Implement Post-Index Features in CohortDiagnostics

[kmkostka]

Post-index characteristics
These features will be described in two different time windows: at index date (day 0) and in the 30 days from index date (0 to 30 days). As time elapses, additional windows of time will be investigated (eg. in the 90 days from index date [0 to 90 days]) and where possible for some surgical outcomes up to 1 and 5 years following surgery. The characteristics will include:

Concept-based:
● Condition groups (SNOMED + descendants), >=1 occurrence during the interval
● Drug era start groups (ATC/RxNorm + descendants), >=1 drug era start during the interval

Cohort-based Medical outcomes: (See #17)
Cohort-based Surgical outcomes: (See #18)