When parents have high health-insurance co-pays, their school-age children with asthma are less likely to receive prescribed medication for their illness. Those children are also more likely to be hospitalized for an asthma-related condition, according to a University of Minnesota study published Tuesday in the Journal of the American Medical Association.

“There has been a trend toward more and more families paying out of pocket,” said Pinar Karaca-Mandic, the study’s lead researcher and an assistant professor of health policy and management at the U of M, in a phone interview. “We know that adults often respond by forgoing care. We wanted to see if this was the case with needed health care for their children.”

The researchers expected not to find that higher co-pays lowered the probability that children received their medicine at the recommended dosage, she added. “We were surprised,” she said. “Before we started the research, we didn’t think we’d find this [result].”

A cross-country study

For the study, Karaca-Mandic and her colleagues examined one year of insurance claims for 8,834 children with asthma whose parents were privately insured through 37 employers across the United States. They chose these families because asthma is the leading chronic disease among children. Children with chronic asthma are generally prescribed daily medications, such as a corticosteroid inhaler or an oral pill like montelukast (Singulair) to prevent asthma flare-ups.

The researchers then divided the families into four quartiles according to how much they had to pay out of pocket for their medications.

An analysis of the data found that co-pays made no impact on medication use among children under the age of 5 — perhaps, the researchers speculate in their study, because young children tend to have more severe symptoms of the disease. But the situation was different among children ages 5 to 18. Although none of the quartiles of parents came close to having these older children’s prescriptions filled enough times for the recommended daily use of the drugs, the size of the families’ insurance co-pays did make a difference.

On average, older children whose parents had to pay the least out of pocket for the drugs received enough medication to cover 41.7 percent of the recommended daily doses over the course of the year that was studied. Those whose parents had to pay the most out of pocket received, on average, only 40.3 percent of the doses.

“It’s the difference of about five days,” said Pinar Karaca-Mandic. “It’s a small effect, but it is significant.”

Indeed, the study also found that the older children whose parents had to pay the most for the medications were 30 percent more likely to be hospitalized for an asthma-related incident during the year of the study. (There were 2.4 hospitalizations per 100 children among the group with the highest co-pays versus 1.7 hospitalizations per 100 children among the group with the lowest ones.)

‘Little things add up’

The average out-of-pocket cost for the children’s medications across the four co-pay groups ranged from $89 to $242 a year.

“It’s not a huge difference,” said Karaca-Mandic, “but it can mean a lot to some families,” particularly if the family has other out-of-pocket medical expenses.

Other studies, Karaca-Mandic added, have also shown that even small changes in co-pays can make a significant difference in whether or not people use prescribed medications. “Little things do add up,” she said.

Several factors

The study’s findings suggest that children are just as vulnerable as adults to not receiving prescribed medical treatment when insurance companies shift the cost of medications to patients.

But, stressed Karaca-Mandic, “out-of-pocket expenditures is only one of the factors” behind the low levels of use of asthma drugs among school-age children. And that low use was striking: No matter what the co-pay, more than 50 percent of the parents were not purchasing the recommended dosage of asthma medication for their kids.

Other strategies may be more important than co-pays to ensure treatment compliance, said Karaca-Mandic, “like making sure kids see their doctors more often.”

Of course, many of the co-pays for those visits are also going up.