If the prevalence of diabetes is high in the general Québec population, studies done of Aboriginal communities show that the prevalence in this population are three to four times greater than those observed in the general population (Canada 1999). The prevalence of diabetes has increased significantly over the last 20 years among the Cree population of Northern Québec (Eeyou Istchee) aged 20 years and over, from a few cases before the 1980s, to about 5.2% in the late eighties, to 7.1% in 1991, and climbing to about 15% in 2002 (Brassard, Robinson et al. 1993; CHSSB-JB 2002) (Brassard, Robinson et al. 1993; CCSSSBJ 2002). These results are consistent with the epidemiological data observed in the United States and in other regions of Canada. Data from the Cree Board of Health and Social Services of James Bay shows that in 2002, there were 1,064 known cases of diabetes for all ages in the Eeyou population, or proportionally three times more than in the population residing in Southern Québec (CBHSS-JB) (CCSSS-BJ 2002).
The high prevalence, the Cree Board of Health of Eeyou Istchee will face a staggering increase in complications associated with diabetes, which will add significantly to the burden on its health system in the coming years. Moreover, the scope of this problem prompted the Cree Board of Health to identify diabetes as one of its two health priorities in 1995. For example, of the known cases of diabetes who agreed to permit access to information about their condition: 58% had a kidney damage, 11% suffered retinal damage, 12% had peripheral nerve damage, and 13% of known cases reported vascular disorders (CBHSS-JB 2002) (CCSSS-BJ 2002). In addition, a study of the Aboriginal population of Manitoba estimates that between 1996 and 2016, the incidence of stroke will increase fivefold, cardiovascular disease will increase tenfold, and the use of certain medical services (dialysis, lower limb amputations, blindness) will also increase tenfold (cited in: Canada 2002).
This first study linking data from different sources has shown the possibilities for coenrichment of the various surveillance systems. This linkage allows for a more complete description of the diabetes cases in the Québec Diabetes Surveillance System and in the NDSS. Both these systems augment the completeness of the cases reported, particularly in populations living in a remote region where services are provided essentially by physicians paid by salary or wage payment contract. The Québec Diabetes Surveillance System and the NDSS may also identify more effectively cases of gestational diabetes and glucose intolerance, while being weaker in identifying all subjects. In addition, the Québec Diabetes Surveillance System and the NDSS can, by means of this linkage, produce prevalences for a health region of Québec for which data were not previously available. And the diagnosis date and, consequently, the calculations of the duration of the disease are more accurate.
This linkage of databases produces a better estimate of the hospitalisations and medical consultations that occur outside the Eeyou Istchee region for cases from the Cree Diabetes Information System, thereby give another way to estimate certain complications. It also provides a better idea of the medical procedures performed, and therefore more accurately documents the complications for the various subgroups—information not currently available. Using this linkage of databases it is also possible to estimate the transportations made by subjects entered in the Cree Diabetes Information System and thus to assess the relative cost of these transportations. This information becomes very relevant for planning services for Cree with diabetes as well as for evaluating the activities of the program for tracking cases in the Cree Diabetes Information System.
We suggest linking databases on an annual basis to improve the surveillance and evaluation activities of both the Québec Diabetes Surveillance System and the Cree Diabetes Information System. This linkage could be carried out by adding incident cases for the year to the Québec Diabetes Surveillance System using the same methodology as was used in this study. Discussions between the managers of the two systems will provide a clearer definition of the terms and conditions of data transfer between the two.