When a helicopter rushed a 13-year-old girl showing symptoms suggestive of kidney failure to Stanford's Packard Children's Hospital, Jennifer Frankovich was the rheumatologist on call. She and a team of other doctors quickly diagnosed lupus, an autoimmune disease. But as they hurried to treat the girl, Frankovich thought that something about the patient's particular combination of lupus symptoms — kidney problems, inflamed pancreas and blood vessels — rang a bell. In the past, she'd seen lupus patients with these symptoms develop life-threatening blood clots. Her colleagues in other specialties didn't think there was cause to give the girl anti-clotting drugs, so Frankovich deferred to them. But she retained her suspicions. "I could not forget these cases," she says.
Back in her office, she found that the scientific literature had no studies on patients like this to guide her. So she did something unusual: She searched a database of all the lupus patients the hospital had seen over the previous five years, singling out those whose symptoms matched her patient's, and ran an analysis to see whether they had developed blood clots. "I did some very simple statistics and brought the data to everybody that I had met with that morning," she says. The change in attitude was striking. "It was very clear, based on the database, that she could be at an increased risk for a clot."
The girl was given the drug, and she did not develop a clot. "At the end of the day, we don't know whether it was the right decision," says Chris Longhurst, a pediatrician and the chief medical information officer at Stanford Children's Health, who is a colleague of Frankovich's. But they felt that it was the best they could do with the limited information they had.
A large, costly and time-consuming clinical trial with proper controls might someday prove Frankovich's hypothesis correct. But large, costly and time-consuming clinical trials are rarely carried out for uncommon complications of this sort. In the absence of such focused research, doctors and scientists are increasingly dipping into enormous troves of data that already exist — namely the aggregated medical records of thousands or even millions of patients to uncover patterns that might help steer care.
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http://www.nytimes.com/2014/10/05/magazine/can-big-data-tell-us-what-clinical-trials-dont.html?ref=magazine