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LETTER TO THE EDITOR |
Ancelle della Carità Hospital Cremona and Geriatric Research Group Rehabilitation and Aged Care Unit Brescia, Italy
Poliambulanza Hospital Medical Unit for the Acute Care of the Elderly and Geriatric Research Group Brescia, Italy
Address correspondence to Giuseppe Bellelli, MD, Rehabilitation and Aged Care Unit via Aselli 14, via Romanino 1, Brescia 26100, Italy. E-mail: giuseppebellelli{at}libero.it
To the Editor:
We read with interest the letter by Laurila and colleagues, finding that delirium superimposed on dementia (DSD) is not associated with increased 12-month risk of death. We would like to reply by examining the differences in our and their results from our point of view.
A first reason for the different results may be ascribed to the settings in which the studies have been done. Indeed, Laurila and colleagues recruited patients from acute geriatric wards and nursing homes, while we selected patients from a unique setting. Unexpectedly, in the Laurila's study, patients with dementia (prevalently living in nursing homes) had lower mortality rates than those with neither dementia nor delirium (prevalently recruited from geriatric wards) despite being older, more frequently male, more functionally impaired, and more ill. A similar picture is painted by comparing patients with delirium to those with DSD. Globally, these data seem to suggest that age, gender, comorbidity, and functional status were not related to premature death. However, at their further multivariate analysis, all these variables were independent predictors of poor survival. We believe that this apparent discrepancy should be related to their different sensitivity to detect delirium in patients from acute hospitals and nursing homes, resulting in a relative underreporting of DSD.
A second reason concerns the tools used to assess delirium. While we used the Confusion Assessment Method (CAM) (1), Laurila and colleagues adopted the Diagnostic and Statistical Manual of Mental Disorders, 4th Ed. (DSM-IV) (2), whose criteria state that delirium cannot be better accounted by a preexisting dementia, implicitly assuming a difference between these two conditions. However, because delirium and dementia frequently share common symptoms' presentation and are often indistinguishable (3), by using the DSM-IV criteria Laurila and colleagues may have again underreported delirium among demented patients.
Thirdly, although we agree that delirium in not-demented participants is often sustained by severe noxious insults, while in demented participants it is the result of milder clinical events, it is important to point out that DSD can also develop after exposure to severe noxious insults. Our data indirectly support this observation, showing that delirium is frequent in demented patients after severe noxious events (i.e., hip fracture and surgery) and that DSD significantly increases the mortality risk (4). This notion is also consistent with what we can reasonably expect, that is, that two ominous conditions (delirium and dementia) are worse than one.
In conclusion, we deeply appreciate the contribution of Laurila and colleagues' increasing the interest towards delirium and DSD. We hope that future investigations will contribute to clarify this complex research area.
References
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