"Any move I make is complex," Little said.
Yet in an era of heightened concern over soaring health care costs, such billings are coming under increasing scrutiny by the federal government. In a 2012 report, the inspector general for the Department of Health and Human Services found that billings for complex visits were on the rise, and urged Medicare to review 1,700 providers whose 2010 billings were on the high end of the scale.
Asked if any of those clinicians had since been audited or found to have overcharged the government, Medicare officials declined to answer, but said the physicians had received reports showing how their billings stacked up against their peers.
Meanwhile a new analysis of the latest Medicare data by ProPublica, a nonprofit investigative news organization, shows that the pattern continues.
In 2012, two years after the year analyzed in the inspector general's report, more than 1,800 health professionals nationwide billed Medicare for the most expensive type of office visits at least 90 percent of the time.
Billing experts say a provider with nothing but level-five visits warrants scrutiny.
"I can't see a situation where every visit would be a level five, especially on an established patient," said Cyndee Weston, executive director of the American Medical Billing Association, a trade group. "I was trying to talk myself into it, but I just can't see it."
Medicare pays an average of $14 for a level-one visit and more than $100 for level five. Doctor's offices use a checklist to rate the complexity of each visit, based on such factors as the level of exam and decision-making required.
In Pennsylvania, among providers who billed for at least 100 established-patient visits, 78 claimed that every one of those visits was a level five - the most complicated type - according to an Inquirer analysis of the data. In New Jersey, there were 36 providers who met that description.
In the eight-county region, among those who billed entirely at level five, eight of the top 10 are part of the University of Pennsylvania health system.
All eight treat very complex patients, said Susan Phillips, Penn Medicine's senior vice president for public affairs. Seven specialize in transplants, and the other, Jack Goldberg, specializes in geriatric hematology and oncology, with gravely ill patients who have multiple serious conditions, she said.
Nevertheless, she said the health system would review the data to ensure its physicians were in compliance.
"Penn Medicine treats thousands of patients each year who are facing complex, often life-threatening conditions such as advanced cancer and organ failure," Phillips said. "While we believe the general benchmarking data recently released may not be an apt comparison for sub-specialty academic medicine, we intend to review this new benchmarking data carefully."
In the data, made public for the first time last month, Medicare did not include records of services that a physician provided to fewer than 11 patients, in order to protect patient privacy. So a doctor that shows up as billing for level-five visits 100 percent of the time may in fact have billed Medicare for an additional handful of less-complex visits.
In addition to the eight Penn physicians and Little, the psychiatrist, the other local physician listed with 100 percent level-five visits is Jonathan Grohsman, an ophthalmologist who practices in Jenkintown and Northeast Philadelphia. None was in South Jersey.
Medicare says Grohsman billed for 842 generic established-patient visits in 2012, all of them at level five.
The physician noted that he billed even more frequently under a separate code for eye-related office visits. He said his Medicare billings reflected a complex patient population, as he specializes in a difficult condition called pseudoexfoliation glaucoma.
Many have already lost an eye and have multiple chronic conditions, and are not compliant in taking their medication, he said. Many are recent immigrants and Grohsman must enlist a translator to communicate with them, he said.
None of these 10 Pennsylvania doctors is a leader in total Medicare billings, however. Grohsman is not among the top 200 eye doctors in the state, and the other nine are not even among the top 4,000 billers for the eight-county region.
In its response to the inspector general's report, the Centers for Medicare and Medicaid Services agreed to conduct more doctor education. Agency administrator Marilyn Tavenner said contractors would "focus on" the top 10 billers in each region, but she said the return on investment for detailed reviews of visit billings was not great. The average error cost Medicare $43, while the cost to review a claim ranged from $30 to $55, she said.
A 2013 Medicare report estimated that established patient visits had a 7 percent improper payment rate, accounting for approximately $965 million in 2012.
Nationally, 4.2 percent of established patient visits were rated at the highest level of complexity in 2012. In the eight-county area, the corresponding figure was 4.9 percent - not surprising, given the area's high concentration of specialists.
Little, the psychiatrist, said she would have no problem with a review of her billings for office visits because she codes them correctly. She said she often has to call family members or a nursing home to get details on a patient's history, such as whether they have fallen or are suffering from dizziness or hallucinations. She said she often needs to conduct detailed exams, doing everything from measuring blood pressure to conducting a neurological exam.
Alice Gosfield, a Philadelphia attorney who represents physicians in contract and reimbursement issues, said one reason doctors are billing for more complex patient visits is the advent of electronic medical records. These systems improve physicians' ability to document their services accurately, she said.
She agreed that someone with all level-five visits was unusual, but cautioned against jumping to conclusions from the raw data.
"Is some of this probably medically unnecessary? I'm pretty sure it is." Gosfield said. "But this data isn't going to tell you that."
ProPublica writers Charles Ornstein and Ryann Grochowski Jones and Inquirer staff writer Tom Torok also contributed to this article.