Use of Intravenous Heparin by
North American Neurologists
Do the Data Matter?
Ahmad Al-Sadat, MD; Mohammad Sunbulli, MD; Seemant Chaturvedi, MD
Background and Purpose—Our aim was to determine current usage patterns of intravenous heparin for patients with acute ischemic stroke.
Methods—A survey was undertaken of 280 neurologists from the United States and 270 neurologists from Canada. Brief vignettes were presented for the following 5 scenarios: stroke in evolution, atrial fibrillation-related stroke (A FIB), vertebrobasilar stroke, carotid territory stroke, and multiple transient ischemic attacks. The effect of medicolegal factors was also ascertained. Statistical comparisons were done with chi-squared testing.
Results—US neurologists were significantly more likely than Canadian neurologists to use intravenous heparin for patients with stroke in evolution (51% versus 33%, P
0.001), vertebrobasilar stroke (30% versus 8%, P
0.001), carotid territory stroke (31% versus 4%, P
0.001), and multiple transient ischemic attacks (47% versus 9%, P
0.001). The vast majority of US and Canadian neurologists would use intravenous heparin for acute stroke patients with A FIB (88% and 84%, respectively). US neurologists more often cited medicolegal factors as a potential influence on the decision-making process than Canadian neurologists (33% versus 10%, P
0.001).
Conclusions—In several clinical scenarios, US neurologists were significantly more likely than Canadian neurologists to use intravenous heparin. Fears regarding medicolegal consequences may partially explain the treatment disparity.
Despite the publication of 4 clinical trials, which have not shown any long-term benefit for patients with acute stroke and A FIB (International Stroke Trial, Heparin in Acute Embolic Stroke Trial) or cardioembolic stroke (Trial of Org
10172 in Acute Stroke Treatment, the Tinzaparin in Acute Ischemic Stroke Trial), both US and Canadian neurologists would use intravenous heparin in large numbers for this condition. Further studies are warranted to investigate the lack of impact of “negative” studies on clinician behavior. (Stroke. 2002;33:1574-1577.)
Key Words: heparin
heparin, low-molecular-weight
heparinoids
jurisprudence
stroke, acute ischemic
Intravenous heparin was introduced in the treatment of acute ischemic stroke by Hedenius in 1941.1 Since then its use has been an area of great controversy among neurologists.
Approximately 1 decade ago there were some small clinical trials that did not support the use of heparin,2,3 whereas other authorities concluded that heparin has a role in some types of stroke such as cardioembolic stroke and stroke in evolution
(SIE).4–7 With these controversial data, most neurologists at that time felt that there was a need for further clinical investigation to evaluate the role of heparin in acute ischemic stroke.8 The 1994 American Heart Association guidelines did not give a clear recommendation on the use of intravenous heparin. These guidelines mentioned that “Until more data are available, the use of heparin remains a matter of preference of the treating physician. It should be understood that the use of heparin (or the lack of its administration) may not alter the outcome of a patient with ischemic stroke.” 9
Since the 1994 American Heart Association guidelines, there have been 6 major clinical trials pertaining to the use of heparin, low-molecular-weight heparin, or heparinoids in patients with acute stroke.10–15 Five of these six studies did not show clear benefit associated with the early use of heparin or related compounds in patients with acute stroke.
We sought to obtain updated information regarding the practices of US and Canadian neurologists with regard to acute heparin use. Our hypothesis was that US neurologists would use heparin more frequently and that medicolegal factors would affect US physicians more than Canadian neurologists. Subjects and Methods
A survey was taken of 280 neurologists from the United States and
270 neurologists from Canada. All were active members of the
American Academy of Neurology. A systematic sample of names was chosen from the 2000–2001 American Academy of Neurology
Received January 11, 2002; final revision received February 15, 2002; accepted February 28, 2002.
From the Department of Neurology and Comprehensive Stroke Program, Wayne State University, Detroit, Mich.
Correspondence to Seemant Chaturvedi, MD, Department of Neurology and Comprehensive Stroke Program, Wayne State University, 8C-UHC, 4201
St. Antoine, Detroit, MI 48201. E-mail Schaturv@med.wayne.edu
© 2002 American Heart Association, Inc.
Stroke is available at http://www.strokeaha.org DOI: 10.1161/01.STR.0000018081.33541.E3
Downloaded from http://stroke.ahajo1u5rn7a4ls.org/ by guest on February 17, 2016 directory.16 The sampling methodology involved selecting the first and second name of the active members on each page of the directory for the US neurologists and all of the active members for the
Canadian neurologists. We excluded pediatric neurologists and subspecialists who are unlikely to treat stroke patients. Five vignettes
(Table 1) were presented for the following scenarios: SIE, atrial fibrillation-related stroke (A FIB), vertebrobasilar stroke (VB), carotid territory stroke (CAR), and multiple transient ischemic attacks (TIA). For each vignette, respondents were asked whether they would use intravenous heparin. Response choices were yes, no, and maybe.
The effect of medicolegal factors was also ascertained (Table 1).
We also obtained information regarding how many years the neurologist had been a practicing physician (
10, 10 to 20, 20 years). All surveys were anonymous. Surveys and stamped return envelopes were sent in June 2001. No attempt was made to requery initial nonresponders. Statistical comparisons were made using the chisquared test. Results
One hundred thirteen (40%) of the US neurologists and one hundred thirty-seven (51%) of the Canadian neurologists returned a completed survey. The results are shown in
Table 2.
The results can be summarized as follows: (1) Stroke in evolution (SIE): US neurologists were significantly more likely than Canadian neurologists to use intravenous heparin for patients with SIE (51% versus 33%, P
0.001). (2) Atrial fibrillation-related stroke (A FIB): The vast majority of US and Canadian neurologists would use intravenous heparin for an acute stroke in a patient with A FIB (88% and 84%, respectively). (3) Vertebrobasilar stroke (VB): US neurologists were significantly more likely than Canadian neurologists to use intravenous heparin for patients with VB (30% versus 8%, P
0.001). (4) Carotid territory stroke (CAR): US neurologists were significantly more likely than Canadian neurologists to use intravenous heparin for patients with CAR
(31% versus 4%, P
0.001). (5) Multiple transient ischemic attacks (TIAs): US neurologists were significantly more likely than Canadian neurologists to use intravenous heparin for patients with multiple TIAs (47% versus 9%, P
0.001).
The effect of medicolegal factors is shown in Table 3. US neurologists more often cited medicolegal factors as a potential influence on the decision-making for the use of intravenous heparin than Canadian neurologists (33% of US neurologists responded with “always,” “frequently,” or
“sometimes” versus 10% of the Canadian neurologists,
P
0.001).
The greatest degree of uncertainty (determined by responding to the question “would you use intravenous heparin” as
“maybe”) was found for SIE, for which 35% of US and 25% of Canadian neurologists responded with “maybe.” There was no significant heterogeneity in the responses to the questions based on the number of years that the neurologist was in practice. Discussion
Our study demonstrates that in 4 of 5 common clinical scenarios (SIE, CAR, VB, and multiple TIAs), US neurologists were significantly more inclined to use intravenous anticoagulation compared with their Canadian counterparts.
This type of practice variation has been previously demonstrated in other aspects of cerebrovascular disease. The use of carotid endarterectomy is much higher in the US than in
Canada.17 For the specific scenario of carotid endarterectomy
TABLE 1. The Survey
Case vignettes
1. A 70-year-old man is admitted to your service at 3:00 PM with mild right facial weakness and mild word-finding difficulty. He is placed on aspirin. At 9:00 PM, you are called by the nurse because he has increased right-sided weakness with 3/5 strength in the right arm/leg and moderate dysphasia. Head CT is negative. Patient is in sinus rhythm with
BP 140/80. Would you use IV heparin? (Yes, no, or maybe).
2. A 70-year-old woman is admitted with mild expressive dysphasia and mild right hemiparesis, which began 6 hours ago. She has a history of atrial fibrillation that was treated with aspirin. She continues to be in atrial fibrillation in the emergency room. BP is 140/80. Head CT is negative. Would you use IV heparin? (Yes, no, or maybe).
3. A 70-year-old man with a history of HTN, DM, and smoking is admitted with a new onset of vertigo, ataxia, and diplopia, which began 6 hours ago. BP is 140/80. Head CT is negative. He is in a sinus rhythm, and he was not on an antiplatelet agent previously. Would you use IV heparin? (Yes, no, or maybe).
4. A 70-year-old woman is admitted with new onset dysphasia and mild right-sided weakness, which began 6 hours ago. She is in sinus rhythm with BP 140/80. Head CT is negative. She has a history of DM and smoking, and you hear a left carotid bruit. She was not on an antiplatelet agent previously. Would you use IV heparin? (Yes, no, or maybe).
5. A 70-year-old man is admitted with 2 episodes of transient visual loss in the right eye over the past 2 days, each lasting for 5 minutes. He has a history of DM and smoking. He is in a sinus rhythm. BP is 140/80.
Head CT is negative. He was not on an antiplatelet agent previously.
Would you use IV heparin? (Yes, no, or maybe).
Medicolegal factors
How often do medicolegal factors play a role in your decision to use IV heparin (ie, better to use IV heparin in case the patients worsens in the hospital and there is a subsequent lawsuit)?
(always, frequently, sometimes, rarely, or never).
BP indicates blood pressure; HTN, hypertension; and DM, diabetes mellitus.
TABLE 2. Use of Intravenous Heparin in the 5
Different Vignettes
SIE, % A FIB, % VB, % CAR, % TIA, %
US neurologists
Yes 51 88 30 31 47
No 14 5 50 53 34
Maybe 35 7 20 16 19
Canadian neurologists
Yes 33 84 8 4 9
No 42 3 80 88 79
Maybe 25 13 12 8 12
TABLE 3. Medicolegal Effect
Always,
%
Frequently,
%
Sometimes,
%
Rarely,
%
Never,
%
US neurologists 3 3 27 41 26
Canadian neurologists 1 2 7 40 50
Al-