Identifying injection drug use and estimating population size of people who inject drugs using healthcare administrative datasets

Evaluating differences in opioid and stimulant use-associated infectious disease hospitalizations in Florida, 2016-2017

Background

The opioid epidemic has led to increases in injection drug use (IDU)-associated infectious diseases; however, little is known about how more recent increases in stimulant use have affected the incidence and outcomes of hospitalizations for infections among people who inject drugs (PWID).

Methods

All hospitalizations of PWID for IDU-associated infections in Florida were identified using administrative diagnostic codes and were grouped by substance used (opioids, stimulants, or both) and site of infection. We evaluated the association between substance used and the outcomes: patient-directed discharge (PDD, or “against medical advice”) and in-hospital mortality.

Results

There were 22 856 hospitalizations for infections among PWID. Opioid use was present in 73%, any stimulants in 43%, and stimulants-only in 27%. Skin and soft tissue infection was present in 50%, sepsis/bacteremia in 52%, osteomyelitis in 10%, and endocarditis in 10%. PWID using opioids/stimulants were youngest, most uninsured, and had the highest rates of endocarditis (16%) and hepatitis C (44%). Additionally, 25% of patients with opioid/stimulant use had PDD versus 12% for those using opioids-only. In adjusted models, opioid/stimulant use was associated with PDD compared to opioid-only use (aRR 1.28, 95% CI 1.17–1.40). Younger age and endocarditis were also associated with PDD. Compared to opioid-only use, stimulant-only use had higher risk of in-hospital mortality (aRR 1.26, 95% CI 1.03–1.46).

Conclusions

While opioid use contributed to most IDU-associated infections, many hospitalizations also involved stimulants. Increasing access to harm reduction interventions could help prevent these infections, while further research on the acute management of stimulant use disorder-associated infections is needed.

National Public Health Burden Estimates of Endocarditis and Skin and Soft-Tissue Infections Related to Injection Drug Use: A Review

BACKGROUND

Despite concerns about the burden of the bacterial and fungal infection syndromes related to injection drug use (IDU), robust estimates of the public health burden of these conditions are lacking. The current article reviews and compares data sources and national burden estimates for infective endocarditis (IE) and skin and soft-tissue infections related to IDU in the United States.

METHODS

A literature review was conducted for estimates of skin and soft-tissue infection and endocarditis disease burden with related IDU or substance use disorder terms since 2011. A range of the burden is presented, based on different methods of obtaining national projections from available data sources or published data.

RESULTS

Estimates using available data suggest the number of hospital admissions for IE related to IDU ranged from 2900 admissions in 2013 to more than 20 000 in 2017. The only source of data available to estimate the annual number of hospitalizations and emergency department visits for skin and soft-tissue infections related to IDU yielded a crude estimate of 98 000 such visits. Including people who are not hospitalized, a crude calculation suggests that 155 000-540 000 skin infections related to IDU occur annually.

DISCUSSION

These estimates carry significant limitations. However, regardless of the source or method, the burden of disease appears substantial, with estimates of thousands of episodes of IE among persons with IDU and at least 100 000 persons who inject drugs (PWID) with skin and soft-tissue infections annually in the United States. Given the importance of these types of infections, more robust and reliable estimates are needed to better quantitate the occurrence and understand the impact of interventions.

Syndemic profiles of people living with hepatitis C virus using population-level latent class analysis to optimize health services

BACKGROUND

Hepatitis C (HCV) affects diverse populations such as people who inject drugs (PWID), 'baby boomers,' gay/bisexual men who have sex with men (gbMSM), and people from HCV endemic regions. Assessing HCV syndemics (i.e.relationships with mental health/chronic diseases) among subpopulations using Latent Class Analysis (LCA) may facilitate targeted program planning.

METHODS

The BC Hepatitis Testers Cohort(BC-HTC) includes all HCV cases identified in BC between 1990 and 2015, integrated with medical administrative data. LCA grouped all BC-HTC HCV diagnosed people(n = 73,665) by socio-demographic/clinical indicators previously determined to be relevant for HCV outcomes. The final model was chosen based on fit statistics, epidemiological meaningfulness, and posterior probability. Classes were named by most defining characteristics.

RESULTS

The six-class model was the best fit and had the following names and characteristics: 'Younger PWID'(n =11,563): recent IDU (67%), people born >1974 (48%), mental illness (62%), material deprivation (59%). 'Older PWID'(n =15,266): past IDU (78%), HIV (17%), HBV (17%) coinfections, alcohol misuse(68%). 'Other Middle-Aged People'(n = 9019): gbMSM (26%), material privilege (31%), people born between 1965-1974 (47%). 'People of Asian backgrounds' (n = 4718): East/South Asians (92%), no alcohol misuse (97%) or mental illness (93%), people born <1945 (26%), social privilege (66%). 'Rural baby boomers' (n = 20,401): rural dwellers (32%), baby boomers (79%), heterosexuals (99%), no HIV (100%). 'Urban socially deprived baby boomers' (n = 12,698): urban dwellers (99%), no IDU (100%), liver disease (22%), social deprivation (94%).

CONCLUSIONS

Differences between classes suggest variability in patients' service needs. Further analysis of health service utilization patterns may inform optimal service layout.

The impact of SVR from direct-acting antiviral- and interferon-based treatments for HCV on hepatocellular carcinoma risk

We evaluated the effect of sustained virologic response (SVR) from direct-acting antiviral (DAA)- and interferon-based treatments on hepatocellular carcinoma (HCC) risk in a large population-based cohort in Canada. We used data from the BC Hepatitis Testers Cohort, which includes ~1.3 million individuals tested for HCV since 1990, linked with healthcare administrative and registry datasets. Patients were followed from the end of HCV treatment to HCC, death or 31 December 2016. We assessed HCC risk among those who did and did not achieve SVR by treatment type using proportional hazard models. Of 12 776 eligible individuals, 3905 received DAAs while 8871 received interferon-based treatments, followed for a median of 1.0 [range: 0.6-2.7] and 7.9 [range: 4.4-17.1] years, respectively. A total of 3613 and 6575 achieved SVR with DAAs- and interferon-based treatments, respectively. Among DAAs-treated patients, HCC incidence rate was 6.9 (95%CI: 4.7-10.1)/1000 person yr (PY) in SVR group (HCC cases: 26) and 38.2 (95%CI: 20.6-71.0) in the no-SVR group (HCC cases: 10, P < .001). Among interferon-treated individuals, HCC incidence rate was 1.8 (95%CI: 1.5-2.2) in the SVR (HCC cases: 99) and 13.9 (95%CI: 12.3-15.8) in the no-SVR group (HCC cases: 239, P < .001). Compared with no-SVR from interferon, SVR from DAA- and interferon-based treatments resulted in significant reduction in HCC risk (adjusted subdistribution hazard ratio (adjSHR) DAA = 0.30, 95%CI: 0.19-0.48 and adjSHR interferon = 0.2, 95%CI: 0.16-0.26). Among those with SVR, treatment with DAAs compared to interferon was not associated with HCC risk (adjSHR = 0.93, 95%CI: 0.51-1.71). In conclusion, similar to interferon era, DAA-related SVR is associated with 70% reduction in HCC risk.

HCV Testing and Treatment in a National Sample of US Federally Qualified Health Centers during the Opioid Epidemic

BACKGROUND

Federally qualified health centers (FQHCs) serve diverse communities in the United States (U.S.) and could function as important venues to diagnose and treat hepatitis C virus (HCV) infections.

OBJECTIVE

To determine HCV testing proportion and factors associated with treatment initiation, and treatment outcomes in a large sample of FQHCs around the U.S.

DESIGN

Retrospective cohort study using electronic health records of three hundred and forty-one FQHC clinical sites participating in the OCHIN network in 19 U.S. states.

PARTICIPANTS

Adult patients (≥ 18 years of age) seen between January 01, 2012, and June 30, 2017.

MAIN MEASURES

HCV testing proportion, stratified by diagnosis of opioid use disorder (OUD); treatment initiation rates; and sustained virologic response (SVR), defined as undetectable HCV RNA 6 months after treatment initiation.

KEY RESULTS

Of the 1,508,525 patients meeting inclusion criteria, 88,384 (5.9%) were tested for HCV, and 8694 (9.8%) of individuals tested had reactive results. Of the 6357 with HCV RNA testing, 4092 (64.4%) had detectable RNA. Twelve percent of individuals with chronic HCV and evaluable data initiated treatment. Of those, 87% reached SVR. Having commercial insurance (aOR, 2.11; 95% CI, 1.46-3.05), older age (aOR, 1.07; 95% CI, 1.06-1.09), and being Hispanic/Latino (aOR, 1.87; 95% CI, 1.38-2.53) or Asian/Pacific Islander (aOR, 2.47; 95% CI, 1.46-4.19) were independently associated with higher odds of treatment initiation after multivariable adjustment. In contrast, women (aOR, 0.76; 95% CI, 0.60-0.97) and the uninsured (aOR, 0.15; 95% CI, 0.09-0.25) were less likely to initiate treatment. Only 8% of individuals with chronic HCV were tested for HIV, and 15% of individuals with identified OUD were tested for HCV.

CONCLUSIONS

Fewer than 20% of individuals with identified OUD were tested for HCV. SVR was lower than findings in other real-world cohorts. Measures to improve outcomes should be considered with the expansion of HCV management into community clinics.

Validity of ICD-based algorithms to estimate the prevalence of injection drug use among infective endocarditis hospitalizations in the absence of a reference standard

BACKGROUND

International Classification of Diseases (ICD) code algorithms are routinely used to estimate the frequency of illicit injection drug use (IDU)-associated hospitalizations in administrative health datasets despite a lack of evidence regarding their validity. We aimed to measure the sensitivity and specificity of ICD code algorithms used to estimate the prevalence of current/recent IDU among infective endocarditis (IE) hospitalizations without a reference standard.

METHODS

We reviewed medical records of 321 patients aged 18-64 years old from an urban academic hospital with an IE diagnosis between 2007 and 2017. Diagnostic tests for IDU included self-reported IDU in medical records; a drug use, abuse and dependence (UAD) ICD algorithm; a Hepatitis C Virus (HCV) ICD algorithm; and a combination drug UAD/HCV ICD algorithm. Sensitivity, specificity and the misclassification error (ME)-adjusted IDU prevalence were estimated using Bayesian latent class models.

RESULTS

The combination algorithm had the highest sensitivity and lowest specificity. Sensitivity increased for the drug UAD algorithm in the ICD-10 period compared to the ICD-9 period. The ME-adjusted current/recent IDU prevalence estimated using the drug UAD and HCV algorithms was 23 % (95 % Bayesian credible interval: 16 %, 31 %). The unadjusted prevalence estimate from the drug UAD algorithm underestimated the ME-adjusted prevalence, while the combination algorithm overestimated it.

CONCLUSION

The validity of ICD code algorithms for IDU among IE hospitalizations is imperfect and differs between ICD-9 and ICD-10. Commonly used ICD-based algorithms could lead to substantially biased prevalence estimates in IDU-associated hospitalizations when using administrative health data.

Loss to follow-up: A significant barrier in the treatment cascade with direct-acting therapies

Effectiveness of direct-acting antiviral (DAA) therapies could be influenced by patient characteristics such as comorbid conditions, which could lead to premature treatment discontinuation and/or irregular medical follow-ups. Here, we evaluate loss to follow-up and treatment effectiveness of sofosbuvir/ledipasvir ± ribavirin (SOF/LDV ± RBV), ombitasvir/paritaprevir/ritonavir + dasabuvir ± ribavirin (OBV/PTV/r + DSV ± RBV) for hepatitis C virus (HCV) genotype 1 (GT1) and sofosbuvir + ribavirin (SOF + RBV) for genotype 3 (GT3) in British Columbia Canada: The British Columbia Hepatitis Testers Cohort includes data on individuals tested for HCV since 1992, integrated with medical visit, hospitalization and prescription drug data. HCV-positive individuals who initiated DAA regimens, irrespective of treatment completion, for GT1 and GT3 until 31 December, 2017 were included. Factors associated with sustained virological response (SVR) and loss to follow-up were assessed by using multivariable logistic regression models. In total 4477 individuals initiated DAAs. The most common prescribed DAA was SOF/LDV ± RBV with SVR of 95%. The highest SVR of 99.5% was observed among OBV/PTV/r + DSV-treated patients. Overall, 453 (10.1%) individuals were lost to follow-up. Higher loss to follow-up was observed among GT1 patients treated with OBV (17.8%) and GT3 patients (15.7%). The loss to follow-up rate was significantly higher among individuals aged <60 years, those with a history of injection drug use (IDU), on opioid substitution therapy and with cirrhosis. Our findings indicate that loss to follow-up exceeds viral failure in HCV DAA therapy and its rate varies significantly by genotype and treatment regimen. Depending on the aetiology of lost to follow-up, personalized case management for those with medical complications and supporting services among IDU are needed to achieve the full benefits of effective treatments.

Validity of International Classification of Diseases codes in identifying illicit drug use target conditions using medical record data as a reference standard: A systematic review

BACKGROUND

The twenty-first century opioid crisis has spurred interest in using International Classification of Diseases (ICD) code algorithms to identify patients using illicit drugs from administrative healthcare data. We conducted a systematic review of studies that validated ICD code algorithms for illicit drug use against a reference standard of medical record data.

METHODS

Systematic searches of MEDLINE, EMBASE, PsycINFO, and Web of Science were conducted for studies published between 1980 and 2018 in English, French, Italian, or Spanish. We included validation studies of ICD-9 or ICD-10 code algorithms for an illicit drug use target condition (e.g., illicit drug use, abuse, or dependence (UAD), illicit drug use-related complications) given the sensitivity or specificity was reported or could be calculated. Bias was assessed with the Quality Assessment of Diagnostic Accuracy Studies Version 2 (QUADAS-2) tool.

RESULTS

Six of the 1210 articles identified met the inclusion criteria. For validation studies of broad UAD (n = 4), the specificity was nearly perfect, but the sensitivity ranged from 47% to 83%, with higher sensitivities tending to occur in higher prevalence populations. For validation studies of injection drug use (IDU)-associated infective endocarditis (n = 2), sensitivity and specificity were poor due to the lack of an ICD code for IDU. For all six studies, the risk of bias for the QUADAS-2 "reference standard" and "flow/timing domains" was scored as "unclear" due to insufficient reporting.

CONCLUSIONS

Few studies have validated ICD code algorithms for illicit drug use target conditions, and available evidence is challenging to interpret due to inadequate reporting. PROSPERO Registration: CRD42019118401.

Hepatitis C Virus Antibody Testing Among 13- to 21-Year-Olds in a Large Sample of US Federally Qualified Health Centers

This study characterizes hepatitis C virus (HCV) testing and the HCV care cascade among 13- to 21-year-olds accessing US federally qualified health centers.

The population level care cascade for hepatitis C in British Columbia, Canada as of 2018: Impact of direct acting antivirals

BACKGROUND

Population-level monitoring of hepatitis C virus (HCV) infected people across cascades of care identifies gaps in access and engagement in care and treatment. We characterized the population-level care cascade for HCV in British Columbia (BC), Canada before and after introduction of Direct Acting Antiviral (DAA) treatment.

METHODS

BC Hepatitis Testers Cohort (BC-HTC) includes 1.7 million individuals tested for HCV, HIV, reported cases of hepatitis B, and active tuberculosis in BC from 1990 to 2018 linked to medical visits, hospitalizations, cancers, prescription drugs and mortality data. We defined six HCV care cascade stages: (a) antibody diagnosed; (b) RNA tested; (c) RNA positive; (d) genotyped; (e) initiated treatment; and (f) achieved sustained virologic response (SVR).

RESULTS

We estimated 61 127 people were HCV antibody positive in BC in 2018 (undiagnosed: 7686, 13%; diagnosed: 53 441, 87%). Of those diagnosed, 83% (44 507) had HCV RNA testing, and of those RNA positive, 90% (28 716) were genotyped. Of those genotyped, 61% (17 441) received therapy, with 90% (15 672) reaching SVR. Individuals from older birth cohorts had lower progression to HCV RNA testing. While people who currently inject drugs had the highest proportional progression to RNA testing, this group had the lowest proportional treatment uptake.

CONCLUSIONS

Although gaps in HCV RNA and genotype testing after antibody diagnosis exist, the largest gap in the care cascade is treatment initiation, despite introduction of DAA treatment and removal of treatment eligibility restrictions. Further interventions are required to ensure testing and treatment is equitably accessible in BC.

Prevalence of Injecting Drug Use and Coverage of Interventions to Prevent HIV and Hepatitis C Virus Infection Among People Who Inject Drugs in Canada

Objectives. To determine the number of people who inject drugs (PWID) in Canada and the annual coverage of opioid agonist treatment (OAT) and needle-and-syringe provision for PWID.Methods. We estimated the number of PWID in 11 of 13 Canadian provinces and territories in 2011 by using indirect multiplier methods based on provincial and territorial methadone recipient totals and proportion of surveyed PWID receiving methadone. We modeled annual increases for 2011 to 2016 on Quebec and British Columbia longitudinal data. We calculated needle-and-syringe coverage (World Health Organization [WHO] recommendation: ≥ 200 per PWID) and OAT coverage (WHO recommendation: ≥ 40 per 100 PWID) per province and territory annually.Results. An estimated 130 000 individuals in Canada (0.55%) injected drugs in 2011, increasing to 171 900 individuals (0.70%) in 2016. Needle-and-syringe coverage increased from 193 to 291 per PWID, and OAT coverage increased from 55 to 66 per 100 PWID over the study period.Conclusions. While the number of PWID increased between 2011 and 2016, OAT coverage remained high, and needle-and-syringe coverage generally improved over time.Public Health Implications. These data will inform public health surveillance, service planning, and resource allocation, and assist monitoring of treatment and harm-reduction coverage outcomes.

Modelling the combined impact of interventions in averting deaths during a synthetic-opioid overdose epidemic

BACKGROUND AND AIMS

The province of British Columbia (BC) Canada has experienced a rapid increase in illicit drug overdoses and deaths during the last 4 years, with a provincial emergency declared in April 2016. These deaths have been driven primarily by the introduction of synthetic opioids into the illicit opioid supply. This study aimed to measure the combined impact of large-scale opioid overdose interventions implemented in BC between April 2016 and December 2017 on the number of deaths averted.

DESIGN

We expanded on the mathematical modelling methodology of our previous study to construct a Bayesian hierarchical latent Markov process model to estimate monthly overdose and overdose-death risk, along with the impact of interventions.

SETTING AND CASES

Overdose events and overdose-related deaths in BC from January 2012 to December 2017.

INTERVENTIONS

The interventions considered were take-home naloxone kits, overdose prevention/supervised consumption sites and opioid agonist therapy MEASUREMENTS: Counterfactual simulations were performed with the fitted model to estimate the number of death events averted for each intervention and in combination.

FINDINGS

Between April 2016 and December 2017, BC observed 2177 overdose deaths (77% fentanyl-detected). During the same period, an estimated 3030 (2900-3240) death events were averted by all interventions combined. In isolation, 1580 (1480-1740) were averted by take-home naloxone, 230 (160-350) by overdose prevention services and 590 (510-720) were averted by opioid agonist therapy.

CONCLUSIONS

A combined intervention approach has been effective in averting overdose deaths during British Columbia's opioid overdose crisis in the period since declaration of a public health emergency (April 2016-December 2017). However, the absolute numbers of overdose deaths have not changed.

Effectiveness of Ledipasvir/Sofosbuvir and Sofosbuvir/Velpatasvir in People Who Inject Drugs and/or Those in Opioid Agonist Therapy

We evaluated the effectiveness of ledipasvir/sofosbuvir (LDV/SOF) in treating hepatitis C virus (HCV) genotype 1 and SOF/velpatasvir (SOF/VEL) for all genotypes among people who inject drugs (PWID) and those not injecting drugs and who were on or off opioid agonist therapy (OAT). Study participants comprised a population-based cohort in British Columbia, Canada. The British Columbia Hepatitis Testers Cohort includes data on individuals tested for HCV from 1990 to 2016 that are integrated with medical visits, hospitalization, and prescription drug data. We classified study participants as off OAT/recent injection drug use (off-OAT/RIDU), off OAT/past IDU (off-OAT/PIDU), off OAT/no IDU (off-OAT/NIDU), on OAT/IDU (on-OAT/IDU), and on OAT/no IDU (on-OAT/NIDU). We assessed sustained virologic response (SVR) 10 weeks after HCV treatment among study groups treated with LDV/SOF or SOF/VEL until January 13, 2018. Analysis included 5,283 eligible participants: 390 off-OAT/RIDU, 598 off-OAT/PIDU, 3,515 off-OAT/NIDU, 609 on-OAT/IDU, and 171 on-OAT/NIDU. The majority were male patients (64%-74%) and aged ≥50 years (58%-85%). The SVRs for off-OAT/RIDU, off-OAT/PIDU, off-OAT/NIDU, on-OAT/IDU, and on-OAT/NIDU were 91% (355/390), 95% (570/598), 96% (3,360/3,515), 93% (567/609), and 95% (163/171), respectively. Among those with no SVR, 14 individuals died while on treatment or before SVR assessment, including 4 from illicit drug overdose. In the overall multivariable model, off-OAT/RIDU, on-OAT/IDU, male sex, cirrhosis, treatment duration <8 weeks, treatment duration 8 weeks, and treatment with SOF/VEL were associated with not achieving SVR. Conclusion: In this large real-world cohort, PWID and/or those on OAT achieved high SVRs, although slightly lower than people not injecting drugs. This finding also highlights the need for additional measures to prevent loss to follow-up and overdose-related deaths among PWID.

Test uptake and hepatitis C prevalence in 5483 Danish people in drug use treatment from 1996 to 2015: a registry-based cohort study

BACKGROUND AND AIMS

The aims of this study were, in people in treatment for drug use in Funen, Denmark, to: (1) assess prevalence of hepatitis C virus (HCV) test uptake and prevalence of HCV; (2) identify predictors of test update and HCV infection; and (3) characterize changes between 1996 and 2015 in test uptake, HCV prevalence and drug use.

DESIGN

Cohort study linking the Danish National Registry on Drug Users in Treatment to the regional hepatitis test registry and the Danish Death Certificate Registry, thus combining longitudinal data on drug use with data on HCV testing and results.

SETTING AND PARTICIPANTS

People recorded as having received treatment for drug use between 1996 and 2015 (n = 5483) in Funen, Denmark. In the cohort, 24.8% were female, median age 23 years [interquartile range (IQR) = 20-32] at entry and 50% had self-reported injecting or had received opiate substitution therapy (OST).

MEASUREMENTS

The main outcomes were the test for HCV ever and latest HCV-RNA being positive. The main predictors were for test and infection investigated; ever receiving OST, self-reported injecting, age at entry and connection to treatment centre offering outreach hepatitis care.

FINDINGS

HCV test uptake was 52% and prevalence of current HCV-RNA+ was 21% in people alive at the end of follow-up. Positive predictors of having undergone HCV testing were: receiving OST [odds ratio (OR) = 3.7; 95% confidence interval (CI) = 3.2-4.5], self-reported injecting (OR = 2.3; 95% CI = 2.0-2.7), female gender (OR = 1.7; 95% CI = 1.4-1.9) and having been connected to centres with outreach hepatitis care (OR = 1.4; 95% CI = 1.2-1.7). In people alive, HCV-RNA+ prevalence was 31% if ever on OST or self-reported injecting. Among HCV-infected people, 69% were in drug use treatment at end of follow-up. For participants entering the cohort after 2010, only 5% reported opiates as main drug of use and 17% had experience of injecting.

CONCLUSION

Among Danish people in treatment for drug use from 1996 to 2015, receiving opiate substitution therapy had the largest associating to being tested for hepatitis C virus. As opiate use is declining, adapting test strategies will be necessary.

Applying core theory and spatial analysis to identify hepatitis C virus infection "core areas" in British Columbia, Canada

"Core areas" of transmission for bacterial sexually transmitted infections have been identified. However, it is unclear whether core areas apply to viral infections, such as hepatitis C virus (HCV). We used geographic mapping and spatial analysis to identify distinct core areas of HCV infection in British Columbia (BC) using the BC Hepatitis Testers Cohort (BC-HTC), 1990-2013. The BC-HTC includes all BC residents tested for HCV (~1.5 million; 1990-2013). Core HCV infection areas were identified spatially and temporally for five time periods (1990-1993, 1994-1998, 1999-2003, 2004-2008 and 2009-2013) through thematic mapping, Kernel Density Estimation, Hotspot analysis and cluster analysis at the Census dissemination area level in ArcGIS and SatScan. HCV infection core areas were consistently identified. HCV core areas expanded from the downtown of major cities in different regions of BC (Metro Vancouver, Vancouver Island, and Northern BC; 1990-1998), to smaller cities in Metro Vancouver and Interior BC (2000 onwards). Statistically significant clusters, or hotspots, were also observed for downtown Vancouver, Northern BC (Prince George) and Vancouver Island from 1990 to 2008 with expansion to other urban areas in Metro Vancouver from 1990-2013. Statistically significant clusters persisted after adjustment for injection drug use, number of HCV tests, age, sex, material and social deprivation. Persistence of areas with high HCV diagnoses rates in Vancouver and Prince George supports the theory of core areas of HCV transmission. Identification of core areas can inform prevention, care and treatment programme interventions and evaluate their impact over time.

Patterns and history of prescription drug use among opioid-related drug overdose cases in British Columbia, Canada, 2015-2016

BACKGROUND

British Columbia is the epicenter of the current fentanyl-related overdose crisis in Canada. Our study characterizes prescribing histories of people who had an opioid-related overdose compared to matched controls.

METHODS

We examined linked administrative data for individuals who overdosed between January 1, 2015 and November 30, 2016. Past prescriptions over five years were assessed for opioids for pain, opioid agonist therapy, benzodiazepines/z-drugs, antidepressants, antipsychotics, gabapentinoids, mood stabilizers and anti-epileptics, muscle relaxants, and other sedating medications. Prescribing history of 9964 cases was compared with that of 49,820 matched controls.

RESULTS

Overdose cases were more likely to be prescribed opioids for pain and to have used prescription opioids on a long-term basis in the previous five years compared to controls. However, at the time of overdose, 92% of men and 86% of women did not have an active opioid for pain prescription, and approximately half had not filled one in the past five years. Those who overdosed tended to have more prescriptions for psychotropic substances than controls. Fewer than 10% of cases had an active prescription for opioid agonist therapy and most were not on treatment in the past.

CONCLUSIONS

Low prevalence of active prescriptions for opioids for pain at the time of overdose suggests that opioid prescribing plays a limited short-term impact in the current fentanyl-related crisis of overdoses. While liberal opioid prescribing practices may have contributed to the development of the current overdose crisis, regulation and enforcement of clinicians' prescribing practices will likely have limited impact in reducing overdoses.

What Is Needed to Eliminate Hepatitis B Virus and Hepatitis C Virus as Global Health Threats

Hepatitis B virus (HBV) and hepatitis C virus (HCV) cause 1.3 million deaths annually. To prevent more than 7 million deaths by 2030, the World Health Organization set goals to eliminate HBV and HCV, defined as a 90% reduction in new infections and a 65% reduction in deaths, and prevent more than 7 million related deaths by 2030. Elimination of HBV and HCV is feasible because of characteristics of the viruses, reliable diagnostic tools, and available cost-effective or cost-saving interventions. Broad implementation of infant immunization against HBV, blood safety, and infection-control programs have greatly reduced the burden of HBV and HCV infections. To achieve elimination, priorities include implementation of HBV vaccine-based strategies to prevent perinatal transmission, safe injection practices and HCV treatment for persons who inject drugs, and testing and treatment for HBV- and HCV-infected persons. With sufficient capacity, HBV and HCV elimination programs can meet their goals.

Estimating the impact of early hepatitis C virus clearance on hepatocellular carcinoma risk

Although achieving sustained virological response (SVR) through antiviral therapy could reduce the risk of hepatocellular carcinoma (HCC) attributable to hepatitis C virus (HCV) infection, the impact of early viral clearance on HCC is not well defined. In this study, we compared the risk of HCC among individuals who spontaneously cleared HCV (SC), the referent population, with the risk in untreated chronic HCV (UCHC), those achieved SVR, and those who failed interferon-based treatment (TF). The BC Hepatitis Testers Cohort (BC-HTC) includes individuals tested for HCV between 1990-2013, integrated with medical visits, hospitalizations, cancers, prescription drugs and mortality data. This analysis included all HCV-positive patients with at least one valid HCV RNA by PCR on or after HCV diagnosis. Of 46 666 HCV-infected individuals, there were 12 527 (26.8%) SC; 24 794 (53.1%) UCHC; 5355 (11.5%) SVR and 3990 (8.5%) TF. HCC incidence was lowest (0.3/1000 person-years (PY)) in the SC group and highest in the TF group (7.7/1000 PY). In a multivariable model, compared to SC, TF had the highest HCC risk (hazard ratio (HR):14.52, 95% confidence interval (CI): 9.83-21.47), followed by UCHC (HR: 5.85; 95% CI: 4.07-8.41). Earlier treatment-based viral clearance similar to SC could decrease HCC incidence by 69.4% (95% CI: 57.5-78.0), 30% (95% CI: 10.8-45.1) and 77.5% (95% CI: 69.4-83.5) among UCHC, SVR and TF patients, respectively. In conclusion, using SC as a real-world comparator group, it showed that substantial reduction in HCC risk could be achieved with earlier treatment initiation. These analyses should be replicated in patients who have been treated with direct acting antiviral therapies.

HIV Incidence Among Men Who Have Sex with Men and Inject Drugs in a Canadian Setting

Few data on HIV incidence among men who have sex with men and inject drugs (MSM-PWID) are available. Drawing on a prospective cohort in Vancouver, Canada, we examined the relationship between MSM status and HIV incidence among PWID using Kaplan-Meier analyses and extended Cox regression. Data were collected from 1996 to 2014 and analyzed in 2017. Of 1131 HIV-negative male PWID, 8.6% (n = 97) reported sex with men over the study period. MSM status was crudely associated with HIV incidence [Hazard Ratio (HR) = 1.81; 95% CI 1.08-3.03], but not after adjustment for daily cocaine injection and syringe borrowing (Adjusted HR = 1.33; 95% CI 0.78-2.28). Findings highlight the need for harm reduction interventions and socio-behavioral research focused on MSM-PWID.

Hepatitis C virus reinfection after successful treatment with direct-acting antiviral therapy in a large population-based cohort

BACKGROUND & AIMS

Direct-acting antiviral therapies (DAA) are an important tool for hepatitis C virus (HCV) elimination. However, reinfection among people who inject drugs (PWID) may hamper elimination targets. Therefore, we estimated HCV reinfection rates among DAA-treated individuals, including PWID.

METHODS

We analyzed data from the British Columbia Hepatitis Testers Cohort which included ∼1.7 million individuals screened for HCV in British Columbia, Canada. We followed HCV-infected individuals treated with DAAs who achieved a sustained virologic response (SVR) and had ≥1 subsequent HCV RNA measurement to April 22nd, 2018. Reinfection was defined as a positive RNA measurement after SVR. PWID were identified using a validated algorithm and classified based on recent (<3 years) or former (≥3 years before SVR) use. Crude reinfection rates per 100 person-years (PYs) were calculated. Poisson regression was used to model adjusted incidence rate ratios (IRRs) and 95% CIs.

RESULTS

Of 4,114 individuals who met the inclusion criteria, most were male (n = 2,692, 65%), born before 1965 (n = 3,411, 83%) and were either recent (n = 875, 21%) or former PWID (n = 1,793, 44%). Opioid-agonist therapy (OAT) was received by 19% of PWID. We identified 40 reinfections during 2,767 PYs. Reinfection rates were higher among recent (3.1/100 PYs; IRR 6.7; 95% CI 1.9-23.5) and former PWID (1.4/100 PYs; IRR 3.7; 95% CI 1.1-12.9) than non-PWID (0.3/100 PYs). Among recent PWID, reinfection rates were higher among individuals born after 1975 (10.2/100 PYs) and those co-infected with HIV (5.7/100 PYs). Only one PWID receiving daily OAT developed reinfection.

CONCLUSIONS

Population-level reinfection rates remain elevated after DAA therapy among PWID because of ongoing exposure risk. Engagement of PWID in harm-reduction and support services is needed to prevent reinfections.

LAY SUMMARY

Direct-acting antivirals are an effective tool for the treatment of hepatitis C virus, enabling the elimination of the virus. However, some patients who have been successfully treated with direct-acting antivirals are at risk of reinfection. Our findings showed that the risk of reinfection was highest among people with recent injection drug use. Among people who inject drugs, daily use of opioid-agonist therapy was associated with a lower risk of reinfection.

Syndemic Characterization of HCV, HBV, and HIV Co-infections in a Large Population Based Cohort Study

BACKGROUND

Limited data are available on HBV, HCV, and HIV co-infections and triple infection. We characterized co-occurrence of HIV, HBV, and HCV infections at the population level in British Columbia (BC) to identify patterns of predisposing factors unique to co-infection subgroups.

METHODS

We analyzed data from the BC Hepatitis Testers Cohort, which includes all individuals tested for HCV or HIV in BC between 1992 and 2013, or included in provincial public health registries of HIV, HCV, HBV, and active tuberculosis. Individuals were classified as negative, mono-, and co-infection groups based on HIV, HBV, and HCV status. We evaluated associations between risk factors (injection drug use, sexual orientation etc.) and co-infection groups using multivariate multinomial logistic regression.

FINDINGS

Of a total of 1,376,989 individuals included in the analysis, 1,276,290 were negative and 100,699 were positive for HIV, HBV, and/or HCV. Most cases (91,399, 90.8%) were mono-infected, while 3991 (4.0%) had HBV/HCV, 670 HBV/HIV (0.7%), 3459 HCV/HIV (3.4%), and 1180 HBV/HCV/HIV (1.2%) co-infection. Risk factor and demographic distribution varied across co-infection categories. MSM classification was associated with higher odds of all HIV co-infection groups, particularly HBV/HIV (OR 6.8; 95% CI: 5.6, 8.27), while injection drug use was most strongly associated with triple infection (OR 64.19; 95% CI: 55.11, 74.77) and HIV/HCV (OR 23.23; 95% CI: 21.32, 25.31).

INTERPRETATION

Syndemics of substance use, sexual practices, mental illness, socioeconomic marginalization, and co-infections differ among population groups, highlighting avenues for optimal composition and context for health services to meet each population's unique needs.

FUNDING

BC Centre for Disease Control and Canadian Institutes of Health Research.

Effect of opioid-substitution therapy and mental health counseling on HIV risk among hepatitis C-infected individuals

Background

Understanding differences in HIV incidence among people living with hepatitis C virus (HCV) can help inform strategies to prevent HIV infection. We estimated the time to HIV diagnosis among HCV-positive individuals and evaluated factors that could affect HIV-infection risk in this population.

Patients and methods

The British Columbia Hepatitis Testers Cohort includes all BC residents (~1.5 million: about a third of all residents) tested for HCV and HIV from 1990 to 2013 and is linked to administrative health care and mortality data. All HCV-positive and HIV-negative individuals were followed to measure time to HIV acquisition (positive test) and identify factors associated with HIV acquisition. Adjusted HRs (aHRs) were estimated using Cox proportional-hazard regression.

Results

Of 36,077 HCV-positive individuals, 2,169 (6%) acquired HIV over 266,883 years of follow-up (overall incidence of 8.1 per 1,000 person years). Overall median (IQR) time to HIV infection was 3.87 (6.06) years. In Cox regression, injection-drug use (aHR 1.47, 95% CI 1.33–1.63), HBV infection (aHR 1.34, 95% CI 1.16–1.55), and being a man who has sex with men (aHR 2.78, 95% CI 2.14–3.61) were associated with higher risk of HIV infection. Opioid-substitution therapy (OST) (aHR 0.59, 95% CI 0.52–0.67) and mental health counseling (aHR 0.48, 95% CI 0.43–0.53) were associated with lower risk of HIV infection.

Conclusion

Injection-drug use, HBV coinfection, and being a man who has sex with men were associated with increased HIV risk and engagement in OST and mental health counseling were associated with reduced HIV risk among HCV-positive individuals. Improving access to OST and mental health services could prevent transmission of HIV and other blood-borne infections, especially in settings where access is limited.