Putting The Stroke Issue to Bed

Download all of these so if a patient raises the question regarding Chiropractic adjustments and Vertebral Artery Dissection, you are fully prepared.

Putting the Stroke Issue to Bed Page 3 The Exclusive Dr. Oz Show Analysis Page 51 Katie May Autopsy Update Page 68 Katie May Update Page 76 Learn How To Discern The High Risk Stroke Patient Page 116 Gerry Clum Important Studies Page 131 Stroke Strategy and Public Perception Page 161

The following is an actual transcript of the ChiroSecure Live Event with Dr. Stu Hoffman and Dr. Gerald Clum. We do our best to make sure the transcript is as accurate as possible; however, it may contain spelling or grammatical errors. If you have any questions about the transcript or would like to request any transcripts from our previous shows, feel free to contact us at 866-802-4476

Dr. Hoffman:

Hello everybody. Dr. Stu Hoffman, President of ChiroSecure. The intent of this show is to offer up some information to you on what happens when the stroke issue rears its ugly head. What is the proper way to respond? Utilizing the literature that is available to us and not to just let our emotions get in the way of good, sound judgment. In fact, when we see an article appear or a news show appear that's attacking what we do as chiropractors and we know the information is false, do we just go and respond? I don't know about that. I think that we need to respond, but it needs to be based on sound information. Here we have an article published at Baylor University Medical Center Dallas, Vertebral Artery Dissection after a Chiropractic Neck Manipulation, and they reference an estimated 1 in 20,000 spinal manipulations results in a vertebral artery aneurysm or dissection and ischemic infarct. We all know this is not true, and the facts are absolutely wrong, so I asked Dr. Clum to come on again for us and walk us through the right way to go about letting the university and the author know that their article referenced statistics that are incorrect and not at all based on current research and literature that we have so readily available. I want to bring Dr. Clum on, and our goal is to get inside your head, Dr. Clum, and understand how you approach these situations because you did respond to this on numerous occasions, and I know that's what you're going to bring us up to speed on, and how do you decide when to respond and ultimately what to expect the outcome to be? Can you tell us first, how did you even learn about this article from Baylor? Thanks, Stu. I appreciate it very much, and it's great to be with you again today. The Baylor article came to light in a very odd fashion. There was a promotional piece that was produced by the Vanderbilt University Medical Center last year. It was talking about their neurology department and their helicopter air flight service and that sort of thing, and they used the example of a case of a woman who had a vertebral artery dissection. She was in the chiropractor's office. She had the vertebral artery dissection, and it was recognized. The chiropractor took the appropriate steps, made the appropriate emergency calls. The woman wound up going to the Vanderbilt University Medical Center by way of their ambulance service. The neurology folks did their job. It had a very good outcome, and the woman returned to her family and to her life and, essentially, it was a feel-good story for everybody from Vanderbilt's perspective.

Dr. Clum:

In that article, they made reference to this 1 in 20,000 number that you just spoke of. I thought I had an understanding of where they came up with that

number, I also understood that number that appeared in the literature to have been an opinion piece. I contacted Vanderbilt and, sure enough, Vanderbilt said, "Yeah, we got that from this article in Baylor that you referenced at the start of the discussion today," Stu. I said thank you, went back to Baylor and asked them about it. First, reviewed the article carefully. The first step in the process was, in reviewing the article, if you understand the literature and so on and you see the references that they're making in the article, are the references being applied properly? In this case, they weren't, and the references in the article that they had tied to their assertion that an adjustment resulted in a dissection in 1 in 20,000 cases was completely inaccurate. At first step, I wrote them and pointed out the fact that the evidence they offered, i.e, the reference, didn't support the statement they were making. They wrote back, and they said, "Thank you. We appreciate you pointing out the error. We'll change the reference. We did, in fact, make a mistake on it, and this is what we based it on." They based it on a 1989 article from the British Medical Journal by an author by the name of Vickers. The unfortunate part of the Vickers article is that it's an entirely opinion-based statement. There's no data. There's no study. There's no control group. It's just an opinion. It's kind of like, Stu, how often do people move to Phoenix? A hundred a day. You don't know that, and you don't have any basis to say that. There are people that do know that and can tell you that number, probably down to the family, but you don't know when you say that. This number was tossed out, this 1 in 20,000, as an opinion piece. All of a sudden, it gained a life of its own. Baylor came back, and they said, "By the way, there's two other pieces of literature that we'd also like to add to this discussion," and they came out of Australia. One was by a fellow by the name of Dunn that was in 1990, and then there was another by a fellow by the name of Mann. When you looked at all three of them, you soon realized that they got into this circular argument where each used the other to reinforce its opinion. Mann relied on Vickers, and Dunn relied on Mann and Vickers, so this thing starts to have a life of its own where this number of 1 in 20,000 pops up, and then it gets reinforced by the next person using it and the next person using it, and nobody goes back and says, "Hey, wait a minute. That's just an opinion piece." In 1989, that may have been the best available at the moment, but the bottom line was that, certainly, in 2016 when this was written, let alone 2017, it's certainly not the best available today. The next level of the discussion with Baylor was to point out the literature that's evolved since then, going on and starting with Rothwell in 2001 in Stroke, moving on to Cassidy in 2007 in Spine, moving on to Kosloff in 2015, and then moving on to Church in 2016, and how absolutely inconsistent their data-driven

numbers were with this 1 in 20,000 piece. Bottom line was they really weren't interested in the discussion.

Dr. Hoffman:

Dr. Clum, let me ask you first, when did you even make a decision to even approach them on this and what were we actually looking for as a result of that? The decision to pursue it was based upon the fact that Vanderbilt was running with this number, as I said before, in a promo piece for their own facility. It was members of the chiropractor community in Tennessee who were really being at risk and being disadvantaged by the fact that a very prominent and major university in their area was promoting inaccurate data. In an attempt, naively thinking on some level, that if we put the right numbers in front of them, obviously, they'll default to the right numbers. That wasn't the case. They backed up, and they said, "Well, this came from Baylor." Once I got on the track of it, it kind of became, I don't want to go as far as to say an obsession, but I became irritated about the way they were approaching it and just stayed on it to try to run it to ground to get it corrected. Quite honestly, I talked with a number of people that are active in this area in and around the discipline, and they all laughed and said, "Well, don't expect it to change." I said, "Well, it's a Don Quixote moment. We'll [inaudible 00:09:25] at the window a little bit and hope that we can change the course of the culture in that regard." In the final analysis, we didn't, but the point of this discussion today is for our colleagues and your listeners to understand how a bad number that's based on nothing but opinion can grow legs, get embedded into the literature, and move forward and, if they know how and where that number came from, they can undermine conclusions that are drawn on that number, or based on that number, and set the record straight and put the potential risk, potential risk, not verified risk, but potential risk in context in relationship to other activities in healthcare. This became a process of, if we could change the hearts and the minds of the authors, great. If we could change the record, even better. If we could come to an agreement, fantastic. None of those things happened, but it's a great opportunity to point out to the practicing chiropractor how this stuff gets started, how it gets sustained, and what they can do to deal with it. I think that something that you said is really important, but I want to shift it a little bit. I know that you've gone back and forth with them, on numerous occasions at this point and, to date, nothing has mattered. You won't ever say it, but I will. We have to assume that's a professional/political agenda because why would you ignore all of the overwhelming documentation that you recited in terms of what's been going on in this stroke awareness over the last 15-20 years.

Dr. Clum:

Dr. Hoffman:

The references that you cited are so in contrast to these numbers, how could they just simply ignore it if they didn't have their own motivation. I'm not asking you to even respond to that. That's just my point of view on it. Is there more to this that we're waiting on? Is there more to it that we can do because, as I said, I know you've gone back and forth, not just with Baylor, but with Vanderbilt also and, so far, really more of a stonewall. That's true. In terms of next steps, the only thing that we can do at this point is be diligent. Early on in these discussions relative to this whole subject area, Allan Terrett in Australia produced a magnificent monograph where he went back, and he researched every single piece of literature that had made reference to a chiropractor related to a stroke, and he found, right off the bat, that more than half of them, a chiropractor was never involved. The first thing we need to do is, we need to study the literature that comes out on this subject and hold the authors accountable to what they say. More recently than Allan Terrett's work, Adrian Wenban in Europe at the Barcelona College which, by the way, was accredited over the weekend, and we're very happy for Adrian and his colleagues in Barcelona. Adrian has run to ground a number of misstatements from different authors, particularly in Europe, and has been able to get letters of correction into the literature. The whole goal of this process is to get more information, more correct information, into the literature to be able to offset and to begin to erode the garbage literature from decades ago that still pops up, like the Vickers piece. The Vickers assumption, again, purely a guess but, as you noted in the literature that I talked about from Rothwell to Cassidy to Kosloff and on to Church, they all have good, solid case-controlled, case-crossover data upon which epidemiological conclusions can be drawn. When you have that data and you look at those conclusions, they're light years apart from that 1 in 20,000 discussion in Vickers. The goal in this process is to bring a focused point of view to the author that wrote the piece that you have concerns with, to get it into the literature, to get a correction statement in there that, whenever that's used, we have something else to make reference to and not let a misstatement perpetuate on its own without response. If you're not the editor of that journal, you don't control what's going to go into that journal but, if we don't speak up, we know for a fact it'll never get corrected. The process that, from my side, that I've been involved in and many others have been, is how can we keep the authors honest in relationship to what they write about us and the incidents data and so on. From the practitioners' side, the value is that, when they're confronted with a number, they need to understand that there's a way to deal with it and put it in context that is logical, rational, data-driven, and evidence-based as opposed to being opinion-based. When I'm out, including this last weekend, talking to a number of doctors about the whole stroke blame-game, some of them will say to me, "Well, I'm an

Dr. Clum:

Dr. Hoffman:

activator doctor. It's irrelevant," which is interesting because, this last week, we had an article come out documenting an activator adjustment causing a vertebral body dissection and stroke. In fact, I've been in touch with Arlan Fuhr about that, and he's doing exactly what you did in this situation. He's starting that process of responding to them with information that is relevant utilizing research, some that he's done and some that we've even talked about on here. I think it's very important that the doctors know that this information that comes out will get in the hands of every attorney in the country. When that happens, it's another thing that we have to deal with to overcome whenever you are accused wrongly of causing an actual dissection and stroke. Some of the doctors are very appreciative of that because they either had their own experience and/or know someone that has, but a lot of people don't realize how close this hits to home. One of the examples that I've given a number of times is, one of the claims, unfortunately, that we've taken in was an older woman that came in to the doctor's office, just filling out paperwork, and they see that she's not okay. They call 9-1-1, she winds up going to the hospital, they're saying it was a stroke, and she died. No one in the family knows what was going on. They called it a chiropractic stroke but, in the end, she never saw the chiropractor. She never even finished filling out her paperwork, but the fact that she merely came from the chiropractor's office just like this led to a lot of assumptions. Based on those assumptions, the family sues the chiropractor for causing her stroke and death. We have to understand that this is an attack, whether we like it or not, and we need to utilize information that is credible and just responding, which is what I want to get to, just responding, "No, that doesn't happen. No, this. No, that" and having it be an emotional response does not work. We need to use some of the references like, "You signed it earlier," and we have almost all of those in our informed consent packet already for the doctors to familiarize themselves with and be able to educate rather than defend. That's what my concern is with the doctors being able to understand that this information, when it comes out, it can be very far-reaching. It may not hit home for them personally or for them today, but it's something that we, as a profession, will have to deal with if it's not corrected for a long time to come. That's correct. One of the great things of the moment that we're living is the capacity that the internet provides us, and the problem is that there's no filter on it. There's no truth panel on the internet that says, "This is true. This is false." It's just up there. That's one part of it on the public side. On the more scientific side, when you go to something like PubMed, and that's where that attorney that you're talking about is going to go, they're going to find these case studies. The reality is that case studies cannot be used to establish causation nor can they be used to cause rates of incidence of a given circumstance or problem. That would be like you and me saying, "Stu, the last three people that I had

Dr. Clum:

come through the office had headaches, and they were completely resolved after one adjustment. Therefore, 100% of headaches resolve with one adjustment." That's asinine. We wish that were true, but that's not the reality of the world. The same thing happens in the literature out there is that, when people run with a case study, positively or negatively, if we, as chiropractors, assert because we have a patient that had a great resolution of a problem of a given nature, and we run with that and say, "Chiropractic can address this," that's as wrong as them running with it and saying, "Chiropractic can cause this" in the other direction, in the negative direction. We need to be careful about how we're behaving on our side of the aisle and then, at the same time, we need to hold them accountable on their side of the aisle. The articles that I made reference to before, the Vickers, the Dunn, and the Mann, none of them, none of them have the epidemiological power to assert causation or incidence data or incidence of occurrence of dissection associated with, let alone caused by, a chiropractic adjustment. This house of cards get built up with the improper use of substandard data that has to be displaced by proper data that's properly used, and that's the discussion that we're talking about today. You're absolutely right that, once things get into the literature, they do take on a life of their own, and we have to deal with it. For example, the case that you made relevance to relevant to activator care, I had a chance to review that article, which was really quite interesting but, if I'm understanding I properly, they're suggesting that an elderly woman had a hemorrhage in her occipital lobe as a result of an activator thrust at the cervical/cranial junction. It's not even a vertebral artery dissection. They're saying that the activator, through the skull, caused a hemorrhage in the occipital lobe of the brain. If it's a stretch, no pun intended, for an activator to cause a vertebral artery, how far do you have to stretch to think about an activator being applied to the craniocervical junction causing a hemorrhage inside the brain. It's crazy-making in that regard. It's not biologically possible in any shape, form, or fashion. They did, in the article, say that they've never seen anything like this in history. Well, yeah, that's true because it's Haley's Comet. It's going to come around once every 482 years or whatever, and it hasn't got anything to do with what you're wearing that day or who you went to or what you drank or what you ate. It's going to happen. Those things happen, and they need to be put in the proper context. As our colleagues grapple with these things, I come across two attitudes. One, people that are overwrought with concern about this, to the point that it becomes crippling and gets in the way of them living their professional lives and doing the good they can do, and the other end of the spectrum that blows if off completely.

The truth of the matter is, like most things, the truth is in the middle, and both ends are wrong. That's the perspective I think you and I would like to see our colleagues take, is that every chiropractor, every single chiropractor should be intimately familiar with the literature that we've talked about today and that, when I talk about Rothwell or Cassidy or Kosloff or Church, they should know exactly what I'm talking about in detail. That may sound unreasonable to some people. They may say, "Well, that's just not part of my world." Make it part of your world because the challenges that come to us are best responded to with the information that those articles carry and convey. You need to know what they say. You need to understand the methodology involved. You need to understand the implication relative to the epidemiology involved and the power of those studies in relationship to a case study or a case series or something of that nature. The more we can get our colleagues to understand that, the old story that we were taught since we were kids, the best defense is a good offense, if we have the data, if we know what we have, we can use those tools in our play. If we don't, then we're left with nothing but defense. Lord knows, we don't want that at all. I want to reiterate that this is about elevating our doctors' level of awareness, not elevating their fear. It's actually what I got from you, just a little different format. I think, on top of that, I get the same when I'm talking to doctors all the time. In fact, there was a doctor in the last week or so that contacted me because so many of our colleagues assume this has nothing to do with them or their practice, but the more and more publicity that is out there about this, it is affecting every single practice whether we are keeping our head in the sand, as you said, or not. Some of the doctors don't realize until someone does ask them a question, and this doctor contacted me, do I have any information about this, this, and this? I sent the information that we had, but they wanted more specific. This particular situation was more [inaudible 00:26:25] that we talked about in great lengths. It was all because a patient's father, I believe it was, wanted more information, so this doctor, it's my opinion, felt that they needed more to prove to that one individual that we're okay. We cite different things, even in our informed consent, things to demonstrate how ridiculously safe a chiropractic adjustment actually is, compared to any other healthcare service that's out there. Part of my devotion and passion for bringing this information to the profession is because I don't want this information to, one day, overcome our colleagues and their practices because it can if we don't do something about it and stay vigilant with each one of these things that come out.

Dr. Hoffman:

Thank God someone like you does respond to Baylor and to Vanderbilt on the professions we have, but at least you did it based on the literature and clear,

concise information. That's what everyone should be utilizing and, if they don't have the tools for that, certainly bring to any of our attention things that you see out in the public. You also said something about our own colleagues putting out information about, I'll just pick one, neuropathy. It's not to suggest that we shouldn't take care of patients suffering from neuropathy or diabetic neuropathy, but some of the promotion that we get to see simply says, "Where medicine has failed, we can definitely make you better." I'm exaggerating, but only a little bit. Those are the things that wind up going to our licensing boards, and then we complain that our boards are being unfair. I've written about our boards being activists and some of the things I think are unfair, but not everything. We have to take responsibility, as you said, for what we're talking about, what we're writing, what we're putting out in the public because it affects the entire profession, not just you as an individual. I think that's where you touched on. I appreciate your words on that. I guess it's the long way of saying it. Where do we go from here? Is there any avenues left with this whole Baylor issue? Is there more back and forth? What's still available to us? I don't believe that's a viable option. I don't believe that's ... I think, as much as we want to do that, as much as we feel assaulted by their attitude and their perspective on some of these things, I'll be honest with you, the feedback came from them. I'm paraphrasing this, but it basically said, "Hey, listen. [inaudible 00:30:01] you want us to make to this matter is three times longer than the original article. We're not going to do that." It came down to the length of the response was too much in comparison to the original article. I was dumbfounded by the idea that sometimes it takes a long time to explain a problem. When you put the problem on the table, then it takes a good bit of information to correct it so that it's understandable, why wouldn't we want to pursue this? I didn't understand there was a word limit to addressing these kinds of concerns. Relative to this, the real bottom line is that Stu Hoffman can respond to the things that come onto the table, Jerry Clum can respond to the things that come onto the table, other people who have a good understanding of the literature can do the same thing, but we need to disseminate that knowledge base among the chiropractic community at large, and every chiropractor needs to take responsibility for being on top of this literature and understanding what it says and understanding, more importantly, what it means. I, quite honestly, haven't thought that far into it. If you're suggesting can we bring litigation against them, can we complain to somebody, that sort of thing. I was indicating that, yes.

Dr. Clum:

Dr. Hoffman:

Dr. Clum:

As you had said, one of the things that we do is that we want to get excited and agitated when we're confronted with something in our circle. I would ask that, as people do get angry and respond to those kinds of things, that they think about the logic and the rationale that they respond to concerns that they have in other disciplines and are you applying the same standard to yourself that you're expecting of other people. It leads to that circumstance you were talking about where you wind up with a half-page ad in the morning newspaper as you open it up that has a kernel of truth to it but, by the time you read and get through the entire ad, it's not a kernel, it's a whole ear of corn. Extrapolating out and making inappropriate assertions and conclusions or allowing those to be made in the mind of the reader, it's troublesome. In time, it's eventually going to come back and bite people in the butt, and then they wind up at your doorstep wanting help or they wind up with me saying, "Will you come testify for me before the board," or whatever the case might be. We need to be careful. The formula for the day is, be diligent, pay attention to what comes across the table, and make sure that the information is countered and addressed. Number two, pass it along to other people. Don't assume that because you saw it, everybody else saw it. Send it to you, send it to me. Make sure it gets into the discussion realm that we can begin to address it more formally. Is there an organizational response that you can make? Is there an institutional response that one of our educational institutions can make, and so on? Those are the things that we have to do. To the degree that we can do them effectively, we can impact this whole circumstance more efficiently. Thanks, Dr. Clum. As always, I appreciate your insights. We share a lot of the same things as we cross paths around the country and on the telephone with doctors on a daily basis. For those of you that are watching that don't already utilize and have our informed consent packet, certainly go onto our Facebook and/or our website and sign up for our concierge service, request it. Please like us on Facebook and download our ChiroSecure app on your smartphone, but we will keep you up to date on any and everything that comes out. This last weekend, I was thanked by so many people for the information that we've made available to them that they wouldn't have had had we not brought it to the forefront, so we have people like Dr. Clum that is intimately involved in protecting doctors from reading, understanding, and responding to issues like the Baylor article that came out. We're thankful for him, and we appreciate all of you for participating and staying in tune with what we have to offer. As Dr. Clum said, please read the articles, understand it, and then you could pass along information to your patients and your community that's based on actual research rather than emotion. That's what we want to convey to you, so thank you and have a great day.

Dr. Hoffman:

Sent: Thu, Feb 2, 2017 7:28 am Subject: RE: Requested correction to Vertebral artery dissection after a chiropractic neck manipulation, Proc (Bayl Univ Med Cent) 2015(28)(1)88-90 Dear Dr. Clum, Dr. Nugent has provided a response (see attached), and we can print your letter (or a slightly modified version of it) and his response in the April issue. I'll get the page proofs to you around February 18th. Regards, Cindy Orticio -----Original Message----- From: Dr. Gerard Clum [ mailto:gerard.clum@life.edu ] Sent: Monday, January 23, 2017 3:26 PM To: Subject: {EXTERNAL} FW: Requested correction to Vertebral artery dissection after a chiropractic neck manipulation, Proc (Bayl Univ Med Cent) 2015(28) (1)88-90 Dear Ms., I am writing to you in your role as the Managing Editor of the Proceedings of the Baylor University Medical Center. On December 9, 2016 I sent the attached letter to Dr. Catherine Jones, the corresponding author of "Vertebral artery dissection after a chiropractic neck manipulation" Proc (Bayl Univ Med Cent) 2015(28)(1)88-90 requesting a correction to this paper. The correction requested and the rationale for the correction were detailed in my December 9, 2016 letter. On December 20, 2016 I followed up my letter of December 9, 2016 with a second request for response from Dr. Jones. To date I have not heard anything from Dr Catherine Jones regarding this issue. I now turn to you as the Managing Editor of the Proceedings to secure your help in having the inaccurate and very misleading information put forward in the article in question corrected. I have reviewed the "Policy on Misconduct in Research" found on the Baylor University website. I would appreciate being provided with the e-mail address

and name of the party at Baylor to whom a complaint under this policy should be directed in the event this becomes necessary. My original letter of December 9, 2016 was copied to you. I am assuming that it would have been your expectation that Dr. Jones would have responded to this matter by now. In the absence of any response this message has been necessitated. Thank you for your consideration and follow through. Gerard W. Clum, D.C. gerard.clum@life.edu ________________________________________ From: Dr. Gerard Clum Subject: Requested correction to Vertebral artery dissection after a chiropractic neck manipulation, Proc (Bayl Univ Med Cent) 2015(28)(1)88-90 Dear Dr., Attached please find a letter detailing a correction request with respect to the publication noted above. Thank you for your consideration. Sincerely, Gerard W. Clum, D.C. Life University Marietta, Georgia


February 2, 2017 Response to letter from Gerard W Clum, D.C. regarding case report: Vertebral artery dissection after a chiropractic neck manipulation, Proceedings (Baylor University Medical Center) 2015; 28 (1): 88- 90. Dear Dr. Clum, We appreciate your letter alerting us to the discrepancy between the estimated frequency of vertebral artery dissection following spinal manipulation and the reference cited in our discussion. We did cite the wrong reference in this portion of our discussion of this case report. The original reference for this number comes from a paper written by Andrew Vickers and Catherine Zollman entitled “The manipulative therapies: osteopathy and chiropractic”. This was published in the British Medical Journal in 1999; they provide estimates for severe adverse effects ranging from 1 in 20,000 patients to 1 in 1,000,000 patients undergoing cervical spine manipulation. 1 These authors provided no reference for those numbers. Timothy Mann quotes the same number range and includes an estimate as high as 1 in 4,500 based on abstract from JW Dunne presented at a meeting in 2000. 2,3 Rothwell and colleagues have provided an estimate based on a population-based case-controlled study published in Stroke in 2001. These authors suggest that 1.3 vertebral artery accidents occur per 100,000 persons aged <45 years within 1 week of manipulation. The 95% confidence interval for this estimate is 0.5-16.7 per 100,000. 4 The upper boundary of this confidence interval translates into 1.7 accidents per 10,000 manipulations. Consequently, our second review of this literature indicates that these numbers are difficult to obtain, and that there is a wide range in these estimates. The numbers 1 in 20,000 to 1 in million seem reasonable even though this range is extremely broad. The important point in this case report is that clinicians need to think about cervical spine trauma in young patients who present with vertebral artery dissections or aneurysms.

1. Vickers A, Zollman C. ABC of complementary medicine. The manipulative therapies: osteopathy and chiropractic. BMJ (Clinical research ed) 1999; 319 (7218): 1176-9.


2. Mann T, Refshauge KM. Causes of complications from cervical spine manipulation. Aust J Physiother 2001; 47 (4): 255-66. 3. Dunne JW HNaMD. Neurological complications after spinal manipulation: a regional survey. Proceedings of the 7th Scientific Conference of the International Federation of Orthopaedic ManipulativeTherapists 2000: 90. 4. Rothwell DM, Bondy SJ, Williams JI. Chiropractic manipulation and stroke: a population-based case-control study. Stroke 2001; 32 (5): 1054-60.

Respectfully yours, Jeremy Jones, MD Catherine Jones, MD Kenneth Nugent, MD

SPINE Volume 33, Number 4S, pp S176–S183 ©2008, Lippincott Williams & Wilkins

Risk of Vertebrobasilar Stroke and Chiropractic Care Results of a Population-Based Case-Control and Case-Crossover Study J. David Cassidy, DC, PhD, DrMedSc,*†‡ Eleanor Boyle, PhD,* Pierre Coˆte´, DC, PhD,*†‡ § Yaohua He, MD, PhD,* Sheilah Hogg-Johnson, PhD,† § Frank L. Silver, MD, FRCPC,¶ ! and Susan J. Bondy, PhD†

Study Design. Population-based, case-control and case-crossover study. Objective. To investigate associations between chiro- practic visits and vertebrobasilar artery (VBA) stroke and to contrast this with primary care physician (PCP) visits and VBA stroke. Summary of Background Data. Chiropractic care is popular for neck pain and headache, but may increase the risk for VBA dissection and stroke. Neck pain and head- ache are common symptoms of VBA dissection, which commonly precedes VBA stroke. Methods. Cases included eligible incident VBA strokes admitted to Ontario hospitals from April 1, 1993 to March 31, 2002. Four controls were age and gender matched to each case. Case and control exposures to chiropractors and PCPs were determined from health billing records in the year before the stroke date. In the case-crossover analysis, cases acted as their own controls. Results. There were 818 VBA strokes hospitalized in a population of more than 100 million person-years. In those aged ! 45 years, cases were about three times more likely to see a chiropractor or a PCP before their stroke than controls. Results were similar in the case control and case crossover analyses. There was no increased association between chiropractic visits and VBA stroke in those older than 45 years. Positive associations were found between PCP visits and VBA stroke in all age groups. Practitioner visits billed for headache and neck From the *Centre of Research Expertise for Improved Disability Outcomes (CREIDO), University Health Network Rehabilitation Solutions, Toronto Western Hospital, and the Division of Heath Care and Outcomes Research, Toronto Western Research Institute, Toronto, ON, Canada; †Department of Public Health Sciences, Management and Evaluation, University of Toronto, Toronto, ON, Canada; ‡Department of Health Policy, Management and Evalua- tion, University of Toronto, Toronto, ON, Canada; §Institute for Work & Health, Toronto, ON, Canada; ¶University Health Net- work Stroke Program, Toronto Western Hospital, Toronto, ON, Canada; and ! Division of Neurology, Department of Medicine, Fac- ulty of Medicine, University of Toronto, Toronto, ON, Canada. Supported by Ontario Ministry of Health and Long-term Care. P.C. is supported by the Canadian Institute of Health Research through a New Investigator Award. S.H.-J. is supported by the Institute for Work & Health and the Workplace Safety and Insurance Board of Ontario. The opinions, results, and conclusions are those of the authors and no endorsement by the Ministry is intended or should be inferred. The manuscript submitted does not contain information about medical device(s)/drug(s). University Health Network Research Ethics Board Approval number 05-0533-AE. Address correspondence and reprint requests to J. David Cassidy, DC, PhD, DrMedSc, Toronto Western Hospital, Fell 4-114, 399 Bathurst Street, Toronto, ON, CanadaM5T 2S8; E-mail: dcassidy@uhnresearch.ca

complaints were highly associated with subsequent VBA stroke. Conclusion. VBA stroke is a very rare event in the population. The increased risks of VBA stroke associated with chiropractic and PCP visits is likely due to patients with headache and neck pain from VBA dissection seek- ing care before their stroke. We found no evidence of excess risk of VBA stroke associated chiropractic care compared to primary care. Key words: vertebrobasilar stroke, case control stud- ies, case crossover studies, chiropractic, primary care, complications, neck pain. Spine 2008;33:S176–S183 Neck pain is a common problem associated with consid- erable comorbidity, disability, and cost to society. 1–5 In North America, the clinical management of back pain is provided mainly by medical physicians, physi- cal therapists and chiropractors. 6 Approximately 12% of American and Canadian adults seek chiropractic care annually and 80% of these visits result in spinal manipulation. 7,8 When compared to those seeking medical care for back pain, Canadian chiropractic pa- tients tend to be younger and have higher socioeco- nomic status and fewer health problems. 6,8 In On- tario, the average number of chiropractic visits per episode of care was 10 (median 6) in 1985 through 1991. 7 Several systematic reviews and our best- evidence synthesis suggest that manual therapy can benefit neck pain, but the trials are too small to eval- uate the risk of rare complications. 9 –13 Two deaths in Canada from vertebral artery dissec- tion and stroke following chiropractic care in the 1990s attracted much media attention and a call by some neu- rologists to avoid neck manipulation for acute neck pain. 14 There have been many published case reports linking neck manipulation to vertebral artery dissection and stroke. 15 The prevailing theory is that extension and/or rotation of the neck can damage the vertebral artery, particularly within the foramen transversarium at the C1–C2 level. Activities leading to sudden or sus- tained rotation and extension of the neck have been im- plicated, included motor vehicle collision, shoulder checking while driving, sports, lifting, working over- head, falls, sneezing, and coughing. 16 However, most cases of extracranial vertebral arterial dissection are thought to occur spontaneously, and other factors such as connective tissue disorders, migraine, hyper- tension, infection, levels of plasma homocysteine, ves- sel abnormalities, atherosclerosis, central venous


Risk of VBA Stroke and Chiropractic Care • Cassidy et al


Methods Study Design

catherization, cervical spine surgery, cervical percuta- neous nerve blocks, radiation therapy and diagnostic cerebral angiography have been identified as possible risk factors. 17–21 The true incidence of vertebrobasilar dissection is un- known, since many cases are probably asymptomatic, or the dissection produces mild symptoms. 22 Confirming the diagnosis requires a high index of suspicion and good vascular imaging. The cases that are most likely to be diagnosed are those that result in stroke. 19,22 Ischemic stroke occurs when a thrombus develops intraluminally and embolizes to more distal arteries, or less commonly, when the dissection extends distally into the intracranial vertebral artery, obliterating branching vessels. 22 The best incidence estimate comes from Olmstead county, where vertebral artery dissection causing stroke affected 0.97 residents per 100,000 population between 1987 and 2003. 23 To date there have been two case-control studies of stroke following neck manipulation. Rothwell et al used Ontario health data to compare 582 cases of VBA stroke to 2328 age and sex-matched controls. 24 For those aged ! 45 years, cases were five times more likely than con- trols to have visited a chiropractor within 1 week of VBA stroke. Smith et al studied 51 patients with cervical ar- tery dissection and ischemic stroke or transient ischemic attack (TIA) and compared them to 100 control patients suffering from other strokes not caused by dissections. 25 Cases and controls came from two academic stroke cen- ters in the United States and were matched on age and sex. They found no significant association between neck manipulation and ischemic stroke or TIA. However, a subgroup analysis showed that the 25 cases with verte- bral artery dissection were six times more likely to have consulted a chiropractor within 30 days before their stroke than the controls. Finally, because patients with vertebrobasilar artery dissection commonly present with headache and neck pain, 23 it is possible that patients seek chiropractic care for these symptoms and that the subsequent VBA stroke occurs spontaneously, implying that the associ- ation between chiropractic care and VBA stroke is not causal. 23,26 Since patients also seek medical care for headache and neck pain, any association between pri- mary care physician (PCP) visits and VBA stroke could be attributed to seeking care for the symptoms of verte- bral artery dissection. The purpose of this study is to investigate the asso- ciation between chiropractic care and VBA stroke and compare it to the association between recent PCP care and VBA stroke using two epidemiological designs. Evidence that chiropractic care increases the risk of VBA stroke would be present if the measured associa- tion between chiropractic visits and VBA stroke ex- ceeds the association between PCP visits and VBA strokes.

We undertook population-based case-control and case- crossover studies. Both designs use the same cases. In the case- control design, we sampled independent control subjects from the same source population as the cases. In the case-crossover design, cases served as their own controls, by sampling control periods before the study exposures. 27 This design is most ap- propriate when a brief exposure ( e.g. , chiropractic care) causes a transient change in risk ( i.e. , hazard period) of a rare-onset disease ( e.g. , VBA stroke). It is well suited to our research ques- tions, since within person comparisons control for unmeasured risk factors by design, rather than by statistical modeling. 28–30 Thus the advantage over the case control design is better con- trol of confounding. Source Population The source population included all residents of Ontario (109,020,875 person-years of observation over 9 years) cov- ered by the publicly funded Ontario Health Insurance Plan (OHIP). Available utilization data included hospitalizations with diagnostic coding, and practitioner (physician and chiro- practic) utilization as documented by fee-for-service billings accompanied by diagnostic coding. We used two data sources: (1) the Discharge Abstract Database (DAD) from the Canadian Institute for Health Information, which captures hospital sep- arations and ICD codes, and (2) the OHIP Databases for ser- vices provided by physicians and chiropractors. These data- bases can be linked from April 1992 onward. Cases We included all incident vertebrobasilar occlusion and stenosis strokes (ICD-9433.0 and 433.2) resulting in an acute care hos- pital admission from April 1, 1993 to March 31, 2002. Codes were chosen in consultation with stroke experts and an epide- miologist who participated in a similar past study (SB). 24 Cases that had an acute care hospital admission for any type of stroke (ICD-9433.0, 433.2, 434, 436, 433.1, 433.3, 433.8, 433.9, 430, 431, 432, and 437.1), transient cerebral ischemia (ICD- 9435) or late effects of cerebrovascular diseases (ICD-9438) before their VBA stroke admission or since April 1, 1991 were excluded. Cases residing in long-term care facilities were also excluded. The index date was defined as the hospital admission date for the VBA stroke. Controls For the case-control study, four age and sex-matched controls were randomly selected from the Registered Persons Database, which contains a listing of all health card numbers for Ontario. Controls were excluded if they previously had a stroke or were residing in a long-term care facility. For the case crossover study, four control periods were ran- domly chosen from the year before the VBA stroke date, using a time-stratified approach. 31 The year was divided into disjoint strata with 2 week periods between the strata. For the 1 month hazard period, the disjoint strata were separated by 1 month periods and the five remaining control periods were used in the analyses. We randomly sampled disjoint strata because chiro- practic care is often delivered in episodes, and this strategy eliminates overlap bias and bias associated with time trends in the exposure. 32

S178 Spine • Volume 33 • Number 4S • 2008

Exposures All reimbursed ambulatory encounters with chiropractors and PCPs were extracted for the one-year period before the index date from the OHIP database. Neck-related chiropractic visits were identified using diagnostic codes: C01–C06, cervical and cervicothoracic subluxation; C13–C15, multiple site subluxa- tion; C30, cervical sprain/strain; C40, cervical neuritis/ neuralgia; C44, arm neuritis/neuralgia; C50, brachial radiculi- tis; C51, cervical radiculitis; and C60, headache. For PCP visits, we included community medicine physicians if they submitted ambulatory fee codes to OHIP. Fee codes for group therapy and signing forms were excluded. Headache or neck pain- related PCP visits were identified using the diagnostic codes: ICD-9307, tension headaches; 346, migraine headaches; 722, intervertebral disc disorders; 780, headache, except tension headache and migraine; 729, fibrositis, myositis and muscular rheumatism; and 847, whiplash, sprain/strain and other trau- mas associated with neck (These codes include other diagnoses, and we list only those relevant to neck pain or headache). There is no limit on the number of reimbursed PCP visits per year. However, there are limits chiropractors, but less than 15% of patients surpass them. 24 Statistical Analysis Conditional logistic regression was used to estimate the asso- ciation between VBA stroke after chiropractor and PCP visits. Separate models were built using different a priori specified hazard periods, stratified by age ( ! 45 years and ! 45 years) and by visits with or without head and neck pain related diag- nostic codes. For the chiropractic analysis, the index date was included in the hazard period, since chiropractic treatment might cause immediate stroke and patients would not normally consult a chiropractor after having a stroke. However, the in- dex day was excluded from the PCP analysis, since patients might consult these physicians after experiencing a stroke. We tested different hazard periods, including 1 day, 3 days, 1 week, 2 weeks, and 1 month before the index date. Exposure occurred if any chiropractic or PCP visits were recorded during the des- ignated hazard periods. We also measured the effect of cumulative numbers of chi- ropractic and PCP visits in the month before the index date by computing the odds ratio for each incremental visit. These es- timates were similarly stratified by age and by diagnostic codes related to headache and/or neck pain. Finally, we conducted analyses to determine if our results were sensitive to chiroprac- tic and PCP visits related to neck complaints and headaches. We report our results as odds ratios (OR) and 95% confidence intervals. Confidence intervals were estimated by accelerated bias corrected bootstraps with 2000 replications using the vari- ance-covariance method. 33 All statistical analyses were per- formed using STATA/SE version 9.2. 34 Results A total of 818 VBA strokes met our inclusion/exclusion criteria over the 9 year inception period. Of the 3272 matched control subjects, 31 were excluded because of prior stroke, one had died before the index date and 76 were receiving long-term care. Thus, 3164 control sub- jects were matched to the cases. The mean age of cases and controls was 63 years at the index date and 63% were male. Cases had a higher proportion of comorbid conditions (Table 1). Of the 818 stroke cases, 337

Table 1. Age, Sex, and Comorbid* Condition of Cases and Controls Variable Cases (n " 818) Controls (n " 3164)

Age: mean, median (SD)†

63.1, 66 (15.5)

62.6, 65 (15.4) 2022 (63.9)

Males: n (%)

518 (63.3) 276 (33.7) 275 (33.6) 155 (19.0) 62 (7.6) 515 (63.0)

Hypertension*: n (%) Heart Disease*: n (%) Diabetes*: n (%) High Cholesterol*: n (%) At least one comorbid condition§: n (%)

738 (23.3) 506 (16.0) 247 (7.8) 200 (6.3) 1294 (40.9)

*Comorbid conditions determined by ambulatory diagnostic codes from the Ontario Health Insurance Plan (OHIP) during year prior to index date. †SD is standard deviation. §Indicates the presence of at least one of hypertension, heart disease, diabe- tes or high cholesterol.

(41.2%) were coded as basilar occlusion and stenosis, 443 (54.2%) as vertebral occlusion and stenosis and 38 (4.7%) had both codes. Overall, 4% of cases and controls had visited a chiro- practor within 30 days of the index date, while 53% of cases and 30% of controls had visited a PCP within that time (Table 2). For those under 45 years of age, 8 cases (7.8%) had consulted a chiropractor within 7 days of the index date, compared to 14 (3.4%) of controls. For PCPs, 25 cases (24.5%) under 45 years of age had a consultation within 7 days of the index date, com- pared to 27 (6.6%) of controls. With respect to the number of visits within 1 month of the index date, 7.8% of cases under the age of 45 years had three or more chiropractic visits, whereas 5.9% had three or more PCP visits (Table 2). The case control and case crossover analyses gave sim- ilar results. (Tables 3–7) Age modified the effect of chi- ropractic visits on the risk of VBA stroke. For those un- der 45 years of age, there was an increased association between chiropractic visits and VBA stroke regardless of the hazard period. For those 45 years of age and older, there was no association. Each chiropractic visit in the month before the index date was associated with an in- creased risk of VBA stroke in those under 45 years of age (OR 1.37; 95% CI 1.04–1.91 from the case crossover analysis) (Table 7). We were not able to estimate boot- strap confidence intervals in some cases because of sparse data. Similarly, we found that visiting a PCP in the month before the index date was associated with an increased risk of VBA stroke regardless of the hazard period, or the age of the subject. Each PCP visit in the month before the stroke was associated with an increased risk of VBA stroke both in those under 45 years of age (OR 1.34; 95%CI 0.94–1.87 from the case crossover analysis) and 45 years and older (OR 1.52; 95% CI 1.36–1.67 from the case crossover analysis) (Table 7). Our results were sensitive to chiropractic and PCP visits related to neck complaints and headaches, and we observed sharp increases in the associations when re- stricting the analyses to these visits (Tables 3–7). Overall,

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