Chronic Disease Registry (CDR) data set

Description

Non-communicable diseases (NCDs) or chronic diseases account for a large proportion of increasing healthcare costs in BC. Monitoring patterns and trends of chronic diseases provides critical information for public health actions (prevention, protection, and promotion) and healthcare planning. Since the 1990s, the BC Chronic Disease Registries (CDR) have been released each year to:

• Measure chronic disease burdens in BC: Incidence and prevalence over time, across different health regions and communities.
• Measure health inequalities: Differences in chronic disease burden by sex, age, and geographic area. In the future, the registries will also disaggregate by indigenous identity and socioeconomic level.
• Support clinical and public health research by providing a row-level CDR dataset linkable to other health and non-health datasets in BC via personal health number (PHN).

The CDR includes 25 chronic disease registries built and maintained by the Office of the Provincial Health Officer (OPHO) with new registries being brought on over time. The Chronic Disease Registries draws on data from several administrative data sources, including Medical Services Plan (MSP), Discharge Abstract Databases (DAD), PharmaNet (PNET), and Client Roster (CR).

Using the CDR data, it is possible to estimate the incidence and lifetime prevalence of 25 chronic conditions in BC, as well as active healthcare contact prevalence for 11 relapsing-remitting diseases (marked with a star in the list below):

• 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 and other dementias, epilepsy, multiple sclerosis, Parkinson’s disease
• Mental and substance use disorders: Depressive disorders*, anxiety and mood disorders*, schizophrenia & delusional disorders*, substance use disorders*
• Musculoskeletal disorders: Gout*, osteoarthritis, osteoporosis, rheumatoid arthritis, juvenile idiopathic arthritis
• Diabetes and kidney diseases: Diabetes mellitus, chronic kidney disease, hypertensive diseases, high blood pressure (hypertension)

All chronic disease registries are refreshed (the complete registry is rebuilt using the latest available data) in the fall of each year. While some CDR case definitions are adapted from the Canadian Chronic Disease Surveillance System (CCDSS), which have already been previously validated, many CDR definitions were updated to reflect differences in billing policies and to include prescription information that are specific to BC. The latest CDR version (V2020-21) incorporates data up to March 31, 2021.

Variables available

Both Core and Non-Core fields are available for this data set.

Core vs. Non-Core Data

• Core Data: Some BC Ministry of Health data sets available through PopData and HDPBC are called ‘Core Data’. A Core Data set is a standardized ‘bundle’ of commonly requested variables. A Core Data set may not include ALL the variables available in the data set. For example, some Core Data variables, such as geography or organisational codes, are suppressed to meet privacy legislation requirements.
• Non-Core Data: Non-Core Data are variables that are NOT included in the standardized Core Data set. Non-Core Data is available for request as an addition to the Core Data set.

For the majority of DARs, requesting access to Core Data ONLY may make the data access approval process quicker and may expedite data provision. Data requests that include Non-Core Data will be subject to regular rather than expedited processes, both for application review and data provisioning.

Please note that the overall data access request is subject to meeting ALL of the Five SAFEs requirements. For more detail on the Five SAFEs, visit the Eligibility and the Five SAFES model page of our website.

> download Chronic Disease Registry all available variables (pdf)

 

Data update schedule

CDR data is generally updated annually at the end of the fiscal year by the BC Ministry of Health. PopData updates its data collection quarterly. 

Please note: Our data update schedule depends on when the data is made available to us by the data provider, so the update schedule is an estimation only.  

Inclusions

• Case definition criteria are applied to the data to ascertain the disease status of each individual and obtain the number of persons who meet the qualification criteria (i.e., qualify as a case). A typical case definition might include hospitalization diagnosis data or physician service diagnosis data – either alone or in combination – within a designated time frame, to identify a case. For example, a case might qualify with a single hospitalization diagnosis or with 2 physician service diagnoses within a period of 2 years.

Exclusions

• Chronic disease estimates are based on diagnosis and/or treatment information in health administrative information systems. If a person does not use services, there will be no diagnostic or treatment information available to qualify that person as a case. Undiagnosed or untreated cases of disease will not be included in chronic disease estimates.

Data changes over time

This section summarizes the changes in version 2020/21 of the BC Chronic Disease Registry with respect to version 2019/20.

1. Angina estimates will no longer be reported. Angina been removed from the BCCDR as it is not a disease, but a symptom.
2. Individual-level incidence and active healthcare contact information are now provided in a combined table instead of two separate tables.
3. Age-standardized prevalence and incidence rates calculated using the BC mid-year 2011 population obtained from Client Roster are no longer reported; all age-standardized measures are calculated using the Canadian Census estimate of the 2011 Canadian population.

Additional information

IMPORTANT: The datasets used to create CDR are refreshed every year, which might cause some differences in the number of cases released in the current version compared to the number of cases released in previous years. The current versions of CDR contain refreshed information from previous years plus the last year addition. The historical versions of CDR contain information released in previous years, without any further data refresh. For most research questions, including trend analyses, the current version of CDR should be used. The recommended reporting period for incidence and prevalence using CDR is from 2001/02 onwards.

CDR caveats and limitations that may impact data quality are:

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 MoH 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 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 MoH 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.

Health boundary changes
CHSAs are generated using DB boundaries for the Canada Census in 2016 (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., LHA/HSDA/HA misassignments) for these time periods.