Fast Facts
November 2008
Fast Facts Highlights: Definitions Examples of Diabetes Incidence and Prevalence Examples of Cancer Incidence and Prevalence Newfoundland and Labrador Incidence and Prevalence Facts About our Organization
How to Interpret Data: Incidence versus Prevalence This Fast Facts is the second of a series that is intended to explain commonly used statistical terms to help you interpret data. This Fast Facts demonstrates the difference between incidence and prevalence, using examples based on the Newfoundland and Labrador and Canadian populations.
Prevalence is the total number of cases of a disease or condition in a population at a given time (i.e. it includes both new and existing cases).
Incidence is the number of new cases of a disease or condition in a population over a period of time (e.g. 1 year). It is a measure of the risk of developing a condition or disease among otherwise healthy individuals. Incidence is useful in studying risk factors for developing a condition. Incidence rates can be compared among groups that differ by one or more factors to determine what factors increase the risk of developing the condition (i.e. increase the incidence of the condition).
Prevalence indicates how widespread a disease or a condition is in a population. High prevalence of a condition may mean high risk of developing the condition or it may mean a high survival rate. For example, individuals can live a long time with well controlled diabetes. Low prevalence of a condition may mean a high fatality rate (e.g. fast growing cancers) or the condition is of short duration (e.g. common cold).
Incidence is most often expressed as a rate. The population at risk is those individuals who have not been diagnosed with the disease and excludes those individuals who currently have the disease and those who are not susceptible to the condition because of immunization or other factors (e.g. males cannot develop cervical cancer).
Prevalence is a useful tool for planning health facility needs and other resources, particularly for chronic disease management. For example, measuring the prevalence of kidney disease over time helps health care administrators determine the need for dialysis units.
Incidence = No. of new cases of disease Population at risk To avoid decimals, rates are often multiplied by some other factor (e.g. 100,000) to help with interpretation (see How to Interpret Data: Crude, Specific and Adjusted Rates, issued by the Centre, February 2007).
Prevalence = No. of cases of disease Total population
For more information about this Fast Facts, or other reports published by the Centre for Health Information, call (709) 752-6000 or visit www.nlchi.nl.ca.
Fast Facts
Incidence versus Prevalence
Diabetes Incidence by Sex, Aged 20+ Years, Newfoundland and Labrador, 2005/06 Male
Female
Total
25
Rate per 1,000 population
In 2005/06, the number of new cases of diabetes in Newfoundland and Labrador was highest among those aged 65 years and older. For every 1,000 individuals aged 65 years and older, there were 19.5 new diabetes cases.
21.0 18.2 19.5
20 15
10.7
9.9
9.2
10 5
1.9
2.3 2.1
0 20-39
40-64
65+
Source: National Diabetes Surveillance System, Newfoundland and Labrador Component, 2005/06.
Diabetes Prevalence by Sex, Aged 20+ Years, Newfoundland and Labrador, 2005/06 Male
Total
30
Percentage (%)
In 2005/06, diabetes prevalence was also highest for individuals aged 65 years and older. Approximately 23% of all individuals aged 65 years and older had diabetes in 2005/06.
Female
23.5
22.3 22.8
25 20 15
8.8
7.7
8.2
10 5
1.6
1.8
1.7
0 20-39
40-64
65+
Source: National Diabetes Surveillance System, Newfoundland and Labrador Component, 2005/06.
Fast Facts
In 2004, breast cancer was also more prevalent among Canadian women than colorectal and lung cancer. However, there were more females living with colorectal cancer than with lung cancer (i.e. the prevalence of colorectal cancer was higher than the prevalence of lung cancer).
Incidence of Common Cancers, Females, Canada, 2004
Rate per 100,000
120
96.1
100 80 42.5
60
45.5
40 20 0
Breast
Colorectal
Lung
Source: Canadian Cancer Society/National Cancer Institute of Canada: Canadian Cancer Statistics 2008.
Prevalence of Common Cancers, Females, Canada, 2004
2.0
Percentage (%)
In 2004, there were more Canadian women diagnosed with breast cancer than with colorectal and lung cancer combined. Further, more females were diagnosed with lung cancer than colorectal cancer (i.e. the incidence of lung cancer was higher than the incidence of colorectal cancer).
Incidence versus Prevalence
1.5 1.0 1.0 0.3
0.5
0.1
0.0
Breast
Colorectal
Lung
Source: Canadian Cancer Society/National Cancer Institute of Canada: Canadian Cancer Statistics 2008.
Fast Facts
Incidence versus Prevalence
Newfoundland and Labrador Incidence and Prevalence Facts •
According to the National Diabetes Surveillance System (NDSS), the agestandardized diabetes prevalence was 5.5% among the population aged 1 year and older in Newfoundland and Labrador in 2005/06.
•
There were 2,350 new cases of cancer diagnosed in Newfoundland and Labrador in 2005.
•
In 2007, the self-reported prevalence of obesity was higher in Newfoundland and Labrador (22%) compared to Canada (16%).
•
In 2006, the incidence of positive HIV test reports among individuals 15 years of age and older in Newfoundland and Labrador was 1.4 per 100,000 population, the lowest among all provinces and territories in Canada.
•
In 2007, the prevalence of smoking among the Newfoundland and Labrador population age 12 years and older was 25.3%; it was 24% and 23.1% in 2003 and 2005, respectively.
The next Fast Facts in this series will focus on Statistical Significance. Also see our previously released Fast Facts on Crude, Specific and Adjusted Rates at http://www.nlchi.nl.ca/pdf/How_to_interpret.pdf . If you have other ideas for this Fast Facts series, please contact us by calling (709) 752-6000, e-mail: [email protected] or visit our web site at www.nlchi.nl.ca.
About our Organization… The Newfoundland and Labrador Centre for Health Information was established by the Government of Newfoundland and Labrador to provide quality information to health professionals, the public, researchers and health system decisionmakers. Through collaboration with the health system, the Centre supports the development of data and technical
standards, maintains key health databases, prepares and distributes health reports, and supports and carries out applied health research and evaluations. The Centre’s mandate also includes the development of a confidential and secure provincial Electronic Health Record.
Fast Facts Highlights: Definitions Examples of Diabetes Incidence and Prevalence Examples of Cancer Incidence and Prevalence Newfoundland and Labrador Incidence and Prevalence Facts About our Organization
How to Interpret Data: Incidence versus Prevalence This Fast Facts is the second of a series that is intended to explain commonly used statistical terms to help you interpret data. This Fast Facts demonstrates the difference between incidence and prevalence, using examples based on the Newfoundland and Labrador and Canadian populations.
Prevalence is the total number of cases of a disease or condition in a population at a given time (i.e. it includes both new and existing cases).
Incidence is the number of new cases of a disease or condition in a population over a period of time (e.g. 1 year). It is a measure of the risk of developing a condition or disease among otherwise healthy individuals. Incidence is useful in studying risk factors for developing a condition. Incidence rates can be compared among groups that differ by one or more factors to determine what factors increase the risk of developing the condition (i.e. increase the incidence of the condition).
Prevalence indicates how widespread a disease or a condition is in a population. High prevalence of a condition may mean high risk of developing the condition or it may mean a high survival rate. For example, individuals can live a long time with well controlled diabetes. Low prevalence of a condition may mean a high fatality rate (e.g. fast growing cancers) or the condition is of short duration (e.g. common cold).
Incidence is most often expressed as a rate. The population at risk is those individuals who have not been diagnosed with the disease and excludes those individuals who currently have the disease and those who are not susceptible to the condition because of immunization or other factors (e.g. males cannot develop cervical cancer).
Prevalence is a useful tool for planning health facility needs and other resources, particularly for chronic disease management. For example, measuring the prevalence of kidney disease over time helps health care administrators determine the need for dialysis units.
Incidence = No. of new cases of disease Population at risk To avoid decimals, rates are often multiplied by some other factor (e.g. 100,000) to help with interpretation (see How to Interpret Data: Crude, Specific and Adjusted Rates, issued by the Centre, February 2007).
Prevalence = No. of cases of disease Total population
For more information about this Fast Facts, or other reports published by the Centre for Health Information, call (709) 752-6000 or visit www.nlchi.nl.ca.
Fast Facts
Incidence versus Prevalence
Diabetes Incidence by Sex, Aged 20+ Years, Newfoundland and Labrador, 2005/06 Male
Female
Total
25
Rate per 1,000 population
In 2005/06, the number of new cases of diabetes in Newfoundland and Labrador was highest among those aged 65 years and older. For every 1,000 individuals aged 65 years and older, there were 19.5 new diabetes cases.
21.0 18.2 19.5
20 15
10.7
9.9
9.2
10 5
1.9
2.3 2.1
0 20-39
40-64
65+
Source: National Diabetes Surveillance System, Newfoundland and Labrador Component, 2005/06.
Diabetes Prevalence by Sex, Aged 20+ Years, Newfoundland and Labrador, 2005/06 Male
Total
30
Percentage (%)
In 2005/06, diabetes prevalence was also highest for individuals aged 65 years and older. Approximately 23% of all individuals aged 65 years and older had diabetes in 2005/06.
Female
23.5
22.3 22.8
25 20 15
8.8
7.7
8.2
10 5
1.6
1.8
1.7
0 20-39
40-64
65+
Source: National Diabetes Surveillance System, Newfoundland and Labrador Component, 2005/06.
Fast Facts
In 2004, breast cancer was also more prevalent among Canadian women than colorectal and lung cancer. However, there were more females living with colorectal cancer than with lung cancer (i.e. the prevalence of colorectal cancer was higher than the prevalence of lung cancer).
Incidence of Common Cancers, Females, Canada, 2004
Rate per 100,000
120
96.1
100 80 42.5
60
45.5
40 20 0
Breast
Colorectal
Lung
Source: Canadian Cancer Society/National Cancer Institute of Canada: Canadian Cancer Statistics 2008.
Prevalence of Common Cancers, Females, Canada, 2004
2.0
Percentage (%)
In 2004, there were more Canadian women diagnosed with breast cancer than with colorectal and lung cancer combined. Further, more females were diagnosed with lung cancer than colorectal cancer (i.e. the incidence of lung cancer was higher than the incidence of colorectal cancer).
Incidence versus Prevalence
1.5 1.0 1.0 0.3
0.5
0.1
0.0
Breast
Colorectal
Lung
Source: Canadian Cancer Society/National Cancer Institute of Canada: Canadian Cancer Statistics 2008.
Fast Facts
Incidence versus Prevalence
Newfoundland and Labrador Incidence and Prevalence Facts •
According to the National Diabetes Surveillance System (NDSS), the agestandardized diabetes prevalence was 5.5% among the population aged 1 year and older in Newfoundland and Labrador in 2005/06.
•
There were 2,350 new cases of cancer diagnosed in Newfoundland and Labrador in 2005.
•
In 2007, the self-reported prevalence of obesity was higher in Newfoundland and Labrador (22%) compared to Canada (16%).
•
In 2006, the incidence of positive HIV test reports among individuals 15 years of age and older in Newfoundland and Labrador was 1.4 per 100,000 population, the lowest among all provinces and territories in Canada.
•
In 2007, the prevalence of smoking among the Newfoundland and Labrador population age 12 years and older was 25.3%; it was 24% and 23.1% in 2003 and 2005, respectively.
The next Fast Facts in this series will focus on Statistical Significance. Also see our previously released Fast Facts on Crude, Specific and Adjusted Rates at http://www.nlchi.nl.ca/pdf/How_to_interpret.pdf . If you have other ideas for this Fast Facts series, please contact us by calling (709) 752-6000, e-mail: [email protected] or visit our web site at www.nlchi.nl.ca.
About our Organization… The Newfoundland and Labrador Centre for Health Information was established by the Government of Newfoundland and Labrador to provide quality information to health professionals, the public, researchers and health system decisionmakers. Through collaboration with the health system, the Centre supports the development of data and technical
standards, maintains key health databases, prepares and distributes health reports, and supports and carries out applied health research and evaluations. The Centre’s mandate also includes the development of a confidential and secure provincial Electronic Health Record.
