Mobility impairment in older patients after AMI is associated with subsequent functional decline
Association Between Mobility Measured During Hospitalization and Functional Outcomes in Older Adults With Acute Myocardial Infarction in the SILVER-AMI Study
Introduction and methods
Over one-third of acute myocardial infarctions (AMIs) occur in persons of 75 years and older . Survival after AMI in this age group has improved [2,3], but many face functional decline, such as loss of ability to independently perform everyday activities. Functional decline not only reduces independence and quality of life, it is also an omen of poor outcomes, such as readmissions , institutionalization  and mortality .
Little is known, however, about factors that put older adults at risk for functional decline after hospitalization for AMI. Evidence suggests that poor mobility is linked to higher mortality risk , frailty  and functional decline , but prior studies had limited generalizability or untimely collections of mobility data.
This prospective study in adults of 75 years and older therefore examined the association between mobility, assessed during AMI hospitalization and risk of functional decline at 6 months after discharge. The SILVER-AMI study  included 3041 older adults at 94 hospitals in the U.S. 454 Patients were lost to follow-up, leaving 2587 participants.
Mobility status was assessed during the baseline interview, by means of the Timed ‘Up and Go’ (TUG), a performance-based assessment that has been validated for use in populations with cardiac concerns. Participants were also asked about their functioning 1 month before admission. To complete TUG, participants are asked to rise from a seated position, walk 3 m, turn, walk 3 m back to the chair and sit down. Use of assistive devices were allowed, but not help from a person. Time needed to complete TUG (in seconds) was used as the score. Mobility was categorized as preserved (≤15s), mild impairment (>15 to ≤25s), moderate impairment (>25s) and severe impairment (unable to complete assessment). This study assessed the effect of mobility impairment on the ability to independently perform 1 or more essential activities of daily living (ADLs) and ability to walk 0.4 km at 6 months after hospital discharge relative to premorbid functional status.
- Mean age of the cohort was 81.4 years (SD: 4.8). 35.4% Were impaired in ADLs or 0.4-km mobility before admission and 31% were free of mobility impairment during the in-hospital admission.
- 648 Of 2587 (25.0%) participants reported functional decline at 6 months after discharge compared with 4 weeks before admission. 12.8% Of participants reported ADL decline, and 16.7% reported decline in 0.4-km mobility.
- Bathing was the most common ADL in which participants experienced decline (8.5%), followed by dressing (6.5%), getting in and out of a chair (4.4%) and walking around the home (4.1%).
- Mobility impairment during hospitalization was associated with decline in ADLs and 0.4-km mobility at 6 months after discharge. 3.8% of those with preserved mobility reported ADL decline, as compared with 6.9% of those with mild impairment, 18.6% in those with moderate impairment and 34.7% in participants with severe impairment.
- Adjusted OR for any ADL decline, compared with those with preserved mobility, was aOR: 1.24 (95%CI: 0.74-2.09) for those with mild impairment, 2.67 for moderate impairment (95%CI: 1.67-4.27) and 5.45 for severe impairment (95%CI: 3.29 to 9.01). For decline in 0.4 km-walking, the respective aORs were 1.51 (95%CI: 1.04-2.20), 2.03 (95%CI: 1.37-3.02) and 3.25 (95%CI: 2.02-5.23).
This multicenter, prospective study reveals that mobility impairment in elderly patients (>75 year) at the time of AMI hospitalization, as measured with TUG, is associated with higher risk of functional decline at 6 months after discharge. Several activities of daily living and neighborhood-level activity were affected. These findings suggest that TUG may serve as a useful ‘geriatric biomarker’ to identify older patients with AMI who are at risk for functional decline.