Preinjury functional status is associated with functional status after hip fracture in older adults without preinjury perceived social support

We investigated if preinjury perceived social support moderated the association between pre- and postinjury functional status after hip fracture in older adults. Using data from the longitudinal Health and Retirement Study (biennial interviews from 1998 to 2018), we analyzed perceived social support measured preinjury and functional status [activities of daily living (ADL) or instrumental activities of daily living (IADL) limitations] measured at pre- and postinjury interviews. Among 709 respondents, 61% anticipated social support from friends or family if they required future assistance with personal care, 16% had difficulty with ADL preinjury, and 9% had difficulty with IADL preinjury. Among 1697 postinjury follow-up interviews (mean follow-up time: 2.8 years), ADL limitations and IADL limitations were reported in 752 and 683 interviews, respectively. During follow-up, any preinjury IADL limitations were associated with more postinjury IADL limitations among people without social support [adjusted incidence rate ratio (aIRR): 2.505, 95% confidence interval (CI): 1.765-3.555] but not among people with preinjury perceived social support (aIRR: 1.355, 95% CI: 0.950-1.940, interaction P = 0.016). Any preinjury ADL limitations were associated with more postinjury ADL limitations among people with (aIRR: 1.471, 95% CI: 1.124-1.925) or without (aIRR: 2.084, 95% CI: 1.563-2.778) preinjury perceived social support. Preinjury perceived social support moderates the association between pre- and postinjury functional status in older adults experiencing a hip fracture. Older adults experiencing pre-existing IADL limitations without social support are at high risk for continued or increased activity limitations.