Independence Blue Cross is cutting some payments to doctors by 50 percent, a move that has alarmed some physicians.

On Aug. 1, the biggest health insurer in Southeastern Pennsylvania will change how it pays a subset of services that doctors may perform during a single appointment.

The 50 percent cut does not apply to overall reimbursement rates.

In a hypothetical example of a dermatology visit, the doctor might now get $100 for a full-body skin exam and $50 for a biopsy, if it is done during the same visit by the same doctor. Under the new rules, the payment for the exam would be cut to $50, for a total payment of $100, or a 33 percent overall reduction for the episode.

Under other scenarios, the smaller of the two payments would be cut, with the variation driven by the type of practice and other factors.

The change worries Emily Schwarz, a dermatologist, who in May opened a solo practice in North Wales in hopes of providing patient-focused care after the practice where she used to work was purchased by a company in Florida.

"This 50 percent cut is alarming and definitely keeps me up at night," Schwarz said.

Ginny Calega, Independence's vice president of medical management and policy, said the policy is part of the Philadelphia insurer's effort to shift from paying for volume of services to paying for results in a market that has among the highest health-care costs in the nation without the outcomes to go with the expense.

What specifically prompted the 50 percent reduction was an analysis that found doctors under contract with Independence were using a coding modifier that led to payment for an added service nearly twice as often as doctors in a national benchmark, Calega said.

"We're in a changing environment. We're looking to be good stewards of our customers' and our members' health-care dollars, and we're benchmarking ourselves with other payers, regulators for national trends," Calega said.

The Pennsylvania Medical Society warned in a letter addressed to Daniel J. Hilferty, Independence's president and chief executive, that the doctors will have no choice but to require patients to come back for an additional visit to preserve the full payment for the office visit.

"Implementation of this policy will result in increased cost to patients in the form of additional co-pays due to multiple visits, resulting in decreased patient satisfaction. Additionally, access to care and the likelihood of worsening clinical outcomes due to delays will follow," the letter from the medical group said.

"If we are really talking about good patient care, a good member experience, we would really hope that our providers would not resort to bringing somebody back on two different days," Calega said. "It's not really in the patient's best interest to do that."

Officials at Independence, which had $16.7 billion in revenue last year, declined to estimate how much the new reimbursement policy would reduce what it spends on health care.

"It is not a number we're willing to share because we don't know exactly how billing will change, and, therefore, we don't know exactly how much of an impact it will have," said Richard Snyder, Independence's chief medical officer.