Prospective study of patients with altered mental status: clinical features and outcome

Patients with altered mental status (AMS) present commonly to the Emergency Department (ED). The aim of this prospective study is to identify the various clinical features of this diverse group of patients and trace their outcomes. This will allow clinicians to be aware of the natural history of the symptom complex and the difficulties in managing them.

In this prospective observational study, we recruited patients aged 18 and above diagnosed with AMS at Tan Tock Seng Hospital ED from December 2006 to October 2007. This is an urban ED. Demographic, clinical, radiology, laboratory data, final diagnosis and length of stay were collected from their entry into the ED till discharge or demise using the ED's and inpatient electronic records.

From December 2006 to October 2007, 967 patients with a mean age of 66.5 years diagnosed with AMS were recruited into our study. The total number of CT scans done during the study period was 674, of which 246 (37%) were abnormal and 428 (63%) were normal. The mean hospital length of stay was 11.6 days. Patients with abnormal CT results stayed longer than those whose results were normal (median of 9 days versus median of 6 days). The three most common causes of AMS in our study population were of neurological (34.4%), infectious (18.3%) and metabolic (12%) aetiologies. Overall, 106 (11%) patients died during hospitalisation; 36 (33.9%) and 39 (36.8%) deaths were attributed to ischaemic stroke and haemorrhagic stroke, respectively.

AMS remains a symptom complex that carries a significant length of hospital stay and mortality. The most common causes of AMS are those that require timely intervention and are highly treatable. This study will provide insight into proper allocation of resources to manage this group of patients, from triaging to investigations and treatment at the ED and inpatient levels.