At the heart of President Obama's massive health reform law is an effort to make health insurance available to everyone. Coverage can no longer be denied to those who are sick and most in need of care. But will insurance alone make any actual difference in their health?

Millions of Americans are now covered though the law, which took full effect this year. The administration reports that more than eight million have signed up for policies through the new insurance exchanges and at least three million have gained Medicaid coverage under expanded eligibility rules.

Insurance coverage clearly helps with the financial burdens of care, but does it translate into more or better care? Will the Obama plan actually make Americans healthier?

According to a study published this week in the prestigious Annals of Internal Medicine, the answer is clearly yes.

Researchers examined death rates in several Massachusetts counties after that state reformed its health care system in 2006. Those reforms, often referred to as Romneycare after the governor who supported and signed them into law, served as a model for the Obama plan (often referred to, as most people know, as Obamacare for similar reasons). The study compared death rates in those counties to rates in demographically matched counties in other states.

The researchers found a marked effect. Death rates among the nonelderly were 2.9% lower in the Massachusetts counties than in the counties in other states. Based on this difference, they estimated that the state's health reforms prevented 320 deaths a year. The difference in mortality was particularly evident for causes of death most likely to be prevented with timely health care, such as infections, cancer, and cardiovascular disease. It was also greater in counties with lower median incomes and with a higher percentage of uninsured before the reforms took effect.

The Obama health reform plan still has a long way to go before it is operating smoothly. But experience with a similar program now suggests it can achieve a significant goal. It can save lives.