My colleague Aaron Carroll wrote last week that directly charging consumers for part of their health care costs (the practice known as cost-sharing) can harm the health of poorer or sicker people. But for the rest of us, it seems to reduce spending without harming health. This is the basic conclusion of a famous 1970s experiment funded by the RAND Corporation that randomly assigned families to different levels of responsibility for medical costs.

But would even more cost-sharing lead to savings as significant as those already seen? Recent studies suggest not.

The results of the RAND experiment are impressive. For example, families in the study that were responsible for 95 percent of costs of care (up to a cap of $1,000) used far less of it and spent 30 percent less than those with full coverage. And, apart from the poorest families with relatively sicker family members, this lower use of care did not adversely affect health.

The extent to which the RAND study results apply today is controversial. On the one hand, its study design — explicitly randomly assigning families to different plan types — is the gold standard and has not been replicated since. This alone makes the study’s findings quite significant. On the other hand, the study was conducted over three decades ago, when medical care and health insurance differed from that of today. More recent studies with good methods suggest we should be cautious in extrapolating the RAND experiment’s results.