Age-Standardized: 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 1991 Canadian Census. 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.
Case Definitions: 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 2 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.
Confidence Intervals (CI): The rates and proportion of disease 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 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 CI's of 5.87 and 6.02, you can be very confident in that stated incidence. However, wide confidence intervals may suggest that there is uncertainty in the estimate. In this report, 95% CI's are used, which means that the true value should lie between the CI's 95% of the time.
Crude: 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.
Data Suppression: There are two reasons for data being blank or marked with "<5" in a chart or table. The first is if the number of cases in a specific time and place are less than 5, then the value has been hidden. Second, if it is possible to back-calculate the number of cases using aggregated geographies or sex breakdowns, then other areas or sex breakdowns may also be suppressed. True zeros (0) remain in the data set.
Episodic: 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 the following year for a depression-related service, they would meet the definition for episodic depression.
Fiscal Year: 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.
Incidence: 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 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.
Limitations: The estimates presented only include persons who have been diagnosed or treated for the condition of interest. These estimates do not include those who have not yet been diagnosed. Case definitions used in BC may differ slightly to those used nationally or in other jurisdictions in Canada, and as a result, prevalence and incidence estimates may not be comparable to those from other jurisdictions.
Population: 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 the Medical Services Plan (MSP), drug dispensations paid by PharmaCare, and hospital discharge records.
Population-at-Risk: This is a subset of the population, and reflects those at risk of developing a condition.
Prevalence: This represents the proportion of people that are living with the condition in a specific year. 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 was diagnosed in a previous year. Prevalence is the number of prevalent cases divided by the total population in that year.