I'm designing a database for a primary health center, the idea
We basically have a Patient with many Encounters, also the Encounters have to be entered from different Users (Health Professionals). Patient info is unlikely to change, the Encounter is the "important" part of this database, already persisted data it's not going to be modified, as we only have to insert new encounters as the patient comes to their controls. Users info it's also (very) unlikely to change. It could be possible that we are going to need to add more columns once a year in case the Health Ministry decides we need to start "logging" something else.
Right now, the "Encounters paper" (tarjetón) is basically a table with around 20 columns, where each row is a new Encounter.
This is a small center, so I'm not going to be dealing with lots of data, concurrency won't be an issue either, since only a couple of professionals are going to "write" to the database.
I started building using mongodb (rails app, using mongoid)