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

INTRODUCTION

Opioid 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 after tapering, this practice is not recommended by clinical guidelines, however, clients may still request to taper off medication. The ideal time to initiate an OAT taper is not known. However, ethically, taper plans should acknowledge clients' preferences and autonomy but apply principles of shared informed decision-making regarding safety and efficacy. Linked population-level data capturing real-world tapering practices provide a valuable opportunity to improve existing evidence on when to contemplate starting an OAT taper. Our objective is to determine the comparative effectiveness of alternative times from OAT initiation at which a taper can be initiated, with a primary outcome of taper completion, as observed in clinical practice in British Columbia (BC), Canada.

METHODS AND ANALYSIS

We propose a population-level retrospective observational study with a linkage of eight provincial health administrative databases in BC, Canada (01 January 2010 to 17 March 2020). Our primary outcomes include taper completion and all-cause mortality during treatment. We propose a 'per-protocol' target trial to compare different durations to taper initiation on the likelihood of taper completion. A range of sensitivity analyses will be used to assess the heterogeneity and robustness of the results including assessment of effectiveness and safety.

ETHICS AND DISSEMINATION

The protocol, cohort creation and analysis plan have been classified and approved as a quality improvement initiative by Providence Health Care Research Ethics Board and the Simon Fraser University Office of Research Ethics. Results will be disseminated to local advocacy groups and decision-makers, national and international clinical guideline developers, presented at international conferences and published in peer-reviewed journals electronically and in print.

Prescribing practices in opioid agonist treatment and changes in compliance to clinical dosing guidelines in British Columbia, Canada

BACKGROUND AND AIM

In British Columbia, Canada, clinical guidelines for the treatment of opioid use disorders (OUD) were updated in 2017, during a period in which the potency and composition of the illicit drug supply changed rapidly. We aimed to describe changes in opioid agonist treatment (OAT) prescribing practices at the population level in a setting in which fentanyl and its analogs have become the primary illicit opioid of use.

DESIGN, SETTING AND PARTICIPANTS

This was a population-based retrospective cohort study using three linked health administrative databases in British Columbia (BC), Canada. All individuals with at least one OAT dispensation in BC between 1 January 2014 and 31 August 2021 took part.

MEASUREMENTS

To assess changes in OAT prescribing practices over time, we calculated initiation doses, dose titration intervals, maintenance doses and take-home dosing intervals stratified by medication [methadone, buprenorphine-naloxone and slow-release oral morphine (SROM)] according to recommended guidelines.

FINDINGS

A total of 265 410 OAT episodes (57.5% on methadone, 34.5% on buprenorphine-naloxone and 8.0% on SROM) were initiated during the study period. Compared with the guideline recommendation, observed initiation doses were higher among all medications from 2014 (2017 for SROM) to 2021 (buprenorphine-naloxone: 14-29%; methadone: 53-66%; SROM: 26-55%). Titration intervals were shorter for all medications, consistent with guidelines for buprenorphine-naloxone (26-49%), but shorter than recommended for methadone or SROM (28-51% and 12-41%, respectively). Higher maintenance dosing was observed for methadone (68-78%) and SROM (3-21%). Take-home allowances extending beyond the recommended guideline length increased across medications (buprenorphine-naloxone: 18-35%; methadone: 50-64%; SROM: 34-39%). Changes in prescribing patterns were similar for first-time OAT initiators.

CONCLUSION

In British Columbia, Canada, from 2014 to 2021, prescribers of opioid agonist treatment (OAT) appeared to initiate both new and experienced OAT clients at higher doses than guideline recommendations, titrate them more rapidly and maintain clients at higher doses. Take-home dose allowances also gradually increased.

Comparative Analysis of Instrumental Variables on the Assignment of Buprenorphine/Naloxone or Methadone for the Treatment of Opioid Use Disorder

BACKGROUND

Instrumental variable (IV) analysis provides an alternative set of identification assumptions in the presence of uncontrolled confounding when attempting to estimate causal effects. Our objective was to evaluate the suitability of measures of prescriber preference and calendar time as potential IVs to evaluate the comparative effectiveness of buprenorphine/naloxone versus methadone for treatment of opioid use disorder (OUD).

METHODS

Using linked population-level health administrative data, we constructed five IVs: prescribing preference at the individual, facility, and region levels (continuous and categorical variables), calendar time, and a binary prescriber's preference IV in analyzing the treatment assignment-treatment discontinuation association using both incident-user and prevalent-new-user designs. Using published guidelines, we assessed and compared each IV according to the four assumptions for IVs, employing both empirical assessment and content expertise. We evaluated the robustness of results using sensitivity analyses.

RESULTS

The study sample included 35,904 incident users (43.3% on buprenorphine/naloxone) initiated on opioid agonist treatment by 1585 prescribers during the study period. While all candidate IVs were strong (A1) according to conventional criteria, by expert opinion, we found no evidence against assumptions of exclusion (A2), independence (A3), monotonicity (A4a), and homogeneity (A4b) for prescribing preference-based IV. Some criteria were violated for the calendar time-based IV. We determined that preference in provider-level prescribing, measured on a continuous scale, was the most suitable IV for comparative effectiveness of buprenorphine/naloxone and methadone for the treatment of OUD.

CONCLUSIONS

Our results suggest that prescriber's preference measures are suitable IVs in comparative effectiveness studies of treatment for OUD.

Effect of Risk Mitigation Guidance opioid and stimulant dispensations on mortality and acute care visits during dual public health emergencies: retrospective cohort study

OBJECTIVE

To determine the effect of opioid and stimulant Risk Mitigation Guidance (RMG) dispensations on mortality and acute care visits during the dual public health emergencies of overdose and covid-19.

DESIGN

Population based retrospective cohort study.

SETTING

British Columbia, Canada.

PARTICIPANTS

5882 people with opioid or stimulant use disorder who received RMG prescriptions for opioids (n=5356) and/or stimulants (n=1061) (535 received both) from 27 March 2020 to 31 August 2021.

MAIN OUTCOME MEASURES

All cause and overdose specific mortality and acute care visits in the week after RMG opioid or stimulant dispensation. RMG recipients were matched 1:1 with controls through use of high dimensional propensity score matching. Marginal structural models, executed on weekly time steps, were used to measure the effect of dispensations on outcomes.

RESULTS

RMG opioid dispensations of one day or more were associated with reduced all cause mortality (adjusted hazard ratio 0.39, 95% confidence interval 0.25 to 0.60) and overdose related mortality (0.45, 0.27 to 0.75) in the subsequent week. Dispensations of RMG stimulants (≥1 days) were not significantly associated with reduced all cause mortality (adjusted hazard ratio 0.50, 0.20 to 1.23) or overdose related mortality (0.53, 0.18 to 1.56). The protective effect of RMG opioid dispensations increased with the number of days the medications were dispensed in a given week. People who received four or more days of RMG opioid dispensations had reduced all cause mortality (adjusted hazard ratio 0.09, 0.04 to 0.21) and overdose related mortality (0.11, 0.04 to 0.32) compared with the control group. Opioid RMG dispensations did not significantly modify the odds of all cause or overdose related acute care visits. Dispensations of RMG stimulants were associated with a significant decrease in the odds of acute care visits for any cause but did not affect the odds of overdose related acute care visits.

CONCLUSIONS

RMG opioid dispensations were associated with reduced overdose related and all cause mortality among a sample of people with opioid use disorder. Pharmaceutical alternatives to the illegal drug supply are promising interventions to reduce mortality in people with opioid use disorder.

Influence of physician networks on the implementation of pharmaceutical alternatives to a toxic drug supply in British Columbia

BACKGROUND

Characterizing the diffusion of adopted changes in policy and clinical practice can inform enhanced implementation strategies to ensure prompt uptake in public health emergencies and other rapidly evolving disease areas. A novel guidance document was introduced at the onset of the COVID-19 pandemic in British Columbia (BC), Canada, which supported clinicians to prescribe opioids, stimulants, and benzodiazepines. We aimed to determine the extent to which uptake and discontinuation of an initial attempt at a prescribed safer supply (PSS) program were influenced through networks of prescribers.

METHODS

We executed a retrospective population-based study using linked health administrative data that captured all clinicians who prescribed to at least one client with a substance use disorder from March 27, 2020, to August 31, 2021. Our main exposure was the prescribing patterns of an individuals' peers, defined as the proportion of a prescribers' professional network (based on shared clients), which had previously prescribed PSS, updated monthly. The primary outcome measured whether a clinician had prescribed their initial PSS prescription during a given calendar month. The secondary outcome was the discontinuation of PSS prescribing, defined as an absence for PSS prescriptions for at least 3 months. We estimated logistic regression models using generalized estimated equations on monthly repeated measurements to determine and characterize the extent to which peer networks influenced the initiation and discontinuation of PSS prescribing, controlling for network, clinician, and caseload characteristics. Innovators were defined as individuals initiating PSS prior to May 2020, and early adopters were individuals initiating PSS after.

RESULTS

Among 14,137 prescribers treating clients with substance use disorder, there were 228 innovators of prescribed safer supply and 1062 early adopters through the end of study follow-up, but 653 (50.6%) were no longer prescribing by August 2021. Prescribers with over 20% of peers whom had adopted PSS had a nearly fourfold higher adjusted odds of PSS prescribing themselves (aOR: 3.79, 95% CI: (3.15, 4.56)), compared to those with no connected safer supply prescribers.

CONCLUSIONS

The uptake of PSS in BC was highly dependent on the behavior of prescribers' peer networks. Future implementation strategies to support PSS or other policies would benefit from leveraging networks of prescribers.

Opioid agonist therapy and mortality among First Nations and other residents with concurrent alcohol use disorder in British Columbia, Canada: A population-based cohort study

BACKGROUND

Despite the prevalence of alcohol use among people with opioid use disorder (PWOUD) engaged in opioid agonist therapy (OAT), clinical care guidance for concurrent alcohol use disorder (AUD) and OUD is scarce. We assessed the prevalence and risk of mortality for concurrent AUD among PWOUD who accessed OAT in British Columbia (BC).

METHODS

Data were obtained from six linked population-level health administrative datasets to identify PWOUD from January 1996 to March 2020. All-cause age and sex standardized mortality ratios (SMR) were calculated to determine the mortality risk by OAT status (on vs. discontinued), stratified by First Nations and other residents with concurrent AUD and OUD. Adjusted risk ratios compared the relative risk of mortality by AUD status (AUD detected vs. not) among First Nations and other residents.

RESULTS

We identified 62,110 PWOUD who received OAT, including 6305 (10.2%) First Nations. OAT substantially lowered the SMR among First Nations (SMR=6.6, 95% CI: 5.4-8.1) and other residents (SMR=6.6; 95% CI: 6.2-7.0) with concurrent AUD and OUD, compared to those who discontinued (SMR=22.7, 95% CI: 20.4-25.1, SMR=17.5, 95% CI: 16.8-18.2 respectively). The risk of mortality was 1.9 (95% CI: 1.6-2.2) times higher for First Nations and 2.0 (95% CI: 1.8-2.2) times higher for other residents with concurrent OUD and AUD compared to those without an indication of AUD.

CONCLUSIONS

The protective effect of OAT remained despite the presence of a concurrent AUD among both First Nations and other residents with OUD. Findings have implications for clinical care management of concurrent disorders.

Incremental expenditures attributable to daily dispensation and witnessed ingestion for opioid agonist treatment in British Columbia: 2014-20

BACKGROUND AND AIM

While daily witnessed opioid agonist treatment (OAT) ingestion is common in British Columbia (BC), Canada, and elsewhere, sparse evidence supports this resource-intensive practice. Many settings across North America relaxed restrictions for take-home dosing during the COVID-19 pandemic and have reported consistent or improved patient outcomes. This study measured excess expenditures attributed to daily witnessed pharmacy dispensing compared with weekly or biweekly dispensation schedules.

DESIGN, SETTING AND PARTICIPANTS

This study was a population-level retrospective analysis. We included all methadone, buprenorphine/naloxone and slow-release oral morphine dispensations in BC from 1 January 2014 to 30 December 2020. A total of 24 357 107 OAT dispensations among 51 195 unique individuals with 122 793 person-years of follow-up were included during the study period.

MEASUREMENTS

Total expenditures for each person-week of OAT with an estimated expenditure under two scenarios are as follows: (1) a weekly dispensation scenario and (2) a biweekly dispensation scenario.

FINDINGS

We estimated excess expenditures attributable to current dispensing practices of between $38 million (2014) and $47.4 million (2018) compared with a hypothetical weekly dispensing schedule, and $43.9 million (2014) to $54.9 million (2018) compared with biweekly dispensing. The majority of these expenditures (58-64%) were attributed to pharmacy dispensing fees ($23 million in 2014 to $30 million in 2018 compared with weekly dispensing; $26.6 million in 2014 to $34.7 million in 2018 compared with biweekly dispensing).

CONCLUSION

Daily witnessed opioid agonist treatment ingestion results in more than $30 million in excess expenditures annually in the province of British Columbia, Canada compared with the costs of weekly or biweekly dispensation schedules.

Comparative effectiveness of urine drug screening strategies alongside opioid agonist treatment in British Columbia, Canada: a population-based observational study protocol

INTRODUCTION

Urine drug tests (UDTs) are commonly used for monitoring opioid agonist treatment (OAT) responses, supporting the clinical decision for take-home doses and monitoring potential diversion. However, there is limited evidence supporting the utility of mandatory UDTs-particularly the impact of UDT frequency on OAT retention. Real-world evidence can inform patient-centred approaches to OAT and improve current strategies to address the ongoing opioid public health emergency. Our objective is to determine the safety and comparative effectiveness of alternative UDT monitoring strategies as observed in clinical practice among OAT clients in British Columbia, Canada from 2010 to 2020.

METHODS AND ANALYSIS

We propose a population-level retrospective cohort study of all individuals 18 years of age or older who initiated OAT from 1 January 2010 to 17 March 2020. The study will draw on eight linked health administrative databases from British Columbia. Our primary outcomes include OAT discontinuation and all-cause mortality. To determine the effectiveness of the intervention, we will emulate a 'per-protocol' target trial using a clone censoring approach to compare fixed and dynamic UDT monitoring strategies. A range of sensitivity analyses will be executed to determine the robustness of our results.

ETHICS AND DISSEMINATION

The protocol, cohort creation and analysis plan have been classified and approved as a quality improvement initiative by Providence Health Care Research Ethics Board and the Simon Fraser University Office of Research Ethics. Results will be disseminated to local advocacy groups and decision-makers, national and international clinical guideline developers, presented at international conferences and published in peer-reviewed journals electronically and in print.

Validation and endorsement of health system performance measures for opioid use disorder in British Columbia, Canada: A Delphi panel study

Background

Limited data exists on the performance of the healthcare system in opioid use disorder (OUD). We evaluated the face validity and potential risks of a set of health system performance measures for OUD collaboratively with clinicians, policymakers and people with lived experience of opioid use (PWLE) in the interest of establishing an endorsed set of measures for public reporting.

Methods

Through a two-stage Delphi-panel approach, a panel of clinical and policy experts validated and considered 102 previously constructed OUD performance measures for endorsement using information on measurement construction, sensitivity analyses, quality of evidence, predictive validity, and feedback from local PWLE. We collected quantitative and qualitative survey responses from 49 clinicians and policymakers, and 11 PWLE. We conducted inductive and deductive thematic analysis to present qualitative responses.

Results

A total of 37 measures of 102 were strongly endorsed (9/13 cascade of care, 2/27 clinical guideline compliance, 17/44 healthcare integration, and 9/18 healthcare utilization measures). Thematic analysis of responses revealed several themes regarding measurement validity, unintended consequences, and key contextual considerations. Overall, measures related to the cascade of care (excluding opioid agonist treatment dose tapering) received strong endorsements. PWLE highlighted barriers to accessing treatment, undignified aspects of treatment, and lack of a full continuum of care as their concerns.

Conclusion

We defined 37 endorsed health system performance measures for OUD and presented a range of perspectives on their validity and use. These measures provide critical considerations for health system improvement in the care of people with OUD.

Opioid agonist treatment uptake within provincial correctional facilities in British Columbia, Canada

BACKGROUND AND AIMS

Multiple interventions and policy changes related to opioid agonist treatment (OAT) have been introduced in British Columbia, Canada to increase engagement and retention in OAT. We aimed to estimate the impact of policy changes and the announcement of the opioid overdose-related public health emergency on the use of OAT for incarcerated individuals with opioid use disorder.

DESIGN

Interrupted time-series analysis. Events of interest included the expansion of buprenorphine/naloxone into provincial health-care insurance coverage in October 2015 and the public health emergency declared in April 2016.

SETTING AND PARTICIPANTS

Our study included 9220 incarcerated individuals from 12 provincial corrections facilities in British Columbia, Canada for a total of 75 649 calendar months of incarceration.

MEASUREMENTS

Monthly measures of OAT use during incarceration from 1 January 2013 to 30 September 2017. We estimated changes in OAT use, controlling for individual and facility-level factors, using a general estimating equation, specified with a logit link and an autoregressive correlation matrix.

FINDINGS

After the provincial health insurance coverage expansion, a sharp increase in OAT use during incarceration was observed [adjusted odds ratio (aOR) = 1.16, 95% confidence interval (CI) = 1.13, 1.19]. The public health emergency coincided with an immediate but temporary increase in OAT receipt (aOR = 1.34, 95% CI = 1.22, 1.47). During the entire study period, we estimated a 10-fold increase in the adjusted odds of OAT use during incarceration (aOR = 10.10, 95% CI = 8.98, 11.37).

CONCLUSION

Following an expansion of health-care insurance coverage to include buprenorphine/naloxone, receipt of opioid agonist treatment (OAT) within correctional facilities in British Columbia, Canada increased, largely driven by an increase in buprenorphine/naloxone prescriptions among individuals without recent OAT experience.

Development and validation of health system performance measures for opioid use disorder in British Columbia, Canada

BACKGROUND

Performance measurement provides an evidence-based means to inform development of interventions to improve the quality of care for people who use opioids. We aimed to develop and assess the predictive validity of health system performance measures for opioid use disorder (OUD) in British Columbia (BC), Canada.

METHODS

Performance measures were generated using retrospective population-level administrative datasets (both provincial and regional) and publicly-reported retrospective data according to four domains (care engagement, clinical guideline compliance, integration, and healthcare utilization). The adjusted odds ratio was estimated via generalized linear mixed models to determine predictive validity for all-cause hospitalization or mortality within 6 months of measurement.

FINDINGS

A total of 102 performance measures were constructed. We identified 55,470 diagnosed PWOUD, and 39,456 ever engaged in opioid agonist treatment (OAT). We found divergent rates of treatment for concurrent conditions (7.4% for alcohol use disorder to 80.1% for HIV/AIDS), low levels of linkage to OAT and other outpatient care following acute care, and increasing levels of service provision, including increases in OAT prescribers and pharmacies, naloxone kit distribution and overdose prevention site visitation. Our analyses on the predictive validity measures largely supported a priori hypotheses on the direction of effect on the outcome.

CONCLUSIONS

We identified a range of priorities to improve the quality of care for PWOUD, with critical gaps in linkage to care through acute care settings and long-term engagement in OAT. The proposed measures can be derived for geographic and clinical subgroups and updated over time, providing a basis to monitor and evaluate efforts to address the public health burden of OUD.

Human Immunodeficiency Virus transmission by HIV Risk Group and Along the HIV Care Continuum: A Contrast of 6 US Cities

BACKGROUND

Understanding the sources of HIV transmission provides a basis for prioritizing HIV prevention resources in specific geographic regions and populations. This study estimated the number, proportion, and rate of HIV transmissions attributable to individuals along the HIV care continuum within different HIV transmission risk groups in 6 US cities.

METHODS

We used a dynamic, compartmental HIV transmission model that draws on racial behavior-specific or ethnic behavior-specific and risk behavior-specific linkage to HIV care and use of HIV prevention services from local, state, and national surveillance sources. We estimated the rate and number of HIV transmissions attributable to individuals in the stage of acute undiagnosed HIV, nonacute undiagnosed HIV, HIV diagnosed but antiretroviral therapy (ART) naïve, off ART, and on ART, stratified by HIV transmission group for the 2019 calendar year.

RESULTS

Individuals with undiagnosed nonacute HIV infection accounted for the highest proportion of total transmissions in every city, ranging from 36.8% (26.7%-44.9%) in New York City to 64.9% (47.0%-71.6%) in Baltimore. Individuals who had discontinued ART contributed to the second highest percentage of total infections in 4 of 6 cities. Individuals with acute HIV had the highest transmission rate per 100 person-years, ranging from 76.4 (58.9-135.9) in Miami to 160.2 (85.7-302.8) in Baltimore.

CONCLUSION

These findings underline the importance of both early diagnosis and improved ART retention for ending the HIV epidemic in the United States. Differences in the sources of transmission across cities indicate that localized priority setting to effectively address diverse microepidemics at different stages of epidemic control is necessary.

Assessing the determinants of completing OAT induction and long-term retention: A population-based study in British Columbia, Canada

BACKGROUND

Pharmacological treatments for opioid use disorder are essential, life-saving medications, yet successful induction of them and long-term retention on them is limited in many settings. Induction into opioid agonist treatment (OAT) features the highest risk of mortality throughout the treatment course, and greatest risk of discontinuation. We aimed to identify determinants of completing OAT induction and, among those completing induction, time to OAT discontinuation in British Columbia (BC), Canada.

METHODS

We conducted a retrospective study using linked population-level health administrative databases to capture all individuals in BC receiving at least one OAT dispensation from January 1, 2008, to September 30, 2018. We constructed covariates capturing client demographics, clinical history, and characteristics of the treatment episode and the primary prescribing physician. We estimated a two-part model to identify determinants of the probability of completing induction using a generalized linear mixed model with logit link and the time to OAT discontinuation among those completing induction using a Cox proportional hazards frailty model.

RESULTS

We observed 220,474 OAT episodes (73.9% initiated with methadone, 24.7% with buprenorphine, and 1.4% with slow-release oral morphine) among 45,608 individuals over the study period. Less than 60% of all OAT episodes completed induction (59.0% for methadone episodes, 56.7% for buprenorphine/naloxone, 41.0% for slow-release oral morphine) and half of all episodes that completed induction reached the minimum effective dosage (51.0% for methadone episodes [60 mg/day], 48.2% for buprenorphine/naloxone [12 mg/day], 59.4% for slow-release oral morphine [240 mg/day]). In multiple regression analysis, the adjusted odds of completing induction with buprenorphine improved over time, exceeding that of methadone in 2018: 1.46 (1.40, 1.51). For those who completed induction, buprenorphine use was associated with shorter times to discontinuation throughout the study period, but the estimated rate of discontinuation decreased over time (adjusted hazard ratio, vs. methadone in 2008: 2.50 (2.35, 2.66); in 2018: 1.79 (1.74, 1.85)).

CONCLUSION

We found low rates of completing OAT induction and, for those who did complete it, low rates of reaching the minimum effective dose.

Opioid analgesic prescribing for opioid-naïve individuals prior to identification of opioid use disorder in British Columbia, Canada

BACKGROUND AND AIMS

Prescription opioid analgesics have contributed to the development of opioid use disorder (OUD) in many individuals. We aimed to characterize non-cancer opioid prescribing for opioid-naive individuals prior to OUD identification.

DESIGN

Population-based retrospective cohort study using six linked health administrative databases.

SETTING

British Columbia (BC), Canada.

PARTICIPANTS

People with OUD between 1 January 2001 and 30 September 2018 who initiated opioid analgesic therapy for non-cancer pain prior to OUD identification.

MEASUREMENTS

Dose (morphine milligram equivalent per day), days prescribed and clinical guideline non-concordance for initial opioid prescriptions (dose ≥ 90 morphine milligram equivalent per day; ≥ 7 days prescribed; concomitant sedative prescription). We estimated the probability of non-concordant initial prescriptions by source (inpatient post-discharge, non-inpatient acute, non-acute) using logistic regression, adjusting for individual characteristics and comorbidities.

FINDINGS

Among 66 372 individuals identified with OUD from 2001 to 2018, 21 331 (32.1%) received opioid analgesics prior to OUD identification. This proportion increased from 3.0% in 2001 to 41.0% in 2011, before decreasing to 34.2% in 2017. Roughly half of opioid prescriptions were attributed to non-acute care visits, peaking at 56.8% in 2007, while the proportion from inpatient visits increased from 19.7% in 2001 to 28.5% in 2017. The predicted probability of receiving non-guideline concordant prescriptions declined over time-periods across all three measures for inpatient and non-inpatient acute care, while remaining stable for non-acute care. In particular, the predicted probability of receiving ≥ 7-day prescriptions following inpatient visits decreased from 53.3% [95% confidence interval (CI) = 50.9, 55.8%] in 2001-06 to 37.2% (95% CI = 33.9, 40.5%) in 2013-18.

CONCLUSIONS

Among the 66 372 individuals in British Columbia, Canada diagnosed with opioid use disorder between 2001 and 2018, more than 32% were earlier prescribed non-cancer opioid analgesics. The proportion who had received an opioid analgesic prescription prior to OUD identification peaked at more than 40% in 2011, before stabilizing between 2011 and 2016 and declining thereafter. Guideline concordance improved over time for high-dose and concomitant sedative prescribing.

The effect of British Columbia's Pharmacare coverage expansion for opioid agonist treatment

Opioid agonist treatment (OAT) is the evidence-based standard of care for people with opioid use disorder. In British Columbia, Canada, only social assistance registrants received full coverage for OAT prior to the introduction of the Pharmacare Plan G coverage expansion on February 1st, 2017. We aimed to determine the effect of the coverage expansion on OAT initiation, re-initiation, and retention. Using linked population-level data, we executed a difference-in-differences analysis to compare outcomes of individuals eligible for the additional coverage and social assistance registrants already receiving the most generous coverage for OAT prior to the policy change, adjusting for individual and prescriber characteristics. We found Plan G coverage expansion significantly increased OAT retention. Specifically, coverage expansion decreased the number of OAT episode discontinuations by 12.8% (95% CI: 8.4%, 17.2%).

Opioid Agonist Treatment and Risk of Mortality During an Opioid Overdose Public Health Emergency: A Population-Based Retrospective Cohort Study

IntroductionOpioid agonist treatment (OAT) is a safe and effective treatment for opioid use disorder (OUD). However, people commonly stop and start OAT and their risk of death is high immediately after stopping. The prevalence of illicitly manufactured fentanyl and other highly potent synthetic opioids have increased in the illicit drug supply globally. Yet, there is limited evidence examining the relationship between OAT and mortality when these contaminants are widely available in the illicit drug supply. Objectives and ApproachWe aimed to compare the risk of mortality on and off OAT in a setting with a high prevalence of illicitly manufactured fentanyl and other potent synthetic opioids in the illicit drug supply. We linked five health administrative datasets in British Columbia, Canada, creating a cohort of 55,347 people with OUD who received OAT during a 23-year period (1996 to 2018). We compared the risk of mortality on and off treatment over time, and according to time since starting or stopping treatment and by medication type. Results7,030 of 55,347 (12.7%) OAT recipients died during follow-up. All-cause SMR was substantially lower on OAT (4.6 [4.4 to 4.8]) compared to off OAT (9.7 [9.5 to 10.0]). In a period of increasing prevalence of fentanyl, the relative risk of mortality off OAT was 2.1 [1.8 to 2.4] times higher than on OAT prior to the introduction of fentanyl, and increased to 3.4 [2.8 to 4.3] at the end of the study period (65% increase in relative risk). Conclusion / ImplicationsThe protective effect of OAT on mortality increased as fentanyl and other synthetic opioids became common in the illicit drug supply, while the risk of mortality remained high off OAT. As fentanyl becomes more widespread globally, these findings highlight the importance of interventions that improve retention on opioid agonist treatment and prevent recipients from stopping treatment.

Why Maximizing Quality-Adjusted Life Years, rather than Reducing HIV Incidence, Must Remain Our Objective in Addressing the HIV/AIDS Epidemic

With efficacious behavioral, biomedical, and structural interventions available, combination implementation strategies are being implemented to combat HIV/AIDS across settings internationally. However, priority statements from national and international bodies make it unclear whether the objective should be the reduction in HIV incidence or the maximization of health, most commonly measured with quality-adjusted life years (QALYs). Building off a model-based evaluation of HIV care interventions in British Columbia, Canada, we compare the optimal sets of interventions that would be identified using HIV infections averted, and QALYs as the primary outcome in a cost-effectiveness analysis. We found an explicit focus on averting new infections undervalues the health benefits derived from antiretroviral therapy, resulting in suboptimal and potentially harmful funding recommendations.

Opioid agonist treatment and risk of mortality during opioid overdose public health emergency: population based retrospective cohort study

OBJECTIVE

To compare the risk of mortality among people with opioid use disorder on and off opioid agonist treatment (OAT) in a setting with a high prevalence of illicitly manufactured fentanyl and other potent synthetic opioids in the illicit drug supply.

DESIGN

Population based retrospective cohort study.

SETTING

Individual level linkage of five health administrative datasets capturing drug dispensations, hospital admissions, physician billing records, ambulatory care reports, and deaths in British Columbia, Canada.

PARTICIPANTS

55 347 people with opioid use disorder who received OAT between 1 January 1996 and 30 September 2018.

MAIN OUTCOME MEASURES

All cause and cause specific crude mortality rates (per 1000 person years) to determine absolute risk of mortality and all cause age and sex standardised mortality ratios to determine relative risk of mortality compared with the general population. Mortality risk was calculated according to treatment status (on OAT, off OAT), time since starting and stopping treatment (1, 2, 3-4, 5-12, >12 weeks), and medication type (methadone, buprenorphine/naloxone). Adjusted risk ratios compared the relative risk of mortality on and off OAT over time as fentanyl became more prevalent in the illicit drug supply.

RESULTS

7030 (12.7%) of 55 347 OAT recipients died during follow-up. The all cause standardised mortality ratio was substantially lower on OAT (4.6, 95% confidence interval 4.4 to 4.8) than off OAT (9.7, 9.5 to 10.0). In a period of increasing prevalence of fentanyl, the relative risk of mortality off OAT was 2.1 (95% confidence interval 1.8 to 2.4) times higher than on OAT before the introduction of fentanyl, increasing to 3.4 (2.8 to 4.3) at the end of the study period (65% increase in relative risk).

CONCLUSIONS

Retention on OAT is associated with substantial reductions in the risk of mortality for people with opioid use disorder. The protective effect of OAT on mortality increased as fentanyl and other synthetic opioids became common in the illicit drug supply, whereas the risk of mortality remained high off OAT. As fentanyl becomes more widespread globally, these findings highlight the importance of interventions that improve retention on opioid agonist treatment and prevent recipients from stopping treatment.

Determinants of selection into buprenorphine/naloxone among people initiating opioid agonist treatment in British Columbia

BACKGROUND

Studies assessing the comparative effectiveness of methadone versus buprenorphine/naloxone for opioid use disorder in real-world settings are rare - challenged by structural differences in delivery across settings and factors influencing treatment selection. We identified determinants of selection into buprenorphine/naloxone and quantified contributions of individual and provider-level covariates in a setting delivering both medications within the same healthcare settings.

METHODS

Utilizing linked health administrative datasets, we conducted a retrospective cohort study of people with opioid use disorder (PWOUD) receiving opioid agonist treatment (OAT) in British Columbia, Canada, from 2008-2017. Determinants of buprenorphine/naloxone selection were identified using a generalized linear mixed model with random intercept terms for providers and individuals. We determined the influence of individual demographics, clinical history, measures of provider experience and preference, and dates of key policy changes.

RESULTS

A total of 39,605 individuals experienced 178,976 OAT episodes (methadone:139,439(77.9 %);buprenorphine/naloxone:39,537(22.1 %)). Male sex, less OAT experience, younger age, mental health conditions and chronic pain were associated with higher odds of buprenorphine/naloxone prescription. For providers, higher client-attachment, more complex OAT case-mixes, and higher buprenorphine/naloxone prescribing-preference were also associated with higher odds of buprenorphine/naloxone prescription. Observed individual-level covariates explained 9.7 % of variance in odds of buprenorphine/naloxone selection, while observed provider-level covariates explained 20.0 %. Controlling for covariates, residual unmeasured between-individual variance accounted for 18.5 % of the explained variation in the odds of buprenorphine/naloxone selection, while unmeasured between-provider variance accounted for 28.4 %.

CONCLUSION

Provider characteristics were more influential in selection of buprenorphine/naloxone over methadone informing subsequent analyses of comparative effectiveness of these regimens.

Ending the Epidemic in America Will Not Happen if the Status Quo Continues: Modeled Projections for Human Immunodeficiency Virus Incidence in 6 US Cities

We estimated 10-year (2020-2030) trajectories for human immunodeficiency virus incidence in 6 US cities. Estimated incidence will only decrease in 2 of 6 cities, with the overall population-weighted incidence decreasing 3.1% (95% credible interval [CrI], -1.0% to 8.5%) by 2025, and 4.3% (95% CrI, -2.6% to 12.7%) by 2030 across cities. Targeted, context-specific combination implementation strategies will be necessary to meet the newly established national targets.

Geographic variation in the costs of medical care for people living with HIV in British Columbia, Canada

Background

Regional variation in medical care costs can indicate heterogeneity in clinical practice, inequities in access, or inefficiencies in service delivery. We aimed to estimate regional variation in medical costs for people living with HIV (PLHIV), adjusting for demographics and case-mix.

Methods

We conducted a retrospective cohort study using linked health administrative databases of PLHIV, from 2010 to 2014, in British Columbia (BC), Canada. Quarterly health care costs (2018 CAD) were derived from inpatient, outpatient, prescription drugs, antiretroviral therapy (ART), and HIV diagnostics. We used a two-part model with a logit link for the probability of incurring costs, and a log link and gamma distribution for observations with positive costs. We also estimated quarterly utilization rates for hospitalization-, physician billing- and prescription drug-days. Primary variables were indicators of individuals’ Health Service Delivery Area (HSDA). We adjusted cost and utilization estimates for demographic characteristics, HIV-disease progression, and comorbidities.

Results

Our cohort included 9577 PLHIV (median age 45.5 years, 80% male). Adjusted total quarterly costs for all 16 HSDAs were within 20% of the provincial mean, 8/16 for hospitalization costs, 16/16 for physician billing costs and 10/16 for prescription drug costs. Northern Interior and Northeast HSDAs had 38 and 44% lower quarterly non-ART prescription drug costs, and 2 and 5% higher quarterly inpatient costs, respectively.

Conclusions

We observed limited variation in medical care costs and utilization among PLHIV in BC. However, lower levels of outpatient care and higher levels of inpatient care indicate possible barriers to accessing care among PLHIV in the most rural regions of the province.

Electronic supplementary material

The online version of this article (10.1186/s12913-019-4391-8) contains supplementary material, which is available to authorized users.

Characterizing Human Immunodeficiency Virus Antiretroviral Therapy Interruption and Resulting Disease Progression Using Population-Level Data in British Columbia, 1996-2015

Background

Suboptimal retention is among the biggest challenges to realize the full benefits of combination antiretroviral therapy (ART). We aimed to describe ART interruption patterns and identify determinants of disease progression while off ART in British Columbia, Canada.

Methods

With population-level data on ART utilization and laboratory testing in British Columbia (1996-2015), we described the timing, frequency, and duration of ART interruptions (a gap of ≥90 days in ART dispensation records). A 4-state continuous-time Markov model was implemented to identify determinants of disease progression during individuals' first ART interruption episode. Disease progression was measured according to CD4-based state transitions (cells/μL: ≥500 to 200-499; 200-499 to <200; ≥500 to death; 200-499 to death; and <200 to death).

Results

Among individuals initiating ART, 3129 (38.6%) interrupted ART over a median 8-year follow-up (interquartile range [IQR], 4.3-13.5 years). Those interrupting ART had a median of 1 interruption (IQR, 1.0-3.0), with the first interruption occurring 12.8 (IQR, 4.0-36.1) months after ART initiation, lasting for 7.5 (IQR, 4.1-20.3) months. The proportion of individuals interrupting ART within the first year of ART initiation decreased over time; however, the absolute number of individuals interrupting ART remained high. In a multivariable analysis, age, historical plasma viral load, and ART regimen changes prior to interruption were associated with increased hazard of CD4 decline and death.

Conclusions

Our results demonstrate that ART interruptions are common even in a high-resource setting with universal free access to human immunodeficiency virus care. Further efforts are needed to promote ART reengagement and may consider prioritizing individuals with poorer prognostic factors.

Polydrug use and its association with drug treatment outcomes among primary heroin, methamphetamine, and cocaine users

BACKGROUND

Polydrug use may challenge effective treatment for substance use disorders. We evaluate whether secondary substance use modifies the association between treatment and primary drug use among primary heroin, cocaine and methamphetamine (MA) users.

METHODS

Data were obtained from prospective cohort studies on people who use illicit drugs (PWUD) in California, USA. Using repeated monthly data on self-reported secondary substance use (heroin, cocaine, MA, alcohol or marijuana; ≥1day in a month), primary drug use (≥1day in a month), and treatment participation, collected via timeline follow-back, we fitted generalized linear mixed multiple regression models controlling for potential confounders to examine the interactions between treatment and secondary substance use on the odds of primary heroin, cocaine and MA use, respectively.

RESULTS

Included in our study were 587 primary heroin, 444 primary MA, and 501 primary cocaine users, with a median of 32.4, 13.3 and 18.9 years of follow-up, respectively. In the absence of secondary substance use, treatment was strongly associated with decreased odds of primary drug use (adjusted odds ratios (aORs): 0.25, 95% CI: 0.24, 0.27, 0.07 (0.06, 0.08), and 0.07 (0.07, 0.09)) for primary heroin, MA, and cocaine users, respectively. Secondary substance use of any kind moderated these associations (0.82 (0.78, 0.87), 0.25 (0.21, 0.30) and 0.53 (0.45, 0.61), respectively), and these findings were consistent for each type of secondary substance considered. Moreover, we observed different associations in terms of direction and magnitude between secondary substance use and primary drug use during off-treatment periods across substance types.

CONCLUSION

This study demonstrates secondary substance use moderates the temporal associations between treatment and primary drug use among primary heroin, MA and cocaine users. Disparate patterns of polydrug use require careful measurement and analysis to inform targeted treatment for polydrug users.

Initiating HCV treatment with direct acting agents in opioid agonist treatment: When to start for people co-infected with HIV?

BACKGROUND

Direct acting antivirals (DAA) raise the possibility of eliminating Hepatitis C virus (HCV) among people who inject drugs (PWID). However, concerns regarding treatment retention and reinfection challenge implementation efforts. Opioid agonist treatment (OAT) provides an opportunity to engage HCV-positive PWID into DAA-based treatment. Our objective was to identify when OAT adherence sufficiently improved to inform DAA initiation in OAT settings, assuming continuous OAT retention for at least twelve weeks is necessary to complete the DAA treatment course.

METHODS

This was a retrospective cohort study of HCV/HIV co-infected PWID from a population-level linked administrative database of people diagnosed and living with HIV in British Columbia, Canada between 01/1996 and 12/2013. We used monthly follow-up data after initial OAT entry and considered the effects of demographics, disease severity, and HIV and OAT treatment characteristics over time on the probability of subsequent OAT retention of ≥12 weeks, and ≥8 weeks for sensitivity analysis. We fit a generalized linear mixed model to the overall study population, and on stratified samples of those continuously engaged on combination antiretroviral therapy (≥95% ART adherence). A set of monthly indicator variables (months 1, …, 7, >7) were included to fulfil the study objective.

RESULTS

Our study included 1427 HCV/HIV co-infected PWID (39.0% female, 68.8% OAT-naïve). The odds of subsequent twelve-week retention in OAT were statistically significantly greater in month 3 versus month 1 (adjusted odds ratio: 1.18; 95% confidence interval: 1.02, 1.37); and the odds of subsequent 8-week retention in OAT were statistically significantly greater in month 2 versus month 1 (1.15, 95% CI: 1.02, 1.31). Among continuously ART-adherent individuals, the odds of subsequent twelve-week retention were not statistically significantly greater than in month 1 (month 2: 1.12 (0.82, 1.51); month 3: 1.08 (0.79, 1.47); month 4: 1.24 (0.91, 1.71)).

CONCLUSION

We provide evidence that among HCV/HIV co-infected PWID, those retained in OAT for three or more months had higher odds of completing an additional twelve weeks of OAT, compared to no difference in those already receiving ART. These data may have implications for adherence to DAA therapy and further studies are needed to understand the optimal timing of DAA therapy in PWID receiving and not receiving OAT.

The effect of engagement in an HIV/AIDS integrated health programme on plasma HIV-1 RNA suppression among HIV-positive people who use illicit drugs: a marginal structural modelling analysis

OBJECTIVES

HIV treatment-as-prevention campaigns emphasize early diagnosis and immediate access to care and antiretroviral therapy for HIV-positive individuals in order to increase levels of plasma HIV RNA viral load (VL) suppression. However, the possible role of harm reduction-based programmes in this objective has not yet been well evaluated. The objective of the study was to examine the relationship between being a client of the Dr. Peter Centre (DPC; an HIV/AIDS-focused adult integrated health programme) and VL suppression among highly active antiretroviral therapy (HAART)-exposed HIV-positive people who use illicit drugs (PWUD) in Vancouver, Canada.

METHODS

Data were derived from the AIDS Care Cohort to Evaluate Exposure to Survival Services (ACCESS) study, a study of a community-recruited cohort of HIV-positive PWUD. A marginal structural model using inverse probability of treatment weights was used to estimate the longitudinal relationship between being a DPC client and exhibiting a VL < 50 HIV-1 RNA copies/mL plasma.

RESULTS

Between 2005 and 2014, 746 HAART-exposed participants were included in the study, of whom 269 (36.1%) reported being a DPC client at some time during the study period. A marginal structural model estimated a 1.54 greater odds of achieving VL suppression (95% confidence interval 1.20-1.99) among DPC clients.

CONCLUSIONS

Our findings demonstrate that participating in an innovative HIV/AIDS-focused adult integrated health programme that provides a broad range of clinical, harm reduction, and support services may contribute to optimizing the benefits of HAART in terms of morbidity, mortality and viral transmission among PWUD, and as a result help to fulfill the goals of the treatment-as-prevention strategy.

Cost-Effectiveness of the 'One4All' HIV Linkage Intervention in Guangxi Zhuang Autonomous Region, China

BACKGROUND

In Guangxi Zhuang Autonomous Region, China, an estimated 80% of newly-identified antiretroviral therapy (ART)-eligible patients are not engaged in ART. Delayed ART uptake ultimately translates into high rates of HIV morbidity, mortality, and transmission. To enhance HIV testing receipt and subsequent treatment uptake in Guangxi, the Chinese Center for Disease Control and Prevention (CDC) executed a cluster-randomized trial to assess the effectiveness and cost-effectiveness of a streamlined HIV testing algorithm (the One4All intervention) in 12 county-level hospitals.

OBJECTIVE

To determine the incremental cost-effectiveness of the One4All intervention delivered at county hospitals in Guangxi, China, compared to the current standard of care (SOC).

PERSPECTIVE

Health System.

TIME HORIZON

1-, 5-and 25-years.

METHODS

We adapted a dynamic, compartmental HIV transmission model to simulate HIV transmission and progression in Guangxi, China and identify the economic impact and health benefits of implementing the One4All intervention in all Guangxi hospitals. The One4All intervention algorithm entails rapid point-of-care HIV screening, CD4 and viral load testing of individuals presenting for HIV screening, with same-day results and linkage to counselling. We populated the model with data from the One4All trial (CTN-0056), China CDC HIV registry and published reports. Model outcomes were HIV incidence, mortality, costs, quality-adjusted life years (QALYs), and the incremental cost-effectiveness ratio (ICER) of the One4All intervention compared to SOC.

RESULTS

The One4All testing intervention was more costly than SOC (CNY 2,182 vs. CNY 846), but facilitated earlier ART access, resulting in delayed disease progression and mortality. Over a 25-year time horizon, we estimated that introducing One4All in Guangxi would result in 802 averted HIV cases and 1629 averted deaths at an ICER of CNY 11,678 per QALY gained. Sensitivity analysis revealed that One4All remained cost-effective at even minimal levels of effectiveness. Results were robust to changes to a range of parameters characterizing the HIV epidemic over time.

CONCLUSIONS

The One4All HIV testing strategy was highly cost-effective by WHO standards, and should be prioritized for widespread implementation in Guangxi, China. Integrating the intervention within a broader combination prevention strategy would enhance the public health response to HIV/AIDS in Guangxi.

Inability to access health and social services associated with mental health among people who inject drugs in a Canadian setting

BACKGROUND

People who inject drugs (PWID) face barriers to healthcare due to reasons including comorbidity. We evaluated access to health and social services by three of the most prevalent comorbid conditions among PWID: HIV, hepatitis C (HCV), and mental health, in an urban setting in Canada.

METHODS

Data were derived from prospective cohorts of community-recruited PWID between 2005 and 2015. HIV and HCV serostatuses were based on antibody tests, while mental health conditions and inability to access health and social services (barriers to access) were determined by participants' self-report. We employed generalized linear mixed models controlling for confounders to examine associations between health conditions and barriers to access.

RESULTS

Among 2494 participants, 1632 (65.4%) reported barriers to access at least once over a median of seven (IQR: 3, 12) semi-annual assessments. Mental health conditions were independently associated with increased odds of reporting barriers (adjusted Odds Ratio (aOR): 1.45, 95% Confidence Interval (CI): 1.32, 1.58), while HIV was not (aOR: 0.96, 95% CI: 0.85, 1.08), and HCV was associated with decreased odds (aOR: 0.80, 95% CI: 0.69, 0.93). The associations between mental health conditions and barriers to access were consistent among PWID without HIV/HCV (aOR: 1.35, 95% CI: 1.10, 1.65), with HCV mono-infection (aOR: 1.55, 95% CI: 1.37, 1.75), and HCV/HIV co-infection (aOR: 1.36, 95% CI: 1.15, 1.60).

CONCLUSIONS

Targeted strategies to seek and treat mental health conditions in settings that serve PWID, and assist PWID with mental health conditions in navigating healthcare system may improve the publicly-funded health and social services.

The 'Expanded HIV care in opioid substitution treatment' (EHOST) cluster-randomized, stepped-wedge trial: A study protocol

The public health response to HIV/AIDS has turned its focus onto optimizing health care system delivery to maximize case identification, access and sustained engagement in antiretroviral treatment (ART). Opioid Agonist Treatment (OAT) provides a critical opportunity for HIV testing and linkage to ART. The EHOST study is a cluster-randomized, stepped-wedge trial to evaluate a prescriber-focused intervention to increase HIV testing rates, and optimize ART engagement and retention outcomes among individuals engaged in OAT. The study will encompass all drug treatment clinics currently admitting patients for the treatment of opioid use disorder across the province of British Columbia, encompassing an estimated 90% of the OAT caseload. The trial will be executed over a 24-month period, with groups of clinics receiving the intervention in 6-month intervals. Evaluation of the proposed intervention's effectiveness will focus on three primary outcomes: (i) the HIV testing rate among those not known to be HIV positive; (ii) the rate of ART initiation among those not on ART; and (iii) the rate of ART continuation among those on ART. A difference-in-differences analytical framework will be applied to estimate the intervention's effect. This approach will assess site-specific changes in primary outcomes across clusters while adjusting for potential residual heterogeneity in patient case mix, volume, and quality of care across clinics. Statistical analysis of outcomes will be conducted entirely with linked population-level administrative health datasets. Facilitated by established collaborations between key stakeholders across the province, the EHOST intervention promises to optimize HIV testing and care within a marginalized and hard-to-reach population.

Lack of Effectiveness of Antiretroviral Therapy in Preventing HIV Infection in Serodiscordant Couples in Uganda: An Observational Study

Background

We examined the real-world effectiveness of ART as an HIV prevention tool among HIV serodiscordant couples in a programmatic setting in a low-income country.

Methods

We enrolled individuals from HIV serodiscordant couples aged ≥18 years of age in Jinja, Uganda from June 2009 – June 2011. In one group of couples the HIV positive partner was receiving ART as they met clinical eligibility criteria (a CD4 cell count ≤250 cells/ μL or WHO Stage III/IV disease). In the second group the infected partner was not yet ART-eligible. We measured HIV incidence by testing the uninfected partner every three months. We conducted genetic linkage studies to determine the source of new infections in seroconverting participants.

Results

A total of 586 couples were enrolled of which 249 (42%) of the HIV positive participants were receiving ART at enrollment, and an additional 99 (17%) initiated ART during the study. The median duration of follow-up was 1.5 years. We found 9 new infections among partners of participants who had been receiving ART for at least three months and 8 new infections in partners of participants who had not received ART or received it for less than three months, for incidence rates of 2.09 per 100 person-years (PYRs) and 2.30 per 100 PYRs, respectively. The incidence rate ratio for ART-use was 0.91 (95% confidence interval 0.31-2.70; p=0.999). The hazard ratio for HIV seroconversion associated with ART-use by the positive partner was 1.07 (95% CI 0.41-2.80). A total of 5/7 (71%) of the transmissions on ART and 6/7 (86%) of those not on ART were genetically linked.

Conclusion

Overall HIV incidence was low in comparison to previous studies of serodiscordant couples. However, ART-use was not associated with a reduced risk of HIV transmission in this study.

HIV drug resistance detected during low-level viraemia is associated with subsequent virologic failure

BACKGROUND

The clinical implications of emergent HIV drug resistance on samples with low-level viraemia (LLV <1000 copies/ml) remain unclear. We undertook the present analysis to evaluate the impact of emergent HIV drug resistance at LLV on the risk of subsequent virologic failure.

METHODS

One thousand, nine hundred and sixty-five patients had genotype results at LLV. Risk of virologic failure (≥1000 copies/ml) after LLV was evaluated by Kaplan-Meier analysis and Cox proportional hazards regression. Resistance was assessed using the Stanford algorithm or virtual phenotypes. Patients were grouped into four susceptibility categories ('GSS' or 'vPSS') during LLV, corresponding to the number of 'active' drugs prescribed: <1; 1-1.5; 2-2.5; and ≥3.

RESULTS

A total of 1702 patients with follow-up on constant therapy were eligible for analysis. Participants excluded due to changing therapy or loss to follow-up before their next observation had mostly similar characteristics to included participants. There was a 'dose-dependent' increase in the hazard ratio for virologic failure with susceptibility categories at LLV. Compared with a GSS of at least 3, hazard ratios for virologic failure were 1.4 for GSS 2-2.5; 2.0 for GSS 1-1.5; and 3.0 for GSS less than 1 (P < 0.001). Numerous sensitivity analyses confirmed these findings.

CONCLUSION

Our results demonstrate that emergent HIV drug resistance at LLV is strongly associated with subsequent virologic failure. Furthermore, we uncovered a 'dose-dependent' increase in the hazard ratio for virologic failure with decreasing GSS estimated at the time of LLV. On the basis of these findings, we propose that resistance genotyping be encouraged for HIV-infected individuals on antiretroviral therapy experiencing low-level viraemia.

Decisions, decisions: the importance of condom use decision making among HIV sero-discordant couples in a prospective cohort study in Uganda

OBJECTIVES

We examined sexual decision making type among couples in HIV sero-discordant partnerships in Uganda, and investigated how sexual decision making type changed over time and its effect on condom use.

METHODS

Data were drawn from a longitudinal cohort of HIV sero-discordant couples, recruited through the AIDS Support Organisation in Jinja, Uganda. Sexual decision making was measured using the Sexual Relationship Power Scale, and couples' individual self-report answers were matched to assess agreement for decision making type and condom use. Generalised linear mixed effects modelling was used to assess statistically significant differences in time trend of sexual decision making type, and to investigate the independent association of decision making type on condom use status over time.

RESULTS

Of the 533 couples included in this analysis, 345 (65%) reported using condoms at last sex at study enrolment. In the time trend analysis of decision making, the proportion of couples who decided together increased over time while the proportions of couples who reported that one partner decided or no one decided/did not use condoms, decreased over time (overall p<0.001). Compared with couples who decided together, those who disagreed (adjusted OR=0.42, 95% CI 0.28 to 0.64) and those where one partner decided (adjusted OR=0.20, 95% CI 0.12 to 0.34) had significantly lower odds of condom use at last sex, even after controlling for confounders.

CONCLUSIONS

Couples who disagreed on decision making, or agreed that one partner decides alone, had significantly lower odds of reporting condom use compared with couples who decided together. HIV counselling interventions that encourage joint sexual decision making may improve condom use within this population.

Gender inequities in quality of care among HIV-positive individuals initiating antiretroviral treatment in British Columbia, Canada (2000-2010)

Objectives

We measured gender differences in “Quality of Care” (QOC) during the first year after initiation of antiretroviral therapy and investigated factors associated with poorer QOC among women.

Design

QOC was estimated using the Programmatic Compliance Score (PCS), a validated metric associated with all-cause mortality, among all patients (≥19 years) who initiated ART in British Columbia, Canada (2000–2010).

Methods

PCS includes six indicators of non-compliance with treatment initiation guidelines at baseline (not having drug resistance testing before treatment; starting on a non-recommended regimen; starting therapy at CD4<200 cells/mm³) and during first-year follow-up (receiving <3 CD4 tests; receiving <3 viral load tests; not achieving viral suppression within six months). Summary scores range from 0–6; higher scores indicate poorer QOC. Multivariable ordinal logistic regression was used to measure if female gender was an independent predictor of poorer QOC and factors associated with poorer QOC among women.

Results

QOC was determined for 3,642 patients (20% women). At baseline: 42% of women (34% men) did not have resistance testing before treatment; 17% of women (9% men) started on a non-recommended regimen (all p<0.001). At follow-up: 17% of women (11% men) received <3 CD4; 17% of women (11% men) received <3 VL; 50% of women (41% men) did not achieve viral suppression (all p<0.001). Overall, QOC was better among men (mean PSC = 1.54 (SD = 1.30)) compared with women (mean = 1.89 (SD = 1.37); p<0.001). In the multivariable model, female gender (AOR = 1.16 [95% CI: 0.99–1.35]; p = 0.062) remained associated with poorer QOC after covariate adjustment. Among women, those with injection drug use history, of Aboriginal ancestry, from Vancouver Island, and who initiated ART in earlier years were more likely to have poorer QOC.

Conclusions

Poorer QOC among women, especially from marginalized communities, demands that barriers undermining women's access to high-quality care be addressed to improve treatment and health for women with HIV.

Performance of HIV-1 drug resistance testing at low-level viremia and its ability to predict future virologic outcomes and viral evolution in treatment-naive individuals

BACKGROUND

Low-level viremia (LLV; human immunodeficiency virus [HIV-1] RNA 50-999 copies/mL) occurs frequently in patients receiving antiretroviral therapy (ART), but there are few or no data available demonstrating that HIV-1 drug resistance testing at a plasma viral load (pVL) <1000 copies/mL provides potentially clinically useful information. Here, we assess the ability to perform resistance testing by genotyping at LLV and whether it is predictive of future virologic outcomes in patients beginning ART.

METHODS

Resistance testing by genotyping at LLV was attempted on 4915 plasma samples from 2492 patients. A subset of previously ART-naive patients was analyzed who achieved undetectable pVL and subsequently rebounded with LLV (n = 212). A genotypic sensitivity score (GSS) was calculated based on therapy and resistance testing results by genotyping, and stratified according to number of active drugs.

RESULTS

Eighty-eight percent of LLV resistance assays produced useable sequences, with higher success at higher pVL. Overall, 16 of 212 (8%) patients had pretherapy resistance. Thirty-eight of 196 (19%) patients without pretherapy resistance evolved resistance to 1 or more drug classes, primarily the nucleoside reverse transcriptase (14%) and/or nonnucleoside reverse transcriptase (9%) inhibitors. Patients with resistance at LLV (GSS <3) had a 2.1-fold higher risk of virologic failure (95% confidence interval, 1.2- to 3.7-fold) than those without resistance (P = .007). Progressively lower GSS scores at LLV were associated with a higher increase in pVL over time (P < .001). Acquisition of additional resistance mutations to a new class of antiretroviral drugs during LLV was not found in a subset of patients.

CONCLUSIONS

Routine HIV-1 genotyping of LLV samples can be performed with a reasonably high success rate, and the results appear predictive of future virologic outcomes.

Cost-effective prediction of gender-labeling errors and estimation of gender-labeling error rates in candidate-gene association studies

We describe a statistical approach to predict gender-labeling errors in candidate-gene association studies, when Y-chromosome markers have not been included in the genotyping set. The approach adds value to methods that consider only the heterozygosity of X-chromosome SNPs, by incorporating available information about the intensity of X-chromosome SNPs in candidate genes relative to autosomal SNPs from the same individual. To our knowledge, no published methods formalize a framework in which heterozygosity and relative intensity are simultaneously taken into account. Our method offers the advantage that, in the genotyping set, no additional space is required beyond that already assigned to X-chromosome SNPs in the candidate genes. We also show how the predictions can be used in a two-phase sampling design to estimate the gender-labeling error rates for an entire study, at a fraction of the cost of a conventional design.

Black shale as a sorbent for trichloroethylene and Cr(VI)

Black shale was examined as a natural sorbent for organic and inorganic contaminants. Trichloroethylene (TCE) could be removed well from the water by sorption onto the locally available black shale because of the high organic carbon content (5.2%) of the black shale in this study. Hexavalent chromium Cr(VI) was mainly removed by ionic sorption and reduction in batch and column experiments. Amphiphilic humic acid was also sorbed onto the black shale and could facilitate the sorption of TCE at the same time. Humic acid also enhanced the removal of Cr(VI) by reduction and sorption, but the amount of Cr(VI) adsorbed (mg kg(-1)) was smaller than that of TCE. Considering that the black shale in this study was used without any modifications and has a small surface area, black shale can be a cost-effective natural geosorbent and additive to remove organic contaminants and heavy metals.