Does delirium contribute to poor hospital outcomes?

Absolutely. I am giving the simple answer here. Research has shown that delirum during a hospital stay is associated with a significant risk of both immediate and post hospital stay complications. The good news is that if recognized, delirium is usually treatable. Physicians, hospitals and medical educators are now paying much attention to this complex problem.
Works both ways. Delirium and hospitalization interact in ways to lead to complicated outcomes. Preventing delirium improves outcomes.
Definitely. Often the patient gets labelled a hostile, combative, aggressive etc & has to be restrained chemically & physically & these measures are continued indefinitely sometimes.