WASHINGTON (UPI) -- U.S. lawmakers Wednesday urged antitrust regulators to look closely at whether a pending health-plan mega-merger squeezes out competition, a problem some experts say is a primary driver of runaway healthcare costs.

The proposed consolidation of Pennsylvania health-insurance giants Blue Cross Independence and Highmark provided the backdrop for a hearing before the Senate Judiciary Committee on whether the health-insurance market is becoming the game of a handful of industry giants that, answerable only to their shareholders, continue to hike premiums, cut doctor reimbursements and leave consumers with fewer choices and no apparent increase in quality.

"Take a very close look at that situation," Committee Chairman Arlen Specter, R-Pa., told federal antitrust officials who testified at the hearing.

Blue Cross Independence -- the largest health insurer in the Philadelphia area -- took in 28 percent of the $28 billion spent on the state's health-insurance premiums in 2004, while Highmark picked up 27 percent, according to a report in Daily and Sunday Review.

The potential merger in Pennsylvania -- which reportedly has one of the nation's highest premium rates -- is just the latest example of a rash of super-sized mergers among health plans, which critics say are the largely overlooked culprits in the nation's soaring health spending, one-third of which doesn't even go toward care of patients, but to other expenses like administrative costs.

Sen. Tom Coburn, R-Okla., noted that healthcare spending now accounts for about 16.2 percent of the U.S. gross domestic product, asking, "What are we getting for it?"

Health-policy experts who testified at the hearing urged a health-insurance industry crackdown by, for example, casting a more critical eye on the mega-mergers and imposing new requirements like standardized reporting of health plans' premium-generated revenues, their administrative costs and what percentage of their premiums actually go toward patient care.

Some experts testified that a law allowing doctors to engage in collective bargaining with the health plans -- as the federal government is allowed to do -- might create a more equitable playing field.

Specter asked panelist J. Bruce McDonald, deputy assistant attorney general in the Department of Justice's antitrust division, why DOJ had only challenged two out of 400 recent health-plan mergers. "Is this not quite enough scrutiny?" he said.

McDonald responded that the agency investigated all mergers "presenting anti-competitive problems."

Mark Piasio, a physician and president of the Pennsylvania Medical Society, told the committee that his state's health-insurance market is in the grips of a few major players who engage in "predatory pricing," where rivals are effectively locked out of the market -- particularly in areas like Philadelphia -- and where physicians continue to see their reimbursement rates shrink.

The test of monopolistic behavior in Pennsylvania has been met, he said. "We have the highest (insurance company) profit and the lowest reimbursement rates. There is at least questionable behavior on the part of the large players. Why isn't (Pennsylvania) the focus of an anti-trust investigation?" Piasio asked.

Edward Langston, an Indiana-based family practitioner and chair-elect to the American Medical Association's Board of Trustees, told the lawmakers a recent AMA study revealed that a trend toward "aggressive consolidation" has reached national proportions.

In many of the 294 U.S. markets on which the study focused, "competition has been undermined" and the "hallmarks of monopoly" are in evidence, he said, including the insurers' ability to raise premiums without sacrificing market share and tactics that force doctors to accept unfair contract terms for their services. A monopolistic few "are operating in the interest of shareholders, not patients," Langston told the committee.

He added that, although premiums have been rising in the double digits and health plans spent $55 billion on consolidation and acquisitions in 2004 and 2005, "physician reimbursement is not changing."

"We're blamed for being the driver of high healthcare costs," Langston said. "We're raising red flags (and) calling for transparency in what the real costs are."

However, Stephanie Kanwit, special counsel to health plan trade group America's Health Insurance Plans, told lawmakers that the U.S. health-insurance market is one marked by "vigorous competition," where monopolies are not a problem and where health plans are continually rolling out new products to benefit consumers.

She also testified that collective bargaining for doctors has been "condemned" by DOJ and that such a policy would "inevitably raise prices without increasing quality."

Instead, Kanwit said, the answer to cutting costs lies in creating doctor performance and efficiency measures, an effort already under way in a number of pilot projects "that will lead to a national framework for doctor performance."

Specter noted that a number of health-insurance giants including Aetna, United Health Group and WellPoint were all asked to testify before the committee and that all had declined. "That's not a very good sign if companies won't come in and respond to questions," he said.