The U‐shaped association between hospitalization time and fall incidence in inpatients using publicly available data: A cross‐sectional study in Japan

AIM: To examine the association between the hospitalization time and fall incidence. DESIGN: A secondary analysis using the Dryad Digital Repository public database. METHODS: Data were extracted from the Fukushima Medical University Hospital cohort study between August 2008 and September 2009. The final analytic sample included 8,598 participants, 156 of who fell. The risk of fall incidents according to hospitalization time was estimated using logistic proportional hazards models, and restricted cubic splines with four knots model were developed. RESULTS: The median hospitalization time was 9.00 (4.00, 17.00) days. The incidence of falls was 1.81% (N = 156). A U‐shaped association between the hospitalization time and fall incidence, with an inflextion point of 8 days. We found a decreasing fall incidence as the hospitalization time increased from 0 to 8 days (OR 0.72 [0.62 ~ 0.83], p < .001); beyond 8 days, the fall incidence increased as the hospitalization time increased (OR 1.06 [1.04 ~ 1.09]).