Using Big Data for Cardiovascular Health Surveillance: Insights From 10.3 Million Individuals in the CANHEART Cohort.

BACKGROUND: The increasing availability of large electronic population-based databases offers unique opportunities to conduct cardiovascular health surveillance traditionally done using surveys. We aimed to examine cardiovascular risk-factor burden, preventive care, and disease incidence among adults in Ontario, Canada-using routinely collected data-and compare estimates with health survey data. METHODS: In the Cardiovascular Health in Ambulatory Care Research Team (CANHEART) initiative, multiple health administrative databases were linked to create a population-based cohort of 10.3 million adults without histories of cardiovascular disease. We examined cardiovascular risk-factor burden and screening and outcomes between 2016 and 2020. Risk- factor burden was also compared with cycles 3 to 5 (2012 to 2017) of the Canadian Health Measures Survey (CMHS), which included 9473 participants across Canada. RESULTS: Mean age of our study cohort was 47.9 ± 17.0 years, and 52.0% were women. Lipid and diabetes assessment rates among individuals 40 to 79 years were 76.6% and 78.2%, respectively, and lowest among men 40 to 49 years of age. Total cholesterol levels and diabetes and hypertension rates among men and women 20 to 79 years were similar to Canadian Health Measures Survey (CHMS) findings (total cholesterol: 4.80/4.98 vs 4.94/5.25 mmol/L; diabetes: 8.2%/7.1% vs 8.1%/6.0%; hypertension: 21.4%/21.6% vs 23.9%/23.1%, respectively); however, patients in the CANHEART study had slightly higher mean glucose (men: 5.79 vs 5.44; women: 5.39 vs 5.09 mmol/L) and systolic blood pressures (men: 126.2 vs 118.3; women: 120.6 vs 115.7 mm Hg). CONCLUSIONS: Cardiovascular health surveillance is possible through linkage of routinely collected electronic population-based datasets. However, further investigation is needed to understand differences between health administrative and survey measures cross-sectionally and over time.

Socio-demographic characteristics associated with hospitalization for sepsis among adults in Canada: a Census-linked cohort study.

PURPOSE: Sepsis is a considerable health system burden. Population-based epidemiological surveillance of sepsis is limited to basic data available in administrative databases. We sought to determine if routinely collected Census data, linked to hospitalization data, can provide a broad socio-demographic profile of patients admitted to Canadian hospitals with sepsis. METHODS: Linking the 2006 long-form Canadian Census (most recent available for linkage) to the Discharge Abstract Data from 2006/2007 to 2008/2009, we created a population-based cohort of approximately 3,433,900 Canadians. Patients admitted to hospital with sepsis were identified using the Canadian Institute for Health Information administrative data definition. Age-standardized hospital admission rates for sepsis were calculated. Multivariable modelling was used to examine the relationship between Census characteristics and hospitalization with sepsis. RESULTS: Of those individuals successfully linked to the 2006 long-form Canadian Census, 10,400 patients of 18 yr and older were admitted to hospital with sepsis between the fiscal years 2006/2007 and 2008/2009. These individuals represented a weighted count of approximately 49,000 Canadians from all provinces and territories, excluding Quebec. The age-standardized rate of sepsis hospitalization was 96 cases/100,000 population. Of these, 37/100,000 cases were classified as severe sepsis. The association of Census characteristics with sepsis hospitalization varied with age. In all age-specific models, male sex, never being married, visible minority status, having functional limitations, and not being in the labour force were associated with an increased odds of hospital admission. CONCLUSIONS: Census data identified broad socio-demographic risk factors for admission to hospital with sepsis. Consideration should be given to incorporating Census data linked to administrative hospital data in population-based epidemiologic surveillance.

Factors associated with hypertension control among older Canadians.

BACKGROUND: In Canada, hypertension control is significantly less likely in older women taking antihypertensive medication than in older men. This study examines factors that may explain some of the differences in hypertension control between women and men. DATA AND METHODS: The analysis is based on data collected for 2,111 adults aged 60 to 79 who were treated for hypertension in the first four cycles of the Canadian Health Measures Survey. Hypertension, treatment and control were estimated based on measured systolic and diastolic blood pressure and on the Drug Identification Numbers of antihypertensive medications. Risk factors included health behaviours, comorbidities and a family history of hypertension. Sex-specific logistic regression models examined associations between risk factors and hypertension control. RESULTS: The systolic blood pressure of women taking antihypertensive medication was higher than that of men, regardless of hypertension control. For women, older age and diabetes were significantly associated with poorer hypertension control, while older age, ethnicity, diabetes, no cardiovascular disease, and nonsteroidal anti-inflammatory drug use were significant for men. DISCUSSION: Based on current blood pressure targets, women and men aged 60 to 79 taking antihypertensive medication in Canada continue to differ in control and factors associated with control. Further research to better understand the underlying cause of these associations may help reduce disparities in hypertension control rates between women and men in Canada.

Population health impact of statin treatment in Canada.

BACKGROUND: Statins are prescribed to treat dyslipidemia (abnormal amount of lipids such as cholesterol and/or fat in the blood) and reduce cardiovascular disease (CVD) risk. This study describes the CVD risk profile of Canadians aged 20 to 79, compares current treatment patterns with guideline recommendations, and investigates the population health impact of statin treatment. DATA AND METHODS: The baseline CVD risk of the Canadian population aged 20 to 79 was estimated by applying population-weighted risk factor data from the 2007 to 2011 Canadian Health Measures Survey (CHMS) to the Framingham Risk Score. Estimates of statin effectiveness from the literature were applied to baseline risk to assess the number of CVD events avoided owing to actual (CHMS-reported) and recommended (2012 Canadian Cardiovascular Society guidelines) statin treatment. RESULTS: An estimated 2.8 million Canadian adults (about 1 in 10) were treated with statin drugs. The mean 10-year CVD risk of those treated was 27%. Assuming optimal adherence, it was estimated that statin treatment avoided around 18,900 CVD events annually and yielded a number-needed-to-treat (average number of patients treated to prevent one additional CVD event) of 15 over 10 years. In comparison, 6.5 million Canadian adults (about 1 in 4) were recommended for treatment under the 2012 guidelines. The mean 10-year CVD risk of those recommended for treatment was 24%, which translates into a number-needed-to-treat of 17 over 10 years, or approximately 38,600 CVD events avoided annually. The largest gaps in treatment and potential CVD events avoided were among people at high and intermediate risk for CVD. INTERPRETATION: Canadians' CVD risk could be lessened with enhanced targeting of statin treatment to individuals at high and intermediate risk. Such a strategy would likely require additional investments.

The Population Health Model (POHEM): an overview of rationale, methods and applications.

The POpulation HEalth Model (POHEM) is a health microsimulation model that was developed at Statistics Canada in the early 1990s. POHEM draws together rich multivariate data from a wide range of sources to simulate the lifecycle of the Canadian population, specifically focusing on aspects of health. The model dynamically simulates individuals' disease states, risk factors, and health determinants, in order to describe and project health outcomes, including disease incidence, prevalence, life expectancy, health-adjusted life expectancy, quality of life, and healthcare costs. Additionally, POHEM was conceptualized and built with the ability to assess the impact of policy and program interventions, not limited to those taking place in the healthcare system, on the health status of Canadians. Internationally, POHEM and other microsimulation models have been used to inform clinical guidelines and health policies in relation to complex health and health system problems. This paper provides a high-level overview of the rationale, methodology, and applications of POHEM. Applications of POHEM to cardiovascular disease, physical activity, cancer, osteoarthritis, and neurological diseases are highlighted.

Comparing Guidelines for Statin Treatment in Canada and the United States.

BACKGROUND: New guidelines for cardiovascular disease risk assessment and statin eligibility have recently been published in the United States by the American College of Cardiology and the American Heart Association (ACC-AHA). It is unknown how these guidelines compare with the Canadian Cardiovascular Society (CCS) recommendations. METHODS AND RESULTS: Using data from the Canadian Health Measures Survey 2007-2011, we estimated the cardiovascular disease risk and proportion of the Canadian population, aged 40 to 75 years without cardiovascular disease, who would theoretically be eligible for statin treatment under both the CCS and ACC-AHA guidelines. The survey sample used (n=1975) represented 13.1 million community dwelling Canadians between the ages of 40 and 75 years. In comparing the CVD risk assessment methods, we found that calculated CVD risk was higher based on the CCS guidelines compared with the ACC-AHA guidelines. Despite this, a similar proportion and number of Canadians would be eligible for statin treatment under the 2 sets of recommendations. Some discordance in recommendations was found within subgroups of the population, with the CCS guidelines recommending more treatment for individuals who are younger, with a family history of CVD, or with chronic kidney disease. The ACC-AHA recommend more treatment for people who are older (age 60+ years). These results likely overestimate the treatment rate under both guidelines because, in primary prevention, a clinician-patient discussion must occur before treatment and determines uptake. CONCLUSIONS: Implementing the ACC-AHA lipid treatment guidelines in Canada would not result in an increase in individuals eligible for statin treatment. In fact, the proportion of the population recommended for statin treatment would decrease slightly and be targeted at different subgroups of the population.

Implementation of ICD-10 in Canada: how has it impacted coded hospital discharge data?

BACKGROUND: The purpose of this study was to assess whether or not the change in coding classification had an impact on diagnosis and comorbidity coding in hospital discharge data across Canadian provinces. METHODS: This study examined eight years (fiscal years 1998 to 2005) of hospital records from the Hospital Person-Oriented Information database (HPOI) derived from the Canadian national Discharge Abstract Database. The average number of coded diagnoses per hospital visit was examined from 1998 to 2005 for provinces that switched from International Classifications of Disease 9(th) version (ICD-9-CM) to ICD-10-CA during this period. The average numbers of type 2 and 3 diagnoses were also described. The prevalence of the Charlson comorbidities and distribution of the Charlson score one year before and one year after ICD-10 implementation for each of the 9 provinces was examined. The prevalence of at least one of the seventeen Charlson comorbidities one year before and one year after ICD-10 implementation were described by hospital characteristics (teaching/non-teaching, urban/rural, volume of patients). RESULTS: Nine Canadian provinces switched from ICD-9-CM to ICD-I0-CA over a 6 year period starting in 2001. The average number of diagnoses coded per hospital visit for all code types over the study period was 2.58. After implementation of ICD-10-CA a decrease in the number of diagnoses coded was found in four provinces whereas the number of diagnoses coded in the other five provinces remained similar. The prevalence of at least one of the seventeen Charlson conditions remained relatively stable after ICD-10 was implemented, as did the distribution of the Charlson score. When stratified by hospital characteristics, the prevalence of at least one Charlson condition decreased after ICD-10-CA implementation, particularly for low volume hospitals. CONCLUSION: In conclusion, implementation of ICD-10-CA in Canadian provinces did not substantially change coding practices, but there was some coding variation in the average number of diagnoses per hospital visit across provinces.

Do coder characteristics influence validity of ICD-10 hospital discharge data?

BACKGROUND: Administrative data are widely used to study health systems and make important health policy decisions. Yet little is known about the influence of coder characteristics on administrative data validity in these studies. Our goal was to describe the relationship between several measures of validity in coded hospital discharge data and 1) coders' volume of coding (> or = 13,000 vs. <13,000 records), 2) coders' employment status (full- vs. part-time), and 3) hospital type. METHODS: This descriptive study examined 6 indicators of face validity in ICD-10 coded discharge records from 4 hospitals in Calgary, Canada between April 2002 and March 2007. Specifically, mean number of coded diagnoses, procedures, complications, Z-codes, and codes ending in 8 or 9 were compared by coding volume and employment status, as well as hospital type. The mean number of diagnoses was also compared across coder characteristics for 6 major conditions of varying complexity. Next, kappa statistics were computed to assess agreement between discharge data and linked chart data reabstracted by nursing chart reviewers. Kappas were compared across coder characteristics. RESULTS: 422,618 discharge records were coded by 59 coders during the study period. The mean number of diagnoses per record decreased from 5.2 in 2002/2003 to 3.9 in 2006/2007, while the number of records coded annually increased from 69,613 to 102,842. Coders at the tertiary hospital coded the most diagnoses (5.0 compared with 3.9 and 3.8 at other sites). There was no variation by coder or site characteristics for any other face validity indicator. The mean number of diagnoses increased from 1.5 to 7.9 with increasing complexity of the major diagnosis, but did not vary with coder characteristics. Agreement (kappa) between coded data and chart review did not show any consistent pattern with respect to coder characteristics. CONCLUSIONS: This large study suggests that coder characteristics do not influence the validity of hospital discharge data. Other jurisdictions might benefit from implementing similar employment programs to ours, e.g.: a requirement for a 2-year college training program, a single management structure across sites, and rotation of coders between sites. Limitations include few coder characteristics available for study due to privacy concerns.

A comparison between the APACHE II and Charlson Index Score for predicting hospital mortality in critically ill patients.

BACKGROUND: Risk adjustment and mortality prediction in studies of critical care are usually performed using acuity of illness scores, such as Acute Physiology and Chronic Health Evaluation II (APACHE II), which emphasize physiological derangement. Common risk adjustment systems used in administrative datasets, like the Charlson index, are entirely based on the presence of co-morbid illnesses. The purpose of this study was to compare the discriminative ability of the Charlson index to the APACHE II in predicting hospital mortality in adult multisystem ICU patients. METHODS: This was a population-based cohort design. The study sample consisted of adult (>17 years of age) residents of the Calgary Health Region admitted to a multisystem ICU between April 2002 and March 2004. Clinical data were collected prospectively and linked to hospital outcome data. Multiple regression analyses were used to compare the performance of APACHE II and the Charlson index. RESULTS: The Charlson index was a poor predictor of mortality (C = 0.626). There was minimal difference between a baseline model containing age, sex and acute physiology score (C = 0.74) and models containing either chronic health points (C = 0.76) or Charlson index variations (C = 0.75, 0.76, 0.77). No important improvement in prediction occurred when the Charlson index was added to the full APACHE II model (C = 0.808 to C = 0.813). CONCLUSION: The Charlson index does not perform as well as the APACHE II in predicting hospital mortality in ICU patients. However, when acuity of illness scores are unavailable or are not recorded in a standard way, the Charlson index might be considered as an alternative method of risk adjustment and therefore facilitate comparisons between intensive care units.

Trophic factor-induced intracellular calcium oscillations are required for the expression of postsynaptic acetylcholine receptors during synapse formation between Lymnaea neurons.

Nervous system functions in all animals rely upon synaptic connectivity that is established during early development. Whereas cell-cell signaling plays a critical role in establishing synapse specificity, the involvement of extrinsic growth factors cannot, however, be undermined. We have previously demonstrated that trophic factors are required for excitatory but not inhibitory synapse formation between Lymnaea neurons. Moreover, in the absence of trophic factors, neurons from a number of species establish inappropriate inhibitory synapses, which can, however, be corrected by the addition of trophic factors. The precise site of trophic factor actions (presynaptic versus postsynaptic) and the underlying mechanisms remain, however, undefined. Here, we provide the first direct evidence that the trophic factor-mediated excitatory synapse formation involves activity-induced calcium (Ca(2+)) oscillations in the postsynaptic left pedal dorsal 1 (LPeD1) but not the presynaptic visceral dorsal 4 (VD4, cholinergic) neuron. These oscillations involved Ca(2+) influx through voltage-gated Ca(2+) channels and required receptor tyrosine kinase activity which was essential for the expression of excitatory, nicotinic acetylcholine receptors in the postsynaptic cell during synapse formation. We also demonstrate that selectively blocking the electrical activity presynaptically did not perturb trophic factor-induced synapse formation between the paired cells, whereas hyperpolarizing the postsynaptic cell prevented appropriate synaptogenesis between VD4 and LPeD1 cells. Together, our data underscore the importance of extrinsic trophic factors in regulating the electrical activity of the postsynaptic but not the presynaptic cell and that the resulting Ca(2+) oscillations are essential for the expression of postsynaptic receptors during specific synapse formation.