Chapter 2 Prevalence and Incidence

Introduction

The ability to determine the extent of the disease on a national scale has been limited. The National Population Health Survey (NPHS) has been conducted three times (1994/1995, 1996/1997, 1998/1999), but for the most part the sample size has made it difficult to produce statistically significant analysis for anything but a national analysis. Therefore, these data are not particularly useful for provincial and territorial analysis and some other subpopulations. To fill this void, a number of surveys have been conducted aimed at specific subpopulations, especially Aboriginal communities and also people with type 1 diabetes. More recently, the National Diabetes Surveillance System (NDSS) has been implemented to address some of these limitations.

The National Diabetes Surveillance System (NDSS), within the framework of the Canadian Diabetes Strategy, is still in its infancy but prevalence information was available for this report. One of the significant strengths of the NDSS is that it is based on physician services data and hospitalization data and it does not rely on self-reporting of diabetes status.

The surveys or systems have not yet been able to differentiate between type 1 and type 2 diabetes. Best estimates have shown that about 10% of all people with diabetes mellitus have type 1 and about 90% have type 2¹. The NPHS is limited to those 12 years of age and over, and the NDSS data have been validated only for people aged 20 years and over, although work continues to improve this system. In addition, because type 1 diabetes tends to occur mainly in younger people, it is difficult to give a comprehensive picture of this type of diabetes.

The frequency of a disease may be measured in two (standard) ways:

Incidence is the number of new cases detected in the population at risk for the disease during a specific period.

Prevalence is the total number of persons known to have had the disease at any time during a specific period. It gives an idea of the importance/burden of disease at a given time, and it is widely used in public health monitoring and planning.

---

[Previous] [Table of Contents] [Next]