Contributions of environment, comorbidity, and stage of dementia to the onset of walking and eating disability in long-term care residents.

OBJECTIVES To estimate the relative effects of environment, comorbidities, stage of dementia and other variables on disability onset. DESIGN A 1-year prospective cohort study was conducted in which the walking and eating abilities of long-term care residents were observed fortnightly. Structural equation modeling was used to assess the contributions of individual and environmental factors to the onset of disability. SETTING Fifteen nursing homes in western Canada. PARTICIPANTS One hundred twenty residents with middle-stage Alzheimer disease or related dementia. MEASUREMENTS Environmental quality was assessed using the Professional Environmental Assessment Protocol, comorbidity using the Charlson Comorbidity Index, and stage of dementia using the Global Deterioration Scale. RESULTS More-advanced baseline dementia had a direct effect on onset of walking and eating disability (standardized maximum likelihood estimate (SMLE) = 0.24, P = .006). Resident environment (SMLE = -0.25, P = .007) and comorbidities (SMLE = 0.32, P < .001) influenced disability onset approximately as strongly as stage of dementia. Smaller and publicly owned facilities provided superior environmental quality, which indirectly contributed to a delay in onset of walking and eating disability. CONCLUSION Environmental quality and extent of comorbidity are at least as important as progression of dementia in initiating or delaying the onset of disability.