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Graduate Student Supervision
Master's Student Supervision (2010 - 2018)
The International Consultation on Incontinence Questionnaire Short-Form (ICIQ-UI-SF) is a four-item patient-reported outcome (PRO) measure. Its intended use is screening for incontinence, assessing impact of incontinence on quality of life, and facilitating patient-clinician discussions. Evaluations of this instrument to date have relied on a simple set of analytical tools—limiting user’s confidence of the instrument’s validity and reliability. The purpose of this thesis was to conduct a comprehensive evaluation of the ICIQ-UI-SF. The analyses were conducted on 177 completed ICIQ-UI-SF instruments by men with chronic urinary incontinence waitlisted for urological surgery for treatment of their condition. This comprehensive evaluation included application of the following methods: confirmatory factor analysis (CFA), principal component analysis, measures of reliability (classical test theory (CTT) and McDonald’s coefficient), item response theory (IRT), and differential item functioning (DIF). A supplemental investigation examined previously constructed ICIQ-UI-SF severity categories. Specific goals included assessing: instrument characteristics (dimensionality, ceiling effects), reliability, performance of individual items, whether socioeconomic status influences patients’ ICIQ-UI-SF scores, and concordance with other commonly collected PROs (EQ-5D-3L, Visual Analogue Scale). Responses to all items were left skewed and ceiling effects were identified. Model fit could not be assessed through the CFA, however the factor loadings of items one and two differed significantly (p
Introduction: Non-invasive prenatal testing (NIPT) is an accurate and safe screening test for detection of Down syndrome, trisomy 18, and trisomy 13, which can be used to reduce the need for invasive diagnostic testing in high-risk women. In November 2015, British Columba (BC) introduced publicly-funded NIPT as a contingent screening test for women at an increased risk of having a trisomic pregnancy. The objective of this research was to quantify the extent to which the introduction of publicly-funded NIPT influenced the utilization of invasive diagnostic testing in BC.Methods: We used linked population-based provincial prenatal biochemistry and cytogenetic laboratories data maintained by the BC Prenatal Genetic Screening Program and Perinatal Services BC. Our study population included all known singleton pregnancies in BC between April 1, 2011 and April 30, 2017 with a positive result from provincially-funded serum integrated prenatal screen (SIPS), integrated prenatal screen (IPS), and quad marker screen (Quad). We divided this timeframe into three periods: period 1 with no NIPT (April 1, 2011-January 31, 2013), period 2 with self-pay NIPT only (February 1, 2013-October 31, 2015), and period 3 with publicly-funded NIPT (November 1, 2015-April 30, 2017). We performed an interrupted time series analysis using log-binomial regression to evaluate the change in use of invasive diagnostic testing after the introduction of self-pay NIPT and publicly-funded NIPT. Models were adjusted for maternal age and self-reported maternal race.Results: Among the 8,649 pregnancies included in the study, the estimated rate of invasive diagnostic testing decreased by 12.7% (95% CI: 0.79 to 0.97) when self-pay NIPT was introduced. With the introduction of publicly-funded NIPT, the estimated rate of invasive diagnostic testing decreased by 47.8% (95% CI: 0.40 to 0.68). The estimated trend of decrease in the rate of invasive diagnostic testing utilization was 1.7% per month (95% CI: 0.98 to 0.99) within the second period with self-pay NIPT.Conclusions: The introduction of publicly-funded NIPT was associated with a significant decrease in the number of invasive diagnostic tests performed in BC among singleton pregnancies screened positive with provincially-funded SIPS, IPS, and Quad. Future cost-consequences studies including detailed healthcare costs would be valuable.
The Fecal Incontinence Quality of Life scale (FIQL) is a patient reported outcome measure (PROM) that is used to measure the effect that fecal incontinence has on quality of life, and has previously demonstrated high reliability and validity. It measures four domains of quality of life: lifestyle, coping/behavior, depression/self-perception, and embarrassment. Despite its wide use, previous studies have not applied rigorous modern methods to evaluate the FIQL's psychometric properties at the item and test level. This thesis used a cohort of prospectively recruited patients from an elective surgical registry and applied methods from classical test theory (CTT), exploratory factor analysis (EFA), item response theory (IRT), and differential item and test functioning (DIF) to identify strengths and weaknesses in the FIQL. Specifically, this thesis aims to 1) confirm the reliability of the instrument, 2) describe the domains of quality of life measured by the instrument, 3) identify high and low quality items, and 4) determine whether one's score on the FIQL is influenced by gender or surgical procedure. Out of 317 completed questionnaires from 880 total eligible patients, 236 were included for analysis. Reliability for all four domains was high as measured by Cronbach's α. Exploratory factor analysis failed to identify the four domains the FIQL claims to measure. Individual items demonstrated high discrimination but most had low difficulty. Items 2c, 2l, 3a, and 3h failed to demonstrate good separation between response categories. Five item pairs demonstrated local item dependence, most from question 3. Only item 2g demonstrated differential item functioning, based on gender. Differential test functioning was minimal. The FIQL demonstrated a high degree of reliability, and the lifestyle domain can be used as is or with minor improvements. The FIQL can be improved by making response options consistent, distributing items from different domains evenly throughout the instrument, adding items with higher difficulty and better response separation, and removing items 2c, 2l, 3a, and 3h. Further research is needed before the FIQL can be used confidently as a stand-alone measure of fecal incontinence-related quality of life.