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Dive into the research topics where Mark Lowerison is active.

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Featured researches published by Mark Lowerison.


Pediatric Neurology | 2012

Prevalence of Tic Disorders: A Systematic Review and Meta-Analysis

Tristan Knight; Thomas Steeves; Lundy Day; Mark Lowerison; Nathalie Jette; Tamara Pringsheim

This study evaluated the prevalence of tic disorders. MEDLINE and EMBASE databases were searched, using terms specific to Tourette syndrome and tic disorders, for studies of incidence, prevalence, and epidemiology. Thirty-five studies reporting data from 1985-2011 on the incidence or prevalence of tic disorders in a defined population were included. One reported incidence, and 34 reported prevalence. Meta-analysis of 13 studies of children yielded a prevalence of Tourette syndrome at 0.77% (95% confidence interval, 0.39-1.51%). Prevalence is higher in boys: 1.06% of boys were affected (95% confidence interval, 0.54-2.09%) vs 0.25% of girls (95% confidence interval, 0.05-1.20%). Transient tic disorder comprised the most common tic disorder in children, affecting 2.99% (95% confidence interval, 1.60-5.61%). Meta-analysis of two studies assessing adults for Tourette syndrome revealed a prevalence of 0.05% (95% confidence interval, 0.03-0.08%). The prevalence of tic disorders was higher in all studies performed in special education populations. Tic disorders are more common in children than adults, in boys than girls, and in special education populations. Parents, educators, healthcare professionals, and administrators should be aware of the frequency with which tic disorders occur, and ensure proper access to appropriate care.


Circulation | 2016

Analysis of Workflow and Time to Treatment on Thrombectomy Outcome in the Endovascular Treatment for Small Core and Proximal Occlusion Ischemic Stroke (ESCAPE) Randomized, Controlled Trial

Bijoy K. Menon; Tolulope T. Sajobi; Yukun Zhang; Jeremy Rempel; Ashfaq Shuaib; John Thornton; David Williams; Daniel Roy; Alexandre Y. Poppe; Tudor G. Jovin; Biggya Sapkota; Blaise W. Baxter; Timo Krings; Frank L. Silver; Donald Frei; Christopher Fanale; Donatella Tampieri; Jeanne Teitelbaum; Cheemun Lum; Dar Dowlatshahi; Muneer Eesa; Mark Lowerison; Noreen Kamal; Andrew M. Demchuk; Michael D. Hill; Mayank Goyal

Background— The Endovascular Treatment for Small Core and Proximal Occlusion Ischemic Stroke (ESCAPE) trial used innovative imaging and aggressive target time metrics to demonstrate the benefit of endovascular treatment in patients with acute ischemic stroke. We analyze the impact of time on clinical outcome and the effect of patient, hospital, and health system characteristics on workflow within the trial. Methods and Results— Relationship between outcome (modified Rankin Scale) and interval times was modeled by using logistic regression. Association between time intervals (stroke onset to arrival in endovascular-capable hospital, to qualifying computed tomography, to groin puncture, and to reperfusion) and patient, hospital, and health system characteristics were modeled by using negative binomial regression. Every 30-minute increase in computed tomography-to-reperfusion time reduced the probability of achieving a functionally independent outcome (90-day modified Rankin Scale 0–2) by 8.3% (P=0.006). Symptom onset-to-imaging time was not associated with outcome (P>0.05). Onset-to-endovascular hospital arrival time was 42% (34 minutes) longer among patients receiving intravenous alteplase at the referring hospital (drip and ship) versus direct transfer (mothership). Computed tomography-to-groin puncture time was 15% (8 minutes) shorter among patients presenting during work hours versus off hours, 41% (24 minutes) shorter in drip-ship patients versus mothership, and 43% (22 minutes) longer when general anesthesia was administered. The use of a balloon guide catheter during endovascular procedures shortened puncture-to-reperfusion time by 21% (8 minutes). Conclusions— Imaging-to-reperfusion time is a significant predictor of outcome in the ESCAPE trial. Inefficiencies in triaging, off-hour presentation, intravenous alteplase administration, use of general anesthesia, and endovascular techniques offer major opportunities for improvement in workflow. Clinical Trial Registration— URL: http://www.clinicaltrials.gov. Unique identifier: NCT01778335.


Journal of Clinical Epidemiology | 2016

Registry-based randomized controlled trials- what are the advantages, challenges, and areas for future research?

Guowei Li; Tolulope T. Sajobi; Bijoy K. Menon; Lawrence Korngut; Mark Lowerison; Matthew T. James; Stephen B. Wilton; Tyler Williamson; Stephanie J. Gill; Lauren L. Drogos; Eric E. Smith; Sunita Vohra; Michael D. Hill; Lehana Thabane

Registry-based randomized controlled trials are defined as pragmatic trials that use registries as a platform for case records, data collection, randomization, and follow-up. Recently, the application of registry-based randomized controlled trials has attracted increasing attention in health research to address comparative effectiveness research questions in real-world settings, mainly due to their low cost, enhanced generalizability of findings, rapid consecutive enrollment, and the potential completeness of follow-up for the reference population, when compared with conventional randomized effectiveness trials. However several challenges of registry-based randomized controlled trials have to be taken into consideration, including registry data quality, ethical issues, and methodological challenges. In this article, we summarize the advantages, challenges, and areas for future research related to registry-based randomized controlled trials.


Stroke | 2017

Early Trajectory of Stroke Severity Predicts Long-Term Functional Outcomes in Ischemic Stroke Subjects: Results From the ESCAPE Trial (Endovascular Treatment for Small Core and Anterior Circulation Proximal Occlusion With Emphasis on Minimizing CT to Recanalization Times).

Tolulope T. Sajobi; Bijoy K. Menon; Meng Wang; Oluwaseyi Lawal; Ashfaq Shuaib; David M. Williams; Alexandre Y. Poppe; Tudor G. Jovin; Leanne K. Casaubon; Thomas Devlin; Dar Dowlatshahi; Chris Fanale; Mark Lowerison; Andrew M. Demchuk; Mayank Goyal; Michael D. Hill

Background and Purpose— The trajectory of neurological improvement after stroke treatment is clinically likely to be an important prognostic signal. We compared the accuracy of early longitudinal National Institutes of Health Stroke Scale (NIHSS) measurement versus other early markers of stroke severity post treatment in predicting subjects’ 90-day stroke outcome. Methods— Data are from the Endovascular treatment for Small Core and Anterior circulation Proximal occlusion with ESCAPE trial (Endovascular Treatment for Small Core and Anterior Circulation Proximal Occlusion With Emphasis on Minimizing CT to Recanalization Times). Stroke severity was assessed at baseline, 1, 2, 5, 30, and 90 days. Subjects’ functional outcome was assessed using the modified Rankin Scale at baseline, 30 days, and 90 days. Group-based trajectory model was used to identify distinct subgroups of longitudinal trajectories of NIHSS measured over the first 2, 5, and 30 days. The accuracy of baseline NIHSS, infarct volume, 24-hour change in NIHSS, infarct volume, and disease severity trajectory subgroups in predicting 90-day stroke outcome were assessed using logistic regression analysis. Results— Group-based trajectory model of the 2-day longitudinal NIHSS data revealed 3 distinct subgroups of NIHSS trajectories—large improvement (41.6%), minimal improvement (31.1%), and no improvement (27.3%) subgroups. Individuals in the large improvement group were more likely were more likely to exhibit good outcomes after 90 days than those in the minimal improvement or no improvement subgroup. Among candidate predictors, the 2-day trajectory subgroup variable was the most accurate in predicting 90-day modified Rankin Scale at 84.5%. Conclusions— Early trajectory of neurological improvement defined by 2-day longitudinal NIHSS data predicts functional outcomes with greater accuracy than other common variables. Clinical Trial Registration— URL: http://www.clinicaltrials.gov. Unique identifier: NCT01778335.


JAMA Neurology | 2017

Association of Depression and Treated Depression With Epilepsy and Seizure Outcomes: A Multicohort Analysis

Colin B. Josephson; Mark Lowerison; Isabelle A. Vallerand; Tolulope T. Sajobi; Scott B. Patten; Nathalie Jette; Samuel Wiebe

Importance A bidirectional relationship exists between epilepsy and depression. However, any putative biological gradient between depression severity and the risk of epilepsy, and the degree to which depression mediates the influence of independent risk factors for epilepsy, has yet to be examined. Objective To determine the effect of depression on the risk of epilepsy and seizure outcomes. Design, Setting, and Participants An observational study of a population-based primary care cohort (all patients free of prevalent depression and epilepsy at 18-90 years of age who were active after the Acceptable Mortality Reporting date in The Health Improvement Network database) and a prospectively collected tertiary care cohort (all patients whose data were prospectively collected from the Calgary Comprehensive Epilepsy Programme). The analyses were performed on March 16, 2016. Main Outcome and Measures The hazard of developing epilepsy after incident depression and vice versa was calculated. In addition, a mediation analysis of the effect of depression on risk factors for epilepsy and the odds of seizure freedom stratified by the presence of depression were performed. Results We identified 10 595 709 patients in The Health Improvement Network of whom 229 164 (2.2%) developed depression and 97 177 (0.9%) developed epilepsy. The median age was 44 years (interquartile range, 32-58 years) for those with depression and 56 years (interquartile range, 43-71 years) for those with epilepsy. Significantly more patients with depression (144 373 [63%] were women, and 84 791 [37%] were men; P < .001) or epilepsy (54 419 [56%] were women, and 42 758 [44%] were men; P < .001) were female. Incident epilepsy was associated with an increased hazard of developing depression (hazard ratio [HR], 2.04 [95% CI, 1.97-2.09]; P < .001), and incident depression was associated with an increased hazard of developing epilepsy (HR, 2.55 [95% CI, 2.49-2.60]; P < .001) There was an incremental hazard according to depression treatment type with lowest risk for those receiving counselling alone (HR, 1.84 [95% CI, 1.30-2.59]; P < .001), an intermediate risk for those receiving antidepressants alone (HR, 3.43 [95% CI, 3.37-3.47]; P < .001), and the highest risk for those receiving both (HR, 9.85 [95% CI, 5.74-16.90]; P < .001). Furthermore, depression mediated the relationship between sex, social deprivation, and Charlson Comorbidity Index with incident epilepsy, accounting for 4.6%, 7.1%, and 20.6% of the total effects of these explanatory variables, respectively. In the Comprehensive Epilepsy Programme, the odds of failing to achieve 1-year seizure freedom were significantly higher for those with depression or treated depression. Conclusions and Relevance Common underlying pathophysiological mechanisms may explain the risk of developing epilepsy following incident depression. Treated depression is associated with worse epilepsy outcomes, suggesting that this may be a surrogate for more severe depression and that severity of depression is associated with severity of epilepsy.


Clinical and translational gastroenterology | 2016

The Association of Smoking and Surgery in Inflammatory Bowel Disease is Modified by Age at Diagnosis

Alexandra D. Frolkis; Jennifer de Bruyn; Nathalie Jette; Mark Lowerison; Jordan D. T. Engbers; William A. Ghali; James D. Lewis; Isabelle A. Vallerand; Scott B. Patten; Bertus Eksteen; Cheryl Barnabe; Remo Panaccione; Subrata Ghosh; Samuel Wiebe; Gilaad G. Kaplan

Objectives:We assessed the association of smoking at diagnosis of inflammatory bowel disease (IBD) on the need for an intestinal resection.Methods:The Health Improvement Network was used to identify an inception cohort of Crohn’s disease (n=1519) and ulcerative colitis (n=3600) patients from 1999–2009. Poisson regression explored temporal trends for the proportion of newly diagnosed IBD patients who never smoked before their diagnosis and the risk of surgery within 3 years of diagnosis. Cox proportional hazard models assessed the association between smoking and surgery, and effect modification was explored for age at diagnosis.Results:The rate of never smokers increased by 3% per year for newly diagnosed Crohn’s disease patients (incidence rate ratio (IRR) 1.03; 95% confidence interval (CI): 1.02–1.05), but not for ulcerative colitis. The rate of surgery decreased among Crohn’s disease patients aged 17–40 years (IRR 0.96; 95% CI: 0.93–0.98), but not for ulcerative colitis. Smoking at diagnosis increased the risk of surgery for Crohn’s disease patients diagnosed after the age of 40 (hazard ratio (HR) 2.99; 95% CI: 1.52–5.92), but not for those diagnosed before age 40. Ulcerative colitis patients diagnosed between the ages of 17 and 40 years and who quit smoking before their diagnosis were more likely to undergo a colectomy (ex-smoker vs. never smoker: HR 1.66; 95% CI: 1.04–2.66). The age-specific findings were consistent across sensitivity analyses for Crohn’s disease, but not ulcerative colitis.Conclusions:In this study, the association of smoking and surgical resection was dependent on the age at diagnosis of IBD.


Epilepsia | 2015

Correlates of disability related to seizures in persons with epilepsy

Tolulope T. Sajobi; Nathalie Jette; Kirsten M. Fiest; Scott B. Patten; Jordan D. T. Engbers; Mark Lowerison; Samuel Wiebe

Seizure‐related disability is an important contributor to health‐related quality of life in persons with epilepsy. Yet, there is little information on patient‐centered reports of seizure‐related disability, as most studies focus on specific constructs of health‐related disability, rather than epilepsy. We investigated how patients rate their own disability and how these ratings correlate with various clinical and sociodemographic characteristics.


The American Journal of Gastroenterology | 2018

A Randomized Trial Comparing High Definition Colonoscopy Alone With High Definition Dye Spraying and Electronic Virtual Chromoendoscopy for Detection of Colonic Neoplastic Lesions During IBD Surveillance Colonoscopy

Marietta Iacucci; Gilaad G. Kaplan; Remo Panaccione; Oluseyi Akinola; Brendan C. Lethebe; Mark Lowerison; Yvette Leung; Kerri L. Novak; Cynthia H. Seow; Stefan J. Urbanski; Parham Minoo; Xianyong Gui; Subrata Ghosh

Objectives:Dye spraying chromoendoscopy (DCE) is recommended for the detection of colonic neoplastic lesions in inflammatory bowel disease (IBD). The majority of neoplastic lesions are visible endoscopically and therefore targeted biopsies are appropriate for surveillance colonoscopy. To compare three different techniques for surveillance colonoscopy to detect colonic neoplastic lesions in IBD patients: high definition (HD), (DCE), or virtual chromoendoscopy (VCE) using iSCAN image enhanced colonoscopy.Methods:A randomized non-inferiority trial was conducted to determine the detection rates of neoplastic lesions in IBD patients with longstanding colitis. Patients with inactive disease were enrolled into three arms of the study. Endoscopic neoplastic lesions were classified by the Paris classification and Kudo pit pattern, then histologically classified by the Vienna classification.Results:A total of 270 patients (55% men; age range 20–77 years, median age 49 years) were assessed by HD (n=90), VCE (n=90), or DCE (n=90). Neoplastic lesion detection rates in the VCE arm was non-inferior to the DCE arm. HD was non-inferior to either DCE or VCE for detection of all neoplastic lesions. In the lesions detected, location at right colon and the Kudo pit pattern were predictive of neoplastic lesions (OR 6.52 (1.98–22.5 and OR 21.50 (8.65–60.10), respectively).Conclusions:In this randomized trial, VCE or HD-WLE is not inferior to dye spraying colonoscopy for detection of colonic neoplastic lesions during surveillance colonoscopy. In fact, in this study HD-WLE alone was sufficient for detection of dysplasia, adenocarcinoma or all neoplastic lesions.


British Journal of Dermatology | 2018

Risk of depression among patients with acne in the U.K.: a population‐based cohort study

Isabelle A. Vallerand; Ryan T. Lewinson; Laurie M. Parsons; Mark Lowerison; Alexandra D. Frolkis; Gilaad G. Kaplan; Cheryl Barnabe; Andrew G. M. Bulloch; Scott B. Patten

DEAR EDITOR, Acne has been associated with adverse psychiatric symptoms. In dermatology outpatient clinics, approximately 25.2% of patients with acne experience some psychiatric morbidity. However, few studies have evaluated the clinically significant diagnostic category of major depressive disorder (MDD) among people with acne. Here, we investigated whether patients with acne are at an increased risk of developing MDD compared to the general population, using one of the largest electronic medical records databases in the world. A retrospective cohort study was conducted using data from The Health Improvement Network (THIN) (1986–2012), a large primary care database in the U.K. that also includes data from specialists. All individuals between 7 and 50 years of age with ≥ 1 Read codes (diagnostic codes linked to International Classification of Diseases codes) for acne were identified. A general population cohort without acne was also identified. The study was approved by the Conjoint Health Research Ethics Board at the University of Calgary (ID 24423) and from the Scientific Review Committee in the U.K. (ID 16THIN036), authorizing access to extract relevant data from THIN. A complete list of codes used to identify exposures, outcomes and covariates is available from the authors. All patients were followed from their start date for ≥ 2 years in THIN until the earliest of either their first MDD Read code (main outcome), transfer out of practice, death or end of data collection. Observations were censored at the end of follow-up in patients where MDD was not observed during the study period. To identify only incident cases, patients with an acne or MDD Read code prior to the start of follow-up were excluded. Baseline covariates at the start of follow-up included age (young ≤ 19; adult > 19 years), sex, obesity (BMI ≥ 30 kg m ), smoking status (never, former, current), alcohol use (yes or no), medical comorbidities using the Charlson Comorbidity Index (0 or ≥ 1 comorbidity) and socioeconomic status using the Townsend Deprivation Index (quintiles 1–5, with 1 least and 5 most deprivation).


Canadian Journal of Neurological Sciences | 2013

Evaluation of neurological patient registries

Jean K. Mah; Janet Warner; Ruth Hall; Eric E. Smith; Thomas Steeves; Elizabeth J. Donner; James J. Marriott; Megan Johnston; Mark Lowerison; Paula de Robles; Vanessa K. Noonan; Essie Mehina; Nathalie Jette; Tamara Pringsheim; Lawrence Korngut

in the number of national as well as international registries for a variety of neurological conditions, with corresponding increase in the amount of publications arising from these efforts [ref]. The registries were established for determining the natural history of a specific disease, the effectiveness of new treatments, the quality of care and/or other patient-related outcomes. The purpose of this chapter is to provide an approach to registry evaluation and quality assessment. In preparation of this chapter, we reviewed current literature and consensus guidelines on registry evaluations. We also consulted with medical experts and registry/database specialists as part of a national registry meeting to provide feedback and consensus on criteria to be used for evaluation of disease registries in Canada.

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