Wednesday, January 2, 2019

Etiologies and yield of diagnostic testing in children presenting to the emergency department with altered mental status

Button K, Capraro A, Monuteaux M, Mannix R. Etiologies and Yield of Diagnostic Testing in Children Presenting to the Emergency Department with Altered Mental Status. J Pediatr. 2018 Sep;200:218-224.e2.


To identify etiologies of altered mental status in pediatric patients presenting to the emergency department (ED) and to characterize the yield of diagnostic testing in these patients.

Retrospective chart review of children aged 1-17 years presenting to a pediatric tertiary care ED between December 31, 2013 and December 31, 2014 with a chief complaint or International Classification of Disease, Ninth Edition code of altered mental status. The primary outcome was the etiology, defined as "immediate diagnosis" if the etiology was known in triage, "definitely established" if established by physical examination and abnormal laboratory results, imaging, or electrocardiogram findings, "probable" if the etiology was highly suspected in the ED but not confirmed with positive test results, or "unknown." The secondary outcome was testing utilization and contribution to the diagnosis.

Three hundred thirty-six eligible subjects were identified; mean age of 9 years (±6 years). The etiology of altered mental status was immediately established in 114 subjects (34%, 95% CI 29, 39). Among the remaining eligible subjects (N = 222), a definite or probable cause of altered mental status was identified in 82% (N = 182, 95% CI 76, 86) of cases and the etiology remained "unknown" in 18% (N = 40, 95% CI 14, 24). Only 10% of diagnostic tests performed were abnormal and contributed to a diagnosis. The median number of diagnostic tests per patient was 6 (IQR 3, 8).

Etiologies of altered mental status in children varied widely and often an underlying diagnosis was not found. Broad diagnostic testing was commonly performed although the overall yield was low.

From the paper:

Among all eligible subjects, including those for whom an immediate diagnosis was made, the most common etiology was neurologic, occurring in 24% (N = 79, 95% CI 19, 28) of children. Other common etiologies included toxicological (20%, N = 69, 95% CI 17, 25) and infectious (14%, N = 46, 95% CI 10, 18) conditions. Among subjects aged 1-5 years and 6-12 years, the most common overall etiology was neurologic. For subjects aged 13-17 years, the most common etiology was toxicological. Examining etiologies by age separately among the immediate and nonimmediate diagnosis groups  underscores trauma as an important etiology in the immediate diagnosis group for children ages 1-5 years (35%, N = 13) and 6-12 years (33%, N = 9,). In the nonimmediate diagnosis group, infection was the most common etiology for children 1-5 years of age (N = 17, 22%, 95% CI 14, 33) and neurologic the most common for children 6-12 years of age (N = 17, 25%, 95% CI 16, 37). Toxicological etiologies were consistently the most common among children aged 13-17 years in 

In the 222 subjects for whom the underlying etiology of altered mental status was not immediately established, the median number of diagnostic tests performed per subject was 6 (IQR 3, 8). A total of 1208 diagnostic tests were performed including laboratory testing and imaging. Laboratory tests performed in the greatest number of patients were basic chemistry (N = 186, 83%, 95% CI 78, 88), complete blood count (N = 168, 76%, 95% CI 70, 81), and liver function tests (N = 117, 53%, 95% CI 46, 59). Head CT was the most frequently performed imaging study (N = 80, 36%, 95% CI 30, 43). Diagnostic tests that most often contributed to a diagnosis (relative to how frequently they were performed) were lumbar puncture (N = 11, 42%, 95 CI 26, 61), magnetic resonance imaging/ magnetic resonance angiography brain (N = 17, 33%, 95 CI 22, 46), and head CT (N = 15, 19%, 95 CI 12, 29). Tests that contributed the least often to a diagnosis were serum liver function tests (N = 0, 0%, 95% CI 0, 3), serum lactate (N = 0, 0%, 95% CI 0, 8), ultrasound for intussusception (N = 0, 0%, 95% CI 0, 43), and electrocardiogram (N = 3, 3%, 95% CI 1, 9). Overall, 10% (N = 125) of the total number of diagnostic tests performed were abnormal and contributed to identifying an underlying diagnosis

An important take-home message is that practitioners should not be surprised to find that they can't make a diagnosis in about 1 of every 10 children presenting with altered mental status—and almost 1 out of 5 of those whose diagnosis is not immediately obvious.

Being comfortable with that fact is part of the "art of medicine."

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