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Michael Varenbut

Michael Varenbut
Canadian Addiction Treatment Centres

MD, CCFP, FCFP, DABSM, DABAM

About

47
Publications
6,886
Reads
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865
Citations
Additional affiliations
July 2005 - June 2013
University of Toronto
Position
  • Professor (Assistant)
July 2000 - June 2005
University of Toronto
Position
  • Lecturer

Publications

Publications (47)
Conference Paper
Objectives Without treatment opioid addiction can incur a substantial increase in mortality and risk for serious comorbidities such as HIV and hepatitis. Opioid substitution and antagonistic therapies (OSATs) are front-line treatments for opioid addiction. The emergence of multiple OSATs renders traditional meta-analysis of direct evidence from ran...
Article
Background Opioid use disorder (OUD) affects approximately 21.9 million people worldwide. This study aims to determine the association between age of onset of opioid use and comorbid disorders, both physical and psychiatric, in patients receiving methadone maintenance treatment (MMT) for OUD. Understanding this association may inform clinical pract...
Article
Full-text available
Background Cannabis will soon become legalized in Canada, and it is currently unclear how this will impact public health. Methadone maintenance treatment (MMT) is the most common pharmacological treatment for opioid use disorder (OUD), and despite its documented effectiveness, a large number of patients respond poorly and experience relapse to illi...
Article
Full-text available
Objective: Opioid use disorder has been declared a public health crisis across North America and opioid agonist therapy (OAT) is the standard of care for these patients. Despite the increasing adoption of telemedicine as a delivery method for OAT, its effectiveness has not yet been evaluated against traditional in-person treatment. This study comp...
Article
Background: Current tools such as the Maudsley Addiction Profile (MAP) exist to evaluate different facets of addiction severity, however these instruments have neither been designed for nor validated within patients on methadone maintenance treatment (MMT). Objectives: We aimed to provide a reliable tool to evaluate multiple domains of treatment re...
Data
Variable definitions. Current age (years) Current age of GENOA Participants This variable is measured as a continuous variable. Sex Biological sex This variable is measured as a dichotomous variables representing male or female categories Marital Status This variable identifies whether the participant is currently living with and participating in a...
Article
Introduction: Concomitant opioid abuse is a serious problem among patients receiving methadone maintenance treatment (MMT) for opioid use disorder. This is an exploratory study that aims to identify predictors of the length of time a patient receiving MMT for opioid use disorder remains abstinent (relapse-free). Methods: Data were collected from...
Article
Background: While chronic pain has been said to impact patient's response to methadone maintenance treatment for opioid dependence, the reported findings are inconsistent. These discrepancies may be a direct result of variations in the measurement of chronic pain or definitions of response to methadone treatment. The goal of this study is to evalu...
Article
Full-text available
Background: Chronic pain is implicated as a risk factor for illicit opioid use among patients with opioid addiction treated with methadone. However, there exists conflicting evidence that supports and refutes this claim. These discrepancies may stem from the large variability in pain measurement reported across studies. Objectives: We aim to det...
Article
Background The consequences of opioid relapse among patients being treated with opioid substitution treatment (OST) are serious and can result in abnormal cardiovascular function, overdose, and mortality. Chronic pain is a major risk factor for opioid relapse within the addiction treatment setting. There exist a number of opioid maintenance therapi...
Article
Background: The heritability of opioid use disorder has been widely investigated; however, the influence of specific genes on methadone treatment outcomes is not well understood. The association between response to methadone treatment and genes that are involved in substance use behaviors and reward mechanisms is poorly understood, despite evidenc...
Article
Full-text available
Background Despite the growing numbers of men and women with opioid use disorder in Canada, sex-specific issues in treatment have not been re-examined in the current population of patients with opioid addiction. We aimed to evaluate sex differences in substance use, health, and social functioning among men and women currently receiving methadone tr...
Chapter
The overall concept and aim of this chapter is to provide a basic sleep medicine “crash course,” with a specific goal of describing a practical approach to treating the patient population afflicted with substance dependence and concomitant sleep complaints. A sleep medicine overview will be provided, with specific emphasis on sleep physiology, noso...
Article
Full-text available
Eligibility criteria that result in the exclusion of a substantial number of patients from randomized trials jeopardize the generalizability of treatment effect to much of the clinical population. This is important when evaluating opioid substitution and antagonist therapies (OSATs), especially given the challenges associated with treating the opio...
Article
Full-text available
Background: Opioid use disorder is a serious international concern with limited treatment success. Men and women differ in their susceptibility to opioid use disorder and response to methadone treatment and can therefore benefit from sex-specific treatment. We performed a systematic review of the literature on outcomes of methadone maintenance tre...
Article
Full-text available
background: While a number of pharmacological interventions exist for the treatment of opioid use disorder, evidence evaluating the effect of pain on substance use behavior, attrition rate, and physical or mental health among these therapies has not been well established. We aim to evaluate these effects using evidence gathered from a systematic re...
Data
Full-text available
Table S1. Cross-sectional risk of bias assessment using national institute of health quality assessment tool for observational cohort and cross-sectional studies. Table S2. Newcastle ottawa scale risk of bias assessment for cohort studies. Table S3. Risk of bias assessment for randomized controlled trials using the cochrane risk of bias tool. Table...
Article
Full-text available
Whether used for pain management or recreation, opioids have a number of adverse effects including hormonal imbalances. These imbalances have been reported to primarily involve testosterone and affect both males and females to the point of interfering with successful treatment and recovery. We conducted a systematic review and meta-analysis to dete...
Article
Background: Chronic pain is the most commonly reported comorbidity among patients with opioid addiction receiving methadone maintenance treatment (MMT), with an estimated prevalence ranging between 30% and 55%. Evidence suggests that patients with comorbid pain are at high risk for poor treatment response, including continued illicit substance use....
Article
Full-text available
Background: Chronic pain is the most commonly reported comorbidity among patients with opioid addiction receiving methadone maintenance treatment (MMT), with an estimated prevalence ranging between 30% and 55%. Evidence suggests that patients with comorbid pain are at high risk for poor treatment response, including continued illicit substance use....
Article
Full-text available
Background Opioids are psychoactive analgesic drugs prescribed for pain relief and palliative care. Due to their addictive potential, effort and vigilance in controlling prescriptions is needed to avoid misuse and dependence. Despite the effort, the prevalence of opioid use disorder continues to rise. Opioid substitution therapies are commonly used...
Article
Full-text available
Sex hormones may have a role in the pathophysiology of substance use disorders, as demonstrated by the association between testosterone and addictive behaviour in opioid dependence. Although opioid use has been found to suppress testosterone levels in men and women, the extent of this effect and how it relates to methadone treatment for opioid depe...
Article
Full-text available
Introduction Treatment of opioid addiction with methadone is effective; however, it is known to produce interindividual variability. This may be influenced in part by genetic variants, which can increase the initial risk of developing opioid addiction as well as explain differences in response to treatment. This pilot study aimed to assess the feas...
Article
Full-text available
Introduction: Treatment of opioid addiction with methadone is effective; however, it is known to produce interindividual variability. This may be influenced in part by genetic variants, which can increase the initial risk of developing opioid addiction as well as explain differences in response to treatment. This pilot study aimed to assess the fea...
Article
Background: Methadone can prolong the QT interval, a precursor to ventricular dysrhythmias. Measurement of the QT interval can vary with intrinsic and extrinsic factors. Our objective was to assess the agreement and repeatability between different QT interval measurements. Methods: We recorded ECGs daily for five consecutive days from adults receiv...
Article
Objectives: To estimate the cost of providing methadone maintenance treatment in Ontario, Canada, from the perspective of the public payer. Methods: We analyzed a database of all patient clinic visits, laboratory tests for urine toxicology screening, and methadone scripts from a group of methadone clinics in Ontario. The database consisted of pa...
Article
Background: While there are significant harms and dangers associated with illicit methadone use, the exact scope of the problem is largely unknown. However, we do know that annual deaths from methadone are rising and the literature indicates that a significant number of these deaths are directly related to illicit methadone use. Given this, methado...
Article
This study sought to determine whether case management was positively associated with improved outcomes and treatment compliance in those enrolled in a methadone maintenance treatment (MMT) program. An intervention group (n = 396) received case management while the other group (n = 1308) did not. Total N = 1704. Statistically significant reductions...
Article
We sought to test the assumption that a low urine creatinine level is indicative of the presence of alcohol in the urine of patients prescribed methadone. This is a medical record review of 261,055 urine samples from approximately 6,000 patients prescribed methadone during a one-year period and for whom both urine creatinine and ethanol levels were...
Article
Substance abusers account for the largest number of hepatitis C infected cases in developed countries. We describe a care model for treating current or former substance abusers with antiviral therapy for hepatitis C virus (HCV) infection. The care model involved hepatitis nurses, a psychologist, infectious disease specialist and primary care physic...
Article
Full-text available
Screening for ethanol use amongst the methadone maintained population has been the subject of some debate over recent years. Of particular concern is the diagnostic value of self report of alcohol use in patients enrolled in a methadone maintenance program (MMTP). This study demonstrates unequivocally that denial of alcohol use by MMTP patients is...
Article
Full-text available
Methadone Maintenance Treatment (MMT) is among the most widely studied treatments for opiate dependence with proven benefits for patients and society. When misused, however, methadone can also be lethal. The issue of methadone diversion is a major concern for all MMT programs. A potential source for such diversion is from those MMT patients who rec...
Article
Full-text available
Alcohol use among Methadone Maintenance Treatment (MMT) patients poses a major health risk, exacerbates psychopathology, and increases the risk of death by accidental overdose. Despite these factors, screening for alcohol use remains underutilized in the methadone community. Utilizing a self-report screening measure - the Michigan Alcohol Screening...
Article
It is clear that information about sleeping problems in the substance-using population is murky and ambiguous. With such lack of clarity, assessment is really a process. Denial is a part of addiction and this works against the clinician, but engagement allows the denial to unravel in its own due time. When substance use is minimal and is not associ...
Article
Although the focus of this article is on the sleep problems of psychiatric disorders, the message is: Be comprehensive in assessment. Sometimes a thoughtful history can differentiate what is substance-induced and what is secondary to psychiatric illness. Obtaining a lifetime history of sleep can help determine that a primary sleep disorder preceded...
Article
Full-text available
Virtually all psychiatric and substance use disorders are associated with sleep disruption. Studies indicate that psychiatric disorders are related closely to chronic insomnia and that psychoactive substances have acute and chronic effects on sleep architecture. Several aspects of sleep are compromised in individuals taking these substances, rangin...
Article
This study examined the Anesthesia-Assisted Rapid Detoxification (AAROD) procedure and the measurement of withdrawal symptom severity within a 24-hour period. The Clinical Opiate Withdrawal Scale (COWS) was utilized at various time intervals, post detoxification. This study demonstrated that all of the patients who underwent the AAROD procedure had...
Article
Full-text available
This study examined the Anesthesia-Assisted Rapid Detoxification (AAROD) procedure and the measurement of withdrawal symptom severity within a 24-hour period. The Clinical Opiate Withdrawal Scale (COWS) was utilized at various time intervals, post detoxification. This study demonstrated that all of the patients who underwent the AAROD procedure had...
Article
Using the DSM-IV criteria for personality disorders, prevalence rates for these disorders were evaluated among methadone maintenance patients, with a psychometric test--the Millon Clinical Multiaxial Inventory (MCMI-III). We found that 77% of patients met the study criteria for at least one personality disorder. Of those who had a personality disor...

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Projects (2)
Project
Ongoing work on the GENOA research project