I don't really like the idea of handling it at display time either, but there
are all sorts of legacy data sets w/ empty cells, which certainly came from
spreadsheets of clinical data w/ empty cells (not sure why there are a variety
of ways that's getting parsed by R and thus a variety of ways it is being
inserted into the DB though - I figured there'd be only *one* 'empty'.

There could presumably be some sort of filter when loading the datasets to
convert empty cells in the pData to "NA".