Insurance coverage and the treatment of mental illness: effect on medication and provider use.

BACKGROUND: Canada's public health insurance system fully covers medically necessary hospital and physician services, but does not cover community-based non-physician mental health provider services or prescription drugs. Almost 2/3 of Canadians have private supplemental insurance for extended health benefits, typically through their employer, so its distribution is skewed to higher-income, employed Canadians, and typically features substantial cost-sharing and coverage limits. A recent national survey suggests only one-third of Canadians with selected mental disorders talked to a health professional during the previous 12 months and only a minority (19.3%) receive drug treatment. Financial barriers to care constitute a potentially important contributor to this under-use of mental health treatments. AIMS OF THE STUDY: The objective is to understand how private supplemental insurance status affects the utilization of prescription medication and four types of community-based providers for mental health problems in Canada.
METHODS: The data derive from a special mental health supplement to the nationally representative Canadian Community Health Survey. Utilization of five types of prescribed medications (sleep, anxiety, mood stabilizers, anti-depressants and anti-psychotics) is measured dichotomously as use/no-use in the previous 12 months. Utilization of community-based provider services (family physician, psychiatrist, psychologist and social worker) is measured as (i) use/no-use and (ii) conditional on use, number of contacts in the previous 12 months. We employ multivariate regression methods appropriate to the binary and count nature of the dependent variable to measure the impact of supplemental private insurance status on utilization, controlling for health, demographic and socio-economic characteristics. We test for endogeneity of insurance status using instrumental variable techniques.
RESULTS: Having private supplemental insurance significantly increases the odds of using medications for mental illness, with particularly large increases for anti-psychotic and mood-stabilizer medications. Private supplemental insurance coverage does not increase use of provider services. We find little evidence of endogeneity of private insurance. DISCUSSION: Lack of supplemental insurance for prescription medication is a potentially important financial barrier to mental health treatment in Canada. The estimated effect is likely understated because the utilization measure does not capture quantity of medication use. It is not surprising that no significant relationship between private insurance status and utilization of provider services is found for publicly-covered family physician and psychiatry services, where the link between supplemental insurance and use is indirect, through the need to visit a physician to obtain a prescription. The result is surprising for psychologists and social workers, and may reflect limits to private coverage which are not fully captured here. IMPLICATIONS FOR HEALTH CARE PROVISION AND USE: Insurance coverage has an important relative impact on the likelihood of drug use for mental illness. IMPLICATIONS FOR HEALTH POLICIES: A program that offers insurance coverage for anti-psychotic and mood-stabilizing medication could reduce the high personal and societal burden associated with serious mental illness, without a large overall budgetary impact. IMPLICATIONS FOR FUTURE RESEARCH: Future research should incorporate insurance measures which capture details of coverage among all survey respondents. Linking survey to utilization data will help to overcome issues of recall bias.