Public Health Commons^™

Quantifying And Predicting Real-World Iatrogenic Severe Hypoglycemia In Adults With Type 1 Or 2 Diabetes Mellitus (The Inphorm Study, United States), Alexandria A. Ratzki-Leewing

Electronic Thesis and Dissertation Repository

Clinical outpatient strategies to accurately predict diabetes-related iatrogenic severe hypoglycemia (SH) are lacking. To redress this gap, we conducted the first-ever prognosis investigation of guideline-defined (Level 3) SH in the United States (US) (iNPHORM).

Chapter 4 details the design and implementation of iNPHORM: a prospective 12-wave panel survey (2020–2021). N=1206 adults with type 1 or insulin- and/or secretagogue-treated type 2 diabetes mellitus (T1DM or T2DM) were recruited from a US-wide, probability-based internet panel. For one-year, we collected monthly data on SH occurrence (frequencies, detection methods, symptoms, causes, and treatments) and related factors (anthropometric, sociodemographic, clinical, environmental/situational, behavioural, and psychosocial).

iNPHORM …

Developing Artificial Intelligence And Machine Learning To Support Primary Care Research And Practice, Jacqueline K. Kueper

Electronic Thesis and Dissertation Repository

This thesis was motivated by the potential to use "everyday data", especially that collected in electronic health records (EHRs) as part of healthcare delivery, to improve primary care for clients facing complex clinical and/or social situations. Artificial intelligence (AI) techniques can identify patterns or make predictions with these data, producing information to learn about and inform care delivery. Our first objective was to understand and critique the body of literature on AI and primary care. This was achieved through a scoping review wherein we found the field was at an early stage of maturity, primarily focused on clinical decision support …

Spin And Distortion In Surgical Trials, Andrea Mataruga

Electronic Thesis and Dissertation Repository

Research problem: Randomized controlled trials (RCTs) are essential; however, their validity can be threatened through distortion or spin. This study quantifies publication bias and distorted outcome reporting.

Methodology: All surgical RCTs registered on ClinicalTrials.gov from 1997-2017 were identified and a sample was obtained through random and intentional selection. Failure to publish (proportion of studies that remain unpublished), outcome distortion (changing intended outcomes), and spin (distorted presentation) were explored. Comparisons were made for positive versus negative studies and for high-income (HICs) versus low-middle income countries (LMICs).

Results: In total, 13,761 RCTs were registered (median enrollment size = 96, 94% from …

Fate Of Registered Studies From London, Ontario, Alex Bi

Electronic Thesis and Dissertation Repository

Introduction: Lack of study publication leads to bias in the scientific literature. It is important to better understand this phenomenon and find methods for mitigation.

Research Question: How many clinical trials registered on ClinicalTrials.gov in London, Ontario are started, completed, and published?

Methods: Data from all studies in the ClinicalTrials.gov registry associated with London, Ontario were collected, from registry conception until the end of 2017. We determined whether these registered studies were published by July 2020 and whether their first publication included their planned primary outcome at all. Main factors associated with non-publication were assessed using multivariable log-binomial regression. Multivariable …

The Association Of Alcohol Use And Fruit And Vegetable Consumption With Cataracts Among Adults: Results From The Longitudinal Canadian National Population Health Survey (Nphs), Yuguang Kang

Electronic Thesis and Dissertation Repository

Background: Cataracts are the leading cause of blindness globally, so advancing the understanding their etiology is of paramount importance for development of the preventive interventions. The findings for the association of alcohol intake and fruit and vegetable consumption with cataracts in previous literature were inconsistent.

Objective: The first study objective was to assess whether alcohol intake increases the risk of cataracts among adults. The second study objective was to assess whether fruit and vegetable consumption reduces the risk of cataracts among adults.

Methods: A retrospective cohort study design was used. Data were obtained from the Household, Longitudinal component of the …

Investigating Haemoglobin Thresholds For Red Blood Cell Transfusion In Patients With Acute Upper Gi Bleeding, Natalie May Nightingale

Electronic Thesis and Dissertation Repository

Red blood cell transfusion is frequently used to treat the harmful effects of anemia in patients with acute upper gastrointestinal bleeding. However, there is no clear consensus on when red blood cell transfusion is warranted. No studies thus far have defined the optimal threshold for transfusion, and none have looked at whether volume of blood transfused is associated with clinical outcome. This thesis attempts to addresses these gaps by analyzing hemoglobin and volume of blood transfused as predictors of patient outcomes using multivariable logistic regression models. Main results showed a statistically significant interaction between initial hemoglobin and whether a patient …

An Application Of The Modifiable Areal Unit Problem: Optimizing Cluster Method Parameters To Produce Predictive Data For Hiv Outbreaks, Connor J. Chato, Art Fy Poon

Western Research Forum

Background

A popular approach to study HIV outbreaks is to cluster cases based on genetic similarity. However, there is no widely-used statistical criterion which optimizes the parameters for sequence-based clustering methods. The relationship between a cluster-defining similarity threshold and it’s associated set of clusters can be analogized to the aggregation level in the Modifiable Areal Unit Problem (MAUP).

Hypothesis

Based on the selection of aggregation level for study partitions in MAUP, we present a statistical framework to optimize the similarity threshold for pairwise distance algorithm TN93 (http://github.com/veg/tn93). We hypothesize that defining this threshold includes case connections such that …

Predicting Important Patient-Reported Outcomes For Glaucoma Management: Cross-Sectional Study, Lavanya Uruthiramoorthy

Electronic Thesis and Dissertation Repository

The initiative to understand patient-reported outcomes (PROs) has increased to improve glaucoma management. We sought to identify important predictors of four PROs: social support and community integration, presence of depressive symptoms, vision-related quality of life (VRQoL) and preference-based Health-Related quality of life (HRQoL). A cross-sectional study was conducted among patients in London, Ontario (n=250). Regression models, and classification and regression trees were built. Leave-one-out cross-validation assessed the models’ predictive performance. Mobility aid use, best corrected visual acuity (BCVA), income and living arrangements were predictors identified for VRQoL, and social support and community integration. Mobility aid use was also predictive of …

Cognition And Motor Function: A Novel Outcome Measure For Studies On Pre-Dementia Syndromes, Jacqueline K. Kueper

Electronic Thesis and Dissertation Repository

Advances in dementia research have shifted attention towards earlier stages in the natural history, such as Mild Cognitive Impairment. The current gold standard outcome measure, the Alzheimer’s Disease Assessment Scale-Cognitive Subscale, is not optimally responsive to changes in pre-dementia populations. Modifications to scoring methodology and content have improved the measurement performance of the ADAS-Cog. However, no published modifications have addressed a second key shift in the field towards understanding motor function as an important component of dementia and pre-dementia syndromes. This thesis used a Pooled Index approach to combine an ADAS-Cog-Proxy measure with assessments of gait velocity and dual-task cost. …

Reducing Distortion – Identifying Areas To Improve The Quality Of Randomized Clinical Trials Published In Anesthesiology Journals, Jeffrey T.Y. Chow

Electronic Thesis and Dissertation Repository

Randomized clinical trials (RCTs) provide important evidence to inform clinical decision making; if these trials are of low quality, the resulting clinical decision will likely also be of low quality. The main purpose of this thesis was to conduct a series of methodological surveys that would identify potential areas of improvement in the quality of reporting for RCTs published in anesthesiology journals. Trial registration adequacy, adherence to CONSORT for Abstracts guidelines, and sample size calculation quality were all assessed, with a final chapter exploring the effect of industry funding on these methodological quality measures. While the results suggest improvement over …

Evidence Reversal: An Exploratory Analysis Of Randomized Controlled Trials From The New England Journal Of Medicine, Riaz G. Qureshi

Electronic Thesis and Dissertation Repository

BACKGROUND: Evidence Reversal (ER) is the phenomenon whereby new and stronger evidence contradicts previously established evidence.

OBJECTIVES: To quantify evidence reversals and to determine characteristics associated with reversibility.

METHODS: Original articles from the New England Journal of Medicine (2000 to 2016) were screened for three inclusion criteria: tested a clinical practice; Randomized Controlled Trial design; and tested an established clinical practice. The proportion of RCTs that represented ER was determined. Association of trial characteristics with reversal was explored using logistic regression in order to inform a potential framework of reversibility.

RESULTS: In total, 611 RCTs met the inclusion criteria, of …

Sample Size Formulas For Estimating Intraclass Correlation Coefficients In Reliability Studies With Binary Outcomes, Mengxiao Xu

Electronic Thesis and Dissertation Repository

Introduction: Measurement errors can seriously affect quality of clinical practice and medical research. It is therefore important to assess such errors by conduct- ing studies to estimate a coefficients reliability and assessing its precision. The intraclass correlation coefficient (ICC), defined on a model that an observation is a sum of information and random error, has been widely used to quantify reliability for continuous measurements. Sample formulas have been derived for explicitly incorporation of a prespecified probability of achieving the prespecified precision, i.e., the width or lower limit of a confidence interval for ICC. Although the concept of ICC is applicable …

Catheter Ablation For Atrial Fibrillation: Predicting Recurrence, Kendra Thomas

Electronic Thesis and Dissertation Repository

Background

Catheter ablation has emerged as treatment for atrial fibrillation (AF). Health care-related variables have not been explored as predictors of first ablation outcome. Determining factors associated with arrhythmia recurrence may help select patients likely to benefit. The objective was to identify variables associated with recurrence following AF ablation.

Methods

Retrospective cohort design of 314 AF patients who had undergone first ablation. Follow-up visits occurred at 3, 6 and 12 months. Variables and the outcome of recurrence were modeled with Cox proportional hazards analysis.

Results/Conclusions

After mean follow-up of 239+/-125 days, 110/314 patients (35.0%) experienced recurrence. Adjusted Cox proportional hazards …

Total Versus Partial Splenectomy In Pediatric Hereditary Spherocytosis: A Systematic Review And Meta-Analysis, Leonardo Guizzetti

Epidemiology and Biostatistics Publications

To compare the clinical effectiveness of total (TS) or partial (PS) splenectomy in pediatric hereditary spherocytosis, a systematic review and meta-analysis was performed (PROSPERO registration CRD42015030056). There were 14 observational studies comparing pre- and post- operative hematologic parameters. Secondary outcomes include in-hospital infections, surgical complications, symptomatic recurrence and biliary disease. TS is more effective than PS to increase hemoglobin (3.6 g/dL vs 2.2 g/dL) and reduce reticulocytes (12.5% vs 6.5%) after one year; outcomes following PS are stable for at least 6 years. There were no cases of overwhelming post-splenectomy sepsis. A population-based patient registry is needed for long-term follow-up.

Physical Exertion As A Risk Factor For Ventricular Arrhythmia: A Prospective Cohort Study, Harpreet S. Chahal

Electronic Thesis and Dissertation Repository

Episodes of physical exertion are associated with an immediately higher risk of cardiovascular events while physical activity over the long-term is cardioprotective. To assess the transient and long-term risk of ventricular arrhythmia (VA), we conducted a nested case-crossover study within a prospective cohort of 97 patients with implantable cardioverter-defibrillators (ICD). Within an hour of episodes of exertion, the risk of VA was 5.3 (95% CI 2.7 – 10.6) times greater compared to periods of rest. The association was higher among patients with aerobic fitness below the median (RR[relative risk]=17.5, 95% 5.2 – 58.5) than for patients with aerobic fitness above …

Provincially-Funded Insulin Pump Therapy And Glycaemic Control: Real-World Experience In London, Ontario, Selina L. Liu

Electronic Thesis and Dissertation Repository

Background: Limited “real-world” evidence exists supporting insulin pump therapy (IPT) benefits in adults with type 1 diabetes mellitus (T1DM).

Methods: A retrospective matched cohort study compared the change in glycated hemoglobin (A1C) and incidence of adverse events before and after IPT start in adults with T1DM at St. Joseph’s Healthcare in London, Ontario started on IPT between September 2008 – August 2011 to those of a matched control cohort. Paired t-tests, McNemar’s test and negative binomial regression were used.

Results: 174 matched pairs were included. At 1 year, glycaemic control significantly improved in IPT users but not in controls—the …

Risk Of Kidney Stones In Living Kidney Donors: A Matched Cohort Study, Sonia Thomas

Electronic Thesis and Dissertation Repository

A kidney stone in a person with one kidney requires urgent attention which may result in surgical and/or hospital attention. We conducted a matched retrospective cohort study to determine if living kidney donors compared to healthy non-donors have a higher risk of: 1) kidney stones with surgical intervention, and 2) hospital encounters for kidney stones. We reviewed and linked information from pre-donation charts to Ontario healthcare databases. We selected healthy non-donors from the general population, matching ten non-donors to every donor, to generate a cohort of 2,019 donors and 20,190 non-donors. There was no difference in the rate of 1) …

Atypical Antipsychotic Drugs And The Risk Of Acute Kidney Injury: A Population-Based Cohort Study, Yoseob Joseph Hwang

Electronic Thesis and Dissertation Repository

Older adults are frequently prescribed atypical antipsychotic drugs and may be at a risk for kidney-related adverse events. This population-based retrospective cohort study examined the 90-day risk of acute kidney injury (AKI) and the potential reasons for AKI in 96,471 matched pairs of older adults who received and who did not receive a new atypical antipsychotic drug prescription from 2003 to 2011 in Ontario. Atypical antipsychotic drug use was associated with a higher risk of hospitalization with AKI (relative risk (RR) 2.06 [95% confidence interval (CI) 1.85–2.29]). The drug use was also associated with potential reasons for AKI including hypotension …

Patency And Complication Rates Of The Arteriovenous Fistula: A Systematic Review, Ahmed A. Al-Jaishi

Electronic Thesis and Dissertation Repository

Advantages of fistulas, which include long patency and low complication rates, were ascertained over two decades ago and may not apply to the contemporary dialysis population. We conducted a systematic review to summarize the patency and complication rates of fistulas from literature published after 1999. We screened 7,008 citations and 62 articles met our criteria. The risk of primary failure was 27% (95% confidence interval (CI): 23–32%). When primary failures were included, the primary and secondary patency rates were 59% (CI 53–64%) and 66% (CI 58–74%) at one year, respectively. The median rates of infection, ischemic steal syndrome, and thrombosis …

Evaluating The Montreal Cognitive Assessment (Moca) And The Mini Mental State Exam (Mmse) For Cognitive Impairment Post Stroke: A Validation Study Against The Cognistat, Lauren Friedman

Electronic Thesis and Dissertation Repository

Objective. To identify the better of two commonly used screening tools for detecting probable cognitive impairment in stroke patients in a large regional rehabilitation hospital (ParkwoodHospital,London,Ontario). This was a validation study of the Mini-Mental State Exam (MMSE) and the Montreal Cognitive Assessment (MoCA), using the Cognistat, as the criterion or ‘gold standard’. It was hypothesized that the MoCA is a superior screening instrument to the MMSE for the detection of cognitive impairment in stroke patients.

Methods. The MMSE and the MoCA were administered by occupational therapists and the Cognistat was administered by the student investigator. A second Cognistat was administered …

Shift Work And Cardiovascular Events: Systematic Review And Meta-Analysis, Manav V. Vyas

Electronic Thesis and Dissertation Repository

The prevalence of shift work is increasing in the general population. There is conflicting epidemiologic evidence on the association between shift work and cardiovascular disease. We performed a systematic review and meta-analysis of observational studies that measured shift work-cardiovascular disease associations. We screened 12,350 articles and identified 35 eligible studies. The pooled risk ratios (RR) for myocardial infarction, all coronary events and ischemic stroke were 1.23 (95% confidence interval [CI] 1.15 to 1.31, I² = 0), 1.24 (95% CI 1.10 to 1.39, I² = 85%) and 1.05 (95% CI 1.01 to 1.09, I² = 0), respectively. The …