Clinical predictors of abnormal computed tomography findings in patients with altered mental status

Lim BL, Lim GH, Heng WJ, Seow E
Correspondence: Dr Lim Beng Leong, beng_leong_lim@ttsh.com.sg

ABSTRACT
Introduction While non-contrast computed tomography (CT) of the brain can be used to rapidly identify patients with altered mental status (AMS) in the emergency department (ED), with an acute intracranial bleed or infarct, a wide variation in its use exists. The aim of this pilot study was to identify the clinical predictors of an abnormal CT result in ED patients with AMS.
Methods We conducted a retrospective study of patients aged 15 years and older presenting with undifferentiated AMS in a busy urban ED over one year. Data collected included demographical, clinical, laboratory and radiological features. The primary outcome of interest was the presence of an abnormal CT result defined as an acute infarct or intracranial bleed. Secondary outcomes were clinical predictors of an abnormal CT result. The data was analysed using descriptive statistics. Logistic regression was used to identify clinical predictors of an abnormal CT result. Odds ratios (ORs) were reported with 95 percent confidence intervals (CIs).
Results 578 patients were recruited, of which 284 (49.1 percent) were males. 327 (56.6 percent) patients underwent CT of the brain. 128 scans (39.1 percent) were abnormal. Logistic regression revealed seven clinical features that were associated with an abnormal CT result. They were mean age greater than or equal to 73 years (OR 1.03; 95 percent CI 1.015–1.045), drowsiness or unresponsiveness (OR 1.73; 95 percent CI 0.17–17.72), previous cerebrovascular accident (OR 2.03; 95 percent CI 0.82–5.02), previous epilepsy (OR 1.63; 95 percent CI 0.63–4.19), tachycardia [greater than 120/min] (OR 1.16; 95 percent CI 0.38–3.54), bradycardia [less than 60/min] (OR 1.35; 95 percent CI 0.19–9.59) and exposure to drugs (OR 1.90; 95 percent CI 0.58–6.26).
Conclusion We identified seven clinical predictors of an abnormal CT result in AMS patients. Future research in prospective studies is needed to validate these findings.

Keywords: altered mental status, brain infarction, cerebral computed tomography, intracranial haemorrhage
Singapore Med J 2009; 50(9): 885-888