Data notes
We acknowledge the Title and Rights of BC First Nations who have cared for and nurtured the lands, air and waters for all time, including the
xʷməθkʷəy̓əm (Musqueam),
Sḵwx̱wú7mesh Úxwumixw (Squamish Nation), and
səl̓ílwətaʔ (Tsleil-Waututh Nation) on whose unceded, occupied, and ancestral territory BCCDC is located. As a provincial organization, we also recognize and acknowledge the inherent Title and Rights of BC First Nations whose territories stretch to every inch of the lands colonially known as “British Columbia.”
BC is also home to many First Nations, Métis, and Inuit people from homelands elsewhere in Canada. We recognize the distinct rights of First Nations, Inuit, and Métis people and BCCDC is beginning its work to uphold a
distinctions-based approach to Indigenous data sovereignty and self-determination. All Indigenous Peoples who live in BC have rights to self-determination, health and wellness, and respectful use of their data in alignment with Indigenous data governance principles, including but not limited to
OCAP®.
BCCDC is working to address the consequences of colonial policies which have had lasting effects on all Indigenous Peoples living in the province. Consistent with the
Coast Salish teaching of thee-eat (truth) gifted to PHSA by Coast Salish Knowledge Keeper Sulksun, we recognize that ongoing settler colonialism in BC undermines the inherent rights of Indigenous Peoples who live in BC and significantly contributes to health inequities and data gaps. While the data shown in this report represent BC residents, there is no stratification by Indigeneity and as such, the results are not reflective of the situation for First Nations, Métis, and Inuit Peoples and communities. For public health surveillance and chronic disease indicators pertaining to First Nations, Métis, and Inuit Peoples in BC, please see:
Non-communicable diseases (NCDs) or chronic diseases account for a large proportion of increasing healthcare costs. Monitoring patterns and trends of chronic diseases provide critical information for public health actions (disease prevention, health protection, and health promotion) and healthcare planning. Since the 1990s, the British Columbia Chronic Disease Registries (BCCDR) have been released each year to measure chronic disease burdens in BC, measure health inequalities, and support clinical and public health research.
COVID-19 pandemic
Incidence measures in the dashboard were influenced by the COVID-19 pandemic during fiscal years 2020/21, 2021/22, and 2022/23. Changes in such measures may be driven by multiple factors, including (but not limited to) changes in healthcare seeking behaviour, the availability, accessibility, and patterns of use of healthcare services, as well as true changes in health status. As a result, estimates during the pandemic should be interpreted with caution.
- The Longitudinal Family Physician (LFP) payment model came into effect in BC on February 1, 2023, which may impact incidence rates of some chronic conditions that are identified primarily through Medical Services Plan billing records in the BCCDR. The impacts on annual rates in the 2022/23 fiscal year are not expected to be large because this change has only been in effect for two months of the current data release (February and March 2023). Potentially larger effects in subsequent data cycles will be closely monitored and reported.
- As of 2022, the Canadian Institute for Health Information requires hypertension to be recorded whenever documented by a physician or primary care provider, regardless of significance. This has led to a notable increase in hospital-based hypertension records in fiscal year 2022/23 which at least partially explains the rise in hypertension in the 2022/23 dashboard data. This coding change may lead to future revisions to the algorithm used to identify cases.
- The diabetes case definition was updated such that all diabetes medications except insulin now require confirmation of being prescribed within one year of a practitioner visit with a diabetes mellitus diagnostic code to be considered in the case detection algorithm. This prevents off-label use of diabetes medications from being used to identify cases. This change is applied across all years displayed on the dashboard. Rates from more recent years may appear lower if compared to data obtained from past dashboard versions.
- The chronic kidney disease (CKD) case definition was modified such that four ICD codes were excluded that are not related to the condition (V564-V567) and ICD code V4510 was changed to V451. These changes did not have a notable impact on CKD case numbers.
- The Alzheimer’s disease and other types of dementia case definition was updated to include more specific diagnosis codes (e.g., code 294 replaced with 294.1 and 294.2).
- Age standardized rates now use Statistics Canada’s 2011 postcensal population estimates, replacing the previous cycle’s unadjusted census counts from 2011.
- Highest reported age group is now ≥90 years old (previously ≥95 years old) due to a change in the data source for age standardized rates.
- Lifetime prevalence rates for Juvenile Arthritis now exclude cases exceeding 15 years of age (previously, all cases were included regardless of age).
- Incidence rate denominator is now calculated as reporting year’s prevalent cases minus the reporting year’s incident cases (previously, the sum of all prior years’ incident cases was used).
The BCCDR utilises health care administrative data to determine the incidence and prevalence of chronic conditions in the province. The list below summarizes the main data sources and their purpose.
- Client Roster: A record of people who are registered in the BC healthcare system.
- Medical Services Plan (MSP): Information on all medically required services, including general practitioners and specialist visits, laboratory services, and diagnostic procedures.
- PharmaNet (PNET): Records for prescription drugs and benefit non-prescription drugs/medical supplies/devices dispensed to patients at community pharmacies in BC.
- Discharge Abstract Database (DAD): Abstract summaries of patient hospital stays.
Chronic disease case definitions are determined using health care system usage data. This data is obtained from administrative health service data holdings. The Client Roster data holding is used to obtain a record of people who use the BC health care system; it contains information on people who live or have lived in BC over time, specifically focusing on people who have registered in the health care system with a Personal Health Number (PHN). Health care system data is obtained for each person, including data on MSP, prescription drugs, and hospitalizations. This information is then used to assign chronic disease cases based on their definitions, and to calculate disease incidence and prevalence in the province. For osteoarthritis, for example, patients are ascertained as a case if they have one or more hospitalizations with osteoarthritis diagnosis codes, or two or more practitioner claims within one year with osteoarthritis diagnosis codes.
The trends and distributions of incidence and prevalence of chronic conditions are then studied according to BC health boundaries, age groups, and sex.
The following conditions are included in the BCCDR (25 chronic conditions, including 11 relapsing-remitting diseases indicated by an asterisk*):
- Chronic respiratory diseases: Asthma*, chronic obstructive pulmonary disease
- Cardiovascular diseases: Acute myocardial infarction*, heart failure, ischemic heart disease, stroke*, haemorrhagic stroke*, ischemic stroke*, transient ischemic attack*
- Neurological disorders: Alzheimer's disease and other dementias, epilepsy, multiple sclerosis, Parkinson’s disease/Parkinsonism
- Mental and substance use disorders: Depression*, mood and anxiety disorders*, schizophrenia and delusional disorders*, substance use disorder*
- Musculoskeletal disorders: Gout*, osteoarthritis, osteoporosis, rheumatoid arthritis, juvenile idiopathic arthritis
- Diabetes and kidney diseases: Diabetes, chronic kidney disease, hypertension
A person is identified as having one of the chronic conditions in this report if they meet the criteria set out in the case definition for that specific condition. While the definitions are different for each condition, a typical case might be identified if the person has had a hospitalization diagnosis, a physician diagnosis, or drug utilization (i.e. from a pharmacy) - either alone or in combination - with a specified time frame relative to the year in question. For example, if a person has a hospitalization or two physician visits in any one year for asthma, or one physician visit and two asthma prescriptions in any single year, then they are counted as a case in every subsequent year.
Case definition criteria may be revised over time in response to new validation studies, new data sources, or new chronic disease surveillance or chronic disease management requirements. Where possible, case definitions used for national surveillance through the Canadian Chronic Disease Surveillance System (CCDSS) are adopted.
This measures the number and rate of people who have been newly diagnosed with the condition during a specific year - for example, all the people who never had asthma previously, but who were diagnosed with asthma during 2014/15. The incidence rate is the number of incident cases divided by the population-at-risk during a specific year. Notably, the population-at-risk excludes the people who have been previously diagnosed with asthma.
This represents the proportion of people who have had the condition for at least part of their lives at any time during their life course (lifetime prevalence). For example, the number of prevalent cases for asthma in 2014/15 represents all the people that developed asthma in 2014/15 (incidence) along with all the people living with asthma that were diagnosed in a previous year and were still alive and residing in the province in 2014/15. Prevalence is the number of prevalent cases divided by the total population in that year.
Conditions are considered episodic if they meet the case definition for a given year and have further condition-related health service utilization in subsequent years. For example, if someone were to meet the case definition for depression in the previous fiscal year and had an additional physician visit during a later reporting year for a depression-related service, they would meet the definition for episodic depression. This measure is useful for describing the existing burden of service utilization directly related to relapsing-remitting diseases.
This refers to all the people in a given geography in a given year that have had contact with the BC Health Care system and had health insurance coverage in BC, or had other coverages or services paid for by the BC government. This includes MSP, drug dispensations paid by PharmaCare, and hospital discharge records.
This is a subset of the population and reflects those at risk of developing a condition.
These rates are not adjusted to the standard population and represent the number of cases in a specific geographic region divided by the population/population-at-risk in that region. Crude rates are representative of the burden of disease in the population.
To account for differences in the age structure of different geographical regions, rates are calculated as if all regions shared the same age structure, that of the Canada’s 2011 postcensal population estimates. Age-standardized rates are appropriate for comparing regions or trends over time. They are not a good representation of the burden of disease in the population.
The rates and proportions of diseases in this report should be thought of as estimates, and therefore may not represent the true rate in a given place and time. Confidence intervals (CIs) are the upper and lower limits within which the true value probably lies. For example, if the asthma incidence for BC in 2014/15 is 5.94, with narrow CIs of 5.87 and 6.02, you can be very confident in that stated incidence. However, wide CIs may suggest that there is uncertainty in the estimate. In this report, 95% CIs are used, which means that the true value should lie between the CIs 95% of the time.
Morbidity case definitions
While many case definitions have been validated in other Canadian jurisdictions or internationally, no case definitions have been validated in BC due to the lack of access to gold standard patient data. We expect the case definitions, especially definitions validated in other Canadian jurisdictions, to perform reasonably well in BC because of the similarities in overall healthcare systems. In some cases, we modified the case definitions after consulting with clinicians (physicians, nurses, and pharmacists), due to the differences in public health insurance coverage, disease coding, physician billing, and information management.
Case algorithms based on administrative data are never 100% sensitive (sensitivity is the ability to completely identify all cases of a given disease – true positives) or 100% specific (specificity is the ability to correctly identify non-cases – true negatives). Only persons using the BC healthcare system (primary care, hospital care, and/or Pharmacare) can be identified as a chronic disease case. If a person does not use these services, there will be no diagnostic or treatment information available to qualify that person as a case. Also, individuals that were diagnosed in another province or another country and never used healthcare in BC for the conditions will not be identified as cases. Therefore, undiagnosed or untreated cases of disease will not be included in chronic disease estimates. As such, the chronic disease counts and rates/proportions may underestimate the actual number of cases in the province.
Prevalent cases misclassified as incident cases
Incident cases identified in the BCCDR might have been diagnosed with a chronic disease before the BC Ministry of Health data holdings started operating in 1992/93. In other words, many incident cases identified by BCCDR algorithms in early years were actually prevalent cases. This is reflected by the high incidence values for many diseases in the first few years of the BCCDR and a trend of significant incidence decline over time during this period (i.e., reporting washout period). Therefore, the recommended reporting period for incidence and prevalence is from 2001/02 onwards.
Data source update
Administrative data sources at the Ministry of Health are updated periodically, resulting in small changes of individual records. Every effort has been made to minimize the impacts of these updates on the BCCDR (e.g., creating snapshots of data sources), but discrepancies cannot be ruled out. The lack of complete synchronization among data sources might create discrepancies in some variables such as date of birth, place of residence, and service date. There is also a small proportion of records with unknown sex, date of birth, or health boundary assignment in the source tables. No imputations are conducted for these missing values when the BCCDR is created. Cases with unknown sex or health boundary assignment values are included in the total number of cases at the provincial level, but reporting on measures for unknown stratifiers such as health boundary specifically may not be meaningful and is likely misleading.
Sex and gender-based analysis
The chronic disease dashboard presents information stratified by sex as recorded in administrative databases. Information on gender is currently unavailable in the BCCDR
Health boundary changes
Community Health Service Areas (CHSAs) are generated using Dissemination Block (DB) boundaries for the Canada Census in 2021 (i.e., a DB-CHSA relationship table). Due to DB boundary changes over time, applying these boundaries to residential addresses in previous and later years might have resulted in CHSA misassignments (i.e., Local Health Area/Health Service Delivery Area/Health Authority misassignments) for these time periods.
The Ministry of Health and all health authorities in BC report for the year starting April 1 and ending March 31. For example, the 2014/15 fiscal year includes all cases identified between April 1, 2014 to March 31, 2015.
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Disclaimer & Limitation of Liability
This dashboard, and data contained in it, are provided "as is" without representations or warranties of any kind, either expressed or implied, including but not limited to, representations or warranties regarding the accuracy of the information in the dashboard and associated data, implied warranties of merchantability and fitness for a particular purpose, non-infringement or other violation of rights. The British Columbia Centre for Disease Control operates in a live database environment. Data are updated regularly and may change over time as the source data feeds are refreshed. Information presented in this report may not reflect the current situation, and therefore should only be used for reference purposes. Access to this dashboard and associated data may be suspended or discontinued, and the content of the dashboard may be altered, in part or in whole, at any time and for any reason, with or without prior notice, at the discretion of the British Columbia Centre for Disease Control and the Provincial Health Services Authority. All inferences, opinions, and conclusions drawn in this report are those of the authors, and do not reflect the opinions or policies of the Data Steward(s). Anyone using this information does so at their own risk. In no event will the British Columbia Centre for Disease Control or the Provincial Health Services Authority be liable for any direct, indirect, special, punitive, incidental, or consequential damages arising from the use of, or the inability to use, this dashboard.
