Benzodiazepine Use and Hepatitis C Seroconversion in a Cohort of Persons Who Inject Drugs

Incidence of HIV and hepatitis C virus among people who inject drugs, and associations with age and sex or gender: a global systematic review and meta-analysis

BACKGROUND

Measuring the incidence of HIV and hepatitis C virus (HCV) infection among people who inject drugs (PWID) is key to track progress towards elimination. We aimed to summarise global data on HIV and primary HCV incidence among PWID and associations with age and sex or gender.

METHODS

In this systematic review and meta-analysis, we updated an existing database of HIV and HCV incidence studies among PWID by searching MEDLINE, Embase, and PsycINFO, capturing studies published between Jan 1, 2000, and Dec 12, 2022, with no language or study design restrictions. We contacted authors of identified studies for unpublished or updated data. We included studies that estimated incidence by longitudinally re-testing people at risk of infection or by using assays for recent infection. We pooled incidence and relative risk (RR; young [generally defined as ≤25 years] vs older PWID; women vs men) estimates using random-effects meta-analysis and assessed risk of bias with a modified Newcastle-Ottawa scale. This study is registered with PROSPERO, CRD42020220884.

FINDINGS

Our updated search identified 9493 publications, of which 211 were eligible for full-text review. An additional 377 full-text records from our existing database and five records identified through cross-referencing were assessed. Including 28 unpublished records, 125 records met the inclusion criteria. We identified 64 estimates of HIV incidence (30 from high-income countries [HICs] and 34 from low-income or middle-income countries [LMICs]) and 66 estimates of HCV incidence (52 from HICs and 14 from LMICs). 41 (64%) of 64 HIV and 42 (64%) of 66 HCV estimates were from single cities rather than being multi-city or nationwide. Estimates were measured over 1987-2021 for HIV and 1992-2021 for HCV. Pooled HIV incidence was 1·7 per 100 person-years (95% CI 1·3-2·3; I2=98·4%) and pooled HCV incidence was 12·1 per 100 person-years (10·0-14·6; I2=97·2%). Young PWID had a greater risk of HIV (RR 1·5, 95% CI 1·2-1·8; I2=66·9%) and HCV (1·5, 1·3-1·8; I2=70·6%) acquisition than older PWID. Women had a greater risk of HIV (RR 1·4, 95% CI 1·1-1·6; I2=55·3%) and HCV (1·2, 1·1-1·3; I2=43·3%) acquisition than men. For both HIV and HCV, the median risk-of-bias score was 6 (IQR 6-7), indicating moderate risk.

INTERPRETATION

Although sparse, available HIV and HCV incidence estimates offer insights into global levels of HIV and HCV transmission among PWID. Intensified efforts are needed to keep track of the HIV and HCV epidemics among PWID and to expand access to age-appropriate and gender-appropriate prevention services that serve young PWID and women who inject drugs.

FUNDING

Canadian Institutes of Health Research, Fonds de recherche du Québec-Santé, Canadian Network on Hepatitis C, UK National Institute for Health and Care Research, and WHO.

Polysubstance Use Patterns Among High Dose Benzodiazepine Users: A Latent Class Analysis and Differences Between Male and Female Use

Benzodiazepines (BZDs) represent one of the most widely used groups of pharmaceuticals, but if used for long periods of time they are associated with dependence and an increased risk of harmful effects. High-dose (HD) BZD dependence is a specific substance use disorder associated with a poor quality of life. It is especially important to pinpoint differences in HD BZD addict subgroups in order to tailor treatment to the individual's specific needs, also considering possible comorbidities with other substance use disorders. We conducted a study to evaluate HD BZD dependence (converted doses to diazepam equivalents, mg) in an Italian sample of 1,354 participants. We also investigated if and to which extent participants co-used other substances (alcohol, tobacco, cannabis/cannabinoids, cocaine, and heroin). We then performed latent class analysis (LCA) to identify the use patterns of these substances, finding three classes: participants in Class 1 (4.3% of the sample) had the highest probability of also using cocaine and alcohol (Polysubstance BZD users); Class 2 comprised subjects with the highest probability of being former heroin, cocaine, THC, and alcohol users (Former polysubstance BZD users); Class 3 represented mono-dependence BZD users (78.5% of the sample) and was the most prevalent among women, while young men were most prevalent in Class 1. The present study underlines different characteristics in HD BZD users both concerning other addictions and sex, and also highlights the need for a stricter control of BZD use, ranging from prescriptions to sales.

Psychoactive Substances Taken with Mephedrone and HCV Infection

Background: In recent years, the observed frequency of hospitalization of patients taking mephedrone with other psychoactive substances has increased. There are no data in the literature on the effect of mephedrone use on liver function in patients, including the frequency of HCV infection. We have analysed the impact of taking mephedrone together with other psychoactive substances on the incidence of HCV infection. We have also analysed the effect of taking mephedrone with heroin, alcohol, and benzodiazepines on liver enzyme levels. Methods: The study included patients taking mephedrone with: alcohol (n = 115), heroin (n = 85) and benzodiazepines (n = 130) hospitalized in 2010–2018. The control group consisted of patients addicted to alcohol (n = 180), heroin (n = 221) and benzodiazepines (n = 152). Clinical data and laboratory findings were collected from medical records. Results: Taking mephedrone together with benzodiazepines is a statistically significant predictor of HCV infection in this group of patients, OR (8.44); 95% CI 5.63–12.64; p < 0.001). A statistically significant interaction of the group with HCV infection was observed, i.e., for the level of alanine transaminase (p < 0.001) and aspartate transaminase (p < 0.001). Increased levels of liver enzymes in each of the studied groups was characteristic in patients with HCV infection (p < 0.001). Taking additional mephedrone by this group of patients did not increase the level of liver enzymes. Conclusion: HCV infection is a statistically significant factor affecting the increase in liver enzymes levels in the group of patients taking mephedrone.

Substances detected in used syringes of injecting drug users across 7 cities in Europe in 2017 and 2018: The European Syringe Collection and Analysis Project Enterprise (ESCAPE)

BACKGROUND AND AIMS

Injecting drug use is a matter of public health concern, associated with risks of overdoses, addiction and increased risk of bloodborne viral transmissions. Self-reported data on substances injected can be inaccurate or subject to bias or drug users might be oblivious to their injected substances or adulterations. Gathering of robust analytical information on the actual composition of substances injected might provide better information about the drugs that are being used. Therefore, this study aimed to analyse the residual content of discarded syringes collected across 7 European cities, collectively called the European Syringe Collection and Analysis Project Enterprise (ESCAPE).

METHODS

Used syringes were collected at street automatic injection kit dispensers or at harm-reduction services in Amsterdam, Budapest, Cologne, Glasgow, Helsinki, Lausanne and Paris. Two sampling periods were executed thus far, in 2017 and 2018. Qualitative chemical analysis of the content of used syringes was performed combining gas chromatographic (GC) and ultra(high)performance liquid chromatographic ((U)HPLC) analytical techniques with detection by mass spectrometry (MS).

RESULTS

Substances detected most frequently across both campaigns were cocaine, heroin, buprenorphine, amphetamines and synthetic cathinones. In Amsterdam, Cologne, Lausanne and Glasgow heroin and cocaine were the psychoactive substances most often detected, often in conjunction with each other. Helsinki showed a high presence of buprenorphine and amphetamines. In Budapest and Paris, synthetic cathinones were frequently detected. Less synthetic cathinones and cocaine was detected in 2018, whereas buprenorphine was detected almost twice as much. Inner-city variations were found, probably reflecting the types of people who inject drugs (PWID) in different areas of the city.

CONCLUSION

Overall, laboratory-confirmed local data on injected substances showed resemblance to national surveys done among PWID. However, the ESCAPE data also showed some interesting differences, showing it can be used for local interventions and complementing existing monitoring data.

Hepatitis C Virus Prevalence and Incidence in a Large Nationwide Sample of Patients in Opioid Substitution Treatment in Germany: A Prospective Cohort Study

BACKGROUND

Hepatitis C virus (HCV) infection is highly prevalent among people who inject drugs (PWID). Accurate data on HCV prevalence and incidence rates among patients receiving opioid substitution treatment (OST) are needed to estimate the current and future burden of HCV infections in this high-risk population.

METHODS

Baseline data from routine care were collected between October 2014 and June 2016 from randomly selected OST facilities in Germany. The primary outcome measure was the HCV status (antibody and RNA prevalence). Patients who were HCV antibody-negative at baseline were followed up after 12 months to calculate the HCV incidence rate.

RESULTS

Sixty-three facilities from 14 German Federal States provided clinical data for a total of 2466 OST patients. HCV antibody and HCV RNA prevalence were 58.8% (95% confidence interval [CI], 56.8%-60.8%) and 27.3% (95% CI, 25.5%-29.2%), respectively. At baseline, a total of 528 patients (21.4%) had previously undergone antiviral treatment. Moreover, lower HCV RNA prevalence was associated with female gender, employment, younger age, and shorter duration of OST and opioid dependence. The HCV incidence rate was 2.5 cases per 100 person-years.

CONCLUSIONS

The low HCV RNA prevalence and HCV incidence rates confirm that OST in Germany is an effective setting both for treating chronic HCV infections and for preventing new infections among PWID. Scaling up the provision of OST, HCV testing, and HCV treatment among OST patients are important public health strategies for reducing HCV infections in this high-risk population.

A prospective cohort study of risk behaviours, retention and loss to follow-up over 5 years among women and men in a needle exchange program in Stockholm, Sweden

BACKGROUND

Needle exchange programs (NEP) are important in reducing risk behaviours among people who inject drugs (PWID), also exposed to HIV and hepatitis C (HCV) through injecting drug use (IDU). Women (WWID) compared to men who inject drugs (MWID), are particularly vulnerable with complex needs, however less is known about their risk determinants and NEP outcomes.

METHODS

In an open prospective NEP cohort, 697 WWID and 2122 MWID were followed, 2013-2018. Self-reported socio/drug-related determinants for receptive injection (needle/syringe and paraphernalia) and sexual risk behaviours at enrolment, lost to follow-up (LTFU) and probability of retention, were assessed for both groups. Multivariable logistic regression (adjusted odds ratios, aOR) for enrolment and Poisson regression (adjusted incidence rate ratios, aIRR) for LTFU, were used. Cumulative NEP-retention probability was analysed using a six- and 12-month scenario.

RESULTS

At NEP enrolment, injection risk behaviours among WWID were associated with: younger age; homelessness; amphetamine-IDU; non-participation in opioid substitution therapy (OST); history of custody and among MWID: lower education level; cohabitation; homelessness, being a tenant; amphetamine-IDU; non-participation in OST; history of being sectioned, HIV-negative and HCV-positive. Condomless sex among WWID was associated with: younger age; lower education-level; cohabitation; having a partner; amphetamine-IDU; non-participation in OST; being HIV-negative and HCV-positive and among MWID: younger age; married; cohabitation; having a partner; amphetamine-IDU; non-participation in OST; history of custody, prison and being HIV-negative. WWID had higher NEP-retention levels compared to MWID over time. Being LTFU among WWID was associated with being HIV-negative and reporting injection risk behaviours and among MWID, younger age, non-participation in OST, being HIV-negative and having protected sex.

CONCLUSIONS

Despite better NEP compliance among WWID, high injection and sexual risk behaviours in both gender-subgroups, especially in intimate relationships, suggests ongoing HCV and HIV-infection risks. Subgroup-variation in the NEP continuum of care warrants more gender-disaggregated research and tailoring gender-sensitive services may improve prevention, health and retention outcomes.

Frequent Cannabis Use and Cessation of Injection of Opioids, Vancouver, Canada, 2005-2018

Objectives. To evaluate the impact of frequent cannabis use on injection cessation and injection relapse among people who inject drugs (PWID).Methods. Three prospective cohorts of PWID from Vancouver, Canada, provided the data for these analyses. We used extended Cox regression analysis with time-updated covariates to analyze the association between cannabis use and injection cessation and injection relapse.Results. Between 2005 and 2018, at-least-daily cannabis use was associated with swifter rates of injection cessation (adjusted hazard ratio [AHR] = 1.16; 95% confidence interval [CI] = 1.03, 1.30). A subanalysis revealed that this association was only significant for opioid injection cessation (AHR = 1.26; 95% CI = 1.12, 1.41). At-least-daily cannabis use was not significantly associated with injection relapse (AHR = 1.08; 95% CI = 0.95, 1.23).Conclusions. We observed that at-least-daily cannabis use was associated with a 16% increase in the hazard rate of injection cessation, and this effect was restricted to the cessation of injection opioids. This finding is encouraging given the uncertainty surrounding the impact of cannabis policies on PWID during the ongoing opioid overdose crisis in many settings in the United States and Canada.

Patterns of Polysubstance Use among Adults with Tranquilizer Misuse

Background: The misuse of benzodiazepine tranquilizers is prevalent and is associated with increased risk of overdose when combined with other substances. Yet, little is known about other substance use among those who misuse tranquilizers. Objectives: This study characterized subgroups of individuals with tranquilizer misuse, based on patterns of polysubstance use. Methods: Data were extracted from the 2015-2017 National Survey on Drug Use and Health; adults with past-month tranquilizer misuse were included (N = 1253). We utilized latent class analysis to identify patterns of polysubstance use in the previous month. Results: We identified three distinct latent classes, including the: (1) limited polysubstance use class (approximately 54.6% of the sample), (2) binge alcohol and cannabis use class (28.5% of the sample), and (3) opioid use class (16.9% of the sample). The binge alcohol and cannabis use class and the opioid use class were characterized by high probabilities of other substance misuse, including cocaine and prescription stimulants. Those in the binge alcohol and cannabis use class and the opioid use class reported more motives for tranquilizer misuse and higher rates of sexually transmitted infection, criminal involvement, and suicidal ideation. Those in the opioid use class also had greater psychological distress and higher rates of injection drug use. Conclusions: Nearly half of those with tranquilizer misuse in a general population sample were categorized into one of two high polysubstance use classes, and these two classes were associated with poorer functioning. Findings from these analyses underscore the need to reduce polysubstance use among those who misuse tranquilizers.

Characterising the association between positive hepatitis C virus antibody and pain among people who inject drugs

INTRODUCTION AND AIMS

People who inject drugs (PWID) are a key group within the hepatitis C virus (HCV) pandemic. Chronic pain is a common condition among PWID as these individuals are often exposed to soft tissue infections due to injections and violence. This study aims to characterise the relationship between HCV exposure and pain among PWID.

DESIGN AND METHODS

Data were derived from three prospective cohorts of PWID in Vancouver, Canada, between December 2011 and November 2016. The primary outcome was pain severity, which was defined based on the Euroqol EQ-5D-3L pain subscale. A bivariable and multivariable ordinal generalised estimating equations model was used to quantify the association between HCV exposure and pain among participants.

RESULTS

One thousand and twelve of 2038 participants (50%) reported moderate/extreme pain at baseline. In total, 1473 (72%) participants were HCV-antibody positive. In unadjusted analyses, HCV exposure was positively associated with increased pain [odds ratio (OR) = 1.47; 95% confidence interval (CI): 1.20-1.81]. However, once adjusted for known confounders in multivariable analyses, HCV exposure did not remain significantly associated with increased pain (adjusted OR = 1.00; 95%CI: 0.78-1.28).

DISCUSSION AND CONCLUSIONS

In this sample of PWID, HCV exposure was not significantly associated with pain once other factors were considered. These various factors may explain the elevated risk of pain among PWID and should be addressed in future initiatives when managing pain among PWID with HCV exposure. Future studies should also examine whether pain changes with changes in HCV status (i.e. active vs. cleared infection).

The epidemiology of benzodiazepine misuse: A systematic review

BACKGROUND

Benzodiazepine misuse is a growing public health problem, with increases in benzodiazepine-related overdose deaths and emergency room visits in recent years. However, relatively little attention has been paid to this emergent problem. We systematically reviewed epidemiological studies on benzodiazepine misuse to identify key findings, limitations, and future directions for research.

METHODS

PubMed and PsychINFO databases were searched through February 2019 for peer-reviewed publications on benzodiazepine misuse (e.g., use without a prescription; at a higher frequency or dose than prescribed). Eligibility criteria included human studies that focused on the prevalence, trends, correlates, motives, patterns, sources, and consequences of benzodiazepine misuse.

RESULTS

The search identified 1970 publications, and 351 articles were eligible for data extraction and inclusion. In 2017, benzodiazepines and other tranquilizers were the third most commonly misused illicit or prescription drug in the U.S. (approximately 2.2% of the population). Worldwide rates of misuse appear to be similar to those reported in the U.S. Factors associated with misuse include other substance use, receipt of a benzodiazepine prescription, and psychiatric symptoms and disorders. Benzodiazepine misuse encompasses heterogeneous presentations of motives, patterns, and sources. Moreover, misuse is associated with myriad poor outcomes, including mortality, HIV/HCV risk behaviors, poor self-reported quality of life, criminality, and continued substance use during treatment.

CONCLUSIONS

Benzodiazepine misuse is a worldwide public health concern that is associated with a number of concerning consequences. Findings from the present review have implications for identifying subgroups who could benefit from prevention and treatment efforts, critical points for intervention, and treatment targets.

Use of Hypnotics and Risk of Cancer: A Meta-Analysis of Observational Studies

Background

Previous observational epidemiological studies have shown inconsistent results on the relationship between hypnotics use and risk of cancer. To determine the association between hypnotics use and risk of cancer, we conducted a meta-analysis of available literature.

METHODS

We searched databases PubMed, EMBASE, and the bibliographies of relevant articles to locate additional publications in February 2016. Three evaluators independently reviewed and selected eligible studies based on pre-determined selection criteria.

RESULTS

A total of six observational epidemiological studies including three case-control studies and three cohort studies, which involved 1,830,434 participants (202,629 hypnotics users and 1,627,805 non-users), were included in the final analyses. In a random-effects meta-analysis, compared with non-use of hypnotics, the odds ratio for overall hypnotics use was 1.29 for various cancers (95% confidence interval, 1.08-1.53). Subgroup meta-analyses by various factors such as study design, type of case-control study, study region, and methodological quality of study revealed consistent findings.

CONCLUSION

Our findings from a meta-analysis of low-biased epidemiological studies suggested evidence linking the use of hypnotics to an increased risk of cancers. The results should be cautiously interpreted because of considerable heterogeneity with a high I square value.

Use of hypnotics and the risk of or mortality from heart disease: a meta-analysis of observational studies

BACKGROUND/AIMS

Some observational epidemiologic studies have reported conflicting results on the relationship between hypnotics use and the risk of developing and/or dying from heart disease. We investigated these associations using a meta-analysis of available literatures.

METHODS

We searched the databases PubMed and EMBASE, along with the bibliographies of relevant articles to find additional publications in February 2016.

RESULTS

Of 495 articles satisfying our initial criteria, two case-control studies and six cohort studies met our inclusion criteria and were included in the final analyses. Compared with never having used any kind of hypnotics, the odds ratio for overall use was 0.84 for risk of or mortality from heart disease (95% confidence interval, 0.79 to 0.89) in a random-effects meta-analysis of all eight studies. With respect to the geographical region, use of hypnotics was associated with a decreased risk or mortality of heart disease in Asia but not in Western countries. Among various types of sleep medications, zolpidem showed a decreased risk (-29%) of developing or dying from heart disease, but benzodiazepines were related with an increased risk (80%) of or mortality from heart disease.

CONCLUSIONS

The current meta-analysis of observational epidemiological studies suggested an evidence of association between hypnotics use and a decreased risk of heart disease.

Tranquilizer misuse among active cocaine users: Predictors of initiation

INTRODUCTION AND AIMS

Tranquilizer use is associated with negative health outcomes among people who use drugs. This paper aims to estimate the incidence rate (initiation) and identify predictors of tranquilizer misuse (TM) among cocaine users.

DESIGN AND METHODS

A prospective cohort study was conducted in Montreal, Canada. Interviewer-administered questionnaires were carried out at 3-month intervals. Initiation was defined as misusing a tranquilizer for the first time during follow-up. 'Lasting-initiation', defined as reporting TM at the next visit following first use, was also examined. Cox proportional hazard regression analyses were carried out to assess predictors of initiation to TM.

RESULTS

Among the 245 participants who were eligible for the initiation analyses, 123 started TM during follow-up for an incidence rate of 40.49 per 100 person-years (95% confidence interval, CI: 33.80-48.15). Of the 123 initiates, 35.7% were still using at the interview following initiation for an incidence rate of 14.70 per 100 person-years (95% CI: 10.82-19.56). Multivariate models showed that independent predictors of initiation and 'lasting initiation' were identical as having had a criminal activity as the main source of income, having been recently in treatment for a substance use disorder (SUD) and reporting non-medical use of prescription opioids.

DISCUSSION AND CONCLUSIONS

The incidence rate of TM initiation was high among a sample of cocaine users. Initiation was predicted by a problematic drug use pattern involving polydrug use, involvement in the street economy and having been in treatment for a SUD. These findings have implications for prevention and harm reduction strategies.

Prevalence and correlates of benzodiazepine use and misuse among young adults who use prescription opioids non-medically

BACKGROUND

Benzodiazepine use dramatically increases the risk of unintentional overdose among people who use opioids non-medically. However, little is known about the patterns of co-occurring benzodiazepine and opioid use among young adults in the United States.

METHODS

The Rhode Island Young Adult Prescription Drug Study (RAPiDS) was a cross-sectional study from January 2015-February 2016. RAPiDS recruited 200 young adults aged 18-29 who reported past 30-day non-medical prescription opioid (NMPO) use. Using Wilcoxon rank sum test and Fisher's exact test, we examined correlates associated with regular prescribed and non-medical use (defined as at least monthly) of benzodiazepines among NMPO users in Rhode Island.

RESULTS

Among participants, 171 (85.5%) reported lifetime benzodiazepine use and 125 (62.5%) reported regular benzodiazepine use. Nearly all (n=121, 96.8%) reported non-medical use and 43 (34.4%) reported prescribed use. Compared to the 75 participants who did not regularly use benzodiazepines, participants who reported regular use were more likely to be white (66.3% vs. 58.0%, p=0.03), have ever been incarcerated (52.8% vs. 37.3%, p=0.04), and have ever been diagnosed with a psychiatric disorder (bipolar: 29.6% vs. 16.0%, p=0.04; anxiety: 56.8 vs. 36.0%, p=0.01). Although the association was marginally significant, accidental overdose was higher among those who were prescribed the benzodiazepine they used most frequently compared to those who were not (41.9% vs. 24.4%, p=0.06).

CONCLUSION

Benzodiazepine use and misuse are highly prevalent among young adult NMPO users. Harm reduction and prevention programs for this population are urgently needed.

Increasing availability of benzodiazepines among people who inject drugs in a Canadian setting

BACKGROUND

Benzodiazepine misuse is associated with mortality and is common among people who inject drugs (PWID). This study aimed to examine the temporal trends in the availability of benzodiazepines among PWID in a Canadian setting, and to identify factors associated with more immediate access to benzodiazepines.

METHODS

Data were derived from 3 prospective cohorts of PWID in Vancouver, Canada, between June 2012 and May 2015. The primary outcome was the perceived availability of benzodiazepines, measured in 3 levels: not available, delayed availability (available in ≥10 minutes), and immediate availability (available in <10 minutes). The authors used multivariable generalized estimating equations to identify factors associated with availability of benzodiazepines.

RESULTS

In total, 1641 individuals were included in these analyses. In multivariable analyses, factors associated with immediate benzodiazepine availability included incarceration (adjusted odds ratio [AOR]: 1.42, 95% confidence interval [CI]: 1.06, 1.89) and participation in methadone maintenance therapy (MMT) (AOR: 1.35, 95% CI: 1.14, 1.60). Factors associated with delayed benzodiazepine availability included incarceration (AOR: 1.45, 95% CI: 1.02, 2.07) and participation in MMT (AOR: 1.77, 95% CI: 1.48, 2.12). Benzodiazepine availability increased throughout the study period for both immediate (AOR: 1.14, 95% CI: 1.10, 1.18 per 6-month follow-up period) and delayed (AOR: 1.17, 95% CI: 1.12, 1.22 per 6-month follow-up period) availability.

CONCLUSIONS

Among our sample of PWID, benzodiazepine availability is increasing and was associated with health and criminal justice system characteristics. Our findings indicate a need to examine prescribing practices and educate both PWID and health care providers about the risks associated with benzodiazepine use.

Declining rates of health problems associated with crack smoking during the expansion of crack pipe distribution in Vancouver, Canada

Background

Crack cocaine smoking is associated with an array of negative health consequences, including cuts and burns from unsafe pipes, and infectious diseases such as HIV. Despite the well-established and researched harm reduction programs for injection drug users, little is known regarding the potential for harm reduction programs targeting crack smoking to reduce health problems from crack smoking. In the wake of recent crack pipe distribution services expansion, we utilized data from long running cohort studies to estimate the impact of crack pipe distribution services on the rates of health problems associated with crack smoking in Vancouver, Canada.

Methods

Data were derived from two prospective cohort studies of community-recruited people who inject drugs in Vancouver between December 2005 and November 2014. We employed multivariable generalized estimating equations to examine the relationship between crack pipe acquisition sources and self-reported health problems associated with crack smoking (e.g., cut fingers/sores, coughing blood) among people reported smoking crack.

Results

Among 1718 eligible participants, proportions of those obtaining crack pipes only through health service points have significantly increased from 7.2% in 2005 to 62.3% in 2014 (p < 0.001), while the rates of reporting health problems associated with crack smoking have significantly declined (p < 0.001). In multivariable analysis, compared to those obtaining pipes only through other sources (e.g., on the street, self-made), those acquiring pipes through health service points only were significantly less likely to report health problems from smoking crack (adjusted odds ratio: 0.82; 95% confidence interval: 0.73–0.93).

Conclusions

These findings suggest that the expansion of crack pipe distribution services has likely served to reduce health problems from smoking crack in this setting. They provide evidence supporting crack pipe distribution programs as a harm reduction service for crack smokers.

Use of benzodiazepine and risk of cancer: A meta-analysis of observational studies

Several observational epidemiological studies have reported inconsistent results on the association between the use of benzodiazepine and the risk of cancer. We investigated the association by using a meta-analysis. We searched PubMed, EMBASE, and the bibliographies of relevant articles to locate additional publications in January 2016. Three evaluators independently reviewed and selected eligible studies based on predetermined selection criteria. Of 796 articles meeting our initial criteria, a total of 22 observational epidemiological studies with 18 case-control studies and 4 cohort studies were included in the final analysis. Benzodiazepine use was significantly associated with an increased risk of cancer (odds ratio [OR] or relative risk [RR] 1.19; 95% confidence interval 1.16-1.21) in a random-effects meta-analysis of all studies. Subgroup meta-analyses by various factors such as study design, type of case-control study, study region, and methodological quality of study showed consistent findings. Also, a significant dose-response relationship was observed between the use of benzodiazepine and the risk of cancer (p for trend <0.01). The current meta-analysis of observational epidemiological studies suggests that benzodiazepine use is associated with an increased risk of cancer.