Practice variation in neuroimaging to evaluate dizziness in the ED

Abstract

Background: The appropriate role of neuroimaging to evaluate emergency department (ED) patients with dizziness is not established by guidelines or evidence.

Methods: We identified all adults with a triage complaint of dizziness who were evaluated at 20 EDs of a large Northern California integrated health care program in 2008. Using comprehensive medical records, we captured all head computed tomographies (CTs) or brain magnetic resonance images (MRIs) completed at presentation or within 2 days and all stroke diagnoses within 1 week. We assessed variation in neuroimaging use by site using a random-effects logistic model to account for differences in patient- (demographic and vascular risk factors) and site-level factors (volume, % patients with dizziness, and % patients with dizziness admitted) and linear regression to assess the relationship between neuroimaging rates and stroke diagnosis rates by site.

Results: Of 378 992 patients seen in 2008, 20 795 (5.5%) had at least one ED visit for dizziness. Overall, 5585 patients (26.9%) had a head CT and 652 (3.1%) had a brain MRI. Between 21.8% and 32.8% of ED patients with dizziness at each site had a head CT (P<.001). For brain MRI, the range was 0.8% to 6.2%-a nearly 8-fold variation (P<.001) that persisted after adjustment for patient- and site-level factors. Higher neuroimaging rates did not translate into higher stroke diagnoses rates, with 0.7% to 2.5% of patients with dizziness diagnosed with stroke by site.

Conclusion: The use of neuroimaging for ED patients with dizziness varies substantially without an associated improvement in stroke diagnosis, which is identified only rarely.

Fig. 1

Variation in the overall use of neuroimaging to evaluate dizziness across 20 EDs within a Northern California integrated health program in 2008.

Fig. 2

Variation in the use of brain MRI scans to evaluate dizziness across 20 EDs within a Northern California integrated health program in 2008.

Fig. 3

Diagnostic yield for stroke within 7 days as a function of head CT use for patients with dizziness across 20 EDs within a Northern California integrated health program in 2008. Each point represents an individual ED and the line represents the best fit for linear regression weighted by the number of ED patients with dizziness seen at each site (R² = 0.01; slope, 0.8%; 95% CI, −7.1%– 8.7%; P = .84).

Fig. 4

Diagnostic yield for stroke within 7 days as a function of brain MRI use for patients with dizziness across 20 EDs within a Northern California integrated health program in 2008. Each point represents an individual ED and the line represents the best fit for linear regression weighted by the number of ED patients with dizziness seen at each site (R² = 0.10; slope, 8%; 95% CI, −3.8%– 20.0%; P = .17).