Blue Cross of Western Pennsylvania (1985), McGuire, Dickey, and Shively (1985), and the study by the National Association of Private Psychiatric Hospitals (NAPPH) (Rockburn Institute and lewin and Associates 1985) all found that a history of prior psychiatric hospitalization was related to longer LOS, and if a patient's most recent previous hospitalization had been lengthy, then that patient was more likely to have a long LOS in the present hospitalization (Morrisson, Wright, and Frye 1985).
"The NAPPH Study on Prospective Payment for Psychiatric Hospitals: A Summary Report." NAPPH Newsline 4, no.8 (1985): 1-12.