Irfan A Dhalla

Institute for Clinical Evaluative Sciences, Toronto, Ontario, Canada

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Publications (63)382.01 Total impact

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    ABSTRACT: Hospital readmissions are common and costly, and no single intervention or bundle of interventions has reliably reduced readmissions. Virtual wards, which use elements of hospital care in the community, have the potential to reduce readmissions, but have not yet been rigorously evaluated.
    JAMA The Journal of the American Medical Association 10/2014; 312(13):1305-1312. · 30.39 Impact Factor
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    ABSTRACT: The increased use of opioid analgesics, sedative hypnotics and stimulants, coupled with the associated risks of overdose have raised concerns around the inappropriate prescribing of these monitored drugs. We assessed the impact of new legislation, the Narcotics Safety and Awareness Act, and a centralized Narcotics Monitoring System (implemented November 2011 and May 2012, respectively), on the dispensing of prescriptions suggestive of misuse. We conducted a time series analysis of publicly funded prescriptions for opioids, benzodiazepines and stimulants dispensed monthly in Ontario from January 2007 to May 2013, based on information in the Ontario Public Drug Benefit Database. In the primary analysis, a prescription was deemed potentially inappropriate if it was dispensed within 7 days of an earlier prescription and was for at least 30 tablets of a drug in the same class as the earlier prescription, but originated from a different physician and a different pharmacy. After enactment of the new legislation, the prevalence of potentially inappropriate opioid prescriptions decreased by 12.5% in 6 months (from 1.6% in October 2011 to 1.4% in April 2012; p = 0.01). No further significant change was observed after the introduction of the narcotic monitoring system (p = 0.8). By May 2013, the prevalence had dropped to 1.0%. Inappropriate benzodiazepine prescribing was significantly influenced by both the legislation (p < 0.001) and the monitoring system (p = 0.05), which together reduced potentially inappropriate prescribing by 50.0% between October 2011 and May 2013 (from 0.4% to 0.2%). The prevalence of potentially inappropriate prescribing of stimulants was significantly influenced by the introduction of the monitoring system in May 2012, falling from 0.7% in April 2012 to 0.3% in May 2013 (p = 0.02). For a select group of drugs prone to misuse and diversion, legislation and a prescription monitoring program reduced the prevalence of prescriptions suggestive of misuse. This suggests that regulatory interventions can promote appropriate prescribing which could potentially be applied to other jurisdictions and drugs of concern.
    CMAJ open. 10/2014; 2(4):E256-E261.
  • Irfan A Dhalla, Sumit R Majumdar
    Journal of General Internal Medicine 09/2014; · 3.42 Impact Factor
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    ABSTRACT: Harms associated with prescription opioids are a major and increasing public health concern. Prescribing of opioids for inpatients may contribute to the problem, especially if primary care practitioners continue opioid therapy that is initiated in hospital.
    The Canadian journal of hospital pharmacy 09/2014; 67(5):337-42.
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    ABSTRACT: To describe trends in rates of prescribing of high-dose opioid formulations and variations in opioid product selection across Canada.
    Canadian family physician Médecin de famille canadien. 09/2014; 60(9):826-32.
  • Michael Law, Jillian Kratzer, Irfan Dhalla
    Canadian Medical Association Journal 07/2014; 186(10):779. · 5.81 Impact Factor
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    ABSTRACT: Background and AimsThe burden of premature mortality due to opioid-related death has not been fully characterized. We calculated temporal trends in the proportion of deaths attributable to opioids and estimated years of potential life lost (YLL) due to opioid-related mortality in Ontario, Canada.DesignCross-sectional study.SettingOntario, Canada.ParticipantsIndividuals who died of opioid-related causes between January 1991 and December 2010.MeasurementsWe used the Registered Persons Database and data abstracted from the Office of the Chief Coroner to measure annual rates of opioid-related mortality. The proportion of all deaths related to opioids was determined by age group in each of 1992, 2001 and 2010. The YLL due to opioid-related mortality were estimated, applying the life expectancy estimates for the Ontario population.FindingsWe reviewed 5935 opioid-related deaths in Ontario between 1991 and 2010. The overall rate of opioid-related mortality increased by 242% between 1991 (12.2 per 1 000 000 Ontarians) and 2010 (41.6 per 1 000 000 Ontarians; P < 0.0001). Similarly, the annual YLL due to premature opioid-related death increased threefold, from 7006 years (1.3 years per 1000 population) in 1992 to 21 927 years (3.3 years per 1000 population) in 2010. The proportion of deaths attributable to opioids increased significantly over time within each age group (P < 0.05). By 2010, nearly one of every eight deaths (12.1%) among individuals aged 25–34 years was opioid-related.Conclusions Rates of opioid-related deaths are increasing rapidly in Ontario, Canada, and are concentrated among the young, leading to a substantial burden of disease.
    Addiction 07/2014; · 4.60 Impact Factor
  • Reena Pattani, Peter E Wu, Irfan A Dhalla
    Canadian Medical Association Journal 05/2014; 186(10). · 5.81 Impact Factor
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    ABSTRACT: Guidance regarding appropriate and cost-effective use of prescription drugs is published in the Ontario Drug Benefit Formulary in the form of "therapeutic notes." We conducted a cross-sectional study of all residents of Ontario aged 66 and older who received a new prescription for one of two drugs, aliskiren or sitagliptin, between December 1, 2008 and March 31, 2012 to determine how frequently such guidance is followed. Approximately half of initial prescriptions for aliskiren and sitagliptin were prescribed in a manner that did not conform to the therapeutic note recommendations (51.4% and 49.3%, respectively). Given this high rate of non-conformance, policy makers may wish to use other mechanisms to influence prescriber behaviour to improve the quality and efficiency of healthcare.
    05/2014; 9(4):20-30.
  • Michael R Law, Jillian Kratzer, Irfan A Dhalla
    Canadian Medical Association Journal 03/2014; · 5.81 Impact Factor
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    ABSTRACT: The Toronto Central Community Care Access Centre is leading a collaborative local health integration network systemic change initiative to implement and evaluate a practical model of integrated care for older adults with complex needs. The approach is embedded in the community where older adults and their families live and is designed to first and foremost improve the quality of care while ultimately bending the cost curve. The model is leveraging and aligning existing system resources by bringing together sectors from across the health system to create ways of working that build capacity in the system to be more responsive to this population. Outcomes to date will be discussed and next steps described. The secondary goal was to understand the key elements of this integration that can be scaled locally and across the province. Copyright © 2014 Longwoods Publishing.
    Healthcare quarterly (Toronto, Ont.) 01/2014; 17(3):61-9.
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    ABSTRACT: Generic drugs offer a less expensive and therapeutically equivalent alternative to brand name drugs. Nevertheless, many Canadian private drug plans continue to pay for brand name drugs even after generics become available. The objective of this study was to quantify the excess spending resulting from this practice. We used the IMS Brogan PharmaStat database to study private-plan drug spending in Ontario from 2000 to 2009. We focused on three widely used drug classes: proton pump inhibitors (PPIs), selective serotonin reuptake inhibitors (SSRIs), and angiotensin-converting enzyme (ACE) inhibitors. For each specific molecule, we determined the difference between what private plans spent on the brand name version and what would have been spent if an available generic version of the same molecule had been purchased instead. We found that prescriptions paid for by private drug plans were often filled with brand name drugs after generics became available. This led to excess private spending of more than Can$107.8 million for these three drug classes over our study period: Can$54.4 million for PPIs, Can$32.4 million for SSRIs and Can$21.0 million for ACE inhibitors. Brand name drugs continue to be reimbursed by Canadian private drug plans at higher prices even after less expensive generic alternatives are available. By mandating generic substitution, substantial cost savings on benefit plans could be achieved.
    Applied Health Economics and Health Policy 08/2013;
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    ABSTRACT: Most evaluative research is focused on assessing new technologies at the patient level. Comparatively little is focused on assessing how system changes could improve the delivery of healthcare. In this article, the authors describe an opportunity to conduct evaluative trials of system changes affordably and efficiently by using a cluster randomized design and mandatory reporting data, using the prevention of Clostridium difficile infection as an example. They then describe what must be done to make similar trials a regular tool of healthcare policy.
    Healthcare quarterly (Toronto, Ont.) 07/2013; 16(3):22-6.
  • Annals of internal medicine 06/2013; 158(12):923-4. · 16.10 Impact Factor
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    ABSTRACT: Medication non-adherence frequently leads to suboptimal patient outcomes. Primary non-adherence, which occurs when a patient does not fill an initial prescription, is particularly important at the time of hospital discharge because new medications are often being prescribed to treat an illness rather than for prevention. We studied older adults consecutively discharged from a general internal medicine service at a large urban teaching hospital to determine the prevalence of primary non-adherence and identify characteristics associated with primary non-adherence. We reviewed electronic prescriptions, electronic discharge summaries and pharmacy dispensing data from April to August 2010 for drugs listed on the public formulary. Primary non-adherence was defined as failure to fill one or more new prescriptions after hospital discharge. In addition to descriptive analyses, we developed a logistical regression model to identify patient characteristics associated with primary non-adherence. There were 493 patients eligible for inclusion in our study, 232 of whom were prescribed new medications. In total, 66 (28%) exhibited primary non-adherence at 7 days after discharge and 55 (24%) at 30 days after discharge. Examples of medications to which patients were non-adherent included antibiotics, drugs for the management of coronary artery disease (e.g. beta-blockers, statins), heart failure (e.g. beta-blockers, angiotensin converting enzyme inhibitors, furosemide), stroke (e.g. statins, clopidogrel), diabetes (e.g. insulin), and chronic obstructive pulmonary disease (e.g. long-acting bronchodilators, prednisone). Discharge to a nursing home was associated with an increased risk of primary non-adherence (OR 2.25, 95% CI 1.01-4.95). Primary non-adherence after medications are newly prescribed during a hospitalization is common, and was more likely to occur in patients discharged to a nursing home.
    PLoS ONE 05/2013; 8(5):e61735. · 3.53 Impact Factor
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    ABSTRACT: OBJECTIVE: To examine the effects of an intensive 2-day course on physicians' prescribing of opioids. DESIGN: Population-based retrospective observational study. SETTING: College of Physicians and Surgeons of Ontario (CPSO) in Toronto. PARTICIPANTS: Ontario physicians who took the course between April 1, 2000, and May 30, 2008. INTERVENTION: A 2-day opioid-prescribing course with a maximum of 12 physician participants. Educational methods included didactic presentations, case discussions, and standardized patients. A detailed syllabus and office materials were provided. MAIN OUTCOME MEASURES: Participants were matched with control physicians using specific variables. The primary outcome was the rate of opioid prescribing, expressed as milligrams of morphine equivalent per quarter. RESULTS: One hundred thirty-eight course participants (120 family physicians, 15 specialists, and 3 physicians whose status was uncertain) were eligible for analysis. Of these, 68.1% were self-referred and 31.9% were referred by the CPSO. Overall, among physicians referred by the CPSO, the rate of opioid prescribing decreased dramatically in the year before course participation compared with matched control physicians. The course had no added effect on the rate of physicians' opioid prescribing in the subsequent 2 years. There was no statistically significant effect on the rate of opioid prescribing observed among the self-referred physicians. Among 15 of the self-referred physicians who, owing to the high quantities of opioids they prescribed, were not matched with control physicians, the rate of opioid prescribing decreased by 43.9% in the year following course completion. CONCLUSION: Physicians markedly reduced the quantities of opioids they prescribed after medical regulators referred them to an opioid-prescribing course. The course itself did not lead to significant additional reductions; however, a subgroup of physicians who prescribed high quantities of opioids might have responded to what was taught in the course.
    Canadian family physician Medecin de famille canadien 05/2013; 59(5):e231-e239. · 1.19 Impact Factor
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    ABSTRACT: Background: Some evidence suggests that chlorthalidone may be superior to hydrochlorothiazide for the treatment of hypertension. Objective: To compare the effectiveness and safety of chlorthalidone and hydrochlorothiazide in older adults. Design: Propensity score–matched observational cohort study with up to 5 years of follow-up. Setting: Ontario, Canada. Patients: All individuals aged 66 years or older who were newly treated with chlorthalidone or hydrochlorothiazide and were not hospitalized for heart failure, stroke, or myocardial infarction in the prior year were eligible for inclusion. Each chlorthalidone recipient was matched to up to 2 hydrochlorothiazide recipients on the basis of age, sex, year of treatment initiation, and propensity score. Measurements: The primary outcome was a composite of death or hospitalization for heart failure, stroke, or myocardial infarction. Safety outcomes included hospitalization with hypokalemia or hyponatremia. Results: A total of 29 873 patients were studied. During follow-up, chlorthalidone recipients (n = 10 384) experienced the primary outcome at a rate of 3.2 events per 100 person-years of follow-up, and hydrochlorothiazide recipients experienced 3.4 events per 100 person-years of follow-up (adjusted hazard ratio, 0.93 [95% CI, 0.81 to 1.06]). Patients treated with chlorthalidone were more likely to be hospitalized with hypokalemia (adjusted hazard ratio, 3.06 [CI, 2.04 to 4.58]) or hyponatremia (adjusted hazard ratio, 1.68 [CI, 1.24 to 2.28]). In 9 post hoc analyses comparing patients initially prescribed 12.5, 25, or 50 mg of chlorthalidone per day with those prescribed 12.5, 25, or 50 mg of hydrochlorothiazide per day, the former were more likely to be hospitalized with hypokalemia for all 6 comparisons in which a statistically significant association was found. The results of other effectiveness and safety outcomes were also consistent with those of the main analysis. Limitation: Unmeasured differences in baseline characteristics or physician treatment approaches or an insufficiently large sample may have limited the ability to detect small differences in the comparative effectiveness of the drugs. Conclusion: As typically prescribed, chlorthalidone in older adults was not associated with fewer adverse cardiovascular events or deaths than hydrochlorothiazide. However, it was associated with a greater incidence of electrolyte abnormalities, particularly hypokalemia. Primary Funding Source: Ontario Ministry of Health and Long-Term Care.
    Annals of internal medicine 03/2013; 158(6):447-455. · 16.10 Impact Factor
  • David N Juurlink, Irfan A Dhalla, Lewis S Nelson
    JAMA The Journal of the American Medical Association 03/2013; 309(9):879-80. · 29.98 Impact Factor
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    ABSTRACT: BACKGROUND Use of opioids may predispose drivers to road trauma, yet the effect of opioid dose on this association is unknown. METHODS We conducted a population-based nested case-control study of patients aged 18 to 64 years who received at least 1 publicly funded prescription for an opioid from April 1, 2003, through March 31, 2011. Cases were defined as having an emergency department visit related to road trauma. Patients without road trauma served as a control group matched to cases by age, sex, index year, prior road trauma, and a disease risk index. We compared the risk of road trauma among patients treated with doses of opioids ranging from very low to very high (<20 to ≥200 morphine equivalents daily). In a subgroup analysis, we stratified our analysis by driver status. RESULTS Among 549 878 eligible adults, we identified 5300 cases with road trauma and matched an equal number of controls. Multivariate adjustment yielded no significant association between escalating opioid dose and odds of road trauma (adjusted odds ratio ranged between 1.00 and 1.09). However, a significant association between opioid dose and road trauma was observed among drivers. Compared with very low opioid doses, drivers prescribed low doses had a 21% increased odds of road trauma (adjusted odds ratio, 1.21 [95% CI, 1.02-1.42]); those prescribed moderate doses, 29% increased odds (1.29 [1.06-1.57]); those prescribed high doses, 42% increased odds (1.42 [1.15-1.76]); and those prescribed very high doses, 23% increased odds (1.23 [1.02-1.49]). CONCLUSIONS Among drivers prescribed opioids, a significant relationship exists between drug dose and risk of road trauma. This association is distinct and does not appear with passengers, pedestrians, and others injured in road trauma.
    JAMA Internal Medicine 01/2013; · 13.25 Impact Factor
  • Noah Ivers, Irfan A Dhalla, G Michael Allan
    Canadian family physician Medecin de famille canadien 12/2012; 58(12):e708. · 1.19 Impact Factor

Publication Stats

718 Citations
382.01 Total Impact Points


  • 2012–2014
    • Institute for Clinical Evaluative Sciences
      Toronto, Ontario, Canada
    • Queen's University
      • Department of Ophthalmology
      Kingston, Ontario, Canada
  • 2002–2014
    • University of Toronto
      • Department of Medicine
      Toronto, Ontario, Canada
  • 2013
    • Women's College Hospital
      Toronto, Ontario, Canada
  • 2009–2012
    • St. Michael's Hospital
      Toronto, Ontario, Canada
  • 2011
    • Sunnybrook Health Sciences Centre
      Toronto, Ontario, Canada
  • 2010
    • University of Alberta
      • Faculty of Medicine and Dentistry
      Edmonton, Alberta, Canada