Kentucky has been notably successful in signing residents up for coverage under the new health care law. Residents with serious illnesses are getting treatment after years of putting off medical care because of the expense. They’re often receiving that care in a familiar venue, though: the hospital emergency room, with its around-the-clock access and its policy, enforced by federal law, of taking all comers.

Louisville’s Norton Hospital has seen a 12 percent increase in ER patients — 100 more a month — since the health care law took effect in January and added 330,000 people to the Medicaid rolls, the Louisville Courier-Journal reported. The newly covered aren’t getting in to see local primary care doctors and are flocking to the ER instead, says Ryan Stanton, the head of a local ER physician group in Lexington. “We’ve given people an ATM card in a town with no ATMs.”

Although the uninsured go to the ER for care, they haven’t done so readily, asserts Timothy Jost, who advises insurance regulators on consumer issues. But that could be changing.

“I’ve talked to friends who are uninsured and been hurt and I say, ‘Did you go to the emergency room?’ And they say, ‘Well of course not, you end up with a $5,000 bill.’ ” But “once you have health insurance, you are more likely to go to the emergency room in an emergency. And if you’re somebody who works all day and are going to lose your job if you take time off to go to the doctor, you’re likely to go to the emergency room as well.”

Nearly half of ER doctors responding to an April poll by the American College of Emergency Physicians said they are already seeing an increase in patients because of the health care law, and 86 percent said they expect visits to increase over the next three years.

But it’s way too soon to make claims about the impact of the health law, other observers say. “Every time I read about somebody talking about the impact of the Affordable Care Act on behavior and patient volume in the emergency department it makes me cringe,” says James Scheulen, who directs ER services for the five hospitals in the Johns Hopkins University health system. He says ER use was on the rise before the health law anyway, so teasing out the effects of the ACA will be hard. At Hopkins, there’s been no uptick in volume this year compared to the last three months of 2013, he adds.

“Lengthy waits in ERs has always been a constant,” says Harvard School of Public Health Professor John McDonough. “So it’s risky to generalize without real data.” Statistics have to be considered carefully, he adds, pointing to reported increases by Massachusetts physicians in waiting times for appointments after the state’s 2006 coverage law. The data “is actually quite suspect because it’s based on a volunteer survey of physicians and always gets a pathetically poor response rate.”

Carmela Castellano-Garcia, head of the California Primary Care Association, offers a perspective often missing in Washington on the strains on the health system created by the health law. It means people are beginning to get health care as the law is intended, she says. “It’s working!”