Analysis also found that the proportion of medications specifically used to treat HIV was nearly four times higher in the exchanges than in commercial health plans.

Also higher in exchange plans were the proportion of pain medications (35 percent higher in exchanges than in commercial plans), anti-seizure medications (27 percent higher) and antidepressants (14 percent higher). The proportion of contraceptives, however, was 31 percent lower in exchange plans.

Increased volume for higher cost specialty drugs can have a significant impact on the cost burden for both plan sponsors and patients, analysts said. Health insurers’ per-member pharmacy costs so far this year are nearly 35 percent higher for their commercial plans versus their exchange plans, the report found.

Benefits experts say that having healthy enrollees in PPACA plans is important to offset the costs of sicker enrollees and to hold down premiums in the coming years.

The Obama administration has not yet released the breakdown of exchange enrollees, identifying ages or demographics.

The analysis is based on a national sample of more than 650,000 pharmacy claims from January 1 through February 28 for patients enrolled in a public exchange plan with pharmacy benefit coverage administered by Express Scripts.

The analysis does not include the late enrollment surge in PPACA plans in March. Julie Huppert, Express Scripts vice president of health care reform, warned that the report is “a very early analysis.”

Experts have previously noted that sicker patients were expected to sign up for coverage first, while younger and healthy patients were expected to wait until the end of enrollment to sign up.