Bariatric surgery and cardiovascular risk reduction: Meta-analysis

The American Journal of Cardiology just published a new meta-analysis (a study looking at a collection of other studies) that evaluates the effectiveness of bariatric surgery for cardiovascular risk reduction.  As we’ve discussed before, meta-analyses are often used to sort through large numbers of studies to look for trends and weed out aberrant results or poorly designed studies.  (This is particularly helpful when a poorly designed study gives conflicting results in comparison to the rest of the existing studies.) So, we are going to talk a bit more about the meta-analysis.

In this case, the authors started with 637 studies to evaluate, but ended up using the data from only 52 studies involving almost 17,000 patients.  The first step of a meta-analysis is to find every single study even remotely related to your topic. So the authors pulled out, printed and looked at every single study they could find talking about bariatric surgery.

Then the authors start eliminating studies that aren’t relevant to their topic because once you take a closer look; a lot of the studies initially gathered aren’t really related to your topic at all.  (For example: If the authors gathered all studies talking about Bariatric surgery outcomes – on closer examination – a study about the rate of depression in bariatric surgery patients wouldn’t have any information usable to evaluate cardiac risk in these patients.)  Otherwise it would be like comparing apples to oranges.

Once authors have narrowed the pool to studies that are only looking at relevant topics, with measurable results – the authors then examine the studies themselves.  The authors evaluate all aspects of the studies: what is the study design, what does it measure, (is it designed to measure what it is supposed to measure?), what are the results?  (were the results calculated correctly?)  what are the conclusions?  what are the limitations of the study?

Then the authors summarize all of the findings, and draw conclusions based on the results. (if 50 studies involving 16,900 people show one thing – and 2 studies involving 100 people show something completely different – the authors will discuss that.)

The strengths of meta-analyses are that they summarize all of the existing studies out there – and provide readers with fairly powerful results because they involve large numbers of people.

For researchers, meta-analyses are cheap – particularly in comparison to designing, conducting a large-scale study with hundreds or thousands of subjects.  A meta-analysis doesn’t require federal grants or institutional permissions.  It just requires a computer and journal access (along with a good knowledge of study design, statistics).

As you can imagine, the downside of meta-analyses is that they don’t generate NEW knowledge, since they are summaries of other studies.  Meta-analyses are also limited by the AMOUNT of data already published.  If few researchers have written about a topic, then a meta-analysis isn’t very effective or powerful.  (A meta-analysis on three studies involving only 25 total patients, for example).

Now that we’ve discussed the purpose and function of the meta-analysis, let’s discuss the results of Heneghan’s reported results.

Now, readers need to be very careful when reading blogs, and other articles like mine reporting results such as this – because this is filtered, third-hand information by the time it’s published on blogs, or newspaper articles.  (First source is the meta-analysis itself – which as we’ve discussed is actually a summary evaluation of other work).  Secondary is the Medscape article which summarizes and discusses the results of Heneghan’s study.

Now, that means that anything you read here is essentially third-hand information – if it’s based on the Medscape article.  That’s why we provide links to our sources here at Cartagena Surgery – so readers can read it all first-hand.  This is important because just like the children’s game of telephone, as information is passed from source to source, it is edited, filtered and subtly changed (for reasons of space, editorial preference etc.)

heneghan’s meta-analysis results showed significant reductions in weight, blood pressure, cholesterol and hemoglobinA1c (blood glucose levels) after bariatric surgery.  The Framingham risk score (a score developed based on the landmark Framingham study) which predicts the risk of cardiovascular events (heart attacks, strokes) also showed a significant reduction (which would be expected if all the risk factors such as hypertension were improved).

Framingham Risk Score Calculator

Now, a lot of readers might say, “Wait a minute – isn’t this self-evident?  If you lose weight – shouldn’t all of these things (glucose, blood pressure, cholesterol) improve?”

Yes .- logical reasoning suggests that they should – but in medicine we require hard data, in addition to logical reasoning (ie. A should lead to B versus a study with ten thouand patients proving A does lead to B.)

We need to be particularly careful when suggesting or assuming causality from treatments (surgery) for conditions.  A good example of this is liposuction.  Since liposuction involves the removal of subcutaneous fat – and may result a (a small amount) of weight loss – many consumers assumed that this limited weight loss conferred additional health benefits associated with traditional weight loss.  Wrong!

Sucking fat out of your behind (liposuction) will not lower your blood pressure, cholesterol, or blood pressure and does not replace the health benefits of weight loss or exercise.  I can hear readers snickering now – but that’s because of my phrasing.  For years – many people, some health care providers themselves thought that weight loss, any weight loss lead to the above mentioned health benefits, and that included liposuction related weight loss.  It took several studies to disprove this.  So, in medicine – nothing is obvious – until we prove it is obvious!  (Remember: much of what was “obvious” in 1950’s medicine – is now considered absurd.)

Original Research Article Citation:

Heneghan HD, et al “Effect of bariatric surgery on cardiovascular risk profile” Am J Cardiol 2011; DOI:10.1016/j.amjcard.2011.06.076.  (abstract only – article for purchase).

Medpage Summary Article:

Bankhead, C. (2011). Medical News: Bariatric Surgery gets high marks for CVD risk reduction. Medpage Today.

Gastric banding versus gastric bypass: Easy?

Another example in the realm of surgery where easiest doesn’t equal most effective: gastric banding (lap-band). This is one of those procedures highly touted in American medicine – and heavily advertised on television as an ‘easy’ way to lose weight..

First, let’s get some things clear – the ‘easy’ mentality needs to go away in medicine, and so does the pushing of this concept with patients.. None of this; not surgery, weight loss drugs, or conventional treatment is easy for the patient..It’s all hard work, so don’t mislead your patients – that sets them up for failure..

In the article linked here (from the LA times, February 2011) the two doctors interviewed do their best to avoid answering the easy/ effective question. “I let the patient decide,” which is a royal cop-out. Patients come to doctors for expert opinions and recommendations not wishy-washy information that doesn’t present the facts and evidence. The picture accompanying the article is disturbing as well, since it’s captioned as a patient awaiting lap-band.. The patient is clearly morbidly obese – yet is undergoing the least effective option available!

What makes this frustrating to me – is that in talking to patients – is that it’s usually such a long road to even get to bariatric surgery.. Contrary to popular belief and tabloid reporting, the majority of overweight people don’t jump to bariatric surgery.. These patients spend years (sometimes decades) dieting, gaining and losing weight..
This isn’t always the case in other countries where surgery is more readily available – but in the USA where insurance coverage or lack there of, usually dictates care – bariatric surgery is usually the end of a long, frustrating road..

I know I’ve discussed this before on the site – but I feel that there needs to be transparency in treatment options – and that we need to do away with the ‘easy’ concept whether it’s bariatric surgery, stents or even medications.. Don’t sell people easy – give them safe, proven and effective.

I’ll be updating the article over the next few days with links for more information – and hard facts about surgical options and obesity surgery.

Related Articles: Free full-text links: (my titles, the actual titles are a bit longer)

1. It’s Not Easy – a study looking at the patients perspective, and perceptions before and 2 years after bariatric surgery.

2. Current treatment guidelines and limitations – a discussion of current treatment guidelines in the USA and Canada

3. German study with 14 year outcomes after gastric banding – this is a nice study because they use terms that are easily understood for laypeople – and shows decent outcomes for patients with this procedure

4. Single port bariatric surgery – this has been a hot topic over at the sister site. This article discusses the most recent innovations in surgical techniques for bariatric surgery.

5. A review of the current data (2008) surrounding bariatric surgery, obesity, and diabetes and the cost of care.
This is a particularly good article (reviews often are) because it gives a nice summary of multiple other studies – so intead of reading about eight patients in Lebanon or some other small group – you are getting a good general overview..also it gives a good idea the scope of the problem..

I’m trying to collect a wide range of articles for patient education; unfortunately, since surgeons in Latin America are on the forefront of bariatric surgery – a lot of the most interesting articles are in Spanish and Portuguese (or paid articles). i haven’t posted the translations since they are secondary source and all of the other citations are primary source.

Bariatic surgery, revisited

In honor of the Latin-American Bariatric Surgery Congress, currently in progress in Cartagena – (since I couldn’t make time in my research to go) I am posting a brand new article about bariatric surgery and the severely obese. It seems American medicine is finally starting to catch up, and take notice..

It’s hard concept out there – and I still have trouble with it myself, sometimes.. In our society, it seems we are too busy blaming ourselves, and others for being overweight and attaching labels; ‘lazy’, to really see how fundamentally things need to change to improve our health as a nation.

From my perspective, down here in Bogota – it’s interesting, because I am seeing Colombians just beginning to start to struggle with obesity – as more and more imported snack foods, and fast foods replace traditional diets. Obese people are still very rare here – and after several months, I can still say I’ve not seen a single super-obese person here, but the ‘chubbies’ are starting to grow in number..

At the same time, by being in such a walkable city, and having access to (cheap!), delicious, ripe fruit every day, I’ve managed to lose over ten pounds with almost no effort.. I’ve been tracking my walking, and I walk about 6 to 10 miles a day with my various errands. But these are things that aren’t readily available – in the urban sprawl of American life.. A week’s worth of fruit for several meals for ten dollars? Not hardly, unless you gorged yourself on bananas every single day..

Surgery as a solution seems drastic to American healthcare providers, myself including.. Removing/ destroying a perfectly functioning organ.. But then – when you look at the drastic effects, and the desperate states our patients are in – Bariatric surgery really is as lifesaving as cardiac surgery for many people.. Until we change society as a whole (which may never happen), we need to help these individuals regain their health,and their lives..

Bariatric Surgery for the Severely Obese

In the meantime, everyone, stay away from soft drinks (all soft drinks, including ‘diet drinks’, juices and fruit drinks, sweet tea) and stick to water, plain tea. Coffee too – if you remember not to load it up with too many calories.. Try it for a month, and I wager you will be unable to go back to the supersurgery drinks you formerly enjoyed out cringing..

Bariatric surgery in the medical news

New article on Medscape (a medical literature website for health care providers) discussing the benefits of bariatric surgery.  In this article they cite a surgery cost of at least $30,000 which is out of reach for many of the people who need it;  as morbid obesity and related complications push up health care costs for individuals.

I’ve posted the link for you to read it for yourself:

this website does require registration, (which I think is free.)

But as my readers know, there are more cost-effective alternatives, as mentioned in the entire chapter devoted to bariatric surgery in Cartagena.

As readers know, in that chapter, I introduce you to one of Latin America’s most famous surgeons, Dr. Holguin, a former trauma surgeon at Maryland’s Shock Trauma hospital in Baltimore, MY in addition to several other excellent surgeons.  Most North Americans don’t know it but Cartagena is fast gaining a reputation for excellence in bariatric surgery, and is becoming a destination of choice for gastric bypass, lap-band, sleeve resection and other bariatric surgery procedures.