Security for Outswinging Door (Patio) Not Sliding door
Just short of doing something like below, I think the best you can make sure of is:


Steel door
Secured hinges (As Brock Adams suggested - non-removable pins or concealed)
A deadbolt
Reinforced latches, or at least well installed.
Not excessive clearance between the door and the frame that would allow anything between to mess with the latch (A deadbolt also takes care of this)