Association Between Mobility as a Time-Dependent Exposure Factor and Risk of Fall: A Retrospective Cohort Study of...

To examine the frequency of falls during recovery in older patients with orthopedic conditions in a subacute rehabilitation setting and to evaluate the association between mobility and fall risk.

Observational retrospective cohort study.

Single subacute rehabilitation hospital.

Patients with orthopedic conditions (n=845) aged ≥65 years admitted between April 1, 2023, and November 30, 2024.

Not applicable.

Incidence of first fall after admission.

Of the 845 participants, 65 (7.7%) experienced a fall during follow-up (median: 42d; interquartile range, 23-64d). The fall rate per 1000 person-days increased immediately after admission, peaking at 2.41 during weeks 5-6, then declining. The Cox proportional hazards model assessing the association between mobility and fall risk showed no significant difference based on mobility at admission. However, repeated assessments showed a significantly higher hazard ratio (2.65; 95% CI, 1.16-6.04) during light assistance or supervision, defined as requiring minimal physical contact or supervision by a caregiver, compared with independent status.

Repeated assessments of mobility as a time-dependent exposure factor revealed that fall risk was highest during periods requiring light assistance or supervision and was most frequent during weeks 5-6 of the subacute rehabilitation setting. These findings indicate that evaluating mobility only at admission is inadequate for assessing fall risk, underscoring the importance of continuous reassessment throughout the subacute rehabilitation.