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Bariatric Surgery and Bone Health

>> Tuesday, November 20, 2012






The decision to undergo obesity (bariatric) surgery is a complex one, as the potential benefits and potential risks are many.  A longterm potential complication that is often overlooked is the effect that bariatric surgery can have on bones.


As outlined in an excellent review by Brzozowska and colleagues, the effect of bariatric surgery on bone health is not well understood.  As the potential effects, as well as what we know (and don't) is quite variable depending on what type of bariatric surgery is performed, here are a few notes organized by procedure:  (you can also read more about the procedures in general here)

Gastric Bypass Surgery:  We know that gastric bypass alters bone metabolism in favor of bone breakdown.  In many cases, this is at least partially due to vitamin D and/or calcium deficiency - both require supplementation lifelong after gastric bypass, and inadequate replacement will cause bone depletion over time.  There are many other factors involved as well - several hormones made in the fat tissue and the gut that change after gastric bypass surgery have been implicated in changes in bone metabolism as well. 

Sleeve Gastrectomy:  As a newer procedure, very little is known about the effect of sleeve gastrectomy on bone.  The available data suggests that sleeves do affect bone metabolism and can cause bone loss over time.

Gastric Banding:  It is not known whether gastric banding has an adverse effect on bones or not - studies done so far have shown conflicting results.  Gastric banding is a less invasive procedure that doesn't cause calcium or vitamin D deficiency, and doesn't cause as many hormonal changes as the other two surgeries.  (That being said, gastric banding is falling out of favor due to its poor longterm efficacy and high reoperation rates over the long term.)

A few important caveats to the above discussion:

1.  It is not known whether changes in bone metabolism seen with bariatric surgery result in an increase in fracture risk - more study is needed.

2.  The long term effect on bone metabolism is not known, as most studies done to date are only a year or two in duration.  Longer term studies will help us to understand the effect on long term fracture risk as well, which is the most important outcome measure.

3.  The effect on bones may be different not only by the type of surgical procedure, but also by age and gender - again, more study is needed.

The Bottom Line: Anyone having bariatric surgery should have a baseline bone density done before surgery, and bone density should be monitored after surgery as well (guidelines are available here).   While adequate calcium and vitamin D is an important component of bone health, there is much more about the effects of bariatric surgery on bone that we still don't understand.


Dr Sue Pedersen www.drsue.ca © 2012 

Follow me on Twitter for daily tips! @drsuepedersen

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New Data on Type 2 Diabetes and Obesity Surgery

>> Tuesday, October 2, 2012





At the European Association for the Study of Diabetes (EASD) meeting in Berlin today, I had the pleasure of sitting in on a session discussing the effects of obesity surgery on type 2 diabetes.  Whereas previous years of diabetes meetings have seen very sparse attendance at bariatric surgery talks, this session was absolutely packed. 

At this session, a number of fascinating studies were
presented.  Highlights included: (be warned - it's a very science-heavy blog this week!)

A study by S. Steven and colleagues (UK) looked at a group of 92
patients who had type 2 diabetes prior to having gastric bypass
surgery, with the aim of determining which factors were associated
with a greater chance of diabetes remission after surgery. One of
their findings was that the degree of weight loss achieved post op was
the main determinant of diabetes remission - controversial, as the
bulk of currently available evidence suggests that remission of
diabetes is independent of weight lost.

A study by Pournaras and colleagues found that a nifty removable liner placed
inside of the first 60cm of small intestine (called a duodenal-jejunal
bypass liner) improved type 2 diabetes control over a 1 year trial period.
This introduces the question as to whether, in the future, we can
consider less invasive alternatives to bariatric surgery (such as
these) to help control type 2 diabetes.


A couple of elegant studies out of Denmark (including colleagues Jens Juul Holst and Sten Madsbad who I collaborate with on research studies personally) and Sweden were presented, designed to give us a better understanding of just how obesity surgery improves type 2 diabetes (with a lot of arrows pointing to the increase in the hormone GLP-1 that is seen after surgery).

Finally, there was a neat study from Finland showing that the insulin resistance of fat in femoral bone marrow improves with bariatric surgery (I personally had not previously thought about bone marrow being insulin resistant!).  

Overall, a very exciting day, and a very exciting meeting!

Dr Sue Pedersen www.drsue.ca © 2012 drsuetalks@gmail.com

Follow me on Twitter for daily tips! @drsuepedersen

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Obesity Surgery to Treat Type 2 Diabetes?

>> Thursday, August 30, 2012






At the recent inaugural meeting of the Canadian Association of Bariatric Physicians and Surgeons, I was asked to review the recent consensus statement released by the International Diabetes Federation on the use of bariatric (obesity) surgery to treat patients with obesity and type 2 diabetes. 

(Skip to MY BOTTOM LINES below for a summary, or read through for the nitty gritty!)

The International Diabetes Federation consensus states:

1.  Bariatric surgery is an appropriate treatment for people with type 2 diabetes 
and obesity not achieving recommended treatment targets with medical 
therapies, especially when there are other major co-morbidities.

2.  Surgery should be an accepted option in people who have type 2 diabetes 
and a body mass index (BMI) of 35 or more.  (note - you can calculate your BMI in the right column here)

3.  Surgery should be considered as an alternative treatment option in patients 
with a BMI between 30 and 35 when diabetes cannot be adequately controlled 
by optimal medical regimen, especially in the presence of other major 
cardiovascular disease risk factors.


As I reviewed at the meeting, the literature shows that most patients with obesity and poorly controlled type 2 diabetes experience an improvement in their diabetes with obesity surgery (especially gastric bypass and sleeve gastrectomy).  We have more data for patients with a BMI ≥35 than we do for patients with a BMI of 30-35 at this point in time, but the literature for the latter group is growing. 

A large proportion of patients with type 2 diabetes will go into remission from their diabetes (meaning their diabetes goes away) after bariatric surgery, which of course sounds like a very attractive possibility to the person who has to deal with diabetes on a daily basis.


HOWEVER: 

  • Based on the data we have currently available, about half of these cases of diabetes that went into remission after gastric bypass surgery come back by 5 years after surgery (called 'recurrence').
  • Almost all of the long term data for diabetes remission rates is in patients with a BMI ≥ 35; there is almost no data to help us understand what the long term recurrence rate of type 2 diabetes is in the BMI 30-35 group.  People who have diabetes with this lower BMI may have a stronger genetic predisposition towards having diabetes, so it is plausible that these people would be less likely to have their diabetes stay away over the long term.
  • There is little data to help us understand long term recurrence rates of diabetes after sleeve gastrectomy (which is becoming increasingly popular - read more about the types of surgeries here).
  • The definition of diabetes 'remission' was previously quite loose and has now become much stricter; therefore, the remission rates reported in the literature are overinflated.


MY BOTTOM LINES on this controversial topic are:

1.  For people with a BMI of ≥ 35, with POORLY CONTROLLED diabetes:   Bariatric surgery is an option that provides a good opportunity to improve diabetes control.

2.  For people with BMI 30-35, with POORLY CONTROLLED diabetes:  There is very little information to guide us in this group of patients, but so far, it appears that bariatric surgery could provide a good opportunity to improve diabetes control.

3.  For people with BMI of ≥ 35 with GOOD CONTROL of their diabetes: Bariatric surgery can offer an opportunity to make diabetes go away - but for at least half of these patients (and possibly more over the longer term), the diabetes will come back. 

4.  For people with BMI of 30-35 with GOOD CONTROL of their diabetes: Bariatric surgery can make diabetes go away, but we don't yet know what percentage return to diabetes.  Due to genetics, their risk of return to diabetes may be higher than those with BMI ≥35.

5.  Any patient whose diabetes goes into remission after bariatric surgery MUST be followed for the rest of their life for screening for the possible return of diabetes.

And of course, for ALL people who are thinking about having bariatric surgery, the risks and benefits of the procedure as a whole must be carefully weighed by both patient and their health care providers, to decide if this intervention is the right thing for them.



Dr Sue Pedersen www.drsue.ca © 2012 drsuetalks@gmail.com

Follow me on Twitter for daily tips! @drsuepedersen

PS - Bariatric surgery has been shown to PREVENT development of Type 2 diabetes as well (scientists - recent follow up to the SOS study published in the New England Journal of Medicine) - a story for another day's blog!

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Obesity Surgery - Which Type is Best?

>> Saturday, June 9, 2012






This weekend, I've had the pleasure of attending and being invited to speak at the inaugural meeting of the Canadian Association of Bariatric Physicians and Surgeons in Toronto.  While I will share with you the information from my talk in an upcoming post (which was about the treatment of diabetes with obesity surgery), what I would like to share with you today is a fantastic debate held this morning, about which type of obesity surgery is the 'best' overall surgery.


The three main types of bariatric (obesity) surgery were compared:

1.  Gastric Banding:  This is an inflatable band that is placed around the upper part of the stomach.  It works by making the reservoir of the stomach smaller, so that only small amounts of solid food can be consumed, resulting in a sense of fullness after only a small amount of food.  The band can be adjusted to make it looser or tighter by filling or deflating it with salt water via a port that lies just under the skin.




2.  Sleeve Gastrectomy:  In this surgery, most of the stomach is removed, and the shape of the remaining stomach looks like a 'sleeve' - hence the name. 





3.  Gastric Bypass:   This surgery is the most complex of the three.  First, the stomach is made smaller (though the rest of the stomach is not physically removed).  Next, the small intestine is rerouted so that food bypasses the first part of the intestine, and absorption of nutrients first begins about 1.5 meters further down the intestinal canal.




Dr David Urbach of the University of Toronto began the debate with a discussion of the laparascopic adjustable gastric band.    On the positive side, the early complication rate of gastric bands is lower than for sleeve gastrectomy or gastric bypass.  However, the gastric band is not as effective to produce weight loss, and it's not as good to improve complications of obesity (eg diabetes, high blood pressure, sleep apnea).  Over the long term, gastric banding is not looking very good - as blogged previously, at 12 years after gastric banding, one study showed that 60% of people who had gastric banding needed a reoperation of some kind.  At 10 years, about half of patients have had their band removed (either because of complications, or because it was not effective).  While some people do have sustained weight loss over the long term with a band, a substantial proportion regain weight as well.

Dr Urbach concluded that gastric banding is probably not a good long term treatment for obesity, nor for the medical problems that go along with obesity.  He went so far as to say that the band is perhaps best considered only as a cosmetic procedure for patients wishing for weight loss.



Dr James Ellesmere of Dalhousie University reviewed sleeve gastrectomy.    He started off by noting that the sleeve is also quite a safe procedure to perform, with a low complication rate and a low risk of needing reoperation in the future.  In terms of short term risk of surgery, the risk is a bit higher than the short term risk of gastric banding, but lower than the risk of gastric bypass surgery.  The success in weight loss falls between banding and gastric bypass, and the improvement in complications of obesity (diabetes, sleep apnea, high blood pressure etc) also falls between banding and bypass.  An important down side of sleeves is that it is a newer procedure, and therefore, not much is known about long term efficacy (very few studies over 5 years exist).   The few studies that do exist show that there is variability in long term results - as with all of these surgeries, weight regain can occur.

Bottom line of sleeve gastrectomy:  It falls between gastric bands and gastric bypass in terms of benefits and risks, and we don't yet have a lot of long term data (though this data is coming). 


In regards to gastric bypass surgery, Dr John Hagen of the University of Toronto reviewed data that show that gastric bypass is the most effective of these surgeries to cause weight loss, and to improve diseases associated with obesity (diabetes, sleep apnea, etc).  As such, it is considered the gold standard surgery in many centres.  However, there is a significant downside as well: as it's the most invasive surgery, there is higher short term operative risk.  In addition, because food is not digested in the first part of the intestine, many crucial nutrients are not sufficiently absorbed from a regular diet - therefore, the patient undergoing this surgery must be prepared to take a mandatory array of vitamins and nutrients for the rest of their lives. 

Bottom line:  Gastric bypass has the highest success rate, but also the highest risk. 


My take on this discussion?  As always, the decision to undergo obesity surgery is a very serious one, and every person is different.  Risks and benefits not only of the types of surgery, but of surgery in general, must be carefully weighed by the patient and their health care providers.  In terms of which type of surgery to choose, gastric banding does not appear to be a good long term treatment strategy; gastric bypass surgery and sleeve gastrectomy appear to be the best options to consider.


Dr Sue Pedersen www.drsue.ca © 2012 drsuetalks@gmail.com

Follow me on Twitter for daily tips! @drsuepedersen

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Sexual Function Before and After Bariatric Surgery

>> Friday, April 27, 2012




In preparation of patients for bariatric ('weight loss') surgery, there are many issues to discuss with regards to postoperative changes that we need to prepare for, ranging from changes in meal size, to changes in medications, to vitamin supplements, and so on.  One important element that may often go under discussed is changes in sexual function after bariatric surgery.

People who struggle with weight may be at increased risk of sexual dysfunction, for many reasons, including:

1.  There is a higher risk of erectile dysfunction (ED) amongst men with obesity.

2.  Obesity can lead to lower testosterone levels in men. 

3.  Women with obesity are at increased risk of polycystic ovary sydrome, which affects reproductive hormones and is an important cause of infertility.

4.  Some medications that are used to treat complications of obesity (eg some blood pressure medications) can interfere with sexual function.

5.  Excess body weight can lead to body image issues that can negatively affect sex drive. 

And the list goes on....


After bariatric surgery, the effect on sexual function can be variable.   Medications needed to treat obesity related complications may decrease with weight loss, and hormone levels may improve towards normal.  The effect on body image can be highly variable - some may feel empowered and 'sexier' with a lower body weight, whereas others struggle with the excess skin that may become apparent.  The sexual partner's response to a body weight change can be variable as well - some may find it a positive change, whereas others may feel threatened by it. 


Fortunately, there is research going on in this important area!  There is astudy at the University of Pennsylvania ongoing currently, which will examine changes in sexual function, sex hormones, body image, and marital satisfaction after weight loss surgery, compared to people with obesity who do not have surgery. 

I would love to hear from any of my readers who would like to share their thoughts on this important topic.



Dr Sue Pedersen www.drsue.ca © 2012

drsuetalks@gmail.com 

Follow me on Twitter for daily tips! @drsuepedersen 

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Medications vs Bariatric Surgery for Treatment of Type 2 Diabetes

>> Thursday, April 5, 2012






It has become clear that bariatric (obesity) surgery can result in substantial improvement, or even remission, of type 2 diabetes for some people.   Two new articles from the New England Journal of Medicine now add to our knowledge on this topic.

(For the non-scientists in the audience, feel free to skip down to 'So what does this mean?' below.)

One of these studies, by Mingrone and colleagues, looked at 60 patients randomized to receive either gastric bypass surgery, biliopancreatic diversion surgery (BPD), versus their usual diabetes care with medications, and examined how many people would be in remission from their diabetes 2 years later.  They found that 75% of the patients who had gastric bypass and 95% of the patients who had BPD were in remission, whereas none of the control group was in remission.  Interestingly, none of age, gender, baseline body mass index, nor duration of diabetes were predictive of remission.

The other study, by Schauer and colleagues, randomized 150 patients to receiving either gastric bypass surgery, sleeve gastrectomy, versus usual medical care of type 2 diabetes, with the goal being to see how many patients from each group could achieve very tight control of their diabetes (defined by A1C of 6% or less) at one year.  They found that more patients who had surgery achieved this goal (42% of gastric bypass patients and 37% in sleeve gastrectomy patients), compared with 12% of patients receiving medications alone.  At one year, the mean A1C in the medication group was 7.5%, compared to 6.4% in the gastric bypass group and 6.6% in the sleeve gastrectomy group.

While each of these studies could be discussed with chapters of detail, for purposes of brevity I'll highlight just a couple of important caveats.  While a strength of these studies is that they are randomized clinical trials (very hard to do in the area of bariatrics), both studies are small.  In the Mingrone study, BPD was used as a surgical technique, which is a fairly drastic surgery (it bypasses more of the bowel than gastric bypass), and is currently only experimental.  The longer term follow up of these patients is important, as other studies now suggest that at 5 years after bariatric surgery, about half of the diabetes cases that initially went into remission come back (though the diabetes-free years are undoubtedly still of substantial health benefit).   In the Schauer study, one could argue that the diabetes control goal (A1C 6% or less) was too tight and not appropriate for routine clinical care, given that we no longer strive for this tight control in most cases of type 2 diabetes because of the potential risk of harm (see the ACCORD trial).  What is interesting to me, however, is that the overall control was better in the surgical groups compared to the control group. 

So what does this mean?  These studies show us that bariatric (obesity) surgery can put type 2 diabetes into remission, and can improve control of diabetes in those who don't go into remission.  However, it must be noted that remission does NOT mean cure - each patient must be followed on a lifelong basis and monitored for possible recurrence of diabetes down the road.  These surgeries have significant risk associated with them, and the balance of benefit versus risk has to be considered on a patient-by-patient basis.  The improvement in diabetes does not appear to depend on how much the person weighs before surgery, implying that the current body mass index (BMI) critieria for selecting patients for surgery may not be the right way to determine who would benefit the most. (More research needs to be done to figure out what does predict best success with bariatric surgery.)

Overall, (and as noted in the accompanying editorial), studies such as these suggest that bariatric surgery should perhaps not be a 'last resort' in the treatment of patients with obesity and type 2 diabetes.

Dr Sue Pedersen www.drsue.ca © 2012 drsuetalks@gmail.com

Follow me on Twitter for daily tips! @drsuepedersen 

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Who Benefits Most From Bariatric Surgery?

>> Saturday, March 31, 2012






At this week's ISORAM Boot Camp hosted jointly by the Canadian Obesity Network, University of Alberta, and University of Leipzig (Germany), one of the main topics of discussion was bariatric surgery.  While I was only able to attend a fraction of the week long meeting due to my clinic schedule, I had the great pleasure of hearing several great sessions, including the final lecture provided by Dr Arya Sharma.

Dr Sharma, as always, gave a very thought provoking talk, highlighting several points, ranging from the '4 M's' of obesity assessment and management for clinicians to consider, to the '5 A's' of obesity counseling.  When we overeat, he urged us to consider: are we eating in response to hunger (called 'homeostatic hyperphagia' in medicalese), or for the purpose of reward (aka 'hedonic hyperphagia')?

Another of the many topics Dr Sharma explored was the discussion of what type of patient benefits most from bariatric surgery.  He reviewed the 2012 update from the landmark Swedish Obese Subjects (SOS) study for us, which examined the long term effect of obesity surgery on heart attacks and strokes, compared to control patients who did not have obesity surgery.  While the study did show a lower rate of cardiovascular events and cardiovascular deaths in the group that had obesity surgery, it took nearly two decades of study for this difference to emerge.  As the SOS study participants were obese but otherwise quite healthy, thissuggests that body mass index (BMI) alone may not be an appropriate criterion to decide who is the most appropriate candidate for obesity surgery.  As has been suggested by many studies since the SOS study began, it may be more prudent to select patients based on whether they have complications of their excess body weight (eg diabetes, severe hypertension, etc), as there may be greater health benefits to be had for these individuals.

Interestingly, the SOS study also found that it didn't matter how high the patient's starting weight was, nor did it matter how much weight the patient lost by having obesity surgery - the reduction in risk was the same.  Again, this suggests that body weight or BMI alone is probably not the best way to decide who stands to benefit most from bariatric surgery - an assessment based on the presence or absence of complications of excess body weight (ie the EOSS staging system) may be far more appropriate.

Congratulations to the CON on another hugely successful meeting!


Dr Sue Pedersen www.drsue.ca © 2012 drsuetalks@gmail.com

Follow me on Twitter for daily tips! @drsuepedersen 

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