Effects of Mobility and Cognition on Risk of Mortality in Women in Late Life: A Prospective Study

Abstract

Background: This study examines the effects of mobility and cognition on mortality risk in women late in life. Methods: A prospective study was conducted among 1,495 women (mean age 87.6 years) participating in the Study of Osteoporotic Fractures Year 20 examination (2006-2008). Mobility (ascertained by Short Physical Performance Battery [SPPB]) was categorized as poor (SPPB 0-3, n = 312), intermediate (SPPB 4-9, n = 799), or good (SPPB 10-12, n = 384). Cognitive status (adjudicated based on neuropsychological tests) was classified as normal (n = 873), mild cognitive impairment (n = 354), or dementia (n = 268). Deaths (n = 749) were identified from Year 20 through July 31, 2014 (average follow-up 4.9 years). Results: There was not strong evidence of an interaction between mobility and cognition for prediction of mortality risk (p interaction term. 16). Compared to women with good mobility, mortality risks were increased among women with intermediate mobility (hazard ratio [HR] 1.26, 95% confidence interval [CI] 1.02-1.57) and those with poor mobility (HR 1.64, 95% CI 1.24-2.16) after consideration of cognition and other mortality risk factors. Similarly, mortality risks were higher among women with mild cognitive impairment (HR 1.46, 95% CI 1.21-1.76) and those with dementia (HR 1.88, 95% CI 1.54-2.31) compared to women with normal cognition after consideration of mobility and other mortality risk factors. Conclusions: Among women late in life, 5-year mortality risk was substantially increased among women with deficits in mobility even after accounting for cognition and traditional prognostic indicators. Similarly, deficits in cognition were associated with increased 5-year mortality despite consideration of mobility and conventional risk factors.