How does complementary private prescription drug insurance coverage affect seniors' use of publicly funded...

Like in many other high-income jurisdictions, the public drug program in Ontario, Canada provides comprehensive coverage of prescription drugs to the 65 years and older population with some cost sharing. The objective of this study was to examine the marginal impact of holding private drug coverage on the use of publicly funded medicines among the senior population in Ontario.

We drew on linked survey and administrative data sources to examine the impact of private drug coverage first on total spending and utilization of medications, and second, on clinically recommended medications for individuals with a diagnosis of diabetes.

Approximately 27% of Ontario seniors reported having private prescription drug insurance from a current or prior employer. The population-level analysis of all seniors found that individuals with private insurance coverage, on average, took about a quarter of an additional drug and incurred 16% more in costs to the public program in a year compared to those without additional coverage. The disease-specific analysis of seniors with a diagnosis of diabetes found that private coverage was associated with two-fold higher odds of taking an anti-hypertensive drug, but it had no association with the use of statins or anti-diabetic medications.

The results of this study provide some evidence that seniors in Ontario are sensitive to the price of drugs. These findings raise equity concerns relating to the cost sharing arrangements in the public system and our policy of allowing private plans to "top-up" the public plan.