The prevalence and clinical manifestations of delirium in sub-Saharan Africa: a systematic review with inferences.

BACKGROUND: In high-income countries with ageing populations, delirium is most prevalent in older adults and in palliative and intensive care settings. The prevalence and aetiology of delirium are likely to differ in low income countries, including sub-Saharan Africa (SSA), due to different population demographics, disease burden and exposure to pathogens. We reviewed published literature relating to the prevalence, clinical features and underlying causes of delirium in SSA and compare this with that published in high-income countries in order to identify knowledge and clinical service gaps, and priorities for further research.

METHODS: We performed a narrative review by comprehensively searching the following databases: Medline, PsychInfo, Embase and PubMed. Studies published between January 1 1975 and December 31 2013 in all languages, including the terms 'delirium', 'acute brain syndrome', 'organic brain syndrome', or 'acute confusion' originating from SSA were included. In addition, reference lists of included articles and online databases of African medical literature were hand-searched. We also included case series and case reports due to paucity of published studies.

RESULTS: We identified a total of 46 relevant studies. Delirium was the main focus of only one cross-sectional study, whereas most included delirium in studies on neuropsychiatric conditions. Only two studies reported prevalence in older adults. Most studies reported very low (<2%) delirium prevalence, whereas delirium in psychiatric inpatient and outpatient settings was higher than expected (18.2%-29.9%). Descriptive studies of 'bouffee delirante' from psychiatry settings were often describing delirium. Infection and HIV seropositivity were common associations of delirium throughout these studies. There were no studies of intensive, critical or surgical care settings or of management strategies.

CONCLUSIONS: We currently know very little about the prevalence, presentation and aetiology of delirium in developing countries. This knowledge gap should be tackled with some urgency, in order to address questions of screening, diagnosis, prevention and management in this setting.