Canadian Chronic Disease Surveillance System (CCDSS)

Summary of methods

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Background

The Canadian Chronic Disease Surveillance System (CCDSS) is a collaborative network of provincial and territorial surveillance systems supported by the Public Health Agency of Canada (PHAC).

In each province and territory, the health insurance registry database is linked to the physician billing claim and hospitalization databases using the health card number as a unique personal identifier. Where available and specified by the case definition, data from the prescription drug databases are also linked.

Case definitions are applied to these linked databases to identify individuals with chronic diseases/conditions, and aggregate data are sent to PHAC. The aggregate data are used by PHAC to estimate chronic disease/condition incidence/newly identified cases, prevalence, all-cause mortality and use of health services.

The start year for reporting CCDSS data varies by disease/condition. The determination of the first reported year aims to allow enough time to capture all prevalent cases, given the parameters of the disease/condition specific case definition, and to ensure previously prevalent cases are excluded from incident/newly identified cases.

Diseases and conditions

In the current edition of the CCDSS Data Tool, data up to 2023–2024 are reported for the following diseases/conditions:

Autism
  • autism
Cardiovascular diseases
  • acute myocardial infarction
  • heart failure
  • hypertension, excluding gestational hypertension
  • ischemic heart disease
  • stroke
  • hospitalized stroke
Chronic respiratory diseases
  • asthma
  • chronic obstructive pulmonary disease
Diabetes
  • diabetes mellitus (types combined), excluding gestational diabetes
Mental illnesses
  • use of health services for mental illness and alcohol/drug induced disorders
  • use of health services for mood and anxiety disorders
  • use of health services for schizophrenia
  • schizophrenia
Musculoskeletal disorders
  • use of health services for arthritis
  • gout and other crystal arthropathies
  • juvenile idiopathic arthritis
  • osteoarthritis
  • rheumatoid arthritis
  • osteoporosis
  • osteoporosis-related fractures (any fracture, forearm, hip, humerus, pelvic, spine)
  • osteoporosis-related fracture care gap (diagnosis, bone mineral density test, prescribed medication)
Neurological conditions
  • dementia, including Alzheimer disease
  • epilepsy
  • multiple sclerosis
  • parkinsonism, including Parkinson disease
Multimorbidity
  • two or more of the selected CCDSS chronic conditions (see multimorbidity)
  • three or more of the selected CCDSS chronic conditions (see multimorbidity)

Definitions of terms

Age-specific estimate: The age-specific estimates are calculated for a five-year age group or a life-course age group (i.e., 1-19, 20-34, 35-49, 50-64, 65-79, 80+), using counts randomly rounded either up or down to an adjacent multiple of 5 (see random rounding). Data by five-year age groups are reported at the national level only.

Age-standardized estimate: The age-standardized estimates are adjusted to the 2021 Canadian population to account for differences in population age structure, across geographic areas and over time. For all-cause mortality rate ratios, age-standardization also adjusts for differences in age distributions between cases and non-cases. Age-standardized estimates are calculated using unrounded counts and five-year age groups.

Case and non-case

    Case
    An individual who meets the CCDSS disease- or condition-specific case definition according to criteria derived from administrative health data. This classification indicates that the criteria were met, but it does not confirm a clinical diagnosis.
    Non-case
    An individual who does not meet the CCDSS disease- or condition-specific case definition according to criteria derived from administrative health data. This classification indicates that the criteria were not met, but it does not rule out the presence of a clinical diagnosis.

Case definition: CCDSS disease/condition-specific case definitions are applied to identify individuals with the disease/condition (cases). The specific criteria used to identify the disease/condition, including the codes from the 9th or 10th edition of the International Classification of Disease (ICD), the Canadian Classification of Health Interventions (CCI), the Canadian Classification of Diagnostic, Therapeutic and Surgical Procedures (CCP), and the Drug Identification Numbers (DINs), are listed in the CCDSS case definitions documentation.

Coefficient of variation (CV): A measure used to describe the precision of an estimate. More specifically, the CV of an estimate is the ratio of the standard error of the estimate to the estimate itself. Estimates with a CV between 16.6% and 33.3% should be interpreted with caution and those with a CV greater than 33.3% are not reported (see data quality).

Confidence interval (CI): A statistical measurement of the reliability of an estimate. The size of the CI relates to the precision of the estimate, with narrow CIs indicating greater precision than those that are wide. The 95% CI shows an estimated range of values that is likely to include the true value 19 times out of 20.

Crude estimate: The crude estimates are calculated using counts randomly rounded either up or down to an adjacent multiple of five (see random rounding).

Fiscal year: The CCDSS data are reported by fiscal year, April 1 to March 31.

Incidence rate (rate of newly identified cases): The number of individuals in a population at risk who meet the disease- or condition-specific case definition for the first time (newly identified cases — see note below) during a given fiscal year (i.e., from April 1 to March 31), expressed as a rate.

    Note on the rate of newly identified cases:
    For autism, the only neurodevelopmental condition in the CCDSS, the term "newly identified case" is used instead of "incidence" to acknowledge that the characteristics of autism typically become apparent during early childhood, without a distinct point of onset. The rate of newly identified cases is calculated using the same formula as for incidence.

Life-course age groups: The sequence of age categories individuals pass through as they age from childhood to older adult. The categories used in the CCDSS data tool are: 1-19, 20-34, 35-49, 50-64, 65-79, 80+.

Mortality (all-cause) rate: The number of deaths from any cause at any point during a given fiscal year (i.e., from April 1 to March 31) among cases and non-cases, expressed as a rate. Rates are calculated separately for cases and non-cases.

Mortality (all-cause) rate ratio: The ratio of the age-standardized all-cause mortality rate among cases to the corresponding rate among non-cases. A rate ratio greater than one indicates higher overall mortality rate among cases compared with non-cases, which may be directly, indirectly, or not related to the disease or condition.

Multimorbidity: Multimorbidity refers to the concurrent presence of two or more independent chronic medical conditions within an individual. As a chronic condition surveillance indicator, it involves tracking the prevalence and patterns of multiple chronic conditions within a population over time. The list of selected CCDSS chronic conditions in the multimorbidity estimates includes asthma, chronic obstructive pulmonary disease, dementia (including Alzheimer disease), diabetes (types combined, excluding gestational diabetes), epilepsy, gout and other crystal arthropathies, heart failure, hypertension (excluding gestational hypertension), ischemic heart disease, multiple sclerosis, osteoarthritis, osteoporosis, parkinsonism (including Parkinson disease), rheumatoid arthritis, schizophrenia, and stroke.

Population at risk: All individuals within a defined population who are eligible to newly meet the disease- or condition-specific case definition during a given fiscal year (i.e., from April 1 to March 31).

Prevalence estimate: The number of individuals in a population who meet the disease- or condition-specific case definition (newly identified cases and previously identified cases) during a predefined surveillance period, expressed as a proportion for a given fiscal year (i.e., from April 1 to March 31).

In the CCDSS, prevalence may be estimated over three different surveillance periods:

  1. annual prevalence — individuals who meet the case definition at any point during a given fiscal year (see note below);
  2. for life prevalence — individuals who have ever met the case definition over the cumulative surveillance period; and
  3. active prevalence — individuals who meet the active case definition (e.g., evidence of ongoing disease activity or recent health service use) among all individuals who have ever been identified as cases for that disease or condition over the cumulative surveillance period.
Note on other annual estimates:
Refers to the number of condition-specific events, or individuals who used health services during a given fiscal year. Depending on the estimate, the numerator may reflect:
  • health events (e.g., site-specific osteoporosis-related fractures),
  • individuals using health services (e.g., physician visits or hospital contacts for mental illness and alcohol/drug induced disorders, mood and anxiety disorders, schizophrenia, or arthritis).

Standard error (SE): A statistical measure of the degree of variation of an estimate. The size of the SE relates to the precision of the estimate, with a smaller SE suggesting better precision. The SE is used to calculate the confidence intervals associated with an estimate.

Data procedures

Before estimates are calculated, the following data procedures are applied.

Age group aggregation for age-specific estimates

The data submitted by provinces and territories by five-year age groups are aggregated using the following life-course age groups: 1-19, 20-34, 35-49, 50-64, 65-79 and 80+ with a few exceptions:
  • For multimorbidity, parkinsonism including Parkinson disease, osteoporosis, osteoporosis-related fractures and heart failure, the first age group is 40-49;
  • For schizophrenia, the first age group is 10-19;
  • For rheumatoid arthritis, the first age group is 16-34;
  • For autism, only one age group is used, i.e. 1-19; and
  • For juvenile idiopathic arthritis, only one age group is used, i.e. 0-15.

Confidentiality

Two different procedures are used to ensure data confidentiality and avoid residual disclosure:
  • Data suppression
    • Estimates are not reported if the corresponding unrounded counts are less than 10. Note that all provincial/territorial unrounded counts, whether suppressed or not, are part of the total counts used to produce Canadian estimates.
  • Random rounding
    • All provincial/territorial and Canadian counts of 10 or greater are randomly rounded up or down to an adjacent multiple of 5. The Canadian counts are obtained by summing unrounded provincial/territorial counts prior to random rounding. Random rounding is used only to calculate crude estimates. Age-standardized estimates are based on unrounded counts.

Data quality

The estimates with a coefficient of variation exceeding 33.3% are suppressed to ensure that the provincial/territorial data are of acceptable quality. In the CCDSS context, which relies on administrative data with near-complete population coverage, CVs are used to assess estimate stability. While CVs may exceed 100% in rare or low-count scenarios, they reflect statistical instability rather than sampling variability and are used to identify imprecise estimates.

Formulae used for calculation of prevalence, incidence/rate of newly identified cases and all-cause mortality

Prevalence estimate

Annual prevalence/estimate Total number of individuals meeting annualcase definition during the fiscal year Total number of individuals with validhealth insurance during the fiscal year ×100 or 100,000 for any osteoporosis-relatedfractures, acute myocardial infarction,hospitalized stroke events anduse of health services.
Specific to osteoporosis-related fractures:

Total number of osteoporosis-related fractures meetingannual case definition by 6-month episode during the fiscal year Total number of individuals with validhealth insurance during the fiscal year ×100 for osteoporosis-relatedfracture of forearm, hip,humerus, pelvis or wrist
For life prevalence Total number of individuals who met the case definition duringthe capture period and who are alive during the fiscal year Total number of individuals with validhealth insurance during the fiscal year ×100
Active prevalence Specific to epilepsy and, gout and other crystal arthropathies:

Total number of individuals who met the active case definition duringthe capture period and who are alive during the fiscal year Total number of individuals with validhealth insurance during the fiscal year ×100
Specific to asthma:

Total number of individuals who met the active case definition duringthe capture period and who are alive during the fiscal year Total number of cumulative prevalencecases meeting condition case definition ×100

Incidence rate/
Rate of newly identified cases

Incidence rate/
Rate of newly identified cases		 Total number of incident/newly identified cases during the fiscal year Total number of individuals with valid health insurance duringthe fiscal year – prevalent cases + incident/newly identified cases ×100,000

Mortality (all-cause) rates and rate ratio

Mortality (all-cause) rate with the disease/condition Total number of deaths from all causes during the fiscalyear among individuals with the disease/condition Total number of individuals with thedisease/condition during the fiscal year ×100,000 or 1,000for hip fracture
Mortality (all-cause) rate without the disease/condition Total number of deaths from all causes during the fiscalyear among individuals without the disease/condition Total number of individuals without thedisease/condition during the fiscal year ×100,000 or 1,000for hip fracture
Rate ratio of mortality (all-cause) rates All-cause mortality rate amongindividuals with the disease/condition All-cause mortality rate amongindividuals without the disease/condition

Provincial and territorial notes

  • British Columbia: On February 1, 2023, British Columbia (BC) implemented a new Longitudinal Family Physician (LFP) payment model billed through BC’s Medical Services Plan (MSP) database whereby family physicians can now bill for time spent with patients. MSP records for health encounters billed under the new model include use of a placeholder diagnostic code that is not valid for Canadian Chronic Disease Surveillance System (CCDSS) case definitions. Implementation of the LFP model is not anticipated to significantly impact incidence/newly identified case estimates, however indirect effects of the new billing model cannot be ruled out. Data should therefore be interpreted with caution until further validation is completed.

    BC's LFP payment model introduced a new MSP service code that was not included in the previous CCDSS release. As a result, records billed under this new code in February and March 2023 were missed. The current CCDSS release retrospectively includes these records; therefore, estimates for fiscal year 2022–2023 fiscal year may be higher for some conditions compared to estimates from the previous release.
  • New Brunswick: Only indicators with case definitions solely based on hospital data (acute myocardial infarction, hospitalized stroke, hip fracture) are reported. Data are available up to 2020–2021, except for hip fracture, which is available only up to 2019–2020, as data for subsequent years were not available.

    Due to New Brunswick’s 2020 transition to ICD-10-CA codes in physician billing claims, continuity with historical health data has been disrupted, affecting the inclusion of conditions relying on physician billing claim data in the CCDSS. Options are being explored to expedite the reintegration of New Brunswick’s data in future releases.
  • Newfoundland and Labrador: Data before 2008–2009 are excluded.
  • Northwest Territories: The introduction of the Northwest Territories Electronic Medical Record (EMR) in 2016 resulted in more complete and consistent data. Data for 2016–2017 may be slightly underestimated compared to previous years due to the system transition.

    Physician claim data were incomplete for 2021–2022, 2022–2023 and 2023–2024 should therefore be interpreted with caution, as a slight underestimation is suspected.
  • Nunavut: Data before 2005–2006 are excluded.
  • Quebec: To comply with dissemination rules, Quebec applied an unbiased random rounding method with a base of 3 to data cells with counts smaller than 5. As a result, age-specific incidence/newly identified case and mortality rates may be randomly over- or underestimated.

    The modernization of the billing system for fee-for-service medical services by the Régie de l'assurance maladie du Québec (RAMQ) in 2016 has resulted in a decrease in the entry of diagnostic codes in the fee-for-service medical services file. Data for 2016–2017 and subsequent years should therefore be interpreted with caution, as a slight underestimation is suspected.
  • Yukon: Data before 2010–2011 are excluded.

Note: For more information on the interpretation of the data for specific diseases/conditions please see the CCDSS case definitions documentation and the data tool notes.

Acknowledgements

These data were made possible through collaboration between PHAC and the respective provincial and territorial governments of British Columbia, Alberta, Saskatchewan, Manitoba, Ontario, Quebec, New Brunswick, Nova Scotia, Prince Edward Island, Newfoundland and Labrador, Northwest Territories, Yukon, and Nunavut. No endorsement by the provinces and territories is intended. Provincial and territorial data were contributed to the CCDSS as of April 2025.

Please submit any questions or requests to infobase@phac-aspc.gc.ca.

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Date modified:
2025-12-23