Browsing by Author "Chen, Guanmin"
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Item Open Access ACSC Indicator: testing reliability for hypertension(2017-06-26) Walker, Robin L; Ghali, William A; Chen, Guanmin; Khalsa, Tej K; Mangat, Birinder K; Campbell, Norm R C; Dixon, Elijah; Rabi, Doreen; Jette, Nathalie; Dhanoa, Robyn; Quan, HudeAbstract Background With high-quality community-based primary care, hospitalizations for ambulatory care sensitive conditions (ACSC) are considered avoidable. The purpose of this study was to test the inter-physician reliability of judgments of avoidable hospitalizations for one ACSC, uncomplicated hypertension, derived from medical chart review. Methods We applied the Canadian Institute for Health Information’s case definition to obtain a random sample of patients who had an ACSC hospitalization for uncomplicated hypertension in Calgary, Alberta. Medical chart review was conducted by three experienced internal medicine specialists. Implicit methods were used to judge avoidability of hospitalization using a validated 5-point scale. Results There was poor agreement among three physicians raters when judging the avoidability of 82 ACSC hospitalizations for uncomplicated hypertension (κ = 0.092). The κ also remained low when assessing agreement between raters 1 and 3 (κ = 0.092), but the κ was lower (less than chance agreement) for raters 1 and 2 (κ = -0.119) and raters 2 and 3 (κ = -0.008). When the 5-point scale was dichotomized, there was fair agreement among three raters (κ = 0.217). The proportion of ACSC hospitalizations for uncomplicated hypertension that were rated as avoidable was 32.9%, 6.1% and 26.8% for raters 1, 2, and 3, respectively. Conclusions This study found a low proportion of ACSC hospitalization were rated as avoidable, with poor to fair agreement of judgment between physician raters. This suggests that the validity and utility of this health indicator is questionable. It points to a need to abandon the use of ACSC entirely; or alternatively to work on the development of explicit criteria for judging avoidability of hospitalization for ACSC such as hypertension.Item Open Access Analyzing Physician and Patient factors in optimizing Cervical Cancer Screening in Alberta: Progress, Barriers, and Enablers(2023-07-17) Sayed, Sayeeda Amber; Dickinson, James; Naugler Christopher; Chen, Guanmin; Bertazzon, Stefania; McDougall, LauraCervical cancer screening (CCS) program effectiveness is well-accepted; however, inappropriate CCS results in either a woman being tested too often or not being tested at the recommended intervals. Widespread disparities in CCS uptake also exist, even when screening is offered without cost through a publicly funded and organized CCS in Alberta. This thesis has three main objectives: Study 1.To describe temporal trends in screening and outcomes for women, after changes in guidelines in Alberta, Canada, that raised the starting age for screening to 21, then to 25 years of age, and reduced frequency to 3-yearly Study 2. To identify family physicians’ (FP) characteristics that are associated with over- and under-screening for 25-69-year-old women in Calgary, Alberta. Study 3. To study spatial and temporal associations of CCS and sociodemographic variables in Calgary, Canada using Census Canada datasets (2006, 2011, 2016). Methods Study 1: Calgary Laboratory Information System data were used to examine CCS, follow-up procedures, and cancer among women 10 to 29 years from 2007 to 2016 in the whole population of Calgary. Interrupted time-series analyses were used to assess changes in screening and subsequent diagnostic procedures over the ten-year period. Study 2: A population-based retrospective observational study was performed by linking the College of Physicians and Surgeons Alberta physicians’ database of FPs practicing in Calgary with the Calgary Laboratory Services database. We matched physicians’ sex, country and year of medical school graduation, years since medical school graduation, city quadrant of practice, and their estimated patient panel size. Logistic regression models were applied to analyze the over-screening and under-screening patterns. Study 3: CCS rates were obtained from a population-wide laboratory administrative database for Calgary, Alberta for the years 2006, 2011, and 2016 for women 25-69 years of age. These years coincide with Census Canada years, allowing comparison with sociodemographic factors Ordinary Least Square regression (OLS) and geographically weighted regression models (GWR) were used to examine sociodemographic variables associated with CCS rates. Results Study 1: Annual Screening rates dropped by around 10% for all ages over 15 after the 2009 Alberta cervical cancer screening guidelines, followed by a steady decrease. The rates of abnormal test results and biopsies did not increase with decreased screening. Likewise, no increases in Cervical intra-epithelial neoplasias (CIN I, CIN II/III), or invasive cervical cancer rates were observed after reduced testing. Study 2: Among 807 physicians included in the over-screening analysis, 43% of physicians had over-screened their screen-eligible patients. Among the 317 physicians included in the underscreening analysis, 42% had under-screened during the three-year study period. Physician characteristics significantly associated with over-screening included more years of practice and having more female patients in the practice. Female physicians were less likely to under-screen their eligible female patients. Physicians practicing in the Northeast quadrant of the city also had lower odds of screening. Study 3: We analyzed approximately 200,000 cervical cancer screening tests for each year and noted a considerable decrease in screening rates between 2006 and 2011, consistent with changes in screening guidelines. The OLS results showed that a high median household income and university education were strongly associated with higher screening rates in all three census years. 2006 and 2011 OLS models showed negative associations with screening of Aboriginals, Blacks, and recent immigrant women. Conclusions Study 1: The largest decrease in screening and follow-up procedures occurred in the period immediately following the implementation of 2009 Alberta screening guidelines. The number of consequent procedures also decreased in proportion to decreased screening, but there was no increase in cancer rates. Starting screening at age 25 and reducing intervals appears to be safe. Study 2: Screening patterns of family physicians indicate both overuse and underuse, which indicates inconsistencies in adherence to screening guideline recommendations. Identifying strategies and addressing disparities to improve guideline adherence among different physician demographic groups is critical for the success of screening programs. More education and guideline publicity are required to encourage compliance with screening guidelines. Study 3: There were significant sociodemographic differences associated with cervical cancer screening in Calgary. Understanding these sociodemographic associations could form the basis of future education or outreach screening programs, targeting underserved populations, such as women with low income and education.Item Open Access Association between afterhours admission to the intensive care unit, strained capacity, and mortality: a retrospective cohort study(2018-04-17) Hall, Adam M; Stelfox, Henry T; Wang, Xioaming; Chen, Guanmin; Zuege, Danny J; Dodek, Peter; Garland, Allan; Scales, Damon C; Berthiaume, Luc; Zygun, David A; Bagshaw, Sean MAbstract Background Admission to the intensive care unit (ICU) outside daytime hours has been shown to be variably associated with increased morbidity and mortality. We aimed to describe the characteristics and outcomes of patients admitted to the ICU afterhours (22:00–06:59 h) in a large Canadian health region. We further hypothesized that the association between afterhours admission and mortality would be modified by indicators of strained ICU capacity. Methods This is a population-based cohort study of 12,265 adults admitted to nine ICUs in Alberta from June 2012 to December 2014. We used a path-analysis modeling strategy and mixed-effects multivariate regression analysis to evaluate direct and integrated associations (mediated through Acute Physiology and Chronic Health Evaluation (APACHE) II score) between afterhours admission (22:00–06:59 h) and ICU mortality. Further analysis examined the effects of strained ICU capacity and varied definitions of afterhours and weekend admissions. ICU occupancy ≥ 90% or clustering of admissions (≥ 0.15, defined as number of admissions 2 h before or after the index admission, divided by the number of ICU beds) were used as indicators of strained capacity. Results Of 12,265 admissions, 34.7% (n = 4251) occurred afterhours. The proportion of afterhours admissions varied amongst ICUs (range 26.7–37.8%). Patients admitted afterhours were younger (median (IQR) 58 (44–70) vs 60 (47–70) years, p < 0.0001), more likely to have a medical diagnosis (75.9% vs 72.1%, p < 0.0001), and had higher APACHE II scores (20.9 (8.6) vs 19.9 (8.3), p < 0.0001). Crude ICU mortality was greater for those admitted afterhours (15.9% vs 14.1%, p = 0.007), but following multivariate adjustment there was no direct or integrated effect on ICU mortality (odds ratio (OR) 1.024; 95% confidence interval (CI) 0.923–1.135, p = 0.658). Furthermore, direct and integrated analysis showed no association of afterhours admission and hospital mortality (p = 0.90) or hospital length of stay (LOS) (p = 0.27), although ICU LOS was shorter (p = 0.049). Early-morning admission (00:00–06:59 h) with ICU occupancy ≥ 90% was associated with short-term (≤ 7 days) and all-cause ICU mortality. Conclusions One-third of critically ill patients are admitted to the ICU afterhours. Afterhours ICU admission was not associated with greater mortality risk in most circumstances but was sensitive to strained ICU capacity.Item Open Access Blood pressure at age 60–65 versus age 70–75 and vascular dementia: a population based observational study(2017-10-27) Peng, Mingkai; Chen, Guanmin; Tang, Karen L; Quan, Hude; Smith, Eric E; Faris, Peter; Hachinski, Vladimir; Campbell, Norm R CAbstract Background Vascular dementia (VaD) is the second most common form of dementia. However, there were mixed evidences about the association between blood pressure (BP) and risk of VaD in midlife and late life and limited evidence on the association between pulse pressure and VaD. Methods This is a population-based observational study. 265,897 individuals with at least one BP measurement between the ages of 60 to 65 years and 211,116 individuals with at least one BP measurement between the ages of 70 to 75 years were extracted from The Health Improvement Network in United Kingdom. Blood pressures were categorized into four groups: normal, prehypertension, stage 1 hypertension, and stage 2 hypertension. Cases of VaD were identified from the recorded clinical diagnoses. Multivariable survival analysis was used to adjust other confounders and competing risk of death. All the analysis were stratified based on antihypertensive drug use status. Multiple imputation was used to fill in missing values. Results After accounting for the competing risk of death and adjustment for potential confounders, there was an association between higher BP levels in the age 60–65 cohort with the risk of developing VaD (hazard ratio [HR] 1.53 (95% confidence interval: 1.04, 2.25) for prehypertension, 1.90 (1.30, 2.78) for stage 1 hypertension, and 2.19 (1.48, 3.26) for stage 2 hypertension) in the untreated group. There was no statistically significant association between BP levels and VaD in the treated group in the age 60–65 cohort and age 70–75 cohort. Analysis on Pulse Pressure (PP) stratified by blood pressure level showed that PP was not independently associated with VaD. Conclusion High BP between the ages of 60 to 65 years is a significant risk for VaD in late midlife. Greater efforts should be placed on early diagnosis of hypertension and tight control of BP for hypertensive patients for the prevention of VaD.Item Open Access Efficient Estimation of the Varying-Coefficient Partially Linear Proportional Hazards Model with Current Status Data(2016) Dong, Yuan; Lu, Xuewen; Singh, Radhey; Shen, Hua; Chen, GuanminWe consider a semiparametric varying-coefficient proportional hazards model with current status data. This model enables one to assess possibly linear and nonlinear effect of certain covariates on the hazard rate. B-splines are applied to approximate both the unknown baseline hazard function and the varying-coefficient functions. To improve the performance of the model, ridge penalty is added to the log-likelihood to penalize the roughness of the cumulative hazard function. Efficient sieve maximum likelihood estimation method is used for estimation. Simulation studies with the weighted bootstrap method are conducted to examine the finite-sample properties of the proposed estimators. We also present an analysis of renal function recovery data for illustration.Item Open Access Health Economic Evaluation of Antimicrobial Stewardship, Procalcitonin Testing, and Rapid Blood Culture Identification in Sepsis Care: A 90-Day Model-Based, Cost-Utility Analysis(2024-11-19) Sligl, Wendy I.; Yan, Charles; Round, Jeff; Wang, Xiaoming; Chen, Justin Z.; Boehm, Cheyanne; Fong, Karen; Crick, Katelynn; Clua, Míriam G.; Codan, Cassidy; Dingle, Tanis C.; Prosser, Connie; Chen, Guanmin; Tse-Chang, Alena; Garros, Daniel; Zygun, David; Opgenorth, Dawn; Conly, John M.; Doig, Christopher J.; Lau, Vincent I.; Bagshaw, Sean M.Abstract Objective We evaluated the cost-effectiveness of a bundled intervention including an antimicrobial stewardship program (ASP), procalcitonin (PCT) testing, and rapid blood culture identification (BCID), compared with pre-implementation standard care in critically ill adult patients with sepsis. Methods We conducted a decision tree model-based cost-effectiveness analysis alongside a previously published pre- and post-implementation quality improvement study. We adopted a public Canadian healthcare payer’s perspective. Two intensive care units in Alberta with 727 adult critically ill patients were included. Our bundled intervention was compared with pre-implementation standard care. We collected healthcare resource use and estimated unit costs in 2022 Canadian dollars (CAD) over a time horizon from study entry to hospital discharge or death. We calculated the incremental net monetary benefit (iNMB) of the intervention group compared with the pre-intervention group. The primary outcome was cost per sepsis case. Secondary outcomes included readmission rates, Clostridioides difficile infections, mortality, and lengths of stay. Uncertainty was investigated using cost-effectiveness acceptability curves, cost-effectiveness plane scatterplots, and sensitivity analyses. Results Mean (standard deviation [SD]) cost per index hospital admission was CAD $83,251 ($107,926) for patients in the intervention group and CAD $87,044 ($104,406) for the pre-intervention group, though the difference ($3,793 [$7,897]) was not statistically significant. Costs were higher in the pre-intervention group for antibiotics, readmissions, and C. difficile infections. The intervention group had a lower mean expected cost; $110,580 ($108,917) compared with pre-intervention ($125,745 [$113,210]), with a difference of $15,165 ($8278). There were no statistically significant differences in quality adjusted life years (QALYs) between groups. The iNMB of the intervention group compared with pre-intervention was greater than $15,000 for willingness-to-pay (WTP) per QALY values of between $0 and $100,000. In our sensitivity analysis, the intervention was most likely to be cost-effective in roughly 56% of simulations at all WTP thresholds. Conclusions Our bundled intervention of ASP, PCT, and BCID among adult critically ill patients with sepsis was potentially cost-effective, but with substantial decision uncertainty.Item Open Access Home care utilization and outcomes among Asian and other Canadian patients with heart failure(BioMed Central, 2010-03-04) Chen, Guanmin; Khan, Nadia; King, Kathryn M.; Hemmelgarn, Brenda R.; Quan, HudeItem Open Access Impact of clinical presentation and presence of coronary sclerosis on long-term outcome of patients with non-obstructive coronary artery disease(2018-08-22) Kissel, Christine K; Chen, Guanmin; Southern, Danielle A; Galbraith, P. D; Anderson, Todd JAbstract Background Non-obstructive coronary artery disease (NOCAD) is a common finding on coronary angiography. Our goal was to evaluate the long-term prognosis of NOCAD patients with stable angina (SA). Methods The study cohort consisted of 7478 NOCAD patients with normal EF (≥ 50%), and SA who underwent coronary angiography between 1995 and 2012. We compared NOCAD patients (stenosis< 50%) with 10,906 patients with stable obstructive CAD (≥ 50%). The primary endpoint was all-cause mortality. Secondary endpoints included repeat angiography, progressive CAD, and PCI. A second comparison group consisted of 7344 patients with NOCAD presenting with an ACS. Rates of all-cause mortality of NOCAD ACS patients were compared to NOCAD SA patients. Results Median follow-up time was 6.5 years. NOCAD patients had a lower risk of all-cause mortality compared to CAD patients (HR CAD vs. NOCAD 1.33 (1.19–1.49); p < 0.001). This was driven by patients with normal coronary arteries (HR CAD vs. normal 1.63 (1.36–1.94), p < 0.001), whereas patients with minimal disease (> 0% and < 50%) were at similar risk as CAD patients (HR CAD vs. minimal 1.08 (0.99–1.29), p = 0.06). In NOCAD patients, the strongest predictors of all-cause mortality were age and minimal disease. SA patients with NOCAD had low rates of repeat angiography (7.3%), future CAD (2.3%) and PCI (1.7%). NOCAD ACS patients had a 41% increase in all-cause mortality risk compared to NOCAD SA patients (HR 1.41 (1.25–1.6), p < 0.001). Conclusions This study underlines the importance of minimal CAD, as it is not a benign disease entity and portends a similar risk as stable obstructive CAD.Item Open Access Measuring agreement of administrative data with chart data using prevalence unadjusted and adjusted kappa(BioMed Central, 2009) Chen, Guanmin; Faris, Peter; Hemmelgarn, Brenda; Walker, Robin L; Quan, HudeItem Open Access Validation of a case definition for depression in administrative data against primary chart data as a reference standard(2019-01-07) Doktorchik, Chelsea; Patten, Scott; Eastwood, Cathy; Peng, Mingkai; Chen, Guanmin; Beck, Cynthia A; Jetté, Nathalie; Williamson, Tyler; Quan, HudeAbstract Background Because the collection of mental health information through interviews is expensive and time consuming, interest in using population-based administrative health data to conduct research on depression has increased. However, there is concern that misclassification of disease diagnosis in the underlying data might bias the results. Our objective was to determine the validity of International Classification of Disease (ICD)-9 and ICD-10 administrative health data case definitions for depression using review of family physician (FP) charts as the reference standard. Methods Trained chart reviewers reviewed 3362 randomly selected charts from years 2001 and 2004 at 64 FP clinics in Alberta (AB) and British Columbia (BC), Canada. Depression was defined as presence of either: 1) documentation of major depressive episode, or 2) documentation of specific antidepressant medication prescription plus recorded depressed mood. The charts were linked to administrative data (hospital discharge abstracts and physician claims data) using personal health numbers. Validity indices were estimated for six administrative data definitions of depression using three years of administrative data. Results Depression prevalence by chart review was 15.9–19.2% depending on year, region, and province. An ICD administrative data definition of ‘2 depression claims with depression ICD codes within a one-year window OR 1 discharge abstract data (DAD) depression diagnosis’ had the highest overall validity, with estimates being 61.4% for sensitivity, 94.3% for specificity, 69.7% for positive predictive value, and 92.0% for negative predictive value. Stratification of the validity parameters for this case definition showed that sensitivity was fairly consistent across groups, however the positive predictive value was significantly higher in 2004 data compared to 2001 data (78.8 and 59.6%, respectively), and in AB data compared to BC data (79.8 and 61.7%, respectively). Conclusions Sensitivity of the case definition is often moderate, and specificity is often high, possibly due to undercoding of depression. Limitations to this study include the use of FP charts data as the reference standard, given the potential for missed or incorrect depression diagnoses. These results suggest that that administrative data can be used as a source of information for both research and surveillance purposes, while remaining aware of these limitations.