Body mass index, dementia, and mortality in the elderly

Abstract

Objectives-To explore the association between body mass index and mortality in the elderly taking the diagnosis of dementia into account. Design-Cohort study.Setting-cohort study of aging in Medicare recipients in New York City.Participants-1,452 elderly individuals 65 years and older of both genders.Measurements-We used proportional hazards regression for longitudinal multivariate analyses relating body mass index (BMI) and weight change to all-cause mortality.Results-There were 479 deaths during 9,974 person-years of follow-up. There were 210 cases of prevalent dementia at baseline, and 209 cases of incident dementia during follow-up. Among 1,372 persons with BMI information, the lowest quartile of BMI was associated with a higher mortality risk compared to the second quartile (HR = 1.5; 95% CI: 1.1,2.0) after adjustment for age, gender, education, ethnic group, smoking, cancer, and dementia. When persons with dementia were excluded, both the lowest (HR = 1.9; 95% CI =1.3,2.6) and highest (HR = 1.6; 95% CI : 1.1,2.3) quartiles of BMI were related to higher mortality. Weight loss was related to a higher mortality risk (HR = 1.5; 95% CI: 1.2,1.9) but this association was attenuated when persons with short follow-up or persons with dementia were excluded. Conclusion-The presence of dementia does not explain the association between low BMI and higher mortality in the elderly. However, dementia may explain the association between weight loss and higher mortality.

The impact of weight loss and low BMI on mortality of nursing home residents – Results from the nutritionDay in nursing homes

“…To our knowledge there are few studies that compare the relevance of weight loss and a low BMI in older persons within a single data set [1,3,9,11,13]. None of these studies analyzed the possible interference and interaction of these two risk factors and some have conflicting results with regard to the prognostic impact of both factors.…”

Body mass index in dementia

“…Dementia causes weight loss and patients with dementia have lower BMIs than their peers. 23,24 A reduction in BMI is associated with increased risk for dementia 25 and predates onset by at least a decade. 12,13 Among persons with dementia, lower BMI has been associated with increased mortality risk.…”

Self-Reported Height, Calculated Height, and Derived Body Mass Index in Assessment of Older Adults

“…Body weight was obtained by bioelectrical impedance (Tanita, Model TBF 300A, IL, USA) as described elsewhere (32,33). Briefly, the instrument was placed on a non-carpeted, level surface and participants were asked to step on the platform in bare feet until a reading was recorded.…”

“…In reality, height is seldom, if ever, measured in routine practice (31,32), and few clinics have knee-height calipers. Further, as the BMI equation is based on adult height, the use of M-height in older adults has been questioned (2, 6) and the validity of SR-height has not been established.…”