The Day-1 Mobility Loss Model: Development, Validation, and Clinical Applicability of a Model to Predict Hospital Acquired Mobility Loss in Older Adults

ABSTRACT Background Mobility loss is common in hospitalized older adults, and resources to prevent mobility loss are finite. Our goal was to develop a rapid, universal screening tool that identifies individuals at risk of losing the ability to walk during hospitalization on the first hospital day. Second, we determined if the model could inform the use of mobility-preserving interventions. Methods We included patients admitted to a general medical service, aged ≥65 years, who could walk on admission (Braden Scale Activity subset >=3). Patients were considered to have a new mobility impairment if the activity score was <3 on discharge. We used predictors available on the first hospital day to develop (2017-18) and validate (2019) a prediction model. We determined the association between predicted risk and therapy use in the validation cohort to highlight the model’s clinical utility. Results 5542 patients were included (median age 76yrs, 48% women); 7.6% were discharged unable to walk. The model included six predictors: age, marital status, medication administrations, Glasgow Coma Scale verbal score, serum albumin, and urinary catheter presence. In the validation cohort, the model discriminated well (c-statistic 0.75) and was strongly associated with hospital-acquired mobility loss (lowest decile 1%, highest decile 24%). In the validation cohort, therapy consultation ordering increased linearly with predicted risk; however, observed mobility loss increased exponentially. Conclusion The Day-1 Mobility Loss model predicts the risk of mobility loss in hospitalized older adults on the first hospital day. Further, it identifies at-risk older adults who may benefit from mobility interventions.