Insurers offering prescription drug coverage through Medicare routinely failed to provide accurate and complete responses to questions posed over the telephone by federal investigators.

Many of the 43 million people eligible for Medicare drug coverage rely on insurers' call centers for information about what plan would best meet their needs. Investigators made 900 calls to 10 of the largest drug plan sponsors. They got a complete and accurate answer only a third of the time.

The overall accuracy and completeness rate for the centers ranged from 20 percent to 60 percent. Only one insurer gave the proper, full answer more than half the time.

The investigators said that insurers answered the large majority of calls with minimal delay, were courteous, and many offered helpful suggestions. Yet, they were unable to answer 15 percent of the questions posed. Further, operators within the same call center sometimes provided inconsistent answers.

"Our calls to 10 of the largest (drug plan) sponsors' call centers show that Medicare beneficiaries face challenges in obtaining the information needed to make informed choices," concluded the Government Accountability Office in a report released Monday.

Officials with the agency that oversees the drug program disputed the analysis. They said it was based on "inaccurate, incomplete and subjective methods" that limit the report's relevance and validity. But the GAO maintained its methods are sound.

"The lack of accurate and understandable information for our seniors has been a chronic problem since the beginning of Medicare Part D," said Rep. John Dingell, D-Mich, and ranking member of the House Committee on Energy and Commerce. "Senior citizens are being hurt by the indifference and incompetence of the Bush administration and its friends in the insurance industry."

Most of the largest insurers offer more than one drug plan to Medicare beneficiaries. Most offer three, which gives consumers more opportunity to choose coverage that's best for them. Investigators asked operators to identify the plan that would be cheapest for them, based on the medicines they took.

However, operators at three calls centers told the investigators that it was against the insurer's policy to identify the plans that have the lowest costs. Yet, other operators at the same call center did identify a plan as having the lowest annual cost.

Often, when operators did find the lowest-cost plan, they misstated what the true costs would be. For beneficiaries with low drug use, the operators tended to quote costs that were higher than they actually should have been. And, for beneficiaries with high drug costs, the reverse occurred.

Overall, about 43 million seniors and disabled Americans can obtain prescription drug coverage through Medicare. Private insurers administer the benefit, with the federal government subsidizing the costs. Across the country, there are more than 1,400 stand-alone drug plans. Beneficiaries typically can choose from 40 to 50 offering coverage in their state.

Two weeks ago, Mark McCellan, administrator for CMS, said the government sanctioned insurance plans for service problems with the Medicare drug benefit more than 1,000 times so far this year.

The trade group representing insurers assailed the GAO's report as seriously flawed. Investigators asked for help that customer service representatives should not be giving, according to federal regulations, it said.

"They cannot choose or indicate to a particular beneficiary that Plan A is better than Plan B or C," said Karen Ignagni, president and CEO of America's Health Insurance Plans. "They're dinging plans for a reluctance to steer beneficiaries."

Ignagni said the investigators should have coordinated with the Centers for Medicare and Medicaid Services to make sure what are the call center requirements before engaging in the study. But the GAO said that during a meeting in May, agency officials told the investigators that call centers should have been able to accurately answer the questions investigators posed in March.

McClellan said he believed investigators did ask customer service reps for information that they are not required to provide, and may even be prohibited from providing.

"Medicare has never required drug plan call centers to provide detailed information about the prices of specific combinations of drugs," he said. "Despite this fact, two of GAO's five questions were on this topic."