A few years ago, it struck the Washington region’s biggest medical insurer that the doctors who saw its members most often and knew them best got the smallest piece of the health-care dollar.

CareFirst BlueCross Blue­Shield spent billions of dollars on hospital procedures, drugs and specialty physicians to treat sick patients. Only one dollar in 20 went to the family-care doctors and other primary caregivers trained to keep people healthy.

The company’s move to shift that balance tells a lesser-known story of the Affordable Care Act and efforts to change the health system.

While much attention has focused on expanded coverage and online insurance bazaars, Care­First and many others are deciding that the internists and general practitioners who have largely been left behind by health care’s financial boom are the key to improving Americans’ health and cutting the cost of care.

“As long as I can remember, family physicians and general internists have been financially at the low end of the totem pole,” said Michael Merson, a consultant and former hospital executive who was CareFirst’s board chairman until 2012. Raising their pay for the unglamorous work of preventing expensive illness and coordinating care, he said, “was really our starting point.”

Starting in 2011 CareFirst increased reimbursement for what would soon be most of its primary-care doctors in Maryland, the District and Virginia. It began paying even more if they reduced duplicative, unneeded or overly expensive treatment while maintaining or improving quality.

Doctors who scored well have gotten raises of more than $40,000 on top of round-the-clock nursing assistance for their sickest and riskiest patients, according to physicians and the insurance company.

The extra cost for the program, known as a patient-centered medical home, more than pays for itself in reduced expenses elsewhere, CareFirst said.

Members seen by medical home doctors experienced 6 percent fewer hospital admissions, 11 percent fewer days in the hospital and 11 percent fewer outpatient visits than other CareFirst clients last year, according to results to be disclosed Thursday.

Policy experts are far from agreeing that medical homes cut costs in the long run. But even though industrywide spending has slowed, CareFirst credits its medical home for helping keep total patient expense growth at 3.5 percent last year, the least in memory.

The program is saving “hundreds of millions of dollars in accumulated, avoided costs,” said CareFirst chief executive Chet Burrell. “If somebody had said to me 31 / 2 years ago, ‘What would you have hoped for?’ I would not have said anything close to what emerged.”

By paying primary-care doctors to cut specialist and hospital revenue, CareFirst is helping to alter the medical spoils system.

“There will probably be hospital closings and hospital consolidation” in Maryland, thanks to efforts by payers to reduce unneeded procedures, said Susan Dentzer, a senior health policy adviser for the Robert Wood Johnson Foundation who has studied CareFirst’s program.

In 2011, CareFirst began organizing most primary physicians accepting its insurance into panels of around nine or a dozen each. Every participating doctor got an immediate, 12 percent rate increase as well as money for creating care plans for their sickest patients.

For most patients, nothing changed. But the highest-risk members are assigned nurses from a company called Healthways who are available by phone to monitor care and help navigate the system.

Panels that maintain quality and reduce costs are eligible for bonuses that added another 35 percent on average to their reimbursement rates last year. The best-performing physicians collected twice what they would have been paid under CareFirst’s normal fees, the company said.

The idea is to eliminate enough overspending that there is money left over to pass savings to CareFirst members in the form of lower premium increases, Burrell said.

George Lowe talks about a 45-year-old CareFirst patient with back pain who headed to the hospital emergency department one recent Saturday. There the man probably would have been sent to radiology for X-rays or other scans and then been referred to a specialist, said Lowe, medical director at Maryland Family Care, a large practice north of Baltimore that participates in the CareFirst program.

Instead, the patient checked with an on-call Healthways nurse who is independent but paid for by CareFirst. She told him the primary-care practice was open on weekends. The doctor there diagnosed muscle spasms and advised heat applications and over-the-counter ibuprofen. The man felt good enough to cancel a follow-up appointment and return to work Monday.

“Case closed,” said Lowe. “We turned a $1,000 visit to the emergency room into a $75 or $100 visit to the office.”

Doctors said they control expenses by prescribing generic drugs when possible, thinking twice about referrals, referring to lower-cost specialists when possible and avoiding duplicate tests and unnecessary emergency visits.

Like CareFirst, insurers across the country believe that higher pay and cost-control incentives will prompt primary doctors to give more attention to diabetics, the obese and other chronically ill people who account for large portions of the nation’s medical bill.

The government Medicaid program for low-income consumers and the Medicare program for seniors are sharing savings with primary doctors in numerous tests and pilot programs.

Dozens of private insurers are trying the same thing.

In some cases, in return for cost control, insurers are “prepared to pay double” what primary-care doctors have traditionally made, said John Deane, president of consulting at the Advisory Board Co., which works with hospitals and physician practices.

Primary doctors are famously overworked, stressed and, according to many, underpaid for their expensive training. They often make less than $200,000 a year compared to orthopedists and cardiologists who earn about $400,000.

The primary-care treadmill may be an underrated factor in soaring costs. Because they’re usually paid based on how many people they see rather than how many they keep healthy, primary-care doctors have traditionally been too quick to refer complicated cases to specialists, some believe.

“I think it is the single major reason why health-care costs are rising so fast,” said Stephen Schimpff, a former chief executive of the University of Maryland Medical Center who has closely followed CareFirst’s medical home.

Kaiser Health News is an editorially independent program of the Kaiser Family Foundation.