Data on patient access to, and use of, primary and secondary care services are a potential tool for population health and health service planning, and for researchers. The Sax Institute's 45 and Up Study was established to support research about healthy ageing. This paper considers how data from the 45 and Up Study could be useful to Local Health Districts and the Primary Health Networks in New South Wales to support their work, particularly in evaluating integration of primary and secondary health services. Preliminary exploration of these data identified more than 31 000 participants in the 45 and Up Study living in central and eastern Sydney who were included in some demonstration projects. The value of these data to the region included access to a population-based sample of residents, and capacity to link to health data held within different jurisdictions and local data sources. The resultant data collection can address questions of interest to planners working in primary and secondary care, such as integration and coordination of services, including transition of care. These are key performance goals for both sectors.