Is it a good idea to have a universal patient identifier?

The universal patient identifier is a single number that can uniquely identify individual patients. It is usually defined at the national level.

With the advent of electronic medical records that offer the potential of lifetime longitudinal medical and health records, there has been renewed interest in the subject of a universal patient identifier (UID).

As with most things, there are advantages and disadvantages to the UID.

For electronic information systems, the UID offers the promise of a method to link information from many sites (clinics, labs, care and support services) and information that is generated over the patient's lifetime together into a single record (real or virtual) that gives a comprehensive picture of the patient's health history. This comprehensive view can improve the quality of care and avoid unnecessary tests and treatments.
The UID also offers the potential for improved insight into disease diagnosis and treatment. Aggregate information from many patients can show disease patterns and potentially highlight best practices in health care. This information can track population health and provide valuable information for health policy and planning.

However, the UID is not without problems. First is the basic problem of issuing UIDs to ensure that each patient has one and only one UID and that no two patients have the same UID. Patients who present themselves for health services should possess a method of identification. Ideally this will be a UID card and possibly some biometric (fingerprint, iris, etc.) identification. A patient may have lost their card or the biometric information may not be useful. In this case they need to identify themselves using demographic and other information so that the clinic can find their UID in a 'Master Patient Index'. This can be problematic because of similar information or uncertainty of information. Patients may also want to avoid identification for any number of reasons including stigma or financial gain. The result of these problems is that patients may be mis-identified leading to duplicate UIDs for the same patient (when a new UID is issued) or a cross linking of patients where two or more patients are using the same UID. Both of these situations are very bad for the integrity of the data and and extremely difficult to fix.

Perhaps a better solution is to assign each patient a GUID (globally unique number) at each facility along with ancillary identifying information (the usual demographic information plus any other ID numbers that the patient may have. All of this can be submitted to a 'Master Patient Index' which can do the heavy lifting work of sorting out unique patients. Meanwhile, each facility will have a unique record for each of their patients that are uncontaminated by two different patient having the same number. If a patient ends up with several GUID numbers at a facility (and they will have different GUIDs at other facilities), these can all be combined in the MPI.