White House chief technology officer Aneesh Chopra was trying to encourage meaningful use of health IT last week by playing up some success stories with health information exchange in the federal sector. He got me thinking of what I see as the key to HIE: accurate patient identifiers.

What set off my brain was Chopra's reference to the National Cancer Institute's Cancer Biomedical Informatics Grid (caBIG), which has been widely accepted by public and private researchers alike as a hub for sharing data on diagnoses, treatments and outcomes for cancer patients nationwide. CaBIG is successful not only because clinicians have found it to be useful, but because the technology actually works.

We reported a week ago that the Department of Veterans Affairs had temporarily cut off access to Military Health System records because of a glitch in the interface engine that occasionally delivered data unrelated to the patient in question. This problem highlighted the importance of correct patient identifiers.

Nearly three years ago, I heard a success story from another cancer registry, one serving the Canadian province of Ontario. That system, from an agency called Cancer Care Ontario, worked because the CIO for that project decided to start with the master patient index. Not only did it make it easy for clinicians to report and access data, it helped reduce the waiting times that plague Canadian healthcare. Cancer Care Ontario eventually morphed into a full-blown EMR agency called eHealth Ontario, where that CIO was poised to apply a similar strategy to wide interoperability of health information. Unfortunately, that individual in question was Sarah Kramer, who was fired last year for suspected bid-rigging and other abuses, but that stain shouldn't diminish the technology lesson here.

Lack of an MPI also was one of the reasons why the Santa Barbara County (Calif.) Care Data Exchange failed. People have learned since then that when it comes to health information exchange, you need to get the patient identifier right. - Neil