Original ResearchPrevalence and Epidemiology of Diabetes in Canadian Primary Care Practices: A Report from the Canadian Primary Care Sentinel Surveillance Network
Introduction
Diabetes is an important and prevalent chronic health condition. It is a significant contributor to cardiovascular morbidity and renal disease. The management of diabetes and its complications is associated with substantial and increasing healthcare costs 1, 2. Estimates of the prevalence and reports on the epidemiology of diabetes are needed to help plan and guide the management of this condition.
Large-scale reports on the epidemiology of diabetes in Canada have usually relied on administrative datasets such as the National Diabetes Surveillance System (NDSS, a collaborative network supported by the Public Health Agency of Canada) (3) or on survey data such as reports from the Canadian Community Health Survey (4). Similar administrative and survey-based data are available provincially 5, 6, 7. These datasets have consistently reported increases in the prevalence of diabetes (5). The most recent NDSS estimate of the prevalence of diagnosed diabetes in Canada was 6.8% in 2009 (3).
The accuracy of identification of chronic diseases depends on the data sources and methods used to ascertain the presence of conditions 8, 9. There are many potential issues underlying the quality of data in large datasets (10). Health administrative databases use validated algorithms to ascertain disease prevalence and incidence. The assumptions in these algorithms depend on properties of the data (10) such as physician billing behaviour; this can change over time as health systems evolve and billing incentives are modified. Ontario, as an example, has recently switched from a largely fee-for-service billing system to a system in which a majority of family physicians practising comprehensive care are remunerated primarily through capitation for their enrolled patients; physicians receive partial payment (currently 15%) for most fees submitted for services provided (11). The percentage of Canadian family physicians reporting being paid mostly through fee-for-service has decreased from 51% in 2004 to 38% in 2013 (12). The switch to non–fee-for-service payments could be impacting the accuracy of diabetes detection when using administrative data (13). A commonly used Canadian algorithm using administrative data to ascertain the presence of diabetes employs a combination of hospital discharge coding and physician service claims. This had a sensitivity of 86% and a specificity of 97% when validated against primary care chart audits (7); the lower sensitivity leads to an underestimation of true prevalence. A recent systematic review of this algorithm found a pooled sensitivity of 82.3% and noted that periodic revalidations may be needed if trends in the prevalence of diabetes change (14).
The sensitivity of survey-based self-reports may be even lower than that of administrative data. A recent study noted that the prevalence of diabetes in Ontario in 2005 was 7.2% using administrative data and 5.4% using self-reported survey data from the Canadian Community Health Survey; sensitivity was 73% and positive agreement was 82% for self-report as compared to administrative data (8).
Administrative datasets can be limited by the lack of clinical data, such as laboratory data, medication prescriptions for patients not covered by provincial plans, routinely collected vital signs or presence of risk factors such as tobacco use. New methods of data capture could provide rich clinical information, augmenting currently available data sources and improving the accuracy and completeness of information available concerning diabetes and other chronic diseases 15, 16. Because of the increasing uptake of Electronic Medical Records (EMRs) in Canada (64% of family physicians reported using EMRs in 2013) (17), the collection and analysis of routinely recorded clinical data have recently become feasible (18). In this study, we used data extracted from primary care EMRs across Canada. We provide EMR-based information to complement and extend knowledge about the epidemiology of diabetes in Canadian primary care.
Data extracted from EMRs have been used in international settings to study chronic diseases at national levels 19, 20, 21. In addition to improving national surveillance data, the availability of national primary care clinical databases can enable comparisons across different countries using a similar approach.
Our objective was to describe the epidemiology of diabetes primary care, including utilization, comorbidities and patterns of medication use for this condition.
Section snippets
Data sources and study population
We extracted data from the EMRs of primary care providers participating in the Canadian Primary Care Sentinel Surveillance Network (CPCSSN). CPCSSN is Canada's first multidisease EMR-based surveillance system (18). It includes 10 primary care practice-based research networks in 8 provinces across Canada. Consenting family physicians and other primary care providers participating in CPCSSN contribute anonymized EMR data to a regional CPCSSN repository; data from all participating networks are
Results
The population consisted of 272 469 patients and 380 participating primary care providers. Of the patients, 25 425 with diabetes had at least 1 encounter with the practice in 2 years. The age- and gender-adjusted prevalence of diabetes for patients seen in this sample of Canadian primary care practices was 8.2%. The population-based estimate of prevalence, using a corrected yearly contact group practice denominator, was 7.6%. Table 2 provides the age- and gender-specific observed prevalence.
Discussion
We present diabetes prevalence and cross-sectional descriptive data for a new Canadian initiative to study the epidemiology of chronic diseases as they are managed in primary care. This study uses EMRs as a new clinical data source in Canada to provide information on epidemiologic trends and patterns. This is similar to recent approaches using primary care EMR clinical databases for diabetes research and epidemiologic studies in Spain (31), the United Kingdom (32) and the United States 33, 34.
Acknowledgements
Grant provided by the Public Health Agency of Canada under a contribution agreement with the College of Family Physicians of Canada, fund # 6271-15-2009-10010002. The views expressed herein do not necessarily represent the views of the Public Health Agency of Canada. No potential conflicts of interest relevant to this article were reported.
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