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DELIRIUM: PREVALENCE AND IMPACT ON OUTCOMES FOR OLDER RENAL INPATIENTS
Warrell CE, Scott S, Brown EA
Imperial College Renal and Transplant Centre, Hammersmith Hospital
BACKGROUND: Delirium is characterised by a disturbance of consciousness and a change in cognition that develop over a short period of time Itis associated with increased mortality, length of admission and consequently is used as an indicator for the quality of healthcare. Factors predisposing to delirium include existing renal impairment, cognitive impairment and polypharmacy, therefore the renal patient population may be at particularly high risk. . It is preventable in up to a third of cases with management of reversible causes and understanding of precipitant factors in the hospital environment. There is no information about prevalence or impact of delirium on renal inpatients in the UK. The aims of this audit were to identify the prevalence of delirium in elderly renal inpatients, whether it was diagnosed by admitting teams, and to determine its impact on length of stay and mortality amongst renal inpatients at a large London tertiary renal unit.
METHODS: All patients≥60 years on the renal wards were considered for the project and were excluded if they were:planned admission for overnight only, patients on the high dependency unit, patients admitted on end of life pathway and those unable to speak enough English to carry out assessments. Demographic data was collected using patient notes. Cognitive function and delirium screening were based on British Geriatric Society guidelines starting with an initial quick screen usingAbbreviated Mental Test Scoreand CLOX1. If thesewere abnormal, both the CAM score and Informant Questionnaire On Cognitive Decline in the Elderly were used to distinguish longevity of symptoms. Those patients with results suggesting possible underlying dementia went on to have Mini Mental State Examination tests as well. Predictors of delirium were determined using univariate analyses.
RESULTS:72 patients met the inclusion criteria. Overall 51% of inpatients had cognitive impairment. 17% were diagnosed with delirium, 48% with dementia and 75% patients with delirium had a possible underlying diagnosis of dementia. Only 1 patient with delirium had been recognised as being confused by the clinical care team.When comparing those patients with delirium and those without, there was a statistically significant difference in age >75 (p=0.02), patients on dialysis (p=0.02), length of stay (mean 18.8 days vs 7.3 p=0.03) and mortality during admission (16.7% vs 0%) (p=0.001). Univariate analysis showed age (p=0.03 OR 1.10 CI 1.02-1.19) and dialysis (p=0.02 OR 7.3 CI 1.47-36.2) were risk factors for delirium. When adjusted for age and gender in multivariate analysis dialysis no longer remained significant.
RELEVANCE:This is the first UK based audit to show the prevalence of delirium in a renal inpatient population. The presence of acute confusion was mostly missed by the renal team. Elderly (>75years) dialysis inpatients were found to be at particular risk of developing acute confusion. Development of delirium had a major negative impact on patient outcomes withincreased length of stay and mortality. Early diagnosis, managing the environment ofhigh risk patientsand clearly documenting cognitive function on admission and discharge documentation are national recommendations and may improve outcomes of older dialysis patients when admitted to hospital.