Michael Paterson - Profile on Academia.edu (original) (raw)

Papers by Michael Paterson

Fracture Risk in Patients with Myasthenia Gravis: A Population-Based Cohort Study

Journal of Neuromuscular Diseases, 2021

Background: Prednisone is a common treatment for myasthenia gravis (MG), and osteoporosis is a kn... more Background: Prednisone is a common treatment for myasthenia gravis (MG), and osteoporosis is a known potential risk of chronic prednisone therapy. Objective: Our aim was to evaluate the risk of serious fractures in a population-based cohort of MG patients. Methods: An inception cohort of patients with MG was identified from administrative health data in Ontario, Canada between April 1, 2002 and December 31, 2015. For each MG patient, we matched 4 general population comparators based on age, sex, and region of residence. Fractures were identified through emergency department and hospitalization data. Crude overall rates and sex-specific rates of fractures were calculated for the MG and comparator groups, as well as rates of specific fractures. Adjusted hazard ratios (HRs) and 95% confidence intervals (CIs) were estimated using Cox regression. Results: Among 3,823 incident MG patients (followed for a mean of 5 years), 188 (4.9%) experienced a fracture compared with 741 (4.8%) fracture...

The Journal of Rheumatology, 2020

Objective.To compare differences in clinical activity and remuneration between male and female rh... more Objective.To compare differences in clinical activity and remuneration between male and female rheumatologists and to evaluate associations between physician gender and practice sizes and patient volume, accounting for rheumatologists’ age, and calendar year effects.Methods.We conducted a population-based study in Ontario, Canada, between 2000 to 2015 identifying all rheumatologists practicing as full-time equivalents (FTEs) or above and assessed differences in practice sizes (number of unique patients), practice volumes (number of patient visits), and remuneration (total fee-for-service billings) between male and female rheumatologists. Multivariable linear regression was used to evaluate the effects of gender on practice size and volume separately, accounting for age and year.Results.The number of rheumatologists practicing at ≥ 1 FTE increased from 89 to 120 from 2000 to 2015, with the percentage of females increasing from 27.0% to 41.7%. Males had larger practice sizes and pract...

International Journal of Population Data Science, 2022

IntroductionHealth care systems have faced unprecedented challenges due to the COVID-19 pandemic.... more IntroductionHealth care systems have faced unprecedented challenges due to the COVID-19 pandemic. Access to timely population-based data has been vital to informing public health policy and practice. MethodsWe describe how ICES, an independent not-for-profit research and analytic institute in Ontario, Canada, pivoted existing research infrastructure and engaged health system stakeholders to provide near real-time population-based data and analytics to support Ontario's COVID-19 pandemic response. ResultsSince April 2020, ICES provided the Ontario COVID-19 Provincial Command Table and public health partners with regular and ad hoc reports on SARS-CoV-2 testing and COVID-19 vaccine coverage. These reports: 1) helped identify congregate care/shared living settings that needed testing and prevention efforts early in the pandemic; 2) provided early indications of inequities in testing and infection in marginalized neighbourhoods, including areas with higher proportions of immigrants ...

Open Medicine, 2012

Although administrative health care databases have long been used to evaluate adverse drug effect... more Although administrative health care databases have long been used to evaluate adverse drug effects, responses to drug safety signals have been slow and uncoordinated. We describe the establishment of the Canadian Network for Observational Drug Effect Studies (CNODES), a collaborating centre of the Drug Safety and Effectiveness Network (DSEN). CNODES is a distributed network of investigators and linked databases in British Columbia, Alberta, Saskatchewan, Manitoba, Ontario, Quebec and Nova Scotia. Principles of operation are as follows: (1) research questions are prioritized by the coordinating office of DSEN; (2) the linked data stay within the provinces; (3) for each question, a study team formulates a detailed protocol enabling consistent analyses in each province; (4) analyses are “blind” to results obtained elsewhere; (5) protocol deviations are permitted for technical reasons only; (6) analyses using multivariable methods are lodged centrally with a methods team, which is respo...

International Journal of Population Data Science, 2021

ICES upholds a strong reputation for generating high-quality evidence to inform policy and practi... more ICES upholds a strong reputation for generating high-quality evidence to inform policy and practice through its collaborations with a broad range of health system stakeholders including government policymakers and healthcare providers including clinicians. Supported by the Ontario Ministry of Health and Ministry of Long-Term Care, the ICES Applied Health Research Question (AHRQ) Program leverages the data holdings and, scientific and clinical expertise to generate evidence tailored to the information needs of requestors. This paper outlines the approach, process, strengths, challenges and the resulting influence and impact to the healthcare landscape in Ontario.

BMJ Surgery, Interventions, & Health Technologies, 2021

ObjectivesThis study aimed to identify a threshold in annual surgeon volume associated with incre... more ObjectivesThis study aimed to identify a threshold in annual surgeon volume associated with increased risk of revision (for any cause) and deep infection requiring surgery following primary elective total knee arthroplasty (TKA).DesignA propensity score matched cohort study.SettingOntario, Canada.Participants169 713 persons who received a primary TKA between 2002 and 2016, with 3-year postoperative follow-up.Main outcome measuresRevision arthroplasty (for any cause), and the occurrence of deep surgical infection requiring surgery.ResultsBased on restricted cubic spline analysis, the threshold for increased probability of revision and deep infection requiring surgery was <70 cases/year. After matching of 51 658 TKA recipients from surgeons performing <70 cases/year to TKA recipients from surgeons with greater than 70 cases/year, patients in the former group had a higher rate of revision (for any cause, 2.23% (95% Confidence Interval (CI) 1.39 to 3.07) vs 1.70% (95% CI 0.85 to 2...

Association Between Bariatric Surgery and All-Cause Mortality: A Population-Based Matched Cohort Study in a Universal Health Care System

Annals of Internal Medicine, 2020

BACKGROUND Mortality after bariatric surgery has been previously studied, but cohort selection bi... more BACKGROUND Mortality after bariatric surgery has been previously studied, but cohort selection bias, completeness of follow-up, and collection of confounders have limited the inference of results. OBJECTIVE To determine the association between bariatric surgery and all-cause mortality. DESIGN Population-based matched cohort study. SETTING Ontario, Canada. PARTICIPANTS 13 679 patients who underwent bariatric surgery from January 2010 to December 2016 and 13 679 matched nonsurgical patients. INTERVENTION Bariatric surgery. MEASUREMENTS The primary outcome was all-cause mortality, with cause-specific mortality as the secondary outcome. Patients were matched according to age, sex, body mass index, and diabetes duration. RESULTS 13 679 patients who underwent bariatric surgery were matched to 13 679 nonsurgical patients. After a median follow-up of 4.9 years, the overall mortality rate was 1.4% (n = 197) in the surgery group and 2.5% (n = 340) in the nonsurgery group, with a lower adjusted hazard ratio (HR) of overall all-cause mortality (HR, 0.68 [95% CI, 0.57 to 0.81]). Patients aged 55 years or older had an absolute risk reduction of 3.3% (CI, 2.3% to 4.3%), with a lower HR of mortality in the surgery group (HR, 0.53 [CI, 0.41 to 0.69]). Observed relative effects were similar across sex; however, the observed association in absolute terms was greater in men. Surgery also was associated with lower cardiovascular mortality (HR, 0.53 [CI, 0.34 to 0.84]) and lower cancer mortality (HR, 0.54 [CI, 0.36 to 0.80]). LIMITATION The observational design limits causal inference. CONCLUSION Bariatric surgery was associated with substantially lower all-cause, cardiovascular, and cancer mortality. The lowered observed mortality of surgery was significant across most subgroups. The largest absolute effects were for men and patients aged 55 years or older. PRIMARY FUNDING SOURCE Ontario Bariatric Network.

BMC Rheumatology, 2019

Background: Good communication is central to a high-quality consultation process. We assessed the... more Background: Good communication is central to a high-quality consultation process. We assessed the quality of referral information from primary care physicians (PCPs) to rheumatologists and the quality and timeliness of consultation letters from rheumatologists back to PCPs. Methods: We sampled referral letters between 2000 and 2013 from 168 PCPs and performed a retrospective chart review of 2430 patients referred to 146 rheumatologists. We assessed the completeness and timeliness of referral and consultation letters. Results: Osteoarthritis (n = 787, 32%) and systemic inflammatory rheumatic diseases (n = 745, 31%) comprised the top reasons for referral. Only 55% of referral letters summarized the patients' medical history. Referral letters provided some details of diagnostic tests (51% labs, 34% imaging) but there was underreporting of this information on referral letters. Almost all referral letters (92%) contained details of at least one patient symptom, with the most common complaint being joint pain (54%). Only half of all referral letters provided symptom duration. The PCP only stressed an urgent consultation among 211 patients (9%). Overall, 69% of consultation letters were returned to PCPs within 30 days of consultation visit. Conclusion: We found that basic items necessary for appropriate triage, including a description of symptoms or other relevant history and results of investigations were often lacking in referral letters. The delay of receipt of consultation letters may further represent a lost opportunity for coordination and continuity of care, and may affect the quality of care patients receive.

PLOS Medicine, 2017

Prescription opioid use is highly associated with risk of opioid-related death, with 1 of every 5... more Prescription opioid use is highly associated with risk of opioid-related death, with 1 of every 550 chronic opioid users dying within approximately 2.5 years of their first opioid prescription. Although gabapentin is widely perceived as safe, drug-induced respiratory depression has been described when gabapentin is used alone or in combination with other medications. Because gabapentin and opioids are both commonly prescribed for pain, the likelihood of co-prescription is high. However, no published studies have examined whether concomitant gabapentin therapy is associated with an increased risk of accidental opioidrelated death in patients receiving opioids. The objective of this study was to investigate whether co-prescription of opioids and gabapentin is associated with an increased risk of accidental opioid-related mortality. We conducted a population-based nested case-control study among opioid users who were residents of Ontario, Canada, between August 1, 1997, and December 31, 2013, using administrative databases. Cases, defined as opioid users who died of an opioid-related cause, were matched with up to 4 controls who also used opioids on age, sex, year of index date, history of chronic kidney disease, and a disease risk index. After matching, we included 1,256 cases and 4,619 controls. The primary exposure was concomitant gabapentin use in the 120 days preceding the index date. A secondary analysis characterized gabapentin dose as low (<900 mg daily), moderate (900 to 1,799 mg daily), or high (!1,800 mg daily). A sensitivity analysis examined the effect of concomitant nonsteroidal anti-inflammatory drug (NSAID) use in the

Comparing the contribution of prescribed opioids to opioid-related hospitalizations across Canada: A multi-jurisdictional cross-sectional study

Drug and alcohol dependence, Oct 1, 2018

The Canadian opioid crisis is a complex, multifaceted problem involving prescribed, diverted and ... more The Canadian opioid crisis is a complex, multifaceted problem involving prescribed, diverted and illicitly manufactured opioids. This study sought to characterize the contribution of prescribed opioids to opioid-related hospitalizations in Canada. We conducted a cross-sectional study of all individuals who were admitted to hospital for opioid toxicity in British Columbia (BC), Manitoba and Ontario between April 2015 and March 2016. We used prescription claims to ascertain active prescription opioid use at time of hospital admission. In secondary analyses, we defined recent opioid prescriptions as those that were dispensed in the 30 and 180 days up to and including admission, and the prevalence of active co-prescription of benzodiazepines with opioids at time of overdose. We identified 2599 instances of opioid toxicity over the study period. In BC, 34.1% of hospital visits for overdose occurred in people with an active opioid prescription, compared to 52.2% (47 of 90) in Manitoba and...

JAMA internal medicine, 2018

Overlapping surgery, also known as double-booking, refers to a controversial practice in which a ... more Overlapping surgery, also known as double-booking, refers to a controversial practice in which a single attending surgeon supervises 2 or more operations, in different operating rooms, at the same time. To determine if overlapping surgery is associated with greater risk for complications following surgical treatment for hip fracture and arthritis. This was a retrospective population-based cohort study in Ontario, Canada (population, 13.6 million), for the years 2009 to 2014. There was 1 year of follow-up. This study encompassed 2 large cohorts. The "hip fracture" cohort captured all persons older than 60 years who underwent surgery for a hip fracture during the study period. The "total hip arthroplasty" (THA) cohort captured all primary elective THA recipients for arthritis during the study period. We matched overlapping and nonoverlapping hip fractures by patient age, patient sex, surgical procedure (for the hip fracture cohort), primary surgeon, and hospital. P...

CMAJ open, Jan 22, 2017

In February 2012, a reformulated tamper-deterrent form of long-acting oxycodone, OxyNeo, was intr... more In February 2012, a reformulated tamper-deterrent form of long-acting oxycodone, OxyNeo, was introduced in Canada. We investigated the impact of the introduction of OxyNeo on patterns of opioid prescribing. We conducted population-based, cross-sectional analyses of opioid dispensing in Canada between 2008 and 2016. We estimated monthly community pharmacy dispensing of oral formulations of codeine, morphine, hydromorphone and oxycodone, and a transdermal formulation of fentanyl, and converted quantities to milligrams of morphine equivalents (MMEs) per 1000 population. We used time series analysis to evaluate the effect of the introduction of OxyNeo on these trends. National dispensing of long-acting opioids fell by 14.9% between February 2012 and April 2016, from 36 098 MMEs to 30 716 MMEs per 1000 population (p < 0.01). This effect varied across Canada and was largest in Ontario (reduction of 22.8%) (p = 0.01) and British Columbia (reduction of 30.0%) (p = 0.01). The national rat...

BMJ (Clinical research ed.), Jan 17, 2017

Objective To determine the safety of direct oral anticoagulant (DOAC) use compared with warfarin ... more Objective To determine the safety of direct oral anticoagulant (DOAC) use compared with warfarin use for the treatment of venous thromboembolism.Design Retrospective matched cohort study conducted between 1 January 2009 and 31 March 2016.Setting Community based, using healthcare data from six jurisdictions in Canada and the United States.Participants 59 525 adults (12 489 DOAC users; 47 036 warfarin users) with a new diagnosis of venous thromboembolism and a prescription for a DOAC or warfarin within 30 days of diagnosis.Main outcome measures Outcomes included hospital admission or emergency department visit for major bleeding and all cause mortality within 90 days after starting treatment. Propensity score matching and shared frailty models were used to estimate adjusted hazard ratios of the outcomes comparing DOACs with warfarin. Analyses were conducted independently at each site, with meta-analytical methods used to estimate pooled hazard ratios across sites.Results Of the 59 525...

Use of Sodium Glucose Cotransporter 2 Inhibitors in the Hands of Cardiologists: With Great Power Comes Great Responsibility

Circulation, Jan 13, 2016

The Cardiovascular Safety of Dutasteride

The Journal of Urology, 2017

Randomized controlled trials suggest an increased risk of heart failure with dutasteride, which i... more Randomized controlled trials suggest an increased risk of heart failure with dutasteride, which inhibits both the type 1 and type 2 isoforms of 5-α reductase. In contrast, no such association has been suggested for finasteride, which selectively inhibits the type 2 isoform. We investigated the risk of cardiovascular events among patients receiving dutasteride relative to finasteride. Population-based cohort study of Ontario men aged 66 years or older who commenced treatment with dutasteride or finasteride between October 1, 2005 and March 31, 2015. For each individual treated with dutasteride, we identified one treated with finasteride, matching on a propensity score and calendar quarter of treatment initiation to account for temporal changes in prescribing. The primary outcome was hospitalization for heart failure; secondary analyses examined acute myocardial infarction and stroke. Cox proportional hazards regression was used to adjust for differences between groups. We studied 36,311 men who commenced dutasteride and 36,311 treated with finasteride. In the primary analysis, we found no difference in the risk of heart failure among patients receiving dutasteride relative to those receiving finasteride (adjusted hazard ratio 0.98, 95% confidence interval 0.88 to 1.08). Similarly, we found no difference in the risk of acute myocardial infarction (hazard ratio 0.94, 95% confidence interval 0.82 to 1.08) or stroke (hazard ratio 1.03, 95% confidence interval 0.88 to 1.20). In this population-based cohort study of more than 72,000 older men, dutasteride was not associated with an increased risk of cardiovascular events relative to finasteride.

Clinical journal of the American Society of Nephrology : CJASN, Jan 27, 2016

Assisted peritoneal dialysis is a treatment option for individuals with barriers to self-care who... more Assisted peritoneal dialysis is a treatment option for individuals with barriers to self-care who wish to receive home dialysis, but previous research suggests that this treatment modality is associated with a higher rate of hospitalization. The objective of our study was to determine whether assisted peritoneal dialysis has a different rate of hospital days compared to in-center hemodialysis. We conducted a multicenter, retrospective cohort study by linking a quality assurance dataset to administrative health data in Ontario, Canada. Subjects were accrued between January 1, 2004 and July 9, 2013. Individuals were grouped into assisted peritoneal dialysis (family or home care assisted) or in-center hemodialysis on the basis of their first outpatient dialysis modality. Inverse probability of treatment weighting using a propensity score was used to create a sample in which the baseline covariates were well balanced. The study included 872 patients in the in-center hemodialysis group a...

JAMA internal medicine, 2016

The association between incretin-based drugs, such as dipeptidyl peptidase 4 (DPP-4) inhibitors a... more The association between incretin-based drugs, such as dipeptidyl peptidase 4 (DPP-4) inhibitors and glucagon-like peptide 1 (GLP-1) agonists, and acute pancreatitis is controversial. To determine whether the use of incretin-based drugs, compared with the use of 2 or more other oral antidiabetic drugs, is associated with an increased risk of acute pancreatitis. A large, international, multicenter, population-based cohort study was conducted using combined health records from 7 participating sites in Canada, the United States, and the United Kingdom. An overall cohort of 1 532 513 patients with type 2 diabetes initiating the use of antidiabetic drugs between January 1, 2007, and June 30, 2013, was included, with follow-up until June 30, 2014. Current use of incretin-based drugs compared with current use of at least 2 oral antidiabetic drugs. Nested case-control analyses were conducted including hospitalized patients with acute pancreatitis matched with up to 20 controls on sex, age, c...

CMAJ open

Recently, several new atypical antipsychotic agents have been introduced in Ontario, and regulato... more Recently, several new atypical antipsychotic agents have been introduced in Ontario, and regulatory warnings have been issued regarding use of atypical antipsychotics in older adults. We sought to establish the impact of newer atypical antipsychotics on prescribing rates and costs. We performed a population-based cross-sectional study of Ontario adults aged 65 years or more using atypical antipsychotics from Jan. 1, 2007, to Mar. 31, 2013. These people have universal access to publicly funded drugs through the Ontario Health Insurance Plan and the Ontario Drug Benefit. We conducted time-series analysis to assess the impact of the introduction of new atypical antipsychotics on rates of use of atypical antipsychotics and associated expenditures. Rates of atypical antipsychotic use increased following the introduction of new agents in 2009, from 27.6 users per 1000 older adults in the third quarter of 2009 to 29.1 users per 1000 older adults at the end of the study period (p = 0.04). A...

Thorax, 2016

Twitter Follow Mina Tadrous at @mina__t Contributors All authors were involved in the design, int... more Twitter Follow Mina Tadrous at @mina__t Contributors All authors were involved in the design, interpretation of results, writing, conceptualisation of recommendations and revision of the manuscript. MT, MK and TG were involved in the implementation of the study.

Journal of Pharmacy & Pharmaceutical Sciences, 2015

PURPOSE: To examine the association between the provision of professional pharmacy services (PPS)... more PURPOSE: To examine the association between the provision of professional pharmacy services (PPS) and patient complexity as determined by the number of distinct medications dispensed in Ontario. METHODS: We conducted a cross-sectional study among all individuals dispensed one or more medications under the Ontario Public Drug Program (OPDP) between April 1st, 2012 and March 31st, 2013. We compared characteristics of patients receiving 1 or more PPS to those receiving no PPS. To assess the relationship between patient complexity (as measured by the number of chronic medications dispensed) and receipt of PPS, we reported the number and proportion of patients eligible for Ontario Drug Benefits (ODB) who received a PPS within each patient complexity group, and compared these proportions using the Cochran-Armitage test. RESULTS: Over the 1-year study period, 27.1% (N = 799,674 of 2,946,183) of ODB beneficiaries received at least one professional pharmacy service. Among these services, mo...