Objective: Cognitive failure (CF) encompasses delirium, dementia and amnestic disorders. Reported prevalence rates for CF and delirium in palliative care range from 14 - 44% and 28 - 52% respectively, and above 85% develop delirium close to death. Delirium might be reversible, thus, successful treatment has profound impact on patient care and quality of life. This is probably the most frequently encountered psychiatric diagnosis in clinical medicine, but nevertheless overlooked in up to 67%. Raised awareness and selection of validated tools for the assessment of CF is necessary. This review examines published studies on CF and delirium in palliative care.
Methods: PubMed, Cancerlit, PsychInfo, Cinahl and the Cochrane library were sought, employing the MESH terms ‘‘cognitive function’’ or ‘‘cognitive failure’’ or ‘‘delirium’’ and combining with ‘‘palliative care’’ or ‘‘palliative care research’’ or ‘‘palliative medicine’’ or ‘‘hospice’’. The reference lists of the relevant publications were examined.
Results: Twenty-two studies were reviewed, of which 64% were published in 2000 or later. Twelve reports focused on delirium, six on cognitive failure, while the remaining four assessed confusion (2), hallucinations and general psychological morbidity. Median sample size was 100. The reported prevalence rates ranged from 10 - 83% for CF, 20 - 88% for delirium and 50 - 68% for confusion. Mini Mental State Exam was the most frequently employed instrument.
Conclusion: There are few, well-conducted studies that specifically assess CF or delirium in palliative medicine. We recommend that assessment of cognitive function becomes part of the routine of palliative care. Hence, precipitating risk factors for CF might be identified and appropriate treatment strategies might be implemented. Further refinement and validation of observer-rated, simple and sensitive assessment tools that discriminate between CF, delirium and dementia should be undertaken for clinical and research purposes.