Routine pre admission laboratory screening investigations in aggressive patients who require sedation in the emergency department – necessary or unnecessary

Abstract

Background: The triage of aggressive patients who require sedation for behavioural control in the emergency department (ED) at our hospitals is delayed because the results of mandatory screening laboratory investigations to exclude a general medical condition (GMC) must be available prior to a psychiatric referral. The monitoring of these sedated patients in the ED is the problem. Objective: The primary objective of this study was to determine the value of the results of routine pre-admission laboratory screening investigations in the differentiation of a medical from a psychiatric cause of aggression in consecutive aggressive patients who required sedation in the EDs at King Edward V111 and Addington Hospitals. Specific objectives were to determine if there was an association between a history of past psychiatric illness, the physical examination, the results of laboratory screening investigations and the cause of the aggression. Methods: a retrospective chart review of 339 consecutive aggressive patients who required intravenous or intramuscular sedation for behavioural control in the EDs of Addington and King Edward V111 Hospitals in Kwa Zulu Natal (KZN) was conducted from 01 January 2006 to 31 December 2006. Patients who required oral or no sedation were excluded from the study. Results: 82 (24.2%) of the 339 patients in the study had a medical cause for the aggression .40 (11.7%) of these had no previous medical history. Overall the yield of clinically significant results from laboratory investigations was 9.6%. No past history of psychiatric illness, physical examination, the Full Blood Count (FBC), Urea and Electroloyte estimation (U&E) and Random Blood Glucose (RBG) had sensitivities of 28%, 63%, 57%, 40% and 21% respectively for the identification of a GMC causing the aggression. The variables that remained significantly associated with a causal GMC were an abnormal physical examination only (OR 42.151), an abnormal FBC (OR 2.363),an abnormal U & E (OR 3.531) and no past history of mental illness combined with an abnormal physical examination (OR 277.442). A previous history of a mental illness only was not significantly associated with the cause of aggression. These are adjusted odds ratios, ie they are independent of the effects of the other variables. Conclusion: The high rate of a medical cause for the aggressive behaviour and the overall yield from screening laboratory investigations emphasize the need for mandatory screening to exclude a GMC in the EDs of our hospitals. Aggressive patients with a documented past psychiatric history and a normal physical examination can be referred for a psychiatric assessment prior to the results of routine laboratory investigations becoming available.

Keywords

• screening
• aggression
• emergency