Open Access Highly Accessed Research article

Comorbidity of dementia: a cross-sectional study of primary care older patients

Beatriz Poblador-Plou123, Amaia Calderón-Larrañaga1234*, Javier Marta-Moreno15, Jorge Hancco-Saavedra3, Antoni Sicras-Mainar6, Michael Soljak7 and Alexandra Prados-Torres1234

Author Affiliations

1 EpiChron Research Group on Chronic Diseases, Aragón Health Sciences Institute (IACS), IIS Aragón, Miguel Servet University Hospital, Zaragoza, Spain

2 Red de Investigación en Servicios de Salud en Enfermedades Crónicas (REDISSEC), Carlos III Health Institute, Madrid, Spain

3 Teaching Unit of Preventive Medicine and Public Health, Aragón Health Sciences Institute (IACS), IIS Aragón, Zaragoza, Spain

4 Department of Microbiology, Preventive Medicine and Public Health, University of Zaragoza, Zaragoza, Spain

5 Miguel Servet University Hospital Department of Neurology, Zaragoza, Spain

6 Planning Management, Badalona Serveis Assistencials S.A, Badalona, Spain

7 Department of Primary Care & Public Health, Imperial College London, London, UK

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BMC Psychiatry 2014, 14:84  doi:10.1186/1471-244X-14-84

Published: 20 March 2014



The epidemiologic study of comorbidities of an index health problem represents a methodological challenge. This study cross-sectionally describes and analyzes the comorbidities associated with dementia in older patients and reviews the existing similarities and differences between identified comorbid diseases using the statistical methods most frequently applied in current research.


Cross-sectional study of 72,815 patients over 64 seen in 19 Spanish primary care centers during 2008. Chronic diseases were extracted from electronic health records and grouped into Expanded Diagnostic Clusters®. Three different statistical methods were applied (i.e., analysis of prevalence data, multiple regression and factor analysis), stratifying by sex.


The two most frequent comorbidities both for men and women with dementia were hypertension and diabetes. Yet, logistic regression and factor analysis demonstrated that the comorbidities significantly associated with dementia were Parkinson’s disease, congestive heart failure, cerebrovascular disease, anemia, cardiac arrhythmia, chronic skin ulcers, osteoporosis, thyroid disease, retinal disorders, prostatic hypertrophy, insomnia and anxiety and neurosis.


The analysis of the comorbidities associated with an index disease (e.g., dementia) must not be exclusively based on prevalence rates, but rather on methodologies that allow the discovery of non-random associations between diseases. A deep and reliable knowledge about how different diseases are grouped and associated around an index disease such as dementia may orient future longitudinal studies aimed at unraveling causal associations.

Dementia; Comorbidity; Factor analysis; Primary care; Electronic health records