Payment gaps between primary care and speciality doctors, 1979-2003. (The Robert Graham Center)

WellPoint is rolling out a new program Friday that’s worth keeping an eye on. The insurance company — the second largest in the country — will boost its spending on primary care doctors by nearly $1 billion, hoping to see a payoff in fewer trips to the emergency room and less hospital stays. And it will start reimbursing doctors for a lot things “non-visit” that often go uncompensated, things like preparing a care plan for a patient.

More from Christopher Weaver and Anna Wilde Mathews in The Wall Street Journal:

In addition to its fee increase for visits, which will vary by market, WellPoint will offer primary-care doctors payments for services such as developing treatment plans for patients with chronic diseases. It says physicians will get a chance to make even more if they help pare the overall cost of patients’ care: a bonus amounting to as much as 20% to 30% of any savings they achieve.

WellPoint is also promising that it will give doctors data and staffing help to improve their practices. In return, those doctors will have to meet requirements including some form of 24-hour access for patients and keeping a registry to monitor chronic-disease care.

WellPoint officials said they think the company’s upfront investment in primary care could reduce its projected medical costs by as much as 20% by 2015 by improving overall patient health and reducing the need for costlier medical services.

This is a pretty important initiative for a few reasons, the first being a widening pay gap between specialists and primary care doctors. For decades now, primary care doctors have earned less than medical specialists, doctors who go into fields like radiology or surgery. And, as you can see in the chart above, from the Robert Graham Center, the gap is getting worse: A student who goes into primary care can now expect to earn $3.5 million less in a lifetime than a medical school classmate who specializes.

There’s a lot of excitement about primary care right now; the number of American medical students matching into primary care residencies has shot up by 20 percent over the past two years. I’m working on a larger story on the topic right now, and most doctors I’ve spoken with attribute that spike in interest to the health reform law and a renewed focus on primary care as a way to bring down health care costs.

There’s also a lot of concern, however, that this will be a temporary surge. The mid-1990s saw a spike in primary care residencies as well, with Washington abuzz with health reform and HMOs, which tended to limit specialists visits, on the rise. But the Clinton health reform didn’t pass; HMOs fizzled as consumers rejected the limited networks.

And there’s worry that could happen this time around as well: After all the excitement dies down, and a few of health reform’s primary care funding streams run out, interest in primary care will subside.

“What I worry about is young physicians being told for a couple of years that this is totally worth it, and then it doesn’t pan out and then they get discouraged,” Atul Grover, chief advocacy officer at the American Association of Medical Colleges, told me recently. “Unfortunately, I think we are moving in that direction.”

Wellpoint’s $1 billion investment in primary care is notable because it signals some long-term interest in increasing primary care funding. And that could help sustain the higher interest in primary care that we’re seeing right now, rather than having it fade like it did the last time around.