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Funding Bias in TASER Research American Heart Journal 2011

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Electrophysiology

Funding source and author affiliation in TASER
research are strongly associated with a conclusion of
device safety
Peyman N. Azadani, MD, Zian H. Tseng, MD, Simon Ermakov, BA, Gregory M. Marcus, MD, and Byron K. Lee, MD
San Francisco, CA

Background Controversy exists regarding the safety of electrical stun guns (TASERs). Much of the research on TASERs is
funded by the maker of the device and, therefore, could be biased. We sought to determine if funding source or author
affiliation is associated with TASER research conclusions.
Methods MEDLINE was searched for TASER or electrical stun gun to identify relevant studies. All human and animal
studies published up to September 01, 2010, were included. Reviews, editorials, letters, and case reports were excluded from
the analysis. Two independent reviewers blinded to this study hypothesis evaluated each article with regard to conclusions of
TASER safety.
Results Fifty studies were reviewed: 32 (64%) were human studies and 18 (36%) were animal studies. Twenty-three (46%)
studies were funded by TASER International or written by an author affiliated with the company. Of these, 22 (96%) concluded
that TASERs are unlikely harmful (26%) or not harmful (70%). In contrast, of the 22 studies not affiliated with TASER, 15 (55%)
concluded that TASERs are unlikely harmful (29%) or not harmful (26%). A study with any affiliation with TASER International
had nearly 18 times higher odds to conclude that the TASER is likely safe as compared with studies without such affiliation
(odds ratio 17.6, 95% CI 2.1-150.1, P = .001).
Conclusions

Studies funded by TASER and/or written by an author affiliated with the company are substantially more
likely to conclude that TASERs are safe. Research supported by TASER International may thus be significantly biased in favor of
TASER safety. (Am Heart J 2011;162:533-7.)

Conducted electrical weapons are used worldwide
by law enforcement agencies to incapacitate violent,
combative individuals. The deployment of these
devices by police departments is increasing.1 TASERs,
the most popular brand of electrical stun guns,
deliver electrical pulses leading to stimulation of both
sensory and motor nervous system and involuntary
muscle contractions.2
Research studies thus far on TASERs have had conflicting results. Although some have found that TASER
deployment is associated with an increased risk of
injuries and sudden death,3-5 others concluded that
these devices cause no significant harm.6,7
A substantial number of studies on the TASER are
funded by the manufacturer of the device, TASER

From the University of California, San Francisco, School of Medicine, San Francisco, CA.
Submitted February 26, 2011; accepted May 21, 2011.
Reprint requests: Byron K. Lee, MD, UCSF Cardiac Electrophysiology and Arrhythmia
Service 500 Parnassus Avenue Box 1354, MUE 429 San Francisco, CA 94143-1354.
E-mail: leeb@medicine.ucsf.edu
0002-8703/$ - see front matter
© 2011, Mosby, Inc. All rights reserved.
doi:10.1016/j.ahj.2011.05.025

International. It has been suggested that this may have led
to bias.8 We sought to determine whether funding from
TASER International or author affiliation with the
company is associated with the conclusion that the
device is safe.

Methods
Article selection
TASER literature was identified by searching the National
Library of Medicine's MEDLINE for terms TASER and stun
gun. All peer-reviewed articles including human and animal
studies published up to September 01, 2010, were
included. Exclusion criteria were established before study
inclusion and data analysis. All review articles, editorial
letters, and case reports were excluded. No language
restriction was imposed.

Article assessment
The entire manuscript including the conflict of interest
statement and acknowledgment section of all articles were
reviewed by 2 independent reviewers. A study was classified as
having a TASER-affiliated author if one or more of the authors
either had received funding from the company or had disclosed

American Heart Journal
September 2011

534 Azadani et al

Figure 1

150 citations was found in
Medline using search terms:
TASER, Stun gun
34 excluded based on Title and
Abstract
116 potentially relevant
studies for more detailed
evaluation
66 excluded for the following reasons:
22 Case reports
14 Review articles
18 Editorial letters
3 Reports
8 Non-in vivo studies
1 Technical note
50 articles were included in
the analysis

Study flow chart.

a financial relationship with the company somewhere in the
article. The assessment of funding source and author affiliation
was not based on any data beyond what was disclosed in the
articles. Studies either fully or partially funded by TASER
International were considered TASER funded.

and 95% CIs of dichotomous outcomes. Two-tailed P b .05 was
considered significant.
No extramural funding was used to support this work.
The authors are solely responsible for the design and conduct
of this study, all study analyses, the drafting and editing of the
manuscript, and its final contents.

Article conclusions
Two independent reviewers blinded to the hypothesis of our
study evaluated each article's conclusions regarding the safety of
TASERs. Based on the results and conclusion sections, the study
outcomes were classified as harmful, probably harmful, unlikely
harmful, and not harmful. Study outcomes of unlikely harmful
and not harmful were considered a conclusion of safety. If the 2
reviewers classified the conclusions of an article differently, a
third independent reviewer decided which of the 2 preliminary
classifications would be used for analysis.

Statistical analysis
Statistical analyses were performed using SPSS software for
Windows version 16. χ2 Analyses were conducted to compare
proportions to test the null hypothesis that TASER affiliation is
not related to conclusion about safety of TASERs. Logistic
regression analysis was performed to calculate odds ratios (ORs)

Results
A total of 119 published articles on TASER were
identified in the literature. Sixty-nine articles did not
meet the inclusion criteria for the reasons shown in
Figure 1, leaving 50 publications retained for
analysis.3-7,9-53 Descriptive characteristics of the studied
articles are shown in Table I. All the studied articles
were written in English.
Thirty-two (64%) of the articles reported human
studies, and 18 (36%) reported studies performed on
animals. Overall, 23 (46%) of the articles were funded
by TASER or authored by an affiliate of the company
(Table II). Twenty-two (96%) of these articles concluded
that TASERs are unlikely harmful (26%) or not harmful
(70%). In contrast, of the 27 studies not affiliated with

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Volume 162, Number 3

Azadani et al 535

Table I. Descriptive characteristic of articles on TASER
Characteristic

Figure 2

Articles (N = 50)
P = .001

Study population, n (%)
Human
Animal
Author affiliation, n (%)
Yes
No
Funding source, n (%)
TASER
Non-TASER
No funding
Conclusion, n (%)
Harmful
Probably harmful
Unlikely harmful
Not harmful

100

32 (64)
18 (36)

96

14 (28)
11 (22)
25 (50)
7
6
14
23

(14)
(12)
(28)
(46)

Values are presented as n (%).

Percentage

80

19 (38)
31 (62)

55

60

45
40

20
4
0
TASER affiliation
not harmful

No TASER affiliation
harmful

Proportion of TASER articles with device-safety conclusions.
Table II. Level of safety by any commercial affiliation
TASER affiliation
Study
conclusion
Harmful
Probably harmful
Unlikely harmful
Not harmful

Yes (n = 23)
0 (0)
1 (4)
6 (26)
16 (70)

No (n = 27)
7
5
8
7

(26)
(18)
(30)
(26)

Values are presented as n (%).

TASER International, 15 (55%) found that TASERs are
unlikely harmful (29%) or not harmful (26%).
TASER-supported articles included a similar number of
patients as studies without TASER affiliation (mean of 129
vs 166, P = .40). Shown in Figure 2, a study with any
affiliation with TASER International had 17.6 times
greater odds of concluding that the TASER is likely safe
as compared with studies without such affiliation (95% CI
2.1-150.1, P = .001). This corresponds to a 75% greater
probability that studies with TASER affiliation would
conclude that the TASER is unlikely or not harmful.

Discussion
With the rapid expansion of stun gun deployment by
law enforcement agencies, several research studies have
been performed to determine the safety of these devices.
Many of these studies are funded by TASER International,
which manufactures and markets the stun gun most
commonly used by law enforcement in the United States.
In our study, any affiliation with TASER International was
strongly associated with concluding that TASERs are safe.
This finding demonstrates that TASER International
funding source and/or author affiliation may have a
great influence on article conclusions.

Although the safety of electronic control devices
including TASERs has been investigated by several
studies, controversy still exists as to whether TASERs
can cause serious injuries. Some investigations have
demonstrated that TASERs are safe with regard to cardiac
arrhythmias, respiratory arrest, rhabdomyolysis, and
acidosis.9-12 However, all such studies were performed
on animals or healthy volunteers, and the results would
be difficult to extrapolate to the stressful circumstances
during an arrest. Furthermore, many of these studies
were supported by TASER International or authors
affiliated with the company, which may influence the
results and conclusions.13-16 On the other hand, several
studies have concluded that TASER deployment is
dangerous, with the potential to cause ventricular
fibrillation and sudden death.4,5,17,18 There are also 22
case reports describing injuries associated with the
TASER, most of which were not funded by the TASER
International.54-56 Notably, these case reports were
excluded from our analysis.
There are several possible explanations for the
disparate conclusions of the 2 groups of studies. The
first possibility is that the literature may be biased; either
research supported by TASER was done in a way to
misleadingly conclude that the TASER is safe or likely safe
or research performed by independent investigators was
done in a way to misleadingly conclude that the TASER is
harmful or likely harmful. It is clear why researchers
being funded by TASER International or being paid by the
company might have a tendency to bias their research in
favor of the TASER. It is less evident the incentive for
researchers without an affiliation with the TASER
International to bias their research against TASER,
although one might hypothesize that they strive for
recognition for provocative research. Furthermore, some
of these authors may serve as expert witnesses in lawsuits

American Heart Journal
September 2011

536 Azadani et al

against TASER International and thereby have secondary
gain from vilifying the device. We were unable to
accurately ascertain which authors were serving as
expert witnesses in court cases.
The other possibility is that the study protocols chosen
led to disparate conclusions about the TASER. It is
possible that the authors who were funded by TASER
International or had a financial affiliation devised study
protocols more likely to show that the TASER is safe,
whereas the authors with no affiliation with the company
may have devised study protocols more likely to show
that the TASER is harmful. For example, some of the
TASER-funded studies examined the effects of healthy
humans being stunned in the back, distant from the
cardiac axis and thus unlikely to have significant effects
on the heart.9,19 In contrast, some animal studies analyzed
the effect of TASER discharges very close to the heart in
anesthesized pigs.4,5 Swine hearts are more prone to
ventricular tachyarrhythmia than those of humans,57 and
therefore, the choice of a pig model may make the TASER
seem more dangerous.
The other explanation for this discrepancy is that
studies sponsored by TASER International might have
been less likely to be published if they found possible
harm than if they found safety.

Study limitations
Our study has several important limitations. First, our
analysis is based on a relatively small sample size. Given
limited published articles in this field, further studies
are required with regard to the safety of TASERs.
Second, the studies included in our analysis differ from
each other in terms of study design and methodology.
This heterogeneity makes comparison of the conclusions in these studies more difficult. Finally, the
determination of funding source or author affiliation
may have been incomplete or inaccurate. We relied
primarily on the disclosures in the journal article, which
may be unreliable.

Conclusion
These data demonstrate that studies funded by TASER
International or written by authors affiliated with the
company are nearly 18 times more likely to conclude that
TASERs are safe. Research supported by TASER International may thus be significantly biased in favor of TASER
safety. Readers of articles about the TASER should
consider funding and author affiliations in their evaluation of the article's conclusions.

Disclosures
No conflict of interest; No financial support.

References
1. International of TASER. Available at: http://www.taser.com. Last
accessed February 1, 2010.
2. Neuromascular incapacitation of TASER. Available at: http://www.
taser.com/research/technology/Pages/NeuromuscularIncapacitation.aspx. Last accessed February 1, 2010.
3. Lee BK, Vittinghoff E, Whiteman D, et al. Relation of Taser (electrical
stun gun) deployment to increase in in-custody sudden defaths. Am J
Cardiol 2009;103:877-80.
4. Walter RJ, Dennis AJ, Valentino DJ, et al. TASER ×26 discharges in
swine produce potentially fatal ventricular arrhythmias. Acad Emerg
Med 2008;15:66-73.
5. Valentino DJ, Walter RJ, Dennis AJ, et al. Taser ×26 discharges in
swine: ventricular rhythm capture is dependent on discharge vector. J
Trauma 2008;65:1478-87.
6. Dawes DM, Ho JD, Reardon RF, et al. Echocardiographic evaluation
of TASER ×26 probe deployment into the chests of human volunteers.
Am J Emerg Med 2010;28:49-55.
7. Bozeman WP, Barnes , DG, Winslow , JE, et al. Immediate
cardiovascular effects of the Taser ×26 conducted electrical weapon.
Emerg Med J 2009;26:567-70.
8. Chand M, Nash GF. Are TASER guns really safe? Br J Hosp Med
(Lond) 2009;70:314-5.
9. Vilke GM, Sloane CM, Suffecool A, et al. Physiologic effects of the
TASER after exercise. Acad Emerg Med 2009;16:704-10.
10. Vilke GM, Sloane C, Levine S, et al. Twelve-lead electrocardiogram
monitoring of subjects before and after voluntary exposure to the
Taser ×26. Am J Emerg Med 2008;26:1-4.
11. Vilke GM, Sloane CM, Bouton KD, et al. Physiological effects of a
conducted electrical weapon on human subjects. Ann Emerg Med
2007;50:569-75.
12. Ordog GJ, Wasserberger J, Schlater T, et al. Electronic gun (Taser)
injuries. Ann Emerg Med 1987;16:73-8.
13. Dawes DM, Ho JD, Kroll MW, et al. Electrical characteristics of an
electronic control device under a physiologic load: a brief report.
Pacing Clin Electrophysiol 2010;33:330-6.
14. Ho JD, Heegaard WG, Dawes DM, et al. Unexpected arrest-related
deaths in America: 12 months of open source surveillance. West J
Emerg Med 2009;10:68-73.
15. Ho JD, Dawes DM, Bultman LL, et al. Prolonged TASER use on
exhausted humans does not worsen markers of acidosis. Am J Emerg
Med 2009;27:413-8.
16. Ho JD, Dawes DM, Cole JB, et al. Lactate and pH evaluation in
exhausted humans with prolonged TASER ×26 exposure or continued
exertion. Forensic Sci Int 2009;190:80-6.
17. Sun H, Haemmerich D, Rahko PS, et al. Estimating the probability that
the Taser directly causes human ventricular fibrillation. J Med Eng
Technol 2010;34:178-91.
18. Wu JY, Sun H, O'Rourke AP, et al. Taser blunt probe dart-to-heart
distance causing ventricular fibrillation in pigs. IEEE Trans Biomed
Eng 2008;55:2768-71.
19. Dawes D, Ho J, Miner J. The neuroendocrine effects of the TASER
×26: a brief report. Forensic Sci Int 2009;183:14-9.
20. VanMeenen KM, Cherniack NS, Bergen MT, et al. Cardiovascular
evaluation of electronic control device exposure in law enforcement
trainees: a multisite study. J Occup Environ Med 2010;52:197-201.
21. Strote J, Verzemnieks E, Walsh M, et al. Use of force by law
enforcement: an evaluation of safety and injury. J Trauma 2010;69:
1288-93.
22. Ho JD, Clinton JE, Lappe MA, et al. Introduction of the conducted
electrical weapon into a hospital setting. J Emerg Med. [Epub ahead
of print].

American Heart Journal
Volume 162, Number 3

23. Strote J, Walsh M, Angelidis M, et al. Conducted electrical weapon
use by law enforcement: an evaluation of safety and injury. J Trauma
2010;68:1239-46.
24. DeMonte TP, Wang D, Ma W, et al. In-vivo measurement of
relationship between applied current amplitude and current density
magnitude from 10 mA to 110 mA. Conf Proc IEEE Eng Med Biol Soc
2009;2009:3177-80.
25. Kroll MW, Panescu D, Carver M, et al. Cardiac effects of varying
pulse charge and polarity of TASER conducted electrical weapons.
Conf Proc IEEE Eng Med Biol Soc 2009;2009:3195-8.
26. Beason CW, Jauchem JR, Clark 3rd CD, et al. Pulse variations of a
conducted energy weapon (similar to the TASER ×26 device): effects
on muscle contraction and threshold for ventricular fibrillation⁎. J
Forensic Sci 2009;54:1113-8.
27. Jauchem JR, Seaman RL, Klages CM. Physiological effects of the
TASER C2 conducted energy weapon. Forensic Sci Med Pathol 2009;
5:189-98.
28. Swerdlow CD, Fishbein MC, Chaman L, et al. Presenting rhythm in
sudden deaths temporally proximate to discharge of TASER
conducted electrical weapons. Acad Emerg Med 2009;16:726-39.
29. Ho JD, Dawes DM, Heegaard WG, et al. Absence of electrocardiographic change after prolonged application of a conducted
electrical weapon in physically exhausted adults. J Emerg Med.
[Epub ahead of print].
30. Jauchem J, Beason CW, Cook MC. Acute effects of an alternative
electronic-control-device waveform in swine. Forensic Sci Med Pathol
2009;5:2-10.
31. Bozeman WP, Hauda 2nd WE, Heck JJ, et al. Safety and injury
profile of conducted electrical weapons used by law enforcement
officers against criminal suspects. Ann Emerg Med 2009;53:480-9.
32. Wu JY, Nimunkar AJ, Sun H, et al. Ventricular fibrillation time
constant for swine. Physiol Meas 2008;29:1209-19.
33. Ho JD, Dawes DM, Reardon RF, et al. Echocardiographic evaluation
of a TASER-X26 application in the ideal human cardiac axis. Acad
Emerg Med 2008;15:838-44.
34. Lakkireddy D, Wallick D, Verma A, et al. Cardiac effects of electrical
stun guns: does position of barbs contact make a difference? Pacing
Clin Electrophysiol 2008;31:398-408.
35. Sloane CM, Chan TC, Levine SD, et al. Serum troponin I
measurement of subjects exposed to the Taser X-26. J Emerg Med
2008;35:29-32.
36. Dennis AJ, Valentino DJ, Walter RJ, et al. Acute effects of TASER ×26
discharges in a swine model. J Trauma 2007;63:581-90.
37. Holden SJ, Sheridan RD, Coffey TJ, et al. Electromagnetic modelling
of current flow in the heart from TASER devices and the risk of cardiac
dysrhythmias. Phys Med Biol 2007;52:7193-209.
38. Dawes DM, Ho JD, Johnson MA, et al. 15-Second conducted
electrical weapon exposure does not cause core temperature
elevation in non-environmentally stressed resting adults. Forensic Sci
Int 2008;176:253-7.
39. Levine SD, Sloane CM, Chan TC, et al. Cardiac monitoring of human
subjects exposed to the Taser. J Emerg Med 2007;33:113-7.

Azadani et al 537

40. Jauchem JR, Cook MC, Beason CW. Blood factors of Sus scrofa
following a series of three TASER electronic control device exposures.
Forensic Sci Int 2008;175:166-70.
41. Lakkireddy D, Khasnis A, Antenacci J, et al. Do electrical stun guns
(TASER-X26) affect the functional integrity of implantable pacemakers and defibrillators? Europace 2007;9:551-6.
42. Wu JY, Sun H, O'Rourke AP, et al. Taser dart-to-heart distance that
causes ventricular fibrillation in pigs. IEEE Trans Biomed Eng 2007;
54:503-8.
43. Strote J, Range Hutson H. Taser use in restraint-related deaths.
Prehosp Emerg Care 2006;10:447-50.
44. Lakkireddy D, Wallick D, Ryschon K, et al. Effects of cocaine
intoxication on the threshold for stun gun induction of ventricular
fibrillation. J Am Coll Cardiol 2006;48:805-11.
45. Ho JD, Miner JR, Lakireddy DR, et al. Cardiovascular and physiologic
effects of conducted electrical weapon discharge in resting adults.
Acad Emerg Med 2006;13:589-95.
46. Jenkinson E, Neeson C, Bleetman A. The relative risk of police use-offorce options: evaluating the potential for deployment of electronic
weaponry. J Clin Forensic Med 2006;13:229-41.
47. Jauchem JR, Sherry CJ, Fines DA, Cook MC. Acidosis, lactate,
electrolytes, muscle enzymes, and other factors in the blood of Sus
scrofa following repeated TASER exposures. Forensic Sci Int 2006;
161:20-30.
48. Kornblum RN, Reddy SK. Effects of the Taser in fatalities involving
police confrontation. J Forensic Sci 1991;36:434-8.
49. Dawes DM, Ho JD, Reardon RF, et al. The cardiovascular, respiratory,
and metabolic effects of a long duration electronic control device
exposure in human volunteers. Forensic Sci Med Pathol 2010;6:
268-74.
50. Dawes DM, Ho JD, Reardon RF, et al. The physiologic effects of
multiple simultaneous electronic control device discharges. West J
Emerg Med 2010;11:49-56.
51. Ho JD, Dawes DM, Reardon RF, et al. Human cardiovascular effects
of a new generation conducted electrical weapon. Forensic Sci Int
2011;204:50-7.
52. Moscati R, Ho JD, Dawes DM, et al. Physiologic effects of prolonged
conducted electrical weapon discharge in ethanol-intoxicated adults.
Am J Emerg Med 2010;28:582-7.
53. Ho JD, Dawes DM, Nelson RS, et al. Acidosis and catecholamine
evaluation following simulated law enforcement “use of force”
encounters. Acad Emerg Med 2010;17:e60-8.
54. Multerer S, Berkenbosch JW, Das B, et al. Atrial fibrillation after taser
exposure in a previously healthy adolescent. Pediatr Emerg Care
2009;25:851-3.
55. Mangus BE, Shen LY, Helmer SD, et al. Taser and Taser associated
injuries: a case series. Am Surg 2008;74:862-5.
56. Al-Jarabah M, Coulston J, Hewin D. Pharyngeal perforation
secondary to electrical shock from a Taser gun. Emerg Med J 2008;
25:378.
57. Ferris LP, King BG, Spence PW, et al. Effect of electric shock on the
heart. Electr Eng 1936;55:498-515.