Ontario Registry Research Articles

A portrait of older adults in naturally occurring retirement communities in Ontario, Canada: A population-based study.

Naturally occurring retirement communities (NORCs) are geographical areas that have naturally become home to a large concentration of older adults. This density means that NORCs have the potential to become a pillar for aging in place strategies, but at present, there is limited data on residents and their health needs. Our objective was to describe and compare the health and healthcare use of older adults living in high-rise NORC buildings to those in all other housing types in the community. We conducted a population-based descriptive study of community-dwelling older adults aged ≥65 years by linking a provincial NORC registry in Ontario, Canada with health administrative records. Individuals were classified as NORC residents if their residential postal code on January 1, 2020 matched the NORC registry. Sociodemographic, clinical, and healthcare use characteristics were compared by NORC status using standardized differences (STD) and stratified by rurality, and further by age and sex in urban settings. Overall, 219,995 (7.7%) of 2,869,706 older adults were NORC residents. Compared to community-dwelling older adults, NORC residents were older (mean 77.4 vs 74.6 years; STD 0.34), and more were female (61.8% vs 52.2%; STD 0.19) and had low income (16.0% vs 9.3%; STD 0.11). NORC residents also had more active chronic conditions (mean 1.9 vs 1.5; STD 0.27), medications (mean 3.4 vs 2.8; STD 0.21), home care use (15.3% vs 9.8%; STD 0.17), and primary care visits (mean 9.7 vs 7.6 visits in prior 2 years; STD 0.22). Findings were robust across rurality, age, and sex. Our findings suggest that NORC residents have greater health needs than other older adults living in the community and underscore NORCs as important targets for equity-focused strategies to support aging in place.

Outcomes of pregnancies with varying levels of nuchal translucency measurements: A population-based retrospective study in Ontario, Canada.

Nuchal translucency prenatal ultrasound is widely used to screen for chromosomal abnormalities. An elevated nuchal translucency has been associated with adverse outcomes such as pregnancy loss; however, extant studies investigating these associations have had important limitations, including selection bias. This study aimed to investigate the association between nuchal translucency measurements and pregnancy outcome, specifically, a composite of pregnancy loss, termination, stillbirth, or neonatal death. This was a population-based retrospective cohort study conducted with data from the prescribed perinatal registry in Ontario, Canada, Better Outcomes Registry & Network. All singleton pregnancies with an estimated date of delivery from September 1, 2016, to March 31, 2021, and multiple marker screening including a nuchal translucency were included. Pregnancies with measurements 2.0- < 2.5 mm, 2.5- < 3.0 mm, 3.0- < 3.5 mm, 3.5- < 5.0 mm, 5.0- < 6.5 mm, and ≥6.5 mm were compared to a reference group with measurements <2.0 mm. We used multivariable modified Poisson regression models with robust variance estimation to estimate associations between nuchal translucency measurement and pregnancy outcome, with adjustment for age at estimated date of delivery and gestational age at screening. There were 414 268 singleton pregnancies included in the study. The risk of pregnancy loss, termination, stillbirth, or neonatal death increased with increasing levels of nuchal translucency measurements, with an adjusted risk ratio (aRR) of 11.9 (95% confidence interval (CI) 9.9, 14.3) in the group with measurements 3.5- < 5.0 mm. When pregnancies with diagnosed chromosomal abnormalities were excluded, this association remained strong, with an aRR of 6.4 (95% CI 4.8, 8.5). Among pregnancies with a live birth, those with a higher nuchal translucency measurement (>5.0 mm vs. <2.0 mm) were also at increased risk of adverse perinatal outcomes such as admission to the neonatal intensive care unit and APGAR score <7. In this population-based study using robust methods to reduce the risk of selection bias, we found that pregnancies with increased nuchal translucency measurements are less likely to result in a live birth, even with the exclusion of chromosomal abnormalities. Pregnancies with increased nuchal translucency measurements that resulted in a live birth may also be at increased risk of adverse perinatal outcomes.

Abstract 12488: Oral Anticoagulation for New Onset Post-Operative Atrial Fibrillation After Combined Coronary Artery Bypass Grafting and Valve Surgery is Not Associated With Improved Outcomes

Introduction: Post-operative atrial fibrillation (POAF) after cardiac surgery is common and is associated with increased risk of stroke and death. The incidence of POAF is highest among patients who undergo combined CABG and valve surgery, at 40-60%. The risks and benefits of oral anticoagulation (OAC) in this high-risk population are not well established. Research Question: Among patients with POAF after combined CABG and valve surgery, what is the association between OAC use and clinical outcomes? Methods: From a population-based registry in Ontario, Canada, we identified consecutive patients &gt;65 years of age who developed POAF after combined CABG and left-sided, non-mechanical valve surgery from Oct/08-Mar/18. The exposure of interest was OAC prescription within 90 days after hospital discharge. Outcomes included death, cardiovascular death, stroke, MI, thromboembolism, and bleeding. Follow-up began at 90 days after discharge and continued for 24 months. Outcomes were analyzed using inverse probability of treatment weighting using the propensity score. Statistical measures of association were reported as hazard ratios with 95% confidence intervals. Results: Among 4,836 patients who had combined CABG/valve surgery, 1,939 (40.1%) developed POAF and these patients had a higher rate of death (HR 1.31, 95% CI 1.01-1.68 P=0.04). OAC was prescribed in 1,153 (59.5%) patients (86% warfarin and 14% DOAC). The use of OAC was not associated with a lower rate of death, stroke/MI/thromboembolism, or cardiovascular death but was associated with an increased rate of bleeding (HR 1.62, 95% CI 1.00-2.61, P=0.048). Conclusion: Among patients with POAF after combined CABG/valve surgery, use of warfarin or DOAC did not improve ischemic cardiovascular outcomes or survival and was associated with higher rates of bleeding. Randomized control trials are needed to define the risk and benefit of OAC use in this high-risk population. Until then, routine use of OAC is not recommended.

Accuracy of aspirin prophylaxis for preeclampsia prevention documentation within a large administrative dataset.

Low-dose aspirin prophylaxis is recommended for women at risk of preeclampsia. Capturing aspirin prophylaxis within administrative databases can be challenging since it is an over-the-counter medication. The Better Outcome Registry and Network (BORN) database, a perinatal health registry in Ontario, Canada, includes a formal variable that captures aspirin prophylaxis for preeclampsia. This variable has not been formally validated. To assess the accuracy of the aspirin prophylaxis variable in the BORN database against an electronic medical record (EMR). This validation study comprised 200 randomly selected women who had a livebirth at St. Michael's Hospital (SMH) in Toronto, Ontario, from January 2018 to July 2022. Recorded aspirin prophylaxis in pregnancy and maternal sociodemographic characteristics were independently extracted by two abstractors. Accuracy of aspirin prophylaxis use in the BORN database was compared to that in the SMH EMR, expressed as sensitivity, specificity, positive (PPV) and negative predictive values (NPV), Cohen's kappa (κ), and overall percent agreement, with 95% confidence intervals (CI). Sensitivity analyses were performed to account for missing or unclear aspirin prophylaxis use. Among 200 women, 24 (12.0%) received aspirin prophylaxis - 12.5% within the SMH EMR and 8.0% in the BORN database. Women using aspirin were older (37.0 vs 33.0 years) and had higher median gravidity (3 vs. 2). Sensitivity and specificity of the BORN aspirin prophylaxis variable were 62.5% (95% CI 40.6, 81.2) and 100.0% (95% CI 97.3, 100.0), respectively. The corresponding positive and negative predictive values were 100.0% (95% CI 78.2, 100.0), and 93.8% (95% CI 88.6, 97.1), respectively. Cohen's κ was 0.74 (95% CI 0.58, 0.90), and overall percent agreement was 94.4% (95% CI 87.1, 100.0). Aspirin use within the BORN database, based on a standard variable field, appears accurate enough for the potential use in epidemiological studies of aspirin prophylaxis for preeclampsia or as a covariate in related studies.

Fresh Compared With Frozen Embryo Transfer and Risk of Severe Maternal Morbidity: A Study of In Vitro Fertilization Pregnancies in Ontario, Canada

ObjectivesTo quantify the risk of severe maternal morbidity (SMM) in fresh versus frozen-thawed embryo transfers (ETs) among pregnancies conceived by in vitro fertilization (IVF) and to assess SMM risk according to the number of fresh ETs prior to the index pregnancy. MethodsRetrospective cohort study using the provincial birth registry in Ontario, Canada. We included 13 929 individuals aged 18–55 years who conceived via IVF between January 1, 2013, and March 5, 2018, and delivered a live or stillborn infant ≥20 weeks gestation. We compared the primary outcome, a composite of SMM or death, between fresh and frozen ETs. ResultsA total of 174 individuals who conceived via fresh ETs had SMM (30.7 per 1000), compared with 280 among individuals who received frozen ETs (33.9 per 1000); adjusted risk ratio (aRR) 0.85 (95% CI 0.70−1.04). Compared with frozen ET, fresh ET was associated with a lower risk of severe hemorrhage (aRR 0.63; 95% CI 0.48−0.82) but no difference in risk of preeclampsia. Among individuals with 1 (n = 211) or ≥2 (n = 88) prior fresh cycles, the risk of SMM was not increased compared with having no prior cycles; aRR 0.96 (95% CI 0.78−1.18) and 0.91 (95% CI 0.67−1.25), respectively. ConclusionFresh ET was associated with a lower risk of severe hemorrhage compared with frozen ET. These findings may be partly explained by the increased popularity of a freeze-all strategy, reserving fresh ETs for patients with fewer comorbidities.

Outcomes of patients with T1a,b N0 Her2-positive breast cancer treated with adjuvant trastuzumab in a prospective registry in Ontario, Canada.

533 Background: Multiple randomized trials of chemo +/- tras in early stage, Her 2 positive BrCa demonstrated improvement in survival, but patients (pts) with T1a,b N0 disease were mostly excluded. Given the uncertainty of benefit in this group and the toxicities of chemo + tras, treatment in Ontario was funded for these patients conditional upon data collection for toxicity and survival endpoints. We report the outcomes for 483 patients enrolled in this Evidence Building Program (EBP). Methods: Between 2011 and 2018, 483 eligible pts with Her 2 pos disease and adequate cardiac function were treated with chemo + tras in the EBP. Cardiac toxicity, febrile neutropenia (FN), event-free (EFS), and overall survival (OS) were determined for this cohort from administrative datasets, and compared retrospectively to controls of similar stage selected from the Ontario Cancer Registry who did not receive tras and/or chemo. For the EBP cohort, clinicians also reported changes in left ventricular ejection fraction (LVEF). Results: Pt characteristics are shown in the Table. EBP patients had improved OS when compared to controls who received no chemo or tras. The 3-year OS in the EBP pts was 99.1%, versus 96.9% in the controls [adjusted HR 0.59 (95% CI 0.29-1.20)]. Patients receiving EBP tras had a significantly longer EFS than controls with or without chemo [adjusted HR 0.54 (0.36-0.83), p=0.005]. Use of chemo + tras in EBP pts was associated with an increased risk of clinical congestive heart disease (CHD) and febrile neutropenia (FN). About 3.5% of pts experienced CHD during treatment with chemo + tras. About 6% of pts had an absolute reduction of LVEF &gt;10% or reached LVEF &lt;50%. In an adjusted analysis, the risk of CHD was higher in older pts [HR 1.06 (1.03-1.08) per 1-yr increase in age, p&lt;0.0001) and for pts who received anthracyclines [HR 5.00 (1.71-14.7). In a matched analysis, the crude frequency of FN during treatment was 20% in EBP pts vs. 3% among controls who did not receive chemo or tras (p&lt;0.001). Conclusions: Analysis of the Ontario EBP for pts with, T1a,b N0 HER2 pos BrCa revealed that the prognosis is excellent and is improved with the use of chemo + tras. The safety profile was expected and tolerable, especially when non anthracycline chemo was used. These results led to a funding policy change where prospective data collection has been discontinued and chemo + tras is now routinely funded in this population. [Table: see text]

The impact of preoperative imaging on wait times, surgical approach and overall survival in endometrioid endometrial cancers

ObjectivesRoutine preoperative axial imaging studies (CT/MRI) are not recommended for endometrioid endometrial cancer as they are unlikely to change management and may delay surgery. This study evaluated the association of receiving preoperative imaging on various outcomes. MethodsA population-based cohort of Endometrioid Endometrial Cancer cases from 2006 to 2016 were identified from the Cancer Registry in Ontario, Canada. Wait time to surgery, type of surgery and overall survival were evaluated in patients with and without preoperative imaging. Predictive factors for wait time > 56 days and aggressive surgery (radical hysterectomy / lymphadenectomy) were determined using multivariable regression analysis. Results13,050 cases were included. 22.6% of patients received preoperative imaging, mainly CT scans. Most patients (95.9%) received no neoadjuvant treatment. Patients with preoperative imaging were more likely to have neoadjuvant treatment (11.7% vs. 1.8%) and less likely to have surgery at 180 days post diagnosis (87.9% vs 94.6%). Patients with preoperative imaging had median wait time to surgery of 64 days (47–87), compared to 53 days (36–74) than those without imaging (p < 0.001). Multivariable modeling showed preoperative imaging was associated with decreased odds of having surgery within 56 days (OR = 0.68, 95% CI = 0.62–0.75), and increased odds (OR = 1.73, 95% CI = 1.53–1.95) of having aggressive surgery. The 5-year overall survival for patients with imaging was 84.8% versus 91.1% for patients without preoperative imaging. ConclusionsPreoperative imaging was associated with longer wait times to surgery, more aggressive surgery, surgery with a gynecologic oncologist and increased use of neoadjuvant and adjuvant treatment. In early-stage disease there was no observed improvement in overall survival for patients with preoperative imaging. Further research on potential benefits of preoperative imaging in higher risk patients is required.

Derivation and validation of a clinical risk score to predict death among patients awaiting cardiac surgery in Ontario, Canada: a population-based study.

Background:Surgical delay may result in unintended harm to patients needing cardiac surgery, who are at risk for death if their condition is left untreated. Our objective was to derive and internally validate a clinical risk score to predict death among patients awaiting major cardiac surgery.Methods:We used the CorHealth Ontario Registry and linked ICES health administrative databases with information on all Ontario residents to identify patients aged 18 years or more who were referred for isolated coronary artery bypass grafting (CABG), valvular procedures, combined CABG–valvular procedures or thoracic aorta procedures between Oct. 1, 2008, and Sept. 30, 2019. We used a hybrid modelling approach with the random forest method for initial variable selection, followed by backward stepwise logistic regression modelling for clinical interpretability and parsimony. We internally validated the logistic regression model, termed the CardiOttawa Waitlist Mortality Score, using 200 bootstraps.Results:Of the 112 266 patients referred for cardiac surgery, 269 (0.2%) died while awaiting surgery (118/72 366 [0.2%] isolated CABG, 81/24 461 [0.3%] valvular procedures, 63/12 046 [0.5%] combined CABG–valvular procedures and 7/3393 [0.2%] thoracic aorta procedures). Age, sex, surgery type, left main stenosis, Canadian Cardiovascular Society classification, left ventricular ejection fraction, heart failure, atrial fibrillation, dialysis, psychosis and operative priority were predictors of waitlist mortality. The model discriminated (C-statistic 0.76 [optimism-corrected 0.73]). It calibrated well in the overall cohort (Hosmer–Lemeshow p = 0.2) and across surgery types.Interpretation:The CardiOttawa Waitlist Mortality Score is a simple clinical risk model that predicts the likelihood of death while awaiting cardiac surgery. It has the potential to provide data-driven decision support for managing access to cardiac care and preserve system capacity during the COVID-19 pandemic, the recovery period and beyond.

Gender-based differences in physician payments within the fee-for-service system in Ontario: a retrospective, cross-sectional study.

Background:Differences in physician income by gender have been described in numerous jurisdictions, but few studies have looked at a Canadian cohort with adjustment for confounders. In this study, we aimed to understand differences in fee-for-service payments to men and women physicians in Ontario.Methods:We conducted a cross-sectional analysis of all Ontario physicians who submitted claims to the Ontario Health Insurance Plan (OHIP) in 2017. For each physician, we gathered demographic information from the College of Physicians and Surgeons of Ontario registry. We compared differences in physician claims between men and women in the entire cohort and within each specialty using multivariable linear regressions, controlling for length of practice, specialty and practice location.Results:We identified a cohort of 30 167 physicians who submitted claims to OHIP in 2017, including 17 992 men and 12 175 women. When controlling for confounding variables in a linear mixed-effects regression model, annual physician claims were $93 930 (95% confidence interval $88 434 to $99 431) higher for men than for women. Women claimed 74% as much as men when adjusting for covariates. This discrepancy was present in nearly all specialty categories. Men claimed more than women throughout their careers, with the greatest gap 10–15 years into practice.Interpretation:We found a gender gap in fee-for-service claims in Ontario, with women claiming less than men overall and in nearly every specialty. Further work is required to understand the root causes of the gender pay gap.

Derivation and validation of a clinical model to predict death or cardiac hospitalizations while on the cardiac surgery waitlist.

Background:Waitlist management is a global challenge. For patients with severe cardiovascular diseases awaiting cardiac surgery, prolonged wait times are associated with unplanned hospitalizations. To facilitate evidence-based resource allocation, we derived and validated a clinical risk model to predict the composite outcome of death and cardiac hospitalization of patients on the waitlist for cardiac surgery.Methods:We used the CorHealth Ontario Registry and linked ICES health care administrative databases, which have information on all Ontario residents. We included patients 18 years or older who waited at home for coronary artery bypass grafting, valvular or thoracic aorta surgeries between 2008 and 2019. The primary outcome was death or an unplanned cardiac hospitalizaton, defined as nonelective admission for heart failure, myocardial infarction, unstable angina or endocarditis. We randomly divided two-thirds of these patients into derivation and one-third into validation data sets. We derived the model using a multivariable Cox proportional hazard model with backward stepwise variable selection.Results:Among 62 375 patients, 41 729 patients were part of the derivation data set and 20 583 were part of the validation data set. Of the total, 3033 (4.9%) died or had an unplanned cardiac hospitalization while waiting for surgery. The area under the curve of our model at 15, 30, 60 and 89 days was 0.85, 0.82, 0.81 and 0.80, respectively, in the derivation cohort and 0.83, 0.80, 0.78 and 0.78, respctively, in the validation cohort. The model calibrated well at all time points.Interpretation:We derived and validated a clinical risk model that provides accurate prediction of the risk of death and unplanned cardiac hospitalization for patients on the cardiac surgery waitlist. Our model could be used for quality benchmarking and data-driven decision support for managing access to cardiac surgery.

Gastroschisis in Ontario, Canada: 2012-2018.

Gastroschisis is a congenital anomaly of the abdomen in which the intestines are found outside of the body at birth. While no clear causative factors have been identified, it is strongly associated with young maternal age. Other reported associations include low maternal socioeconomic status, low maternal body mass index (BMI), and smoking. This is a retrospective review of epidemiologic data relating to cases of gastroschisis in Ontario from 2012-2018 in the Better Outcomes Registry & Network (BORN) Ontario database, which is the province's prescribed maternal-newborn registry. We describe the epidemiology of gastroschisis in Ontario with respect to birth prevalence, maternal age, health, exposures, and geography. The birth prevalence of gastroschisis is 2.31 cases/10,000 births. There was no apparent change in birth prevalence over the study period and there was no difference between male and female infants. Gastroschisis was associated with younger maternal ages and was inversely correlated with maternal BMI. Gastroschisis was associated with first completed pregnancy. Maternal diabetes was associated with a lower birth prevalence of gastroschisis than average. Mothers of babies with gastroschsis were more likely to report use of tobacco, alcohol, and drugs during pregnancy than those without gastroschisis, with marijuana use showing the largest increase in birth prevalence of gastroschisis. Mothers living in rural areas were more likely to have a baby with gastroschisis than those in urban centers, even after controlling for maternal age. This Ontario registry study reveals that mothers with babies with gastroschisis are more likely to be young and thin, live in rural areas, and report prenatal smoking, alcohol use, and drug use than women whose pregnancies do not have gastroschsis.

Biological measures of synovial inflammation predict pain, symptoms, and ultrasound measures of synovitis in knee OA

Purpose: Synovial inflammation (synovitis or effusion-synovitis) measured via clinical imaging (i.e., magnetic resonance imaging (MRI), ultrasound (US)) has been shown to be related to worse outcomes in people with knee OA, including worse pain, higher risk of OA incidence and progression, and increased risk of requiring a total knee arthroplasty (TKA). Recent studies have shown associations between synovial histopathology and structural features of knee OA and MRI measures of synovitis. However, the relationship between histopathology and patient symptoms remains unclear. Histopathology measures of synovial inflammation represent a set of measures that are related to biological disease activity in OA. Therefore, the aim of this study was to establish the link between synovial inflammation and clinical outcomes. Methods: Patients were recruited from the Western Ontario Registry for Early Osteoarthritis (WOREO): Knee Study. Ninety-two people with severe symptoms and radiographic damage (Kellgren-Lawrence (KL) grades 3 or 4) undergoing surgery for end-stage knee OA were included. Patients completed the Knee Injury and Osteoarthritis Outcome Score (KOOS) questionnaire specific to each knee and a self-reported patient global assessment (PGA). An investigator global assessment (IGA) was also completed for each patient. Musculoskeletal-US was used to measure effusion-synovitis in suprapatellar mid-line, lateral, and medial windows (0-3; None-Severe; summed (0-9) and maximum effusion depth (mm). Power Doppler signal was also assessed as absent or present (0 or 1). Lateral suprapatellar synovial biopsies were obtained at time of surgery. Routine histopathology was scored in six domains, on 5 slides per patient; mean scores were binned into categories 0, 0.5-1.5, and 2-3 (none, mild, moderate-severe). Composite histopathology scores were created based on previously published literature, principal component analysis (Eigen values ≥ 1.0), and biological rationale. We fitted a series of multivariate linear or logistic regression models to evaluate the association of histopathology (individual and composite) scores with clinical outcomes and US imaging measures of synovitis. All analyses were adjusted for age, sex, and body mass index (BMI). Robust sandwich estimators were used. Results include unstandardized β coefficients or odds ratios (OR) with 95% confidence intervals (CIs). All analyses completed using StataIC 15.1. Results: A total of 92 patients were included (Table 1). Of the 6 histopathology domains, more severe perivascular edema was most strongly associated with lower (worse) KOOS pain, ADL, and QoL subscale scores (Table 2). Synovial lining and sub-synovial infiltrate scores were significantly associated with more severe effusion-synovitis measured by US grading and maximum effusion depth (Table 3). Vascularization was associated with higher synovitis score, while more severe fibrosis was associated with high QoL scores (Table 2) and lower US synovitis score (Table 3). Synovial histopathology principal components accounted for approximately 70% of the variance in the dataset but there were minimal associations with clinical and imaging outcomes (Table 4). The histopathology inflammatory composite scores were most strongly associated with KOOS subscale scores (Table 4). Conclusions: Inflammation measured with synovial histopathology is associated with knee-specific pain, symptoms and US imaging measures of inflammation in patients with end-stage knee OA. These findings may help us to better understand OA overall. We provide biological evidence supporting the known relationship between knee inflammation and OA outcomes, which is largely based on imaging assessment in the literature.View Large Image Figure ViewerDownload Hi-res image Download (PPT)View Large Image Figure ViewerDownload Hi-res image Download (PPT)View Large Image Figure ViewerDownload Hi-res image Download (PPT)

The use of imaging in endometrial cancer prior to potential surgery: Are guidelines being followed?

ObjectivesClinical practice guidelines recommend against routine preoperative axial imaging studies (CT/MRI) for endometrial cancer, except for cases of locally advanced disease or aggressive histologies. This study utilized population-based data to evaluate the use of preoperative imaging and factors associated with its use. MethodsA population-based cohort of women diagnosed with endometrial cancer from 2006 to 2016 were identified from the Ontario Cancer Registry in Ontario, Canada. Patients were excluded if they had: hysterectomy prior to the date of diagnosis, non-epithelial histology or a prior cancer diagnosis within 5 years. Preoperative imaging (CT or MRI) rates were calculated over time. Predictive factors for preoperative imaging use were determined using multi-variable regression analysis. Results17,718 cases were eligible for analysis. From 2006 to 2016, the proportion of patients receiving preoperative imaging increased from 22.2% to 39.3%. In a subgroup of patients with low-risk disease (stage 1, endometrioid adenocarcinoma), imaging increased from 16.3% to 29.5%. Multivariate analysis showed an association between preoperative imaging and advanced stage, advanced grade, non-endometrioid morphology, surgery with a gynecologic oncologist, surgery at a teaching hospital and a later year of diagnosis. From 2006 to 2016, the yearly incidence of endometrial cancer increased from 22.3/100,000 to 36.1/100,000, representing a mean annual increase of 3.6% per year. ConclusionsEndometrial cancer incidence and the use of preoperative imaging are increasing. Factors most associated with preoperative imaging are high-risk features. However, preoperative imaging is still being performed in low-risk patients, indicating non-adherence to guidelines, which has implications for constrained healthcare resources.

Use of administrative record linkage to measure medical and social risk factors for early developmental vulnerability in Ontario, Canada.

BackgroundLinkage of demographic, health, and developmental administrative data can enrich population-based surveillance and research on developmental and educational outcomes. Transparency of the record linkage process and results are required to assess potential biases.ObjectivesTo describe the approach used to link records of kindergarten children from the Early Development Instrument (EDI) in Ontario to health administrative data and test differences in characteristics of children by linkage status. We demonstrate how socio-demographic and medical risk factors amass in their contribution to early developmental vulnerability and test the concordance of health diagnoses in both the EDI and health datasets of linked records.MethodsChildren with records in the 2015 EDI cycle were deterministically linked to a population registry in Ontario, Canada. We compared sociodemographic and developmental vulnerability data between linked and unlinked records. Among linked records, we examined the contribution of medical and social risk factors obtained from health administrative data to developmental vulnerability identified in the EDI using descriptive analyses.ResultsOf 135,937 EDI records, 106,217 (78.1%) linked deterministically to a child in the Ontario health registry using birth date, sex, and postal code. The linked cohort was representative of children who completed the EDI in age, sex, rural residence, immigrant status, language, and special needs status. Linked data underestimated children living in the lowest neighbourhood income quintile (standardized difference [SD] 0.10) and with higher vulnerability in physical health and well-being (SD 0.11) , social competence (SD 0.10), and language and cognitive development (SD 0.12). Analysis of linked records showed developmental vulnerability is sometimes greater in children with social risk factors compared to those with medical risk factors. Common childhood conditions with records in health data were infrequently recorded in EDI records.ConclusionsLinkage of early developmental and health administrative data, in the absence of a single unique identifier, can be successful with few systematic biases introduced. Cross-sectoral linkages can highlight the relative contribution of medical and social risk factors to developmental vulnerability and poor school achievement.

Extent of Surgical Resection in Inflammatory Bowel Disease Associated Colorectal Cancer: a Population-Based Study

BackgroundThe extent of surgical resection in inflammatory bowel disease (IBD) patients who develop colorectal cancer (CRC) is not prescribed by guidelines. We aim to evaluate, at a population level, the association of extent of surgical resection with survival outcomes. MethodsUsing a validated Ontario registry of Crohn’s disease (CD) and ulcerative colitis (UC) patients, we identified patients who underwent colorectal cancer resection between 2007 and 2015. Patient, tumor, and treatment factors, including type of surgical resection, were collected. Resections were grouped as segmental, total colectomy, and proctocolectomy. Multivariable cox proportional hazard regression was performed to identify factors associated with survival, including extent of surgical resection. ResultsBetween 2007 and 2015, 84,694 patients had resections for CRC in the province of Ontario, 599 had ulcerative colitis (UC), and 366 had Crohn’s disease (CD). Segmental resection was the most common operation performed and was more common in CD patients compared to UC (68% vs. 45.6%, p < 0.001). Five-year survival was 63.7% (95% CI 59.5–67.7) in UC patients and 57.5% (95% CI 51.9–62.7) in CD patients (p = 0.033). Multivariable analysis showed worse survival in patients undergoing total colectomy, compared to segmental resection [HR 1.70 (95% CI 1.31–2.21), p < 0.001]. There was no significant difference in survival between patients undergoing segmental resection and proctocolectomy [HR 0.99 (95% CI 0.78–1.27)]. This pattern was similar within the subtypes of IBD. ConclusionIn the setting of IBD-associated CRC, segmental resection and proctocolectomy are associated with similar survival outcomes in both UC and CD patients. Prospective study is essential to explore these findings.

Differences in Healthcare Use Between Patients With Persistent and Paroxysmal Atrial Fibrillation Undergoing Catheter-Based Atrial Fibrillation Ablation: A Population-Based Cohort Study From Ontario, Canada.

BackgroundPatients with persistent atrial fibrillation (AF) undergoing catheter‐based AF ablation have lower success rates than those with paroxysmal AF. We compared healthcare use and clinical outcomes between patients according to their AF subtypes.Methods and ResultsConsecutive patients undergoing AF ablation were prospectively identified from a population‐based registry in Ontario, Canada. Via linkage with administrative databases, we performed a retrospective analysis comparing the following outcomes between patients with persistent and paroxysmal AF: healthcare use (defined as AF‐related hospitalizations/emergency room visits), periprocedural complications, and mortality. Multivariable Poisson modeling was performed to compare the rates of AF‐related and all‐cause hospitalizations/emergency room visits in the year before versus after ablation. Between April 2012 and March 2016, there were 3768 consecutive patients who underwent first‐time AF ablation, of whom 1040 (27.6%) had persistent AF. The mean follow‐up was 1329 days. Patients with persistent AF had higher risk of AF‐related hospitalization/emergency room visits (hazard ratio [HR], 1.21; 95% CI, 1.09–1.34), mortality (HR, 1.74; 95% CI, 1.15–2.63), and periprocedural complications (odds ratio, 1.36; 95% CI, 1.02–1.75) than those with paroxysmal AF. In the overall cohort, there was a 48% reduction in the rate of AF‐related hospitalization/emergency room visits in the year after versus before ablation (rate ratio [RR], 0.52; 95% CI, 0.48–0.56). This reduction was observed for patients with paroxysmal (RR, 0.45; 95% CI, 0.41–0.50) and persistent (RR, 0.74; 95% CI, 0.63–0.87) AF.ConclusionsAlthough patients with persistent AF had higher risk of adverse outcomes than those with paroxysmal AF, ablation was associated with a favorable reduction in downstream AF‐related healthcare use, irrespective of AF type.

Abstract P4-10-29: Identifying novel molecular markers of response to trastuzumab in metastatic breast cancer

Abstract Background: The survival of women with HER2+ metastatic breast cancer (MBC) has improved with the introduction of the anti-HER2 antibody trastuzumab, but responses vary greatly among individuals. A predictive signature of response (and lack thereof) to trastuzumab may help personalize therapy for women with HER2+ MBC and enable the discovery of new “druggable” targets. Methods: In this retrospective cohort study, 256 patients with HER2+ MBC at the Sunnybrook Odette Cancer Centre were identified sequentially from January 1999 to December 2013 using the Cancer Care Ontario Registry. In total, 53 patients (21%) had archived metastatic tissue available for analysis, 29 (55%) of whom had samples obtained &amp;lt;3 years prior to the initiation of trastuzumab. Nanostring molecular testing was used to measure the expression of commonly known oncogenes and gene signatures using the Nanostring technologies nCounter Analysis System TM (Seattle, Washington, USA). Descriptive statistics were used to summarize patient results and prognostic scores. Patients were categorized into short-term survivors (died within 12 months) and long-term survivors (survived &amp;gt;30 months after starting trastuzumab). Results were compared between these two groups of patients using a Fisher’s exact test (dichotomous groups) and Wilcoxon rank sum tests (continuous scores). Univariable Cox regression models were evaluated using all patients, to evaluate if risk scores were prognostic of overall survival (OS). Statistical significance was set at the p=0.05 level and all tests were two-sided. Results: The median patient age was 60 years (interquartile range 53-65 years), 24% (n=7) had de-novo MBC and the majority of patients (52%) had ER or PR positive tumors. Among 29 included patients, the median OS was 23.4 months (95%CI 10.3-34.3 months); 10 patients died within 12 months and 10 patients survived &amp;gt;30 months after starting trastuzumab-based therapy. A median of 155 days (range 4-812) elapsed between metastatic biopsy and initiation of trastuzumab. The distribution of the Prosigna ROR Score, Basal Cor, HER2 Cor, Luminal A Cor, Luminal B Cor, Mammaprint Subtype/Risk Group, Oncotype Risk Score/Risk Group, IHC4 mRNA Risk Group and GGI Risk Score/Risk Group did not differ between the short- and long-term survivors. However, the Mammaprint Predictor Score was significantly higher [mean 0.34 (std 5.50) versus -4.95 (std 5.24), p=0.033] and the IHC4 Risk Score was significantly lower among long-term as compared to short-term survivors [mean 99.3 (std 67.1) versus 160.3 (std 40.9), p=0.044]. The association between molecular gene signatures and OS are described in Table 1. Conclusion: Several gene signatures were associated with OS in this exploratory analysis of women with HER2+ MBC who received trastuzumab-based therapy. The Mammaprint Predictor and the IHC4 Risk Scores differed among short- versus long-term survivors, warranting validation in an independent dataset. Table 1. Univariable Survival Results (n=29)ComparatorHR (95% CI)p-valueProsigna ROR Score/ 10 units1.23 (0.92, 1.65)0.17ProsignaHER2 vs Other1.25 (0.50, 3.13)0.64Basal Cor/ unit3.61 (1.10, 11.78)0.034Her2 Cor/ unit0.99 (0.15, 6.40)0.99Luminal A Cor/ unit0.22 (0.05, 0.95)0.042Luminal B Cor/ unit0.26 (0.06, 1.06)0.060Mammaprint Predictor Score/ unit1.10 (1.02, 1.19)0.015Mammaprint SubtypeHER2 vs Other0.85 (0.37, 2.00)0.72Mammaprint RiskHigh vs Low4.20 (1.37, 12.86)0.012Oncotype Risk Score/ 10 units1.27 (0.95, 1.70)0.11Oncotype Risk GroupHigh vs Intermediate4.83 (0.60, 39.07)0.14IHC4 Risk Score/ 10 units1.09 (1.00, 1.18)0.046IHC4 mRNA Risk GroupHigh vs Intermediate4.83 (0.60, 39.07)0.14GGI Risk Score/ 10 units1.63 (1.02, 2.61)0.043GGI Risk GroupHigh vs Low5.14 (1.13, 23.51)0.035 Citation Format: Katarzyna Joanna Jerzak, Danielle N Desautels, Phillip S Blanchette, Jane Bayani, Sharon Nofech-Mozes, Martin J Yaffe, Gregory Pond, Kathleen I Pritchard, John MS Bartlett. Identifying novel molecular markers of response to trastuzumab in metastatic breast cancer [abstract]. In: Proceedings of the 2019 San Antonio Breast Cancer Symposium; 2019 Dec 10-14; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2020;80(4 Suppl):Abstract nr P4-10-29.

Deriving a Passive Surveillance Stroke Severity Indicator From Routinely Collected Administrative Data: The PaSSV Indicator.

Adjusting for stroke severity is crucial for stroke outcomes research. However, this information is not available in administrative healthcare data. We aimed to derive an indicator of baseline stroke severity using these data. We identified patients with stroke enrolled in a population-based registry in Ontario, Canada, and used the Canadian Neurological Scale (CNS), documented in the registry, as a measure of stroke severity. We derived an estimated CNS from a linear regression model in which we regressed the observed CNS on predictor variables: age, sex, arrival by ambulance, interhospital transfer, mechanical ventilation, and an emergency department triage score. The effect of stroke severity on the estimated hazard ratios for 30-day mortality was determined in 3 Cox-proportional hazards models with (1) no CNS, (2) observed CNS, and (3) estimated CNS, all adjusted for age, sex, Charlson index, and stroke type. We assessed model discrimination using C statistics. To assess for construct validity, we repeated these analyses in a subset of patients with documented National Institute of Health Stroke Scale and in a cohort of patients with stroke external to the registry. We derived the estimated stroke severity in 41 481 patients (48.7% female, median age of 75 years [interquartile range, 64- 83]). The magnitude of the association between stroke severity and mortality was similar for the observed and estimated CNS. The discriminative ability of the Cox-proportional hazards models to predict mortality was highest when the observed CNS was included (C statistic, 0.82 [95% CI, 0.81-0.82]), moderate with estimated CNS (0.76 [0.75-0.76]), and lowest without CNS (0.69 [0.69-0.70]. Our findings were replicated with the National Institute of Health Stroke Scale and in the external cohort. We derived an estimated measure of stroke severity using administrative data. This can be applied for risk adjustment in population-based stroke outcomes research and in assessments of health system performance.

Long-Term Mental Health Outcomes in Mothers and Siblings of Children With Cancer: A Population-Based, Matched Cohort Study.

Although a diagnosis of childhood cancer can have a profound effect on the entire family unit, its impact on the long-term mental health of family members is not well characterized. A provincial childhood cancer registry in Ontario, Canada, was linked to birth records to identify separate population-based cohorts of mothers and siblings of children diagnosed with cancer between 1998 and 2014. The mother and sibling cohorts were matched to corresponding population controls and linked to health services data. The rate of mental health-related outpatient visits (family physician, psychiatrist) and the incidence of severe psychiatric events (psychiatric emergency department visit, psychiatric hospitalization, suicide) were compared between mothers and siblings and their controls. Possible predictors of mental health outcomes were examined, including demographics, characteristics of the cancer-affected child, and cancer treatment. We identified 4,773 mothers and 7,897 siblings of children diagnosed with cancer during the study period. Compared with controls, both groups experienced elevated rates of outpatient visits (mothers: rate ratio [RR], 1.4; P < .0001; siblings: RR, 1.1; P < .0001). The risk of severe psychiatric events was not increased in either cohort. Mother and sibling demographic factors associated with increased risk of adverse mental health included younger maternal age at cancer diagnosis, low socioeconomic status, and rural residence among mothers and older sibling age among siblings. Treatment-related variables pertaining to the cancer-affected child were not associated with mental health outcomes. Mental health outcomes clustered within families. Both mothers and siblings experience elevated and prolonged need for mental health-related health care as compared with the general population. Demographic risk factors predict subpopulations at highest risk. Increased psychosocial support for family members during and after cancer therapy is warranted.

PROTAMINE REVERSAL POST HEPARIN ADMINISTRATION FOR IMMEDIATE FEMORAL SHEATH REMOVAL IN CORONARY CATHETERIZATION/INTERVENTION: VASCULAR AND CARDIAC SAFETY AND EFFICACY

Femoral vascular complication rates range from 1-3% for diagnostic and interventional procedures. Longer sheath dwell time is one of the predictors of vascular complication. We tested the vascular and coronary safety of immediate partial heparin reversal with protamine for immediate femoral sheath removal, in a first reported Ontario registry in a primary radial access (85%) program. All consecutive femoral percutaneous coronary intervention (PCI) patients over one year post-procedure were enrolled. Reversal was protamine 0.5 mg/100 U heparin. Activated clotting times (ACTs) were checked before and after protamine administration, with an aim for sheath pull when ACT was less than 170 seconds. Inclusion criteria required a dual antiplatelet load (> 4 hours) and absence of angiographic complications. Of the 105 included, 78 patients underwent stent implants (1.3±1.1 stents) with the remaining undergoing PTCA alone or physiologic testing only. Average heparin dose was 5076 ± 1746 units, peak ACT was 269 ± 68 seconds and post-protamine ACT was 165±31 seconds. Average protamine dose given was 24±6 mg. There were no significant adverse events that occurred except for a single significant hematoma requiring no surgical intervention. Protamine reversal for early sheath removal in this single center registry appears to be efficacious and safe, with no early adverse cardiac events and good vascular safety. A larger multicenter registry documenting safety and efficacy of this approach would be suggested, with a view to reducing cost and expediting care.