Prevalence and outcome of delirium among acute general medical inpatients in Cape Town, South Africa.

Background: Delirium is a common, serious, underdiagnosed condition in medical and surgical inpatients with acute conditions. It is associated with increased risk of mortality and morbidity. Data of geriatric cohorts are largely limited to developed countries.

Objectives: To describe prevalence, risk factors and outcomes of delirium among general medical patients admitted to two hospitals in Cape Town, South Africa.

Methods: This was a prospective cohort study of patients with acute conditions admitted to a general medical inpatient service in secondary- and tertiary-level public hospitals in the Metro West area of Cape Town. Patients ≥18 years of age were recruited daily from all acute medical admissions. Patients were excluded if they were aphasic or their Glasgow coma scale was <8/15. Delirium was diagnosed using the validated confusion assessment method (CAM) tool and performed by trained neuropsychologists. Demographic data were collected by a clinical team and short- and long-term mortality data were obtained using linkage analysis of hospitalised patients and routinely collected provincial death certification records.

Results: The median age of inpatients was 51 (interquartile range 36 - 65) years, 29% were HIV-infected and the overall prevalence of delirium was 12.3%. Multivariate predictors of delirium included the presence of an indwelling urinary catheter (odds ratio (OR) 4.47; confidence interval (CI) 2.43 - 8.23), admission with a central nervous system disease (OR 4.34; CI 2.79 - 7.90), pre-existing cognitive impairment (OR 3.02; CI 1.22 - 7.43) and immobility (OR 1.88; CI 1.01 - 3.51). HIV infection was not associated with increased risk of delirium. Delirium was associated with an increased risk of inhospital (delirium v. no delirium: 29% v. 12%; p<0.01) and 12-month (30% v. 20%; p<0.01) mortality, as well as increased length of hospital stay (7 days v. 5 days; p<0.01).

Conclusions: In this cohort of medical inpatients (relatively young and with a high HIV prevalence) 1 of 8 (12.3%) patients was delirious. Delirium was associated with adverse outcomes. Delirium risk factors in this young cohort were similar to those in geriatric cohorts in developed countries, and neither HIV nor opportunistic infections increased risk.