Factors influencing the length of hospital stay of patients with anorexia nervosa - results of a prospective multi-center study

Background: The length of stay (LOS) strongly influences anorexia nervosa (AN) inpatient weight outcomes. Hence, understanding the predictors of LOS is highly relevant. However, the existing evidence is inconsistent and to draw conclusions, additional evidence is required. Methods: We conducted a prospective, multi-center study including adult female inpatients with AN. Using stepwise linear regression, the following demographic and clinical variables were examined as potential predictors for LOS: admission BMI, AN-subtype, age, age of onset, living situation, partnership status, education, previous hospitalization, self-rated depression, anxiety and somatic symptoms (PHQ-9, PHQ-15, GAD-7), self-rated therapy motivation (FEVER) and eating disorder psychopathology (EDI-2 subscale scores). Results: The average LOS of the sample (n = 176) was 11.8 weeks (SD = 5.2). Longer LOS was associated with lower admission BMI (SS = -1.66; p < .001), purging AN-subtype (SS = 1.91; p = .013) and higher EDI-2 asceticism (SS = 0.12; p = .030). Furthermore, differences between treatment sites were evident. Conclusions: BMI at admission and AN-subtype are routinely assessed variables, which are robust and clinically meaningful predictors of LOS. Health care policies might consider these variables. In light of the differences between treatment sites future research on geographical variations in mental health care seems recommended.