A rise in chronic disease, particularly among baby boomers and older adults, was a key driver of the fact that consumers spent about 40 percent more out of pocket for health care in 2005 than in 1996, researchers report in the January/February 2009 issue of Health Affairs, a thematic volume on chronic illness.

The study shows that the prevalence of chronic disease in the United States has burgeoned not just among the “oldest old” but also among people in midlife and early old age — regardless of sex, race, ethnicity, or income. The percentage of Americans with three or more chronic illnesses rose from 13 percent in 1996 to 22 percent in 2005 for ages 45 to 64, to 45 percent for ages 65 to 79, and rose from 38 percent to 54 percent for those 80 and older. Among all ages, it went from 7 percent in 1996 to 13 percent in 2005.

“The burden of chronic conditions is becoming heavier. People who already have chronic conditions no longer just have one. Now they might have three,” lead coauthor Kathryn Paez, senior research scientist at the Maryland-based Center for Health Policy and Research, Social and Scientific Systems, told Reuters. People with multiple chronic conditions have “to purchase a number of medications, and then their co-payments are higher, because employers are coping with the costs by reducing benefits,” Paez added in an interview with Marketplace.

According to the study, average annual out-of-pocket spending rose from $427 in 1996 to $741 in 2005. After adjusting for inflation, this represents an increase of 39.4 percent in out-of-pocket spending per person. These were costs assumed directly by the consumer, including payments for coinsurance, copayments, deductibles, and other related medical items not covered by insurance.

Drugs were the costliest out-of-pocket expenditure by far for almost all Americans. People over age 65 with multiple chronic conditions spent an annual average of $1,292 on prescription drugs in 2005, more than five times more than what they spent for office visits, the researchers found.