Prevalence and frequency of mental health care provided by general practitioners: differences between 2 national data sources for the same population.

Objective: Estimates from Canada's first national mental health surveillance initiative-which is based on diagnostic codes in administrative health care utilization databases-indicate that the proportion of Canadians who receive mental health care is more than twice as high as reported in Canada's national mental health survey. Our study examines and clarifies the nature and extent of differences between 2 predominant types of data that are used for mental health services research and planning.

Method: A person-by-person data linkage was conducted between the Canadian Community Health Survey: Mental Health and Well-Being and administrative health care utilization records (British Columbia Ministry of Health Services-Medical Services Plan, and Hospital Discharge Abstract Database) within a universal-access, publically funded health care system, to examine the level of agreement between the data sources and respondent characteristics associated with agreement (N = 2378).

Results: The prevalence of mental health care from general practitioners (GPs) was higher in administrative data (19.3%; 95% CI 17.7% to 20.9%) than survey data (8.5%; 95% CI 7.5% to 9.8%). Agreement between prevalence estimates from the 2 data sources was associated with age, mental health characteristics, and the number of GP visits. The median number of visits per person was significantly higher in the survey data.

Conclusions: GPs saw more than twice as many patients for mental health issues according to administrative data, compared with survey data; however, the number of visits per patient was higher in survey data.