Using a linked data set to determine the factors associated with utilization and costs of family physician services in Ontario: effects of self-reported chronic conditions.

Evidence-based health care planning for persons with chronic conditions is difficult. Routinely collected data are not specific enough to obtain prevalence estimates for chronic conditions and accompanying health determinants, whereas available survey data do not provide accurate utilization and/or cost information. The purpose of this study was to determine the association of self- reported demographic factors (age, sex), access (having a regular doctor), socio-economic factors (education/income) and need (comorbidity) with actual family physician costs for persons with arthritis/rheumatism, asthma, back pain, high blood pressure and migraines. Data from consenting Ontario respondents to the 1994 Canadian National Population Health Survey were linked with provincial physician billing claims. More than half of Ontario adults aged 25 and over reported a chronic condition; 24% reported two or more. Age, sex, access, socio-economic status and need were independently associated with family practice utilization and costs, and the magnitude of the effects varied by condition. Linked survey/administrative data can provide valuable information to assist in evidence-based health care planning.