Introduction: Alzheimer dementia (ALZ-D) is among the most frequent diseases in the elderly. Several somatic and psychiatric disorders have been suggested to be related to this diagnosis. The aim of this analysis of a large and representative U.S. nationwide inpatient sample (NIS) was to identify diagnostic correlates of ALZ-D in subjects aged 60 years and older.
Methods: Of the total sample of 800,457 inpatient subjects ( approximately 2% of all inpatients in 2004), 315,244 individuals were 60 years or older. Of these, 9,572 (3.03%) received a diagnosis of ALZ-D, whereas 33,367 (10.59%) were diagnosed with osteoarthritis (OA) and served as a comparison group. Comparisons of potential somatic and psychiatric diagnostic correlates were conducted.
Results: As determined by both univariate comparison and multivariate logistic regression analysis, after controlling for age and gender, subjects with ALZ-D (versus OA) had an overall higher rate of diagnoses of diseases of the vascular system (stroke: odds ratio 1.69; 95% confidence interval: 1.25-2.30) and psychotic and affective disorders (bipolar: 2.78 [1.26-6.12]; schizoaffective: 3.06 [2.10-4.47]). Increasing age and male gender were positively associated with the diagnosis of ALZ-D.
Discussion: Many somatic diagnoses related to ALZ-D were confirmed by these analyses of the NIS. However, psychotic and affective disorders were identified to be equally significant correlates of ALZ-D, even in the presence of all other disorders. Prospective and longitudinal data are needed to investigate potential causal and temporal relationships between ALZ-D with somatic and psychiatric disorders.