This week, Steve Engelberg brings Charlie Ornstein and Tracy Weber to the Storage Closet Studio to talk about the latest piece in their yearlong investigation of Medicare Part D. One of the biggest takeaways from their analysis of the prescribing habits of more than 1.6 million practioners in the U.S.: Just 913 internists, family medicine and general practice physicians cost taxpayers an extra $300 million in 2011 alone by disproportionately choosing name-brand drugs.

Some of those doctors believe that brand-name drugs are better, Ornstein and Weber say, but other factors are at work, too, such as pressure from patients, relationships with drug sales reps -- or direct financial ties to the pharmaceutical companies themselves: Since 2009, 48 percent of those 913 prescribers have received at least $1,000 for speaking, consulting and other promotional purposes, according to data ProPublica compiled from company web sites.

Why hasn't Medicare cracked down on this wasteful prescribing?

"I think that Medicare didn't see it as their job to analyze this data," Weber says, which is particularly troubling because "only Medicare can see the whole prescribing of a doctor and would be able to identify the sort of trends that we did, where doctors have really high rates of brand-name prescribing."

Medicare officials have promised reforms in response to some of the revelations in ProPublica's reporting, and Ornstein and Weber will certainly continue to follow the story.

You can listen to this podcast on iTunes and Stitcher. And for more on their investigation, see: