Letter by Labovitz and Bhupali Regarding Article, “Transient Ischemic Attack in Joinville, Brazil, 2010: A Population-Based Study”
To the Editor:
Fonseca et al1 reported that the transient ischemic attack (TIA) incidence in Joinville, Brazil, is lower than other similarly designed studies and suggest that despite having robust ascertainment methodology, some outpatient cases may have been missed and low public awareness of stroke symptoms might have decreased diagnosis. We also suggest that institutional and regional variations in physicians' perspective may affect TIA incidence.
The short duration of symptoms, numerous clinical mimics, and absence of findings on imaging or other tests make diagnosing TIAs challenging and vulnerable to misclassification. Because the mechanism for TIA is the same as for ischemic stroke, with only duration of vascular occlusion and availability of collateral blood flow separating them, the ratio of TIA cases to ischemic stroke cases should be identical across demographic, clinical, and hospital strata. However, when we examined the TIA to ischemic stroke ratio (the proportion of TIA among all TIA and ischemic stroke cases) at Montefiore Medical Center in the Bronx, NY, we found that the ratio significantly varies depending on a number of factors, including whether the patient is on an internal medicine or neurology service, whether the patient is evaluated by a general neurologist or a board-certified vascular neurologist, and whether the facility had neurology housestaff. For example, from January 2009 to June 2011, the TIA–ischemic stroke ratio for 2 of our facilities with neurology housestaff was 25.5%, whereas the ratio for our hospital lacking neurology housestaff was 38.8% (P<0.0001).
Given such variation between US hospitals in the Bronx, similar differences likely exist internationally for a variety of reasons. The ABCD2 score, assessing symptoms and vascular risk factors, is promoted as a criterion for admission; however, our findings suggest that physician training and perspective can affect TIA incidence and thus assessment of future stroke risk as well.
Daniel L. Labovitz, MD, MS
Deepa Bhupali, MD
Albert Einstein College of Medicine/Montefiore Medical Center
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- © 2012 American Heart Association, Inc.