And that is just the first pass.

We have a pretty decent idea of what poor people do when they lose health insurance. In 2008, Oregon expanded Medicaid coverage to several thousand people selected by a lottery, giving researchers an opportunity to understand the effects of the program by comparing what happened with winners and losers. Knowing how people’s lives change when they gain access to Medicaid can also tell us what happens when Medicaid is lost.

What will happen? Millions of Americans — poor ones, mainly — will use much less health care. They will make fewer outpatient visits, have fewer mammograms and cholesterol checks. Access to Medicaid in Oregon increased use of health care services by some 25 percent. Losing Medicaid is likely to reduce use by a similar amount.

Losers under Mr. Ryan’s plan may not immediately see their physical health deteriorate — researchers did not detect improvements in the health status of lottery winners in Oregon during their first two years under Medicaid. Still, some will be more likely to die, especially those not quite of Medicare age.

Among those who survive, more are likely to report themselves in poorer health. Their rates of depression are likely to rise. Critically, their finances will certainly suffer. This provides a direct glimpse into how cutting off health insurance won’t just reduce access to health care among the poor. It will ricochet across society.

On average, an uninsured person who is hospitalized leaves $6,000 in unpaid bills. Those costs don’t vanish, but show up elsewhere in the system — in lower hospital profits, or maybe in higher medical bills and insurance premiums for the insured. One study concluded that 60 cents out of every dollar spent on Medicaid goes to offsetting those costs.