Body-mass index and mortality in incident dementia: a cohort study on 11,398 patients from SveDem, the Swedish Dementia Registry.
BACKGROUND
Body mass index (BMI) is used worldwide as an indirect measure of nutritional status and has been shown to be associated with mortality. Controversy exists over the cut points associated with lowest mortality, particularly in older populations. In patients suffering from dementia, information on BMI and mortality could improve decisions about patient care.


OBJECTIVE
The objective was to explore the association between BMI and mortality risk in an incident dementia cohort.


METHODS
Cohort study based on SveDem, the Swedish Quality Dementia Registry; 2008-2011.


METHODS
Specialist memory clinics, Sweden.


METHODS
A total of 11,398 patients with incident dementia with data on BMI (28,190 person-years at risk for death).


METHODS
Hazard ratios and 95% confidence intervals for mortality associated with BMI were calculated, controlling for age, sex, dementia type, results from Mini-Mental State Examination, and number of medications. BMI categories and linear splines were used.


RESULTS
Higher BMI was associated with decreased mortality risk, with all higher BMI categories showing reduced risk relative to patients with BMI of 18.5 to 22.9 kg/m(2), whereas underweight patients (BMI <18.5 kg/m(2)) displayed excess risk. When explored as splines, increasing BMI was associated with decreased mortality risk up to BMI of 30.0 kg/m(2). Each point increase in BMI resulted in an 11% mortality risk reduction in patients with BMI less than 22.0 kg/m(2), 5% reduction when BMI was 22.0 to 24.9 kg/m(2), and 3% risk reduction among overweight patients. Results were not significant in the obese weight range. Separate examination by sex revealed a reduction in mortality with increased BMI up to BMI 29.9 kg/m(2) for men and 24.9 kg/m(2) for women.


CONCLUSIONS
Higher BMI at the time of dementia diagnosis was associated with a reduction in mortality risk up to and including the overweight category for the whole cohort and for men, and up to the normal weight category for women.
Division of Clinical Geriatrics, Department of Neurobiology, Care Sciences and Society, Karolinska Institutet, Stockholm, Sweden; Department of Medicine, Universidad Complutense, Madrid, Spain. Electronic address: sara.garcia-ptacek@ki.se.
Sara
S
García-Ptacek
Aging Research Center, Karolinska Institutet and Stockholm University, Stockholm, Sweden; Institute for Gerontology, School of Health Sciences, Jönköping University, Jönköping, Sweden.
Ingemar
I
Kåreholt
Division of Clinical Geriatrics, Department of Neurobiology, Care Sciences and Society, Karolinska Institutet, Stockholm, Sweden.
Bahman
B
Farahmand
Department of Medicine, Universidad Complutense, Madrid, Spain; Neurology Department, Hospital Clínico San Carlos, Madrid, Spain.
Maria Luz
ML
Cuadrado
Department of Geriatric Medicine, Karolinska University Hospital, Stockholm, Sweden; Alzheimer's Disease Research Center, Department of Neurobiology, Care Sciences and Society, Karolinska Institutet, Stockholm, Sweden.
Dorota
D
Religa
Division of Clinical Geriatrics, Department of Neurobiology, Care Sciences and Society, Karolinska Institutet, Stockholm, Sweden; Department of Geriatric Medicine, Karolinska University Hospital, Stockholm, Sweden.
Maria
M
Eriksdotter
D000368:Aged; D000369:Aged, 80 and over; D015992:Body Mass Index; D015331:Cohort Studies; D003704:Dementia / Q000401:mortality*; D005260:Female; D006801:Humans; D008297:Male; D016016:Proportional Hazards Models; D012042:Registries; D018570:Risk Assessment; D012737:Sex Factors; D013548:Sweden / Q000453:epidemiology
Alzheimer disease; Dementia; epidemiology; mortality