HESID matching algorithm

The HESID and the HESID matching algorithm, the process by which activity records are compared to determine which relate to the same patient was improved in December 2008. The change was implemented for two reasons:

• To match records with missing or invalid NHS number or local patient identification.
• To allay information governance concerns that the original HESID was not a 256 bit encrypted field.

These changes have led to the following practical changes:

• The HESID is replaced by a new field, the PSEUDO_HESID, a 16 character alphanumeric field encrypted at 256 bit level in all current and historic Business Objects universes. The PSEUDO_HESID is not comparable with the HESID.
• Customers who request the new PSEUDO_HESID in an extract will receive a unique version of the PSEUDO_HESID called EXTRACT_HESID.

A full document detailing the change from HESID to PSEUDO_HESID will be available from this site shortly.