Anyone who has had the privilege of hearing Clayton Christensen speak knows that he can captivate an audience. First, there's his dramatic and courageous personal story, having survived a heart attack, a stroke and a battle with lymphoma, which is now in remission. Then there's that incredible intellect, matched only by an ability to explain complex economic theories in a way that even a dopey English and political science major like yours truly can understand.

The Harvard Business School professor didn't disappoint at last month's Health ForumAHA Leadership Summit. He spoke at length about his self-coined theory of disruptive innovation, which is what happens when a product or service takes hold at the bottom of a market and then aggressively climbs up, eventually displacing more established brands.

He set the stage with his well-told tale of how Toyota supplanted the Big Three. The Japanese automaker entered the U.S. market in the 1960s with cost-concious cars the Corona and Tercel. U.S. automakers responded with the Pinto, but then went back to building gas guzzlers. Toyota continued to climb the ladder, next with Corolla, then Camry and Avalon and, finally, Lexus. (Interestingly, he noted, Toyota now finds itself on the top, while Korean carmaker Kia nibbles away at the bottom.)

Another parable he likes to tell is about computers. The industry started off with giant mainframes housed by elite institutions. It evolved to minicomputers, then desktops, then laptops. Now, computing is in the palm of your hand on your smart phone. Yet none of the top sellers, he pointed out, are manufacturered by such computing titans as Dell, HP or Lenovo (Apple, of course, is the exception to the rule).

Now, disruptive innovation is at your door. Walgreens, Target, CVS. Do these names ring a bell? How about Walmart? Each is looking to pick off cost-conscious, convenience-loving consumers with retail health clinics. After a relatively flat period in 2009 and 2010, the number of retail clinics jumped 11.2 percent in 2011, according to Merchant Medicine, a research firm that tracks the growth in retail medicine. That seems to indicate that there's enough demand to support these enterprises. My family certainly has taken advantage of them, going in to get the kids (and even myself) tested for ear infections or strep throat. Why waste a visit to the doctor or ED when I can head to Target, get tested, do some shopping, and walk out with a prescription, all within a few minutes? And think for a minute about all of those patients without a primary care doctor or medical home. These clinics can and are filling that void.

Technology is the other part of this disruptive innovation. CVS's MinuteClinic can link with hospital EHRs. Walmart reportedly is bringing telemedicine capabilities to its stores. And some diagnostic tools are becoming highly commoditized, giving retail clinics and others the ability to conduct (affordable) tests that were heretofore the domain of specialists.

This is not to say that Take Care Clinic will become Take Care Hospital, but as health systems look to build new integrated networks, including medical homes, these disruptive competitors warrant attention. Just be sure that you don't show up in a Pinto

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