But insurers tend to receive pharmaceutical claims long before hospital bills. They are poring over these early prescription records for clues about new members' medical status.
Pharmacy-benefit manager Express Scripts published data April 9 showing that marketplace enrollees in January and February were substantially more likely than average to have HIV infections, chronic pain, depression and other high-cost ailments.
But that doesn't necessarily mean average costs will soar.
For one thing, insurers figured they would cover more sick patients this year and priced plans accordingly. Early pharmacy data at Independence Blue Cross, said Lobley, are "on par for what we expected."
Even if carriers signed more chronically ill customers this year than planned, the health law includes "reinsurance" and other safety valves designed to keep high-cost members from pushing up rates.
A sign-up surge at the end of March is another reason not to rely on early claims information.
Just as the first enrollees were more probably likely to need immediate care, insurers believe people who pushed the deadline may be healthier and younger. If so, they would balance the risk and help cover the cost of the early birds.
"It's clear that sick people were signing up" for January coverage, said David Axene, a fellow of the Society of Actuaries working with insurers to set 2015 rates. "The question now is, were the later people healthier?"
Nobody knows. While March enrollees seem to have been younger on balance, their health status remains largely a mystery.
Blue Shield of California signed more than 50,000 people the last two weeks in March.
"It's still too early to draw conclusions," said Amy Yao, Blue Shield's chief actuary. "I have the best actuarial team in the whole country. Even with that, it's less than 50 percent confidence" that they'll hit the rate-setting sweet spot for 2015, she said.
It's unclear how many of the 8 million who enrolled through the exchanges were previously uninsured. Many who did have coverage switched carriers this year, meaning their new insurers couldn't see their health histories.
At CoOportunity Health, a start-up created with funding from the health law, every one of the 74,000 customers is new.
Fri, Apr 25 2014