FW: Risk of Vertebrobasilar Stroke and Chiropractic Care

[Guest guest]

Dear Doctors, Re: Dr. Cassidy’s

article and the ‘risk point’ of age 45 that I was questioning, I

decided to ask him myself about it. See my question below and with his

permission I am posting his response. s. fuchs dc

Dear Sharron:

Thanks for you interest in the study. We

used the cut point of 45 years of age for three reasons:

A previous

study had shown that those under 45 were at risk and those over that age

were not (see Rothwell, 2000 in our references)

There

are two types of VBA strokes. They can occur in older individuals and are

probably due to the usual stroke risk factors such as atherosclerotic

disease and hypertension, or they can occur rarely in younger people and

the cause is less established. Most of the chiropractic related strokes

have been reported in younger individuals.

Consultation

with stroke neurologists agreed with this approach.

However, we could of chosen a cutpoint of

50 or 40 and the results would have been similar.

Best wishes,

J. Cassidy, D.C.,

Ph.D., Dr.Med.Sc.

From: Sharron Fuchs

[mailto:SharronF@...]

Sent: February 2, 2009 5:22 PM

Cassidy

Subject: Risk of Vertebrobasilar

Stroke and Chiropractic Care

http://www.springerlink.com/content/vw8q5187g3j4118t/

Dear Dr.Cassidy, I am a DC in Portland, Oregon.

We are having a discussion about your article and what is it about the age 45

that seems to be a ‘risk point’ for lack of a better term. In other

words, what is it about age 45 that those under it are 3x more likely to have

seen a DC / PCP around the time of the S/S of the stroke ?

Sharron Fuchs DC

[Guest guest]

Dear Doctors, Re: Dr. Cassidy’s

article and the ‘risk point’ of age 45 that I was questioning, I

decided to ask him myself about it. See my question below and with his

permission I am posting his response. s. fuchs dc

Dear Sharron:

Thanks for you interest in the study. We

used the cut point of 45 years of age for three reasons:

A previous

study had shown that those under 45 were at risk and those over that age

were not (see Rothwell, 2000 in our references)

There

are two types of VBA strokes. They can occur in older individuals and are

probably due to the usual stroke risk factors such as atherosclerotic

disease and hypertension, or they can occur rarely in younger people and

the cause is less established. Most of the chiropractic related strokes

have been reported in younger individuals.

Consultation

with stroke neurologists agreed with this approach.

However, we could of chosen a cutpoint of

50 or 40 and the results would have been similar.

Best wishes,

J. Cassidy, D.C.,

Ph.D., Dr.Med.Sc.

From: Sharron Fuchs

[mailto:SharronF@...]

Sent: February 2, 2009 5:22 PM

Cassidy

Subject: Risk of Vertebrobasilar

Stroke and Chiropractic Care

http://www.springerlink.com/content/vw8q5187g3j4118t/

Dear Dr.Cassidy, I am a DC in Portland, Oregon.

We are having a discussion about your article and what is it about the age 45

that seems to be a ‘risk point’ for lack of a better term. In other

words, what is it about age 45 that those under it are 3x more likely to have

seen a DC / PCP around the time of the S/S of the stroke ?

Sharron Fuchs DC

[Guest guest]

Abstract of Rothwell article Dr. Cassidy

refers to :

http://stroke.ahajournals.org/cgi/content/abstract/32/5/1054

s. fuchs dc

From:

[mailto: ] On Behalf Of Sharron Fuchs

Sent: Wednesday, February 04, 2009

11:36 AM

oregon dcs

Subject: FW: Risk

of Vertebrobasilar Stroke and Chiropractic Care

Dear Doctors, Re: Dr. Cassidy’s article and the

‘risk point’ of age 45 that I was questioning, I decided to ask him

myself about it. See my question below and with his permission I am posting his

response. s. fuchs dc

Dear Sharron:

Thanks for you interest in the study. We used the cut point of 45

years of age for three reasons:

A previous study had shown that

those under 45 were at risk and those over that age were not (see

Rothwell, 2000 in our references)

There are two types of VBA

strokes. They can occur in older individuals and are probably due to the

usual stroke risk factors such as atherosclerotic disease and

hypertension, or they can occur rarely in younger people and the cause is

less established. Most of the chiropractic related strokes have been

reported in younger individuals.

Consultation with stroke

neurologists agreed with this approach.

However, we could of chosen a cutpoint of 50 or 40 and the results

would have been similar.

Best wishes,

J. Cassidy, D.C.,

Ph.D., Dr.Med.Sc.

From: Sharron Fuchs [mailto:SharronFtdinjurylaw]

Sent: February 2, 2009 5:22 PM

Cassidy

Subject: Risk of Vertebrobasilar

Stroke and Chiropractic Care

http://www.springerlink.com/content/vw8q5187g3j4118t/

Dear

Dr.Cassidy, I am a DC in Portland,

Oregon. We are

having a discussion about your article and what is it about the age 45 that

seems to be a ‘risk point’ for lack of a better term. In other

words, what is it about age 45 that those under it are 3x more likely to have

seen a DC / PCP around the time of the S/S of the stroke ?

Sharron

Fuchs DC

[Guest guest]

Abstract of Rothwell article Dr. Cassidy

refers to :

http://stroke.ahajournals.org/cgi/content/abstract/32/5/1054

s. fuchs dc

From:

[mailto: ] On Behalf Of Sharron Fuchs

Sent: Wednesday, February 04, 2009

11:36 AM

oregon dcs

Subject: FW: Risk

of Vertebrobasilar Stroke and Chiropractic Care

Dear Doctors, Re: Dr. Cassidy’s article and the

‘risk point’ of age 45 that I was questioning, I decided to ask him

myself about it. See my question below and with his permission I am posting his

response. s. fuchs dc

Dear Sharron:

Thanks for you interest in the study. We used the cut point of 45

years of age for three reasons:

A previous study had shown that

those under 45 were at risk and those over that age were not (see

Rothwell, 2000 in our references)

There are two types of VBA

strokes. They can occur in older individuals and are probably due to the

usual stroke risk factors such as atherosclerotic disease and

hypertension, or they can occur rarely in younger people and the cause is

less established. Most of the chiropractic related strokes have been

reported in younger individuals.

Consultation with stroke

neurologists agreed with this approach.

However, we could of chosen a cutpoint of 50 or 40 and the results

would have been similar.

Best wishes,

J. Cassidy, D.C.,

Ph.D., Dr.Med.Sc.

From: Sharron Fuchs [mailto:SharronFtdinjurylaw]

Sent: February 2, 2009 5:22 PM

Cassidy

Subject: Risk of Vertebrobasilar

Stroke and Chiropractic Care

http://www.springerlink.com/content/vw8q5187g3j4118t/

Dear

Dr.Cassidy, I am a DC in Portland,

Oregon. We are

having a discussion about your article and what is it about the age 45 that

seems to be a ‘risk point’ for lack of a better term. In other

words, what is it about age 45 that those under it are 3x more likely to have

seen a DC / PCP around the time of the S/S of the stroke ?

Sharron

Fuchs DC

[Guest guest]

Here is

a response from Dr. Cassidy when I asked him about his use of the age 45. Also

note, ‘Most of the chiropractic related strokes have been reported in

younger individuals.’

s. fuchs dc

From: Cassidy

Sent: Wednesday, February 04, 2009

8:45 AM

Sharron Fuchs

Subject: RE: Risk of

Vertebrobasilar Stroke and Chiropractic Care

Dear Sharron:

Thanks for you interest in the study. We

used the cut point of 45 years of age for three reasons:

1. A previous study had shown that those under 45 were at risk and

those over that age were not (see Rothwell, 2000 in our references)

2.

There

are two types of VBA strokes. They can occur in older individuals and are

probably due to the usual stroke risk factors such as atherosclerotic disease

and hypertension, or they can occur rarely in younger people and the cause is

less established. Most of the chiropractic

related strokes have been reported in younger individuals.

3. Consultation with stroke neurologists agreed with this approach.

However, we could of chosen a cutpoint of

50 or 40 and the results would have been similar.

Best wishes,

This e-mail may contain

confidential and/or privileged information for the sole use of the intended

recipient. Any review or distribution by anyone other than the person for whom

it was originally intended is strictly prohibited. If you have received this

e-mail in error, please contact the sender and delete all copies. Opinions,

conclusions or other information contained in this e-mail may not be that of

the organization.

From: Sharron Fuchs

[mailto:SharronF@...]

Sent: February 2, 2009 5:22 PM

Cassidy

Subject: Risk of Vertebrobasilar

Stroke and Chiropractic Care

http://www.springerlink.com/content/vw8q5187g3j4118t/

Dear Dr.Cassidy, I am a DC in Portland, Oregon.

We are having a discussion about your article and what is it about the age 45

that seems to be a ‘risk point’ for lack of a better term. In other

words, what is it about age 45 that those under it are 3x more likely to have

seen a DC / PCP around the time of the S/S of the stroke ?

Sharron Fuchs DC

[Guest guest]

With Dr. Freeman’s

permission I am posting his commentary regarding Dr. Cassidy / post

manipulation stroke:

s. fuchs dc

On Feb 17, 2011, at 7:15 PM, " Freeman " <forensictrauma@...> wrote:

Hi Sharron,

Below are my comments about a report Cassidy did in a malpractice case

in which the patient died after the manipulation.

The

first problem with the study was that the total number of subjects who had a

stroke and who had seen a chiropractor in the 7 days prior to the stroke was

only 14, and there were only 6 who saw a chiropractor on the same day as the

stroke. As it is certainly true that chiropractic practices attract patients

with neck pain, and patients who are already having a VBA dissection will have

neck pain, then there is certainly a risk of a reverse causation conclusion

(the manipulation caused the dissection) when the opposite is the case.

This is

NOT the case with the patient who presents with minimal or no neck symptoms and

then has a stroke within 5 minutes of a cervical manipulation, as the

probability of coincidental occurrence of stroke decreases dramatically as the

time between the manipulation and the stroke lessens. If all 6 of the

chiropractic patients had dissections or strokes within minutes of manipulation

this would be extremely important information to have as the relationship would

almost certainly not be coincidental, yet this information does not exist in

the study described by Dr. Cassidy.

Such

study is complicated by the fact that there is no way to know from the study

methods in how many of the 14 patients who saw chiropractors within a week of

their stroke there would have been a causal relationship expected; if the answer is only 1 or 2

then the study would not have had sufficient power (numbers of subjects in each

category) to identify a real difference between the groups. It is easiest to

describe the flaw in this approach with analogy; consider drug A that is

suspected to have fatal reaction in one in every 10,000 doses. If we wanted to

study whether the drug A kills people versus drug B, which we know

doesn’t kill people, we could get 10,000 people who had died, and then

find that 200 had taken drug A and 200 had taken drug B. We would incorrectly

conclude that the rate of death due to drug A is no greater than with drug B,

yet we only assembled 1/50th of the number of people who had taken

the drug to find 1 person who had died from the drug! The erroneous conclusion

would be that drug A doesn’t kill people.

It is

important to note that whether chiropractic procedures are related to stroke is

unrelated to the relationship of stroke and PCP visits. What the study does

demonstrate is that patients who are having a VAD with neck pain will present

to both a PCP and a chiropractor - an unsurprising finding. However, the paper

doesn’t demonstrate that a chiropractic treatment to the neck will not or

cannot precipitate a stroke. The conclusion is fallacious because the methods

of the study cannot disprove a causal relationship.

In

addition to the above comments about the faulty conclusions that Dr. Cassidy

drew with regard to his study, I am in possession of a report of Dr.

Silver, dated March 4, 2009. Dr. Silver is a neurologist and a co-author of Dr.

Cassidy’s, and he clearly does not share Dr. Cassidy’s opinion that

chiropractic manipulation is not causally associated with VBA stroke. In fact,

Dr. Silver pointedly notes in his report that the paper he co-authored included

a specific disclaimer that the research did NOT rule out chiropractic treatment

as a cause of stroke.

When one

looks at the study itself, the reason for the need for the disclaimer which Dr.

Silver brings forward, is simple. The types of epidemiologic studies that Dr.

Cassidy referred to in his report cannot be used as a basis for drawing exclusive

causal inferences, as such a study can, at best, be said to have failed to demonstrate a causal association.

This is a well accepted fact in epidemiologic science and it is highly

inappropriate and frankly wrong for Dr. Cassidy to draw the conclusions he has

from his research, which was in fact designed to arrive at a no-relationship

conclusion. As I have stated above, there are a number of methodologic problems

with Dr. Cassidy’s research, and I have only discussed some of them

above, but would be happy to go into more detail if asked. For various reasons,

some of which are a result of faulty study design, Dr. Cassidy’s research

failed to find an association between manipulation and VBA stroke. As I

mentioned above, Dr. Cassidy began with this hypothesis, and chose to attempt

to find proof to support this hypothesis. No unbiased scientist would interpret

this study’s findings to mean that chiropractic treatment doesn’t

or can’t cause VBA stroke, and this can be seen by Dr. Silver’s

disagreement with the manner in which Dr. Cassidy is trying to use this study.

D Freeman PhD MPH DC

Forensic Epidemiologist

Affiliate Professor

Department of Public Health and Preventive Medicine

Oregon Health and Science University School of Medicine

http://www.ohsu.edu/xd/education/schools/school-of-medicine/departments/clinical-departments/public-health/people/michael-d-freeman-phd-mph-d.cfm

Adjunct Associate Professor of Forensic Medicine and Epidemiology

Institute of Forensic Medicine, Faculty

of Health Sciences

Aarhus University

Aarhus, Denmark

Mailing address: 1234 SW 18th Ave,

Suite 102

Portland, OR

97205

T 971-255-1008, F 971-255-1046

C 503-871-0715

forensictrauma@...

On Feb 17, 2011, at 11:57 AM, Sharron Fuchs wrote:

Thanks. I will remind you. –s-

From: Dr.

Freeman [mailto:forensictrauma@...]

Sent: Thursday, February 17, 2011

11:56 AM

Sharron Fuchs

Subject: Re: FW: Risk of

Vertebrobasilar Stroke and Chiropractic Care

Sharron,

There are other problems with this. If you remind me, I will send you something

that I just wrote on this topic for a case in which a woman died after a

cervical manipulation in Canada.

M

On Thu, Feb 17, 2011 at 11:35 AM, Sharron Fuchs <SharronF@...> wrote:

May I post your response to this study to the list serve? sharron

From: Dr. Freeman [mailto:forensictrauma@...]

Sent: Wednesday, February 24, 2010

7:03 AM

Sharron Fuchs

Subject: Re: FW: Risk of

Vertebrobasilar Stroke and Chiropractic Care

This study is

worthless for assessing stroke causation, and cannot be used to show that

causation is not present in an older patient.

On Tue, Feb 23,

2010 at 4:46 PM, Sharron Fuchs <SharronF@...>

wrote:

FYI -

Dear Sharron:

Thanks for you interest in the study. We used the cut point of 45

years of age for three reasons:

A previous study had shown that

those under 45 were at risk and those over that age were not (see

Rothwell, 2000 in our references)

There are two types of VBA

strokes. They can occur in older individuals and are probably due to the usual

stroke risk factors such as atherosclerotic disease and hypertension, or

they can occur rarely in younger people and the cause is less established.

Most of the chiropractic related strokes have been reported in younger

individuals.

Consultation with stroke

neurologists agreed with this approach.

However, we could of chosen a cutpoint of 50 or 40 and the results

would have been similar.

Best wishes,

J. Cassidy, D.C., Ph.D., Dr.Med.Sc.

Director, Centre of Research Expertise in

Improved Disability Outcomes (CREIDO), University Health Network Rehabilitation

Solutions

Senior Scientist, Division of Health Care and

Outcomes Research, Toronto Western Research Institute

Professor, Dalla Lana School of

Public Health

University of Toronto

From: Sharron Fuchs [mailto:SharronF@...]

Sent: February 2, 2009 5:22 PM

Cassidy

Subject: Risk of Vertebrobasilar

Stroke and Chiropractic Care

http://www.springerlink.com/content/vw8q5187g3j4118t/

We are

having a discussion about your article and what is it about the age 45 that

seems to be a ‘risk point’ for lack of a better term. In other

words, what is it about age 45 that those under it are 3x more likely to have seen

a DC / PCP around the time of the S/S of the stroke ?

Sharron Fuchs

--

D Freeman PhD MPH DC

Forensic Epidemiologist

Clinical/ Affilliate Associate Professor

Department of Public Health and Preventive Medicine

Oregon

Health and Science University School of

Medicine

Adjunct Associate Professor of Forensic Medicine and Epidemiology

Institute of Forensic Medicine,

Faculty of Health Sciences

Aarhus

University

Aarhus, Denmark

Mailing address: 1234 SW 18th Ave, Suite 102

Portland, OR 97205

T 971-255-1008, F 971-255-1046

C 503-871-0715

forensictrauma@...

--

D Freeman PhD MPH DC

Forensic Epidemiologist

Affiliate Professor

Department of Public Health and Preventive Medicine

Oregon

Health and Science University School of

Medicine

http://www.ohsu.edu/xd/education/schools/school-of-medicine/departments/clinical-departments/public-health/people/michael-d-freeman-phd-mph-d.cfm

Adjunct Associate Professor of Forensic Medicine and Epidemiology

Institute of Forensic Medicine,

Faculty of Health Sciences

Aarhus

University

Aarhus, Denmark

Mailing address: 1234 SW 18th Ave, Suite 102

Portland, OR 97205

T 971-255-1008, F 971-255-1046

C 503-871-0715

forensictrauma@...

[Guest guest]

Is it likely that more younger aged people would consult a chiropractor with Pre VBA symptoms while more of the older folks would consult an MD with same symptoms, simply because the older folks would be more likely to consider stroke possibility while the younger folks would be considering subluxation as causative of their symptoms? seems so to me....

Janet L Rueger, DCCertified in CraniopathyCertified BodyTalk Practitioner149 Clear Creek Dr., # 105Ashland, OR, 97520541-690-6799bodytalk@...

On Feb 17, 2011, at 11:24 AM, Sharron Fuchs wrote:

Here is

a response from Dr. Cassidy when I asked him about his use of the age 45. Also

note, ‘Most of the chiropractic related strokes have been reported in

younger individuals.’ s. fuchs dc

From: Cassidy

Sent: Wednesday, February 04, 2009

8:45 AM

Sharron Fuchs

Subject: RE: Risk of

Vertebrobasilar Stroke and Chiropractic Care

Dear Sharron: Thanks for you interest in the study. We

used the cut point of 45 years of age for three reasons: 1. A previous study had shown that those under 45 were at risk and

those over that age were not (see Rothwell, 2000 in our references) 2.

There

are two types of VBA strokes. They can occur in older individuals and are

probably due to the usual stroke risk factors such as atherosclerotic disease

and hypertension, or they can occur rarely in younger people and the cause is

less established. Most of the chiropractic

related strokes have been reported in younger individuals. 3. Consultation with stroke neurologists agreed with this approach. However, we could of chosen a cutpoint of

50 or 40 and the results would have been similar. Best wishes,

This e-mail may contain

confidential and/or privileged information for the sole use of the intended

recipient. Any review or distribution by anyone other than the person for whom

it was originally intended is strictly prohibited. If you have received this

e-mail in error, please contact the sender and delete all copies. Opinions,

conclusions or other information contained in this e-mail may not be that of

the organization.

From: Sharron Fuchs

[mailto:SharronF@...]

Sent: February 2, 2009 5:22 PM

Cassidy

Subject: Risk of Vertebrobasilar

Stroke and Chiropractic Care

http://www.springerlink.com/content/vw8q5187g3j4118t/ Dear Dr.Cassidy, I am a DC in Portland, Oregon.

We are having a discussion about your article and what is it about the age 45

that seems to be a ‘risk point’ for lack of a better term. In other

words, what is it about age 45 that those under it are 3x more likely to have

seen a DC / PCP around the time of the S/S of the stroke ? Sharron Fuchs DC