long-term hospitalization
Refers to being hospitalized for an extended period, typically for chronic illness, severe injury, or long-term care.
My grandfather has been hospitalized for a long time.
I took out insurance in case of long-term hospitalization.
入院 is general hospitalization; 長期入院 specifically emphasizes a long duration.
Compound of 長期 (long-term) and 入院 (hospitalization).