One of the major threats to patient health hasn't received nearly enough attention during the recent negotiations in Washington over comprehensive health care legislation. Millions of Americans aren't sticking to their pharmaceutical drug regimes. As a result, they're compromising their own care, and putting themselves at risk of developing more serious - and more costly - conditions.

According to a recent study by Wolters Kluwer Health, fewer Americans are filling their drug prescriptions. In the fourth quarter of 2008, U.S. patients neglected to fill 6.8 percent of on-patent prescriptions - a 22 percent increase compared to the first quarter of 2007. (On-patent prescriptions are those for which there is no generic alternative to the brand-name drug.)
 

Why?
 

Drug prices. It's not that the cost of prescription drugs is rising - it's patients' out-of-pocket costs, or co-pays. One of the reasons for this is that insurance companies, reluctant to foot the bill for brand-name medications, have been refusing to cover more brand-name prescriptions.
 

In the fourth quarter of 2008, in fact, health insurers denied coverage for 10.8 percent of brand-name drugs - a jump of 21 percent from the first quarter of 2007.
 

And it's not because the medicines themselves are becoming more expensive. Between 1998 and 2003, prescription drug costs increased by $22.48 per person. Meanwhile during that same period, the average health insurance premium went up by $104.62 per person.
 

When co-pays go up, more people see the need to abandon their prescription drug regimen. At least that's what a study from Oregon Health & Science University found. In 2003, researchers looked at what happened when a small $2 to $3 co-payment was introduced for Oregon Medicaid patients. After examining data on 117,000 patients, the researchers found that prescription drug use dropped by 17 percent.
 

And higher co-pays aren't just bad for patients. They're bad for employers as well. In fact, according to a 2007 study by the Integrated Benefits Institute, companies that burden employees with high out-of-pocket prescription drug costs pay a price. The study looked at thousands of arthritis sufferers employed at 17 organizations.
 

Because arthritis drugs can cost as much as $18,000 a year - even for those with insurance - many patients decided to do without their medication. This cost their employers $17.2 million in lost productivity, the study found.
 

As health care costs continue to rise, it's understandable that insurance companies are looking to save money wherever possible. Passing off the cost of prescription drugs to patients, however, will only drive up overall costs while resulting in dramatically poorer health for more Americans. As federal lawmakers look to reform the health care system, they need to take steps to relieve the financial burden borne by patients who require prescription drugs.