TUESDAY, March 1 (HealthDay News) -- On top of criticism that the U.S. Food and Drug Administration approves medical devices with too little oversight comes another troubling finding: Many heart-related devices win FDA approval without being adequately tested on women, despite an agency directive to do so.

This means that heart valves, pacemakers, defibrillators and stents get implanted in women without evidence that they benefit this population, researchers from the University of California, San Francisco say.

"We do not know if a lot of medical devices currently on the market are as safe and effective in women as they are in men," said lead researcher Dr. Rita F. Redberg, a professor of medicine and director of Women's Cardiovascular Services at the university and a member of the FDA Circulatory System Devices Panel.

"The FDA needs to turn away device applications that don't have a gender-bias statement," said Redberg, senior author of the study, published online March 1 in Circulation: Cardiovascular Quality and Outcomes.

Differences in size and bleeding tendencies can affect the way these devices operate in men and women, and side effects can also vary by gender, Redberg said.

Recognizing those distinctions, in 1994 the FDA mandated that manufacturers of new medical devices provide statements that the devices were tested in men and women in the same proportion as men and women experiencing the condition that the device would treat, Redberg said.

The data is also supposed to include any safety or effectiveness problems seen in women using the device.

Redberg's team looked at 123 studies submitted with premarket approval applications for 78 high-risk cardiovascular devices, including heart valves and implanted defibrillators. All the devices were approved by the FDA between 2000 and 2007.

During that period, a time when women's heart disease was gaining unprecedented attention, there was no increase in the proportion of women participating in studies or the number of applications with gender-bias statements, Redberg said.

FDA summaries of 28 percent of the studies made no mention of gender. Of those that did, men made up 67 percent of the study participants, the researchers found.

In addition, only 41 percent of the studies included the required gender statement. Of these, 94 percent showed results by sex, and 26 percent found sex-related differences in the safety and effectiveness, the researchers found.

Only 11 percent of the studies without gender-bias statements included any performance data related to gender difference. Studies of fewer than 50 patients were not included in the sex-based analysis, the authors noted.

Among applications the agency approved, device makers erroneously excluded women from studies, the researchers found. Some manufacturers understated the number of women with a specific heart condition. Other times, they said their study included an equivalent number of women as earlier studies, without acknowledging that those prior studies included only a token number of women.

Since data are not available about devices that the FDA didn't approve, Redberg's team couldn't determine how many of these included gender data.

The FDA, meanwhile, says it is working to correct these shortcomings.

"The findings reported in this study are not new," said FDA spokeswoman Karen Riley. "FDA is aware of the under-representation of women in clinical trials," she added.

Recently, the FDA division that approves medical devices has come under fire from the medical community for approving devices too fast without proper data, while device manufacturers complain it doesn't approve devices fast enough and over-complicates the process.

The agency's own 2009 study found that women, children and minorities were underrepresented in premarket cardiovascular clinical trials. "Women were less often enrolled in the studies than men (33.9 percent versus 66.1 percent)," Riley said.

The agency will issue guidance on gender this year, Riley added. "Interim policy improvements are already under way, intended to address the need for greater consistency in sex-specific analysis and availability of sex-specific information for approved medical devices," she said.

Commenting on the study, Dr. Nieca Goldberg, director of the Women's Heart Program at NYU Langone Medical Center in New York City, said more must be done on women's behalf.

"There has to be greater oversight," Goldberg said. "We have to meet the needs and expectations of women."

A woman needs to ask her doctor about the risks and benefits of these devices, Goldberg said.

"But we can't stop women from having these procedures if they really meet the indications," she said.

Redberg, who was speaking independently of her role with the FDA, says stricter enforcement of guidelines is needed.

More information

For more information on women and heart disease, visit the American Heart Association.