Match Accuracy and the attributes used

According to a study

"Studies using both large and small databases of medical records from the US have demonstrated that the risk of false positive matching decreases from a 2-in-3 chance using last name only to a 1-in-3500 chance when first and last names, postcode and date of birth are used."

https://www.safetyandquality.gov.au/sites/default/files/migrated/Standard5_Oct_2012_WEB.pdf