I have not seen that one, but my personal favorite escaped mental patient movie is
Alone in the Dark (1982)staring Jack Palance and Donald Pleasance.
I saw this movie in high school when the slasher genre was just starting to take off as Friday the 13th was up to Part II at least (III in 3-D was out in '82, but I don't recall if it came out before AitD) and the same for Halloween.
But the thing that made this one memorable to me was that
it could happen. Jason and Michael Meyers always struck me as a bit too supernatural, but Jack Palance in AitD was a normal guy (paranoid schizophrenic as he was), and broke out to murder the doctor he thought was persecuting him.
IIRC, there was some killer gore, too.