Like many others her age, 60-year-old Mary Ann Mason fell through one of the biggest trap doors in the American health care system: She's too young for Medicare, with too much retirement income to qualify for Medicaid or similar low-income insurance programs, and with one too many health problems to buy an affordable individual plan on the open market.

Mason, of Venango County, Pa., was insured through her husband's employer for years. But when Brent Mason left his job several years ago because of a disability, she was without coverage once their COBRA benefits were dropped.

"Mary Ann was denied several times" by companies including Aetna and United Healthcare, Brent Mason said. Her psychiatric condition, bipolar disorder, had made her practically uninsurable, and the couple says they couldn't afford any of the higher-cost "guaranteed issue" policies available through Blue Cross Blue Shield insurers.

"As soon as you mention 'bipolar disorder' to an insurance company, it's an automatic no," Brent Mason said. Beyond the condition itself, he said, lithium, a medication commonly used to treat it, has been known to cause liver complications.

"When I applied for new insurance, it became apparent I was not going to be able to buy a reasonably priced policy," Mary Ann Mason said.

The Masons, like millions of other Americans, have learned that buying an individual health insurance policy on the retail market is a bit like asking out the homecoming queen: Be prepared for rejection.

Obtaining a comprehensive individual health insurance plan can be fraught with denials. Roughly a fifth of applicants for a particular policy will be turned down initially. Many more will see a final monthly premium that's higher than the originally quoted base price.

Last year, the U.S. Department of Health and Human Services began aggregating the cost, and rejection rates, of health insurance policies available for purchase in each state and market region. It has found rejection rates vary by state and by company.

But there's one constant: It can be tough to get affordable, individual, comprehensive health care if you've had previous health scares.

Most people under 65 who have health insurance still get coverage through their employers.

But insurers see individual retail polices as a potential growth market, and a growing number of people get their insurance via individual "direct pay"policies. That's because they can't or don't get coverage through work. The percentage of working-age Americans covered through employer-sponsored plans has been falling for a decade.

The 2010 federal health care overhaul will outlaw the type of medical screening that denies coverage based on pre-existing conditions come 2014, if the law is still in place. For now, states have set up high-risk health insurance pools that offer plans to people who can't get individual plans elsewhere.

Insurers and their industry trade group say denial rates can be misleading, as someone who is rejected may be offered a more suitable policy later and ultimately will find coverage. Nationally, 87 percent of people who apply for individual coverage are eventually offered a policy, says America's Health Insurance Plans, a trade group that represents insurers.

"They're using a fatally flawed definition of denials, which is painting an inaccurate picture" of the marketplace, said Robert Zirkelbach, the group's spokesman.

It's not just people who have health issues who are getting turned down. Some people are rejected because they filled out a form incorrectly or because they make too much money to be eligible for a particular low-income plan. Those denials aren't the insurer's fault.

But health care advocates say the numbers show just how difficult it is for many of the uninsured to obtain insurance under the current system.

Those seeking individually purchased insurance tend to be single, are unable to find full-time work or are self-employed or work for a company that employs fewer than 100 people.

Many, like Mary Ann Mason, are trying to bridge the gap between their late 50s and Medicare eligibility. After several denials, Mason found coverage this year through Pennsylvania's PA Fair Care, a health plan for uninsured adults with pre-existing conditions, subsidized by the federal government.

(Contact Bill Toland at btoland@post-gazette.com.)