I have patients' data set and I have to identify two "consecutive dates" of lab test results dates which are between 90-700 days.
Each patient has several lab test results, how can I compare all two dates together and find the consecutive dates?

Patient_ID Performed_date TestResult
1.00100000023498E15 |
Thu May 28 2015 |
54.0 |
1.00100000023498E15 |
Thu Sep 26 2013 |
59.0 |
1.00100000023498E15 |
Tue Oct 28 2014 |
53.0 |
1.00100000023498E15 |
Wed May 06 2015 |
54.0 |
1.00100000023498E15 |
Tue May 05 2015 |
55.0 |
1.00100000023498E15 |
Fri May 01 2015 |
48.0 |