Our study demonstrates that dizziness is an extremely common ED symptom that preferentially affects older adults. We confirm prior literature that suggests the most frequent diagnostic category is oto-vestibular; however, our results also indicate general medical diagnoses are prevalent in this acute care population, and the proportion harboring a dangerous underlying disorder is high. Resource use for dizziness is disproportionate, particularly for diagnostic imaging, yet many patients leave the ED without an etiologic diagnosis.
From these nationally representative data, at least 3.3% of all ED visits are associated with dizziness or vertigo as a presenting symptom. This fraction is similar to those obtained from chart reviews at single institutions (1.7% ED chief complaint; 6.7% any charted complaint10
) but lower than those obtained with prospective case capture (4.0% chief complaint18
) or direct patient interview (4.4% main reason for the ED visit; 28.8% at least part of the reason for visit; 50.4% any recent dizziness2
). These differences probably reflect differences in sensitivity across techniques for determining the presence of dizziness or its relevance to the visit.19
Our findings corroborate a higher prevalence of dizziness among older ED patients, in accordance with community-based estimates.6
Among those older than 50 years, dizziness represented roughly 5% of all ED visits, about twice that of younger adults. As hypothesized, there was a strong association between the frequency of dangerous diagnoses and increasing age. Notably, even among younger patients, nearly 1 in 10 harbored a dangerous underlying diagnosis. Our findings also confirm a slightly higher frequency of dizziness symptoms among women, described previously in population-based studies.20,21
None of the minor differences we identified between cases and controls in geographic distribution, race, or insurance status appear to be important from a clinical or public health standpoint.
The results confirm our hypothesis that dizziness is often medical. When considered in aggregate, general medical diagnoses (49.2%) were more common than otovestibular ones (32.9%). Nearly half of the medical disorders diagnosed were cardiovascular, in keeping with prior data from both EDs and general medical settings.6
Psychiatric diagnoses were less common (7.2%) than reported in settings other than acute care (eg, chronic dizziness in primary care 40%22
or subspecialty clinic 21%23
Because we did not exhaustively classify all
diagnoses as benign or dangerous, we cannot provide a robust estimate of absolute prevalence of benign or dangerous conditions. However, we can offer an estimate of relative prevalence: prospectively defined dangerous diagnoses (15%) were about as frequent as prospectively defined benign diagnoses (16%). Cerebrovascular diagnoses were not rare (4.0%) and, in aggregate, were the second most common dangerous diagnosis after fluid and electrolyte disturbances (5.6%), outpacing cardiac arrhythmias (3.2%), angina and myocardial infarction (1.7%), anemia (1.6%), and hypoglycemia (1.4%). Three dangerous disorders, although rare (<0.5%), were associated in our sample with a presenting symptom of dizziness (carbon monoxide poisoning [OR, 7.4; 95% CI, 4.0–13.6], subarachnoid hemorrhage/intracranial aneurysm/cervicocranial vascular dissection [OR, 4.4; 95% CI, 0.9–22.0], and aortic dissection/ruptured aneurysm [OR, 2.0; 95% CI, 0.4–9.1]). These disorders were chosen prospectively because of demonstrated dizziness symptoms in disease-based case reports or series,24–29
but their small numbers even in this very large data set underscore the difficulty in describing predictors of rare but critical diagnoses.
Our findings extend prior work suggesting that patients with dizziness consume substantial resources in EDs.13
Given the broad diagnostic spectrum and high risk of dangerous disorders, this consumption is probably appropriate. However, the frequent and disproportionate use of diagnostic imaging technology among dizziness cases vs controls (18.0% vs 6.9% across all years, and 24.0% vs 12.6% in 2005) deserves consideration. Although we cannot be sure that all imaging obtained for dizziness cases was focused on the head or brain, prior research indicates a high rate of neuroimaging among ED patients with dizziness.10
Virtually all imaging was by CT, rather than MRI, even in more recent years (22.8% vs 1.8% in 2005). However, for ED patients with dizziness, the diagnostic yield of head CT is known to be low,30
and CT has recently been shown to identify only about 16% of all acute ischemic strokes (even those imaged 12 hours or more after symptom onset).31
Computed tomography probably identifies even fewer strokes in the posterior cranial fossa because of radiographic artifacts emanating from the skull base.32
Some ED physicians might be falsely reassured by normal results from head CT,33
so heavy use of CT in these patients could be both costly and dangerous. Emergency department physicians worldwide would apparently welcome guidance in making imaging decisions among patients with dizziness or vertigo,33,34
so this represents an important area for future study.
Despite greater ED length of stay and extensive testing, dizziness cases are admitted with greater frequency than controls. Because admissions to the intensive care unit were comparable (2.2% vs 1.8%; P
=.15), dizziness cases were probably not appreciably “sicker” (in a medical sense) than controls without dizziness. Considering the high frequency of symptom-only diagnoses (22.1% vs 8.4%), perhaps many of the non-ICU admissions among dizziness cases (16.6% vs 13.0%; P
<.001) reflect residual diagnostic uncertainty, rather than admission for specific treatment. This suggests a need for new approaches to diagnosis, among them perhaps clinical decision rules, diagnostic protocols, or computer-based diagnostic decision support.35
Data from NHAMCS on ED visits are from a large, nationally representative sample that offers many advantages in ascertaining the overall spectrum of dizziness presentations to the ED. However, the lack of independent diagnostic confirmation and follow-up makes it impossible to precisely gauge the accuracy of diagnoses and appropriateness of diagnostic testing. We identified several potential limitations to our study findings.
The NHAMCS data set does not provide sufficient data to analyze details of clinical presentation. For instance, we cannot be sure, in those cases in which dizziness was one of 2 or 3 presenting symptoms, whether dizziness was the primary symptom. Also, we cannot know how the type of dizziness (vertigo, presyncope, disequilibrium, other) or presence of certain signs (eg, nystagmus) influenced the final diagnosis; nor can we use such data to generate clinical prediction rules.
Because ED diagnoses were unconfirmed, we cannot have absolute confidence that the diagnoses given were accurate, which might bias results. Misdiagnoses could be common with certain vestibular disorders, including cerebrovascular causes of dizziness.7,8
Perhaps 35% of those presenting to the ED with dizziness of confirmed cerebrovascular cause are misdiagnosed.7
However, at least for cerebrovascular disorders, ED overdiagnosis and underdiagnosis appear to be of similar magnitude,36
likely making our prevalence estimate roughly accurate despite diagnostic misclassification. In support of this notion, the one study of a population-based community sample of cerebrovascular diagnoses among ED patients with dizziness estimated a rate of confirmed cerebrovascular cases (3.2%)7
similar to that seen in our study (4.0%).
Overdiagnoses might be frequent for some benign disorders (eg, vasovagal syncope) but are unlikely among acute, life-threatening diseases with well-established diagnostic tests (eg, myocardial infarction, aortic dissection). Underdiagnoses might also be frequent, given the high rate of symptom-only diagnoses. This might be particularly so for certain vestibular disorders, such as multisensory disequilibrium (common among older patients37
but not available as a specific ICD-9-CM
diagnosis code) or vestibular migraine (common at any age but probably unrecognized by many physicians38
). Finally, perhaps some diagnoses were incidental to the symptom of dizziness. This is plausible for some diagnoses (eg, diabetes, hypertension) but less so for others (eg, labyrinthitis, aortic dissection).