The cost of long-term disability claims rose for at least a fifth straight year as expenses tied to the aging workforce drove payments higher for insurance companies.

Insurers paid $9.8 billion in disability claims in 2013, even as the number of workers receiving the payments fell for a second straight year amid a decline in the jobless rate, according to a report today by the Council for Disability Awareness.

Prudential Financial Inc. and Hartford Financial Services Group Inc. are among insurers that have raised prices for the coverage after being caught off guard by higher-than-expected claims costs. About 59 percent of claims last year were tied to people 50 or older, the council’s data show. That compares with less than 55 percent in 2009.

“On average, older people have higher wages and it’s harder for them to get back to work,” CDA President Barry Lundquist said in a phone interview. “When you think about the baby boomers and how old they are now, they have a much higher chance of becoming disabled -- maybe a four or five times higher chance in a given year than someone that’s in their twenties or thirties.”

The council’s survey is based on five years of data from companies including MetLife Inc., the largest U.S. life insurer, and No. 2 Prudential. The Portland, Maine-based council found that about 653,000 workers received long-term disability payments in 2013, a three-percent drop from the previous year.

The coverage compensates policyholders for income- interrupting illness or injury. The number of people receiving payments can decline in an improving economy, because there are more opportunities for people to return to the workforce. The U.S. unemployment rate fell to 6.7 percent at the end of 2013, from 7.9 percent a year earlier.

Stephen Pelletier, chief operating officer for U.S. businesses at Newark, New Jersey-based Prudential, said at an investor presentation this month that 60 percent of the group disability book had been re-priced or lapsed over the past two years, helping to improve the unit’s performance.

“All the metrics we track tell us that our actions are the right ones, that those actions continue to place the business on a path of recovery, a path that will admittedly have its ups and downs,” Pelletier said.