LOS ANGELES -- After months of head counts for Obamacare, it is the medical bills that will start to matter now.
Even before enrollment closes today, California has far exceeded its initial goals for signing up people under the Affordable Care Act. Although the sheer volume of 1.1 million policyholders is impressive for a brand new government program, the number of sicker patients is what's likely to draw the most attention.
How sick they are and the size of their medical bills will be front and center in the weeks to come as insurers begin drawing up next year's insurance rates, which will become public this summer.
The outcome -- hefty rate hikes or more modest increases -- in the pivotal state of California could help shape political races nationwide and the future of enrollment for President Barack Obama's signature law.
WellPoint Inc., parent of California's leading health insurer in the exchange, Anthem Blue Cross, has already predicted "double-digit-plus" rate increases on Obamacare policies across much of the country.
Other experts discount the notion of soaring premiums because the Obama administration has programs in place to help health plans offset losses from higher-cost customers.
Meanwhile, most everyone involved is waiting to see how many additional people rush in by today, the last day to begin enrolling in Obamacare.
Early returns are suggesting the administration may near a projection of 7 million enrollees made before the U.S. health exchange struggled at its startup.
The rollout has been under constant attack from Republican foes and faced a key Supreme Court decision that allowed states to limit the Medicaid expansion that was an important part of the plan. It also suffered from myriad technical flaws in the website that made it unusable for more than a month.
The government last week said 6 million Americans had enrolled by Thursday, and that about 1 million people a day were visiting HealthCare.gov. With four days left, that figure met a mark set by the Congressional Budget Office in February that was revised downward from an initial 7 million estimate after the law's troubled start in October. Republicans on Sunday again questioned the credibility of the administration's numbers.
"I think they're cooking the books on this," said Sen. John Barrasso, R-Wyo., in an appearance Sunday on Fox News Sunday. "What kind of insurance will those people actually have? Will they be able to keep the doctor that they want? How much more is it going to cost them?"
But health insurers aren't wasting any time sizing up what patients are costing them now and what that will mean for 2015 rates.
Hunkered down in conference rooms, insurance actuaries are parsing prescriptions, doctor visits and hospital stays for clues about how expensive these new patients may be. By May, insurance companies must file next year's rates with California's state-run exchange so negotiations can begin.
"If rates in California increase by 20 percent," said Robert Laszewski, a health care consultant in Virginia, "enrollment will go down and any healthy people will bail."
Those concerns are one reason the Covered California exchange, insurers and health-law supporters are trying so hard to persuade young and healthy people to enroll before today's deadline. The goal is to improve the chances of getting a balanced mix of policyholders and keep monthly premiums down.
No matter the final outcome, Covered California officials are confident they have done enough to avert upheaval in the market. "I think we're in a position to be optimistic that if rates go up at all, it will be in the single digits," said Peter Lee, executive director of Covered California.
Harriet Davidson, 60, was one of the first people in line for Obamacare after being shut out of the market for years. The self-employed consultant in Contra Costa County was rejected twice for individual health insurance because of her diabetes and a thyroid condition. The health care law removed that obstacle by guaranteeing access to coverage regardless of pre-existing conditions.
That meant Ms. Davidson could buy a Silver plan from Blue Shield of California that costs her $92 a month -- thanks to a federal subsidy.
"I probably neglected my health the last few years because of the expense," Ms. Davidson said. "Now I'm going to have every test known to man."
She plans to undergo lab tests for her diabetes, a mammogram, a bone density scan and a colonoscopy -- everything she put off while she went without comprehensive insurance.
Ms. Davidson's medical bills are the kind of expenses that could end up being scrutinized in a conference room on the 18th floor of Blue Shield's headquarters in San Francisco.
The company's chief actuary, Amy Yao, and a small team of co-workers meet every other day to pore over the latest data and trends. "It's kind of the sausage-making factory," she said.
Ms. Yao said claims information is usually a better guide to future costs than a customer's age, sex and other demographic data.
But there's a risk to putting too much weight on such a short time period, and there's no guarantee Blue Shield will hang on to these same customers when they get a chance to renew their policies early next year.
"It's really dangerous to draw conclusions from a small sample because you could be off materially," Ms. Yao said. "Pricing is really challenging this year."
Bloomberg News contributed.