Diabetes Lifetime Prevalence

Definition:

Age-standardized prevalence per 100 population for diabetes mellitus, age 1 and older, total for all ages and both sexes.

Methods and Limitations:

The British Columbia Chronic Disease Registry (BCCDR) utilises health care administrative data to determine the incidence and prevalence of chronic conditions in the province.

Incidence measures the number and rate of people who have been newly diagnosed with a condition during a specific year. Prevalence represents the proportion of people that are living with a condition in a specific year.

Age-standardized rates account for differences in the age structure of different geographical regions by calculating rates as if all regions shared the same age structure. 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 main data sources for the BCCDR are:

• Client Roster: A record of people who are registered in the BC healthcare system.
• Medical Services Plan: Information on all medically required services, including general practitioners and specialist visits, laboratory services, and diagnostic procedures.
• PharmaNet: Records for prescription drugs and benefit non-prescription drugs/medical supplies/devices dispensed to patients at community pharmacies in BC.
• Discharge Abstract Database: Abstract summaries of patient hospital stays.

Health care system data are obtained for each person and used to assign chronic disease cases based on case definitions, and to calculate disease incidence and prevalence in the province. Trends and distributions of incidence and prevalence of chronic conditions are then studied according to BC health boundaries, age groups, and sex.

A person is identified as having a chronic disease if they meet the criteria set out in the case definition for that disease or condition. A typical case might be identified if the person has had a hospitalization diagnosis, physician diagnosis, or prescription filled at a pharmacy – either alone or in combination – with a specified time frame. 

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.

The case definition for diabetes mellitus is:

• One or more hospitalization with a diabetes mellitus diagnostic code, OR
• Two or more physician visits with a diabetes mellitus diagnostic code within one year, OR
• Two or more insulin prescriptions within one year, OR
• Two or more oral antihyperglycemic (not including metformin) prescriptions within one year, OR
• One insulin and one oral antihyperglycemic (including metformin) prescription within one year, OR
• Two metformin prescriptions and one physician visit with a diabetes mellitus diagnostic code within one year

This case definition excludes cases of suspected gestational diabetes in women aged 10-54 years.

Data ranges are based on BC Ministry of Health fiscal years, starting April 1 and ending March 31.

Only persons using the BC healthcare system 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.

Data may be suppressed due to low counts, such as if the number of cases in a specific time and place are less than five. Geographical or sex breakdowns may be suppressed if it is possible to back-calculate the number of cases using aggregated geographies or sex breakdowns.

Source(s):

British Columbia Ministry of Health [data provider]. BC Observatory for Population and Public Health [publisher]. Chronic Disease Dashboard. Available at: http://www.bccdc.ca/health-info/disease-system-statistics/chronic-disease-dashboard

Data is updated on Vital Victoria as it becomes available from the data providers.