from application of new genomic technologies. This paper presents recommendations to address these needs and calls for regularized reviews of the Salmonid Enhancement Program and its net value to sustainability of BC's Pacific salmon.

Landslide Deposit Erosion and Reworking Documented by Geomatic Surveys at Mount Meager, BC, Canada

Mount Meager is a deeply eroded quaternary volcanic complex located in southwestern British Columbia (BC) and is known for its frequent large landslides. In 2010, the south face of Mount Meager collapsed, generating a long-runout debris avalanche that was one of the largest landslides (50 × 106 m3) in Canadian history. Over the past 14 years, the landslide deposit has been reworked by stream action, delivering large amounts of sediment to Lillooet River, just downstream. In this study, we investigate 10 years of geomorphic evolution of the landslide deposit using orthophotos and digital elevation models (DEMs) generated using Structure from Motion (SfM) photogrammetry on aerial photographs acquired during unmanned aerial vehicle (UAV) and Global Navigation Satellite System (GNSS) surveys. The SfM products were used to produce a series of precise maps that highlight the geomorphological changes along the lower Meager Creek within the runout area of the landslide. Comparison of DEMs produced from 2010, 2012, 2015, and 2019 imagery allowed us to calculate deposit volume changes related to erosion, transport, and redeposition of landslide material. We estimate that about 1.1 × 106 m3 of sediment was eroded from the landslide deposit over the period 2015–2019. About 5.2 × 105 m3 of that sediment was redeposited inside the study area. About 5.8 × 105 m3 of sediment, mainly sand, silt, and clay, were exported from the study area and are being carried by Lillooet River towards Pemberton, 40 km from Mount Meager, and farther downstream. These remobilized sediments likely reduce the Lillooet River channel capacity and thus increase flood hazards to the communities of Pemberton and Mount Currie. Our study indicates a landslide persistence in the landscape, with an estimated 47-year half-life decay, suggesting that higher flood hazard conditions related to increased sediment supply may last longer than previously estimated. This study shows the value of using SfM in tandem with historic aerial photographs, UAV photos, and high-resolution satellite imagery for determining sediment budgets in fluvial systems.

What is the ideal time to begin tapering opioid agonist treatment? A protocol for a retrospective population-based comparative effectiveness study in British Columbia, Canada

IntroductionOpioid agonist treatment (OAT) tapering involves a gradual reduction in daily medication dose to ultimately reach a state of opioid abstinence. Due to the high risk of relapse and overdose...

The impact of the COVID-19 pandemic on HIV treatment gap lengths and viremia among people living with HIV British Columbia, Canada, during the COVID-19 pandemic: Are we ready for the next pandemic?

The SARS-CoV-2 (COVID-19) pandemic has impacted the care of people living with HIV (PLWH). This study aims to characterize the impact of the pandemic on the length of HIV treatment gap lengths and viral loads among people living with HIV (PLWH) in British Columbia (BC), Canada, with a focus on Downtown Eastside (DTES), which is one of the most impoverished neighbourhoods in Canada. We analyzed data from the HIV/AIDS Drug Treatment Program from January 2019 to February 2022. The study had three phases: Pre-COVID, Early-COVID, and Late-COVID. We compared results for individuals residing in DTES, those not residing in DTES, and those with no fixed address. Treatment gap lengths and viral loads were analyzed using a zero-inflated negative binomial model and a two-part model, respectively, adjusting for demographic factors. Among the 8982 individuals, 93% were non-DTES residents, 6% were DTES residents, and 1% had no fixed address during each phase. DTES residents were more likely to be female, with Indigenous Ancestry, and have a history of injection drug use. Initially, the mean number of viral load measurements decreased for all PLWH during the Early-COVID, then remained constant. Treatment gap lengths increased for all three groups during Early-COVID. However, by Late-COVID, those with no fixed address approached pre-COVID levels, while the other two groups did not reach Early-COVID levels. Viral loads improved across each phase from Pre- to Early- to Late-COVID among people residing and not residing in DTES, while those with no fixed address experienced consistently worsening levels. Despite pandemic disruptions, both DTES and non-DTES areas enhanced HIV control, whereas individuals with no fixed address encountered challenges. This study offers insights into healthcare system preparedness for delivering HIV care during future pandemics, emphasizing community-driven interventions with a particular consideration of housing stability.

Infrastructure of Vulnerability, or, How the Fraser Valley Flooded Twice

AbstractIn November and December of 2021, the Fraser Valley in southwest British Columbia suffered extreme flooding due to an atmospheric river. Although the event was attributed to climate change, I suggest that the recent floods must be understood through the historical geography of flood control infrastructure in the valley, particularly dikes. In this article, I trace the development of these infrastructures from the beginning of colonisation to the completion of the first state‐managed diking system in the early 20th century. I argue that at the same time as dikes secured land for settler farmers, they exposed Indigenous peoples to new hazards—ironically including floods—and multiplied the damage of future flood events. Building on geographic literature demonstrating the participation of dike infrastructure in racialised capital accumulation and settler colonialism, I highlight the way that dikes have abetted these projects through the uneven spatial production of vulnerability.