Introduction

That the population is aging is a well-known fact, and much has been written about the potential impact this might have on the health care system and society as a whole. It is therefore becoming increasingly important to have an understanding of trends in health and health care use, as well as factors related to them - all in an attempt to inform policy decisions that have implications for current and future cohorts of seniors.

The papers in this special issue all examine health and health care use among older adults in Manitoba. Like the other provinces and territories, Manitoba has seen a steady increase in the proportion of seniors, with the proportion of adults aged 65 or over increasing from 11.9 per cent in 1981 to 13.5 per cent in 2001. Manitoba currently ranks second among the provinces and territories in the proportion of older adults; only Saskatchewan has a higher proportion. As is the case for the other provinces, the proportion of older adults is expected to rise substantially in the next 20 years in Manitoba. Thus while the papers in this special issue focus on Manitoba's seniors, the research clearly has implications beyond Manitoba's borders, as researchers and policy makers across the country grapple with similar issues related to the implications that the aging population will have on the health care system and society.

Besides their focus on health and health care use, another common theme of the papers in this special issue is that they are all based on work by researchers at the Manitoba Centre for Health Policy (MCHP), a university-based research unit within the Department of Community Health Sciences at the University of Manitoba. Most of the papers come out of reports that MCHP conducted as part of its contract with the provincial Health Ministry. Each year, MCHP conducts five major reports for the ministry, with the topics being identified in discussion with policy makers.

The research is built around the extensive and well-developed administrative data available in Manitoba, the Population Health Research Data Repository, which is housed at MCHP (see http://www.umanitoba.ca/centres/mchp for further information). Administrative data are data that are collected not for research purposes specifically, but rather as part of administering the health care system. For example, each time a patient sees a physician, a claim is filed by the physician with the provincial Health Ministry for reimbursement. Similarly, each hospitalization is recorded on a hospital discharge abstract. Administrative data files, therefore, contain virtually complete records of encounters with the publicly funded health care system in Manitoba. The Population Health Research Data Repository contains a wide range of data, including hospital, physician, and nursing home files, as well as the population registry. More recently, home care data and prescription drug data have been added to the repository. Public access Census data can be linked to these data to allow examination of potential socio-economic differentials in health and health care use.

A strength of these data is that they are population-based, which means that virtually the entire population of Manitoba - or senior population as the case may be - can be included in studies. Moreover, they allow examination of trends over time (papers in this issue extend over as many as 15 years) and space (e.g., across regional health authorities). Are recent cohorts of seniors healthier than the previous cohorts? How does the changing age structure of the population and physician workforce relate to physician visits? Does home care use vary across regional health authorities? How many hospital beds will be needed in different regions of Manitoba in 2020? These are just some of the questions that are addressed in this issue, using the repository.

Repository data are supplemented in three papers by additional sources of information to allow more detailed examination of specific issues. The addition of the Cataract Surgery Waiting List Registry allows examination of waiting times for cataract surgery. It illustrates the rich data environment that can be created by linking clinical databases to administrative data. Actual reviews of patient hospital charts provide a fuller picture of hospital use in two...