Clinical studies can be based on data newly collected by researchers themselves (primary data collection) or based on data previously collected for another purpose such as for another research project, for health care or for education (secondary use of data). A major advantage of primary data collection is that researchers have full control of participant selection/enrollment and data elements, but this may require more research effort and funding. Secondary use of existing data may save time and cost, however, researchers have no or little control of the data, particularly the quality or format of the data. This means assessment of the data quality is critical before any analysis. Researchers may also be challenged with the absence of important information (e.g., lifestyle).
Researchers are increasingly using data collected in previous studies or data from existing studies collected for other purposes. For example, The Manitoba Follow-Up Study was originally developed for cardiovascular disease research, but has been used for supporting studies on diabetes, aging, and other health issues. This open data concept is gaining popularity and researchers are now able to access data from many studies developed by others, particularly some international consortium studies.
Line-level health data (e.g., cancer registry, hospital discharge abstracts) are important sources of data for clinical research. In Manitoba, The Manitoba Centre for Health Policy houses data on health, education, and justice that are linkable via a unique personal identity. Similar administrative data repositories are available in British Columbia (Population Data BC), Ontario (Institute for Clinical Evaluative Sciences), Nova Scotia (Health Data Nova Scotia), and Quebec (Quebec Health Data Banks). With appropriate approvals, researchers can gain access to these data via a virtual research environment.