AS A KEY enrollment deadline hits today, many people without health insurance have been sizing up policies on the new government health-care marketplace and making what seems like a logical choice: They're picking the cheapest one.

Increasingly, experts in health insurance are becoming concerned that many of these first-time buyers will be in for a shock when they get medical care next year and discover they're on the hook for most of the initial cost.

The prospect of sticker shock after Jan. 1, when those who sign up for policies now can begin to get coverage, is seen as a looming problem for a new national system that has been plagued by trouble since the marketplaces went online in the states in October.

For those without insurance - about 15 percent of the population - "the lesson is it's important to understand the total cost of ownership of a plan," said Matt Eyles, a vice president of Avalere Health, a market-analysis firm. "You just don't want to look only at the premium."

Counselors who have been helping people choose policies say many are focused only on the up-front cost, not what the insurance companies agree to pay.

Meanwhile, the glitch-plagued rollout of President Obama's health-care overhaul was the top news story of 2013, followed by the Boston Marathon bombing and the dramatic papal changeover at the Vatican, according to the Associated Press' annual poll of U.S. editors and news directors.

The saga of "Obamacare" - as the Affordable Care Act is widely known - received 45 first-place votes out of the 144 ballots cast for the top 10 stories. The marathon bombing received 29 first-place votes and the papal transition 21.