A Systems-Level Evaluation Framework for Virtual Care.

The virtual care landscape is significantly changing, largely due to an increased demand initiated by the COVID-19 pandemic and the evolution of technology. Complex questions about how to best leverage virtual care and its impact remain unanswered. Our team developed a systems-level evaluation framework to inform virtual care service design and evaluation to take a more comprehensive approach to planning and implementing virtual care. We designed the framework for application in Alberta Health Services (AHS) by engaging virtual care users (patients, families and healthcare providers), implementation staff and decision makers across the organization. Here we report our design process and key lessons learned. The framework received endorsement by AHS senior leadership for application across the system. Our next step is to test the framework. By sharing our design process and experiences, we aim to help inform other national and international jurisdictions plan virtual care evaluations within their context.

Breaking the 80:20 rule in health research using large administrative data sets.

Objective: To explore the application of online analytic processing (OLAP) to improve the efficiency of analytics using large administrative health data sets. Methods: 18 years of administrative health data (1994/95 to 2012/13) were obtained from the Alberta Ministry of Health in Canada. The data sets included hospitalization, ambulatory care and practitioner claims data. Reference files were obtained that provided information including patient demographics, resident postal code, facility, and provider details. Population counts and projections for each year, sex, age were included for rate calculations. These sources were used to develop a data cube using OLAP tools. Results: Time required for analyses was reduced to 5% of that required when comparing run-time for simple queries that did not require linkage of data sets. The data cube negated the need for many intermediary steps for data extraction and analyses for research activities. Conventional methods required over 250 GB of server space for multiple analytic subsets, compared to only 10.3 GB for the data cube. Conclusions: Cross-training in information technology and health analytics is recommended to provide capacity to better leverage OLAP tools which are available with many common applications.

Rural-Urban Disparities in Realized Spatial Access to General Practitioners, Orthopedic Surgeons, and Physiotherapists among People with Osteoarthritis in Alberta, Canada.

Rural Canadians have high health care needs due to high prevalence of osteoarthritis (OA) but lack access to care. Examining realized access to three types of providers (general practitioners (GPs), orthopedic surgeons (Ortho), and physiotherapists (PTs)) simultaneously helps identify gaps in access to needed OA care, inform accessibility assessment, and support health care resource allocation. Travel time from a patient's postal code to the physician's postal code was calculated using origin-destination network analysis. We applied descriptive statistics to summarize differences in travel time, hotspot analysis to explore geospatial patterns, and distance decay function to examine the travel pattern of health care utilization by urbanicity. The median travel time in Alberta was 11.6 min (IQR = 4.3-25.7) to GPs, 28.9 (IQR = 14.8-65.0) to Ortho, and 33.7 (IQR = 23.1-47.3) to PTs. We observed significant rural-urban disparities in realized access to GPs (2.9 and IQR = 0.0-92.1 in rural remote areas vs. 12.6 and IQR = 6.4-21.0 in metropolitan areas), Ortho (233.3 and IQR = 171.3-363.7 in rural remote areas vs. 21.3 and IQR = 14.0-29.3 in metropolitan areas), and PTs (62.4 and IQR = 0.0-232.1 in rural remote areas vs. 32.1 and IQR = 25.2-39.9 in metropolitan areas). We identified hotspots of realized access to all three types of providers in rural remote areas, where patients with OA tend to travel longer for health care. This study may provide insight on the choice of catchment size and the distance decay pattern of health care utilization for further studies on spatial accessibility.

Rural-Urban Differences in Non-Local Primary Care Utilization among People with Osteoarthritis: The Role of Area-Level Factors.

The utilization of non-local primary care physicians (PCP) is a key primary care indicator identified by Alberta Health to support evidence-based healthcare planning. This study aims to identify area-level factors that are significantly associated with non-local PCP utilization and to examine if these associations vary between rural and urban areas. We examined rural-urban differences in the associations between non-local PCP utilization and area-level factors using multivariate linear regression and geographically weighted regression (GWR) models. Global Moran's I and Gi* hot spot analyses were applied to identify spatial autocorrelation and hot spots/cold spots of non-local PCP utilization. We observed significant rural-urban differences in the non-local PCP utilization. Both GWR and multivariate linear regression model identified two significant factors (median travel time and percentage of low-income families) with non-local PCP utilization in both rural and urban areas. Discontinuity of care was significantly associated with non-local PCP in the southwest, while the percentage of people having university degree was significant in the north of Alberta. This research will help identify gaps in the utilization of local primary care and provide evidence for health care planning by targeting policies at associated factors to reduce gaps in OA primary care provision.

Integrating Care from Home to Hospital to Home: Using Participatory Design to Develop a Provincial Transitions in Care Guideline.

Introduction: Patients worldwide experience fragmented and uncoordinated care as they transition between primary and acute care. To improve system integration and outcomes for patients, in 2017/2018 Alberta Health Services (largest health services delivery organization in Canada) called for a coordinated approach to improve transitions in care (TiC). Healthcare leadership responded by initiating the development of a province-wide guideline outlining core components of effective transitions in care. This case study highlights the extensive design process used to develop this guideline, with a focus on the participatory design (PD) approach used throughout. Methods: An iterative, mixed methods PD approach was used to engage over 750 stakeholders through the following activities to establish Guideline content: i) learning collaborative; ii) design-team; iii) targeted online surveys; iv) primary care stakeholder consultation; v) modified Delphi panel; and vi) patient advisory committee. Results: The result was Alberta's first guideline for supporting patients through TiC: "Alberta's Home to Hospital to Home Transitions Guideline". Conclusion: The extensive design process used to create the Guideline was instrumental in establishing content, encouraging system integration, and creating conditions to support provincial implementation. While intended to improve and standardize patient care in Alberta, the methods used and lessons learned throughout the development of the Guideline are applicable internationally.

Healthy food prescription incentive programme for adults with type 2 diabetes who are experiencing food insecurity: protocol for a randomised controlled trial, modelling and implementation studies.

INTRODUCTION: The high cost of many healthy foods poses a challenge to maintaining optimal blood glucose levels for adults with type 2 diabetes mellitus who are experiencing food insecurity, leading to diabetes complications and excess acute care usage and costs. Healthy food prescription programmes may reduce food insecurity and support patients to improve their diet quality, prevent diabetes complications and avoid acute care use. We will use a type 2 hybrid-effectiveness design to examine the reach, effectiveness, adoption, implementation and maintenance (RE-AIM) of a healthy food prescription incentive programme for adults experiencing food insecurity and persistent hyperglycaemia. A randomised controlled trial (RCT) will investigate programme effectiveness via impact on glycosylated haemoglobin (primary outcome), food insecurity, diet quality and other clinical and patient-reported outcomes. A modelling study will estimate longer-term programme effectiveness in reducing diabetes-related complications, resource use and costs. An implementation study will examine all RE-AIM domains to understand determinants of effective implementation and reasons behind programme successes and failures. METHODS AND ANALYSIS: 594 adults who are experiencing food insecurity and persistent hyperglycaemia will be randomised to a healthy food prescription incentive (n=297) or a healthy food prescription comparison group (n=297). Both groups will receive a healthy food prescription. The incentive group will additionally receive a weekly incentive (CDN$10.50/household member) to purchase healthy foods in supermarkets for 6 months. Outcomes will be assessed at baseline and follow-up (6 months) in the RCT and analysed using mixed-effects regression. Longer-term outcomes will be modelled using the UK Prospective Diabetes Study outcomes simulation model-2. Implementation processes and outcomes will be continuously measured via quantitative and qualitative data. ETHICS AND DISSEMINATION: Ethical approval was obtained from the University of Calgary and the University of Alberta. Findings will be disseminated through reports, lay summaries, policy briefs, academic publications and conference presentations. TRIAL REGISTRATION NUMBER: NCT04725630. PROTOCOL VERSION: Version 1.1; February 2022.

A "Shock Test" to Primary Care Integration: COVID-19 Lessons from Alberta.

The COVID-19 pandemic exposed primary care (PC), and policies aimed at integrating it into provincial health systems, to a "shock test." This paper draws on documentary analysis and qualitative interviews with PC and health system stakeholders to examine shifts in Alberta's pre-pandemic PC integration model during the first nine months of the pandemic. We begin with an account of three elements of the province's pre-pandemic model: finance, health authority activity and community activity. We describe these elements as they shifted, focusing on two indicators of change: novel virtual care billing codes and personal protective equipment (PPE) distribution channels. We draw out policy planning lessons for improving PC integration under normal and future pandemic conditions, namely, by facilitating rapid updates of virtual care billing codes, analyses of the impact of care delivery and backstopping of PPE markets and supply chains for PC.

Achieving Resilience in Primary Care during the COVID-19 Pandemic: Competing Visions and Lessons from Alberta.

The COVID-19 pandemic has tested the resilience of health systems broadly and primary care (PC) specifically. This paper begins by distinguishing the technical and political aspects of resilience and then draws on a documentary analysis and qualitative interviews with health system and PC stakeholders to examine competing resilience-focused responses to the pandemic in Alberta, Canada. We describe the pre-existing linkages between the province's central service delivery agency and its independent PC clinics. Together, these central and independent elements make up Alberta's broader health system, with the focus of this paper being on PC's particular vision of how resilience ought to be achieved. We describe two specific, pandemic-affected areas of activity by showing how competing visions of resilience emerged in the central service delivery agency and independent PC responses as they met at the system's points of linkage. At the first point of linkage, we describe the centralized activation of an incident management system and the replies made by independent PC stakeholders. At the second point of linkage, we describe central efforts to disseminate infection prevention and control guidance to PC clinics and the improvisational efforts of staff at those independent clinics to operationalize the guidance and ensure continuity of operations. We identify gaps between the resilience visions of the central agency and independent PC, drawing broadly applicable policy lessons for improving responses in present and future public health emergencies. Finding ways to include PC in centralized resilience policy planning is a priority.

Opioid prescribing among new users for non-cancer pain in the USA, Canada, UK, and Taiwan: A population-based cohort study.

BACKGROUND: The opioid epidemic in North America has been driven by an increase in the use and potency of prescription opioids, with ensuing excessive opioid-related deaths. Internationally, there are lower rates of opioid-related mortality, possibly because of differences in prescribing and health system policies. Our aim was to compare opioid prescribing rates in patients without cancer, across 5 centers in 4 countries. In addition, we evaluated differences in the type, strength, and starting dose of medication and whether these characteristics changed over time. METHODS AND FINDINGS: We conducted a retrospective multicenter cohort study of adults who are new users of opioids without prior cancer. Electronic health records and administrative health records from Boston (United States), Quebec and Alberta (Canada), United Kingdom, and Taiwan were used to identify patients between 2006 and 2015. Standard dosages in morphine milligram equivalents (MMEs) were calculated according to The Centers for Disease Control and Prevention. Age- and sex-standardized opioid prescribing rates were calculated for each jurisdiction. Of the 2,542,890 patients included, 44,690 were from Boston (US), 1,420,136 Alberta, 26,871 Quebec (Canada), 1,012,939 UK, and 38,254 Taiwan. The highest standardized opioid prescribing rates in 2014 were observed in Alberta at 66/1,000 persons compared to 52, 51, and 18/1,000 in the UK, US, and Quebec, respectively. The median MME/day (IQR) at initiation was highest in Boston at 38 (20 to 45); followed by Quebec, 27 (18 to 43); Alberta, 23 (9 to 38); UK, 12 (7 to 20); and Taiwan, 8 (4 to 11). Oxycodone was the first prescribed opioid in 65% of patients in the US cohort compared to 14% in Quebec, 4% in Alberta, 0.1% in the UK, and none in Taiwan. One of the limitations was that data were not available from all centers for the entirety of the 10-year period. CONCLUSIONS: In this study, we observed substantial differences in opioid prescribing practices for non-cancer pain between jurisdictions. The preference to start patients on higher MME/day and more potent opioids in North America may be a contributing cause to the opioid epidemic.

An implementation history of primary health care transformation: Alberta's primary care networks and the people, time and culture of change.

BACKGROUND: Primary care, and its transformation into Primary Health Care (PHC), has become an area of intense policy interest around the world. As part of this trend Alberta, Canada, has implemented Primary Care Networks (PCNs). These are decentralized organizations, mandated with supporting the delivery of PHC, funded through capitation, and operating as partnerships between the province's healthcare administration system and family physicians. This paper provides an implementation history of the PCNs, giving a detailed account of how people, time, and culture have interacted to implement bottom up, incremental change in a predominantly Fee-For-Service (FFS) environment. METHODS: Our implementation history is built out of an analysis of policy documents and qualitative interviews. We conducted an interpretive analysis of relevant policy documents (n = 20) published since the first PCN was established. We then grounded 12 semi-structured interviews in that initial policy analysis. These interviews explored 11 key stakeholders' perceptions of PHC transformation in Alberta generally, and the formation and evolution of the PCNs specifically. The data from the policy review and the interviews were coded inductively, with participants checking our emerging analyses. RESULTS: Over time, the PCNs have shifted from an initial Frontier Era that emphasized local solutions to local problems and featured few rules, to a present Era of Accountability that features central demands for standardized measures, governance, and co-planning with other elements of the health system. Across both eras, the PCNs have been first and foremost instruments and supporters of family physician authority and autonomy. A core group of people emerged to create the PCNs and, over time, to develop a long-term Quality Improvement (QI) vision and governance plan for them as organizations. The continuing willingness of both these groups to work at understanding and aligning one another's cultures to achieve the transformation towards PHC has been central to the PCNs' survival and success. CONCLUSIONS: Generalizable lessons from the implementation history of this emerging policy experiment include: The need for flexibility within a broad commitment to improving quality. The importance of time for individuals and organizations to learn about: quality improvement; one another's cultures; and how best to support the transformation of a system while delivering care locally.

Geospatial patterns of comorbidity prevalence among people with osteoarthritis in Alberta Canada.

BACKGROUND: Knowledge of geospatial pattern in comorbidities prevalence is critical to an understanding of the local health needs among people with osteoarthritis (OA). It provides valuable information for targeting optimal OA treatment and management at the local level. However, there is, at present, limited evidence about the geospatial pattern of comorbidity prevalence in Alberta, Canada. METHODS: Five administrative health datasets were linked to identify OA cases and comorbidities using validated case definitions. We explored the geospatial pattern in comorbidity prevalence at two standard geographic areas levels defined by the Alberta Health Services: descriptive analysis at rural-urban continuum level; spatial analysis (global Moran's I, hot spot analysis, cluster and outlier analysis) at the local geographic area (LGA) level. We compared area-level indicators in comorbidities hotspots to those in the rest of Alberta (non-hotspots). RESULTS: Among 359,638 OA cases in 2013, approximately 60% of people resided in Metro and Urban areas, compared to 2% in Rural Remote areas. All comorbidity groups exhibited statistically significant spatial autocorrelation (hypertension: Moran's I index 0.24, z score 4.61). Comorbidity hotspots, except depression, were located primarily in Rural and Rural Remote areas. Depression was more prevalent in Metro (Edmonton-Abbottsfield: 194 cases per 1000 population, 95%CI 192-195) and Urban LGAs (Lethbridge-North: 169, 95%CI 168-171) compared to Rural areas (Fox Creek: 65, 95%CI 63-68). Comorbidities hotspots included a higher percentage of First Nations or Inuit people. People with OA living in hotspots had lower socioeconomic status and less access to care compared to non-hotspots. CONCLUSIONS: The findings highlight notable rural-urban disparities in comorbidities prevalence among people with OA in Alberta, Canada. Our study provides valuable evidence for policy and decision makers to design programs that ensure patients with OA receive optimal health management tailored to their local needs and a reduction in current OA health disparities.

Informing Primary Care Changes in Alberta: Continuity and Potential Impacts on Acute Care.

Health systems across Canada are embarking on initiatives to enhance access to primary care services, with the intent of improving patient outcomes and mitigating escalating healthcare costs. However, it is important that such initiatives be carefully weighed with the evidence that the changes will indeed have the desired impact. In Alberta, part of the informative process involved an analysis to examine links between continuity with primary care and utilization of acute care services. The findings provide information regarding expectations for outcomes and potentially useful (and not so useful) measures for monitoring progress and performance.

High-volume general practitioners in Alberta: a descriptive analysis.

BACKGROUND: Alberta is considering capping daily fee-for-service physician billings, but little is known about high-volume practice in the province and its impact on patient health outcomes. In this initial study, we conducted a descriptive analysis of general practitioners' patient volumes and billing practices in relation to associated practitioner demographic characteristics. METHODS: We conducted a retrospective descriptive analysis of the associations of practitioner characteristics, including full-time versus non-full-time practice, provider sex, years in practice, geographic location and international medical graduate status, with high-volume (> 50 visits/d) practice using general practice billing data from 2011 to 2016. Use of general practitioner service codes was described and compared by general practitioner volume status, with adjustment for physician demographic characteristics and geographic parameters. RESULTS: We included 3465 general practitioners practising fee-for-service in Alberta between 2011 and 2016, of whom 233 (6.7%) were identified as high-volume providers. Physicians who had been in practice longer (odds ratio [OR] 1.04 per year, 95% confidence interval [CI] 1.02-1.05) and international medical graduates (OR 1.89, 95% CI 1.40-2.54) were more likely to exceed 50 patient visits/day. Female physicians were less likely to exceed 50 patient visits/day (OR 0.14, 95% CI 0.07-0.28). Rural practice location was negatively associated with high-volume practice (OR 0.87, 95% CI 0.79-0.95) when we controlled for zone within the province. Zone 5 (North) was associated with high-volume practice (OR 1.95, 95% CI 1.06-3.58). Less than full-time practice was prevalent (1836 providers [53.0%]). High-volume general practitioners billed fewer service codes requiring longer visits, except for the most highly remunerated code (patients with complex health issues). INTERPRETATION: These results can inform policy-makers when considering payment system changes. Our next step is to examine the association of high-volume practice with outcomes important to patients, such as evidence of treatment failure (emergency department visits and hospital admissions) for conditions sensitive to primary care management.

Introduction of new technologies and decision making processes: a framework to adapt a Local Health Technology Decision Support Program for other local settings.

PURPOSE: Introducing new health technologies, including medical devices, into a local setting in a safe, effective, and transparent manner is a complex process, involving many disciplines and players within an organization. Decision making should be systematic, consistent, and transparent. It should involve translating and integrating scientific evidence, such as health technology assessment (HTA) reports, with context-sensitive evidence to develop recommendations on whether and under what conditions a new technology will be introduced. However, the development of a program to support such decision making can require considerable time and resources. An alternative is to adapt a preexisting program to the new setting. MATERIALS AND METHODS: We describe a framework for adapting the Local HTA Decision Support Program, originally developed by the Department of Surgery and Surgical Services (Calgary, AB, Canada), for use by other departments. The framework consists of six steps: 1) development of a program review and adaptation manual, 2) education and readiness assessment of interested departments, 3) evaluation of the program by individual departments, 4) joint evaluation via retreats, 5) synthesis of feedback and program revision, and 6) evaluation of the adaptation process. RESULTS: Nine departments revised the Local HTA Decision Support Program and expressed strong satisfaction with the adaptation process. Key elements for success were identified. CONCLUSION: Adaptation of a preexisting program may reduce duplication of effort, save resources, raise the health care providers' awareness of HTA, and foster constructive stakeholder engagement, which enhances the legitimacy of evidence-informed recommendations for introducing new health technologies. We encourage others to use this framework for program adaptation and to report their experiences.

Social equity in Human Papillomavirus vaccination: a natural experiment in Calgary Canada.

BACKGROUND: The Alberta Immunization Program offers a vaccine against the Human Papillomavirus (HPV) free of charge to all girls in Grades 5 and 9. The vaccine is provided in two different service delivery models depending upon the acceptance of the program by the local school board. Vaccinations may be provided "in-school" or in "community" through appointments at Public Health Clinics. The purpose of this study was to determine whether there was a difference in vaccine uptake in Calgary between the two service delivery models, "in-school" and "community", and to examine if socioeconomic status (SES) was a contributing factor. METHODS: Individual data from the Calgary Zone Public Health vaccination database for all grade 5 and 9 girls in Calgary for school years 2008-2011 were analyzed using descriptive statistics. These data included vaccination records for 35,592 girls. Logistic regression was used to examine the effect of delivery system and SES status on being vaccinated, controlling for school type. RESULTS: HPV vaccination completion rates were 75% (95% confidence interval = 74.7%, 75.8%) for girls with an "in-school" compared to 36% (95% confidence interval = 35.3%, 37.2%) for girls in schools with a "community" service delivery model. A girl's neighbourhood SES was related to the likelihood of being HPV vaccinated depending on the service delivery model available to her. For girls attending a Public school with an "in-school" delivery model, the proportion completing vaccination increased as SES decreased (high SES = 79%; medium SES = 79%; low SES = 83%; p-value<0.001). For girls attending Calgary Catholic School District schools with the "community" delivery model there was a decrease in immunization rates from high and mid to low SES (high SES = 41%; medium SES = 42%; low SES = 34%; p-value<0.001). These results show that those with lower SES were differentially disadvantaged by not having access to an "in-school" vaccination delivery model. CONCLUSION: Service delivery models make a difference in HPV vaccination completion rates and create inequities for health protection and disease prevention based on socioeconomic status.

Integrated health systems and integrated knowledge: creating space for putting knowledge into action.

The capacity to innovate and share knowledge is not well developed within health systems. In this paper we highlight essential structures, principles and processes for successful implementation of knowledge utilization strategies in complex health systems. We demonstrate essential links between systems that support knowledge utilization and governance, change management, information management and process improvement.

Location of residence associated with the likelihood of patient visit to the preoperative assessment clinic.

BACKGROUND: Outpatient preoperative assessment clinics were developed to provide an efficient assessment of surgical patients prior to surgery, and have demonstrated benefits to patients and the health care system. However, the centralization of preoperative assessment clinics may introduce geographical barriers to utilization that are dependent on where a patient lives with respect to the location of the preoperative assessment clinic. METHODS: The association between geographical distance from a patient's place of residence to the preoperative assessment clinic, and the likelihood of a patient visit to the clinic prior to surgery, was assessed for all patients undergoing surgery at a tertiary health care centre in a major Canadian city. The odds of attending the preoperative clinic were adjusted for patient characteristics and clinical factors. RESULTS: Patients were less likely to visit the preoperative assessment clinic prior to surgery as distance from the patient's place of residence to the clinic increased (adjusted OR = 0.52, 95% CI 0.44-0.63 for distances between 50-100 km, and OR = 0.26, 95% CI 0.21-0.31 for distances greater than 250 km). This 'distance decay' effect was remarkable for all surgical specialties. CONCLUSION: The present study demonstrates that the likelihood of a patient visiting the preoperative assessment clinic appears to depend on the geographical location of patients' residences. Patients who live closest to the clinic tend to be seen more often than patients who live in rural and remote areas. This observation may have implications for achieving the goals of equitable access, and optimal patient care and resource utilization in a single universal insurer health care system.

Geographical location of residence and uniformity of access to cardiac revascularization services after catheterization.

BACKGROUND: The centralization of health care services has numerous potential benefits but April compromise access for individuals living in remote areas. OBJECTIVES: To examine the association between a patient's place of residence and the likelihood of undergoing a coronary revascularization procedure within one year after cardiac catheterization. METHODS: All Alberta residents undergoing cardiac catheterization between 1995 and 1998 were examined. Geographical distance from patient place of residence to a centralized catheterization facility was calculated. The adjusted odds of undergoing cardiac revascularization within one year of catheterization was determined as a function of distance, controlling for differences in patient age, clinical factors and economic status. RESULTS: Of 21816 residents who underwent cardiac catheterization in the province, 10997 had a revascularization procedure. Graphical examination of distance revealed a change in revascularization rates in patients living more than 450 km from revascularization centres. Further analysis was conducted using this cutpoint. Patients living in these remote areas were more likely to undergo a coronary revascularization procedure within the next year (adjusted odds ratio 1.65, 95% CI 1.05 to 2.59). However, these same residents were also less likely to undergo catheterization in the first place when compared with other Albertans (270 versus 398 procedures per 100000 population). CONCLUSION: Only a small proportion of the population living in Alberta's most remote areas were more likely to undergo a revascularization procedure, indicating a remarkable uniformity of access to revascularization after coronary cardiac catheterization has occurred. This study examines the use of an existing database to gain further insights into the relationship between geography and access to cardiac care, and the distance-access relationship for coronary revascularization in Alberta.

Accuracy of city postal code coordinates as a proxy for location of residence.

BACKGROUND: Health studies sometimes rely on postal code location as a proxy for the location of residence. This study compares the postal code location to that of the street address using a database from the Alberta Provincial Project for Outcome Assessment in Coronary Heart Disease (APPROACHCopyright ). Cardiac catheterization cases in an urban Canadian City were used for calendar year 1999. We determined location in meters for both the address (using the City of Calgary Street Network File in ArcView 3.2) and postal code location (using Statistic Canada's Postal Code Conversion File). RESULTS: The distance between the two estimates of location for each case were measured and it was found that 87.9% of the postal code locations were within 200 meters of the true address location (straight line distances) and 96.5% were within 500 meters of the address location (straight line distances). CONCLUSIONS: We conclude that postal code locations are a reasonably accurate proxy for address location. However, there may be research questions for which a more accurate description of location is required.