Reasons to operate: the ‘wobbly tripod’ of evidence

"When good evidence is lacking, the best and most dedicated of us do wrong in the utter conviction of being right"

(L. Eisenberg 1977, NEJM, 297, 1230-2)

When surgical practice varies between doctors, hospitals, regions and countries (and it does), there are many possible reasons, apart from variations in the disease or the population. Some reasons that have been given for practice variation in surgery are:

Is back fusion surgery just a placebo?

It is possible that spine fusion surgery for back pain achieves its effectiveness through the placebo effect. I would like to make the case that it is not only possible, but also probable.

Achilles tendon ruptures: let the patient decide

As we age, our collagen loses its elasticity and our tendons weaken. A ruptured Achilles tendon (TA) is often the result. This is a common injury; patients are usually aged 30 – 50 and it normally occurs with a sudden push-off during sport. Now, the initial reaction when anything is torn is to repair it, and while this holds true for inanimate objects, living things are different – 4 billion years of evolution has made some headway in that regard. Many people do not appreciate that as surgeons, when something is broken, cut or torn, all we do is put the ends roughly together and it is nature that does all the healing; we just take the credit. Placing the torn ends of a ruptured TA together is easy: you just flex the ankle. And it turns out that if you do this, and gradually bring the ankle back to normal position over a few weeks, it heals fine – without surgery, and without the complications associated with surgery.

Placebo surgery #4: Knee arthroscopy in arthritis

An arthroscopy (key hole surgery to wash out, trim or clean up) in the knee joint is one of the most common procedures in orthopaedics, and one of the most common surgical procedures overall, with over one million performed in the USA each year. An overview of arthroscopy for knee osteoarthritis can be found in a previous blog; this post covers the sham surgery trial as part of a series on that topic.

Lessons from history #3: From railway spine to whiplash

‘Railway spine’ was the name given to the widespread finding of chronic back pain and disability associated with railway injuries, and reaching near epidemic proportions in mid and late nineteenth century England. It has many similarities with other post-traumatic conditions and provides lessons about chasing physical diagnoses, and the role of psychosocial factors (in particular, the role of compensation). Lessons that we never seem to learn.

Financial incentives and surgery rates

Recently, a reader asked me if financial incentives could be responsible for the findings referred to in previous posts, like practice variations and the persistence of some surgical procedures despite evidence of their ineffectiveness. We know that you can change physician behaviour by altering financial incentives (Cochrane review), but anyone who believes in Homo Economicus will tell you that. And there is also evidence that financial incentives lead to increased health care usage amongst primary care doctors (here), but what about the evidence for financial incentives influencing surgery rates?

I'm not sick but I'm not well

This phrase got me thinking: what happens to people who do not have an identifiable disease, but still feel unwell; when the tests do not reveal any pathology, but they still have symptoms? They get a label, that’s what, because doctors cannot say: “Your tests are normal and you do not have any evidence of an underlying disease process. Further opinions and investigations are unlikely to help, and may lead to unnecessary and potentially harmful treatments”.

I don’t have time for a discourse on medicalisation, but I wanted to ask: What label do these people get? It turns out that it depends on the specialty training of the doctor that sees them.

Placebo surgery #3: Meniere's disease

Meniere’s disease is a disorder of balance (dizziness) and hearing (ringing or hearing loss). The underlying cause is not understood (idiopathic), the symptoms often fluctuate, there is crossover with other symptoms (vertigo, migraine), and there are many other conditions that cause “Meniere’s-like” symptoms. This makes the condition ripe for any treatment to look good if we think it works, due to the subjective nature of the symptoms, symptomatology that is open to misinterpretation, and the lack of any objective pathological test. Therefore, for such conditions, reporting good results from a series of patients is not enough; a more scientific (unbiased) assessment is necessary. Fortunately, somebody did just that. Unfortunately, despite the results of that study, surgery (now in many different forms) is still being used for this condition.

Stop the bleeding: questioning emergency trauma care

When trauma patients arrive at hospital with multiple injuries and haemodynamic instability (significant blood loss, low blood pressure, increased risk of dying), apart from resuscitating them (usually by giving blood and other things like clotting factors) the treatment is summed up by the phrase: “Stop the bleeding”.

“Stopping bleeding” is a biologically plausible mechanism for saving life that I will accept on face value. My question is: do our noble attempts to stop the bleeding actually influence the chance of dying? Looking at previous treatments that have fallen out of favour, I would say not. And the treatments currently in vogue are supported by as little evidence as those they replaced.

Anti-depressants make me sad

Anti-depressants have been around since the 1950’s, but it wasn’t until SSRIs (Selective Serotonin Reuptake Inhibitors), the first being Prozac, came on the market in the 1980’s that things really took off. The safer profile meant that primary care physicians could start prescribing, and Prozac itself became a blockbuster drug (over $US1 billion in annual sales) and a household name. Others followed and by 2005, anti-depressants were the most prescribed drugs in the USA. For most patients, however, they are no better than placebo. That doesn’t mean that they don’t’ work, they just don’t work any better than placebo.

Book review: Between the Lines

Prostatectomy: doctors just don’t get it.

The results from the latest randomised trial comparing prostatectomy to non-operative treatment for prostate cancer are all over the news, but what caught my eye was the response from a senior clinician in my country. I will address his comment, and a related comment, below.

The study (here) recruited 731 men less than 75 years of age and found that the overall mortality after 10 years was 47% in the surgical group and 50% in the non-operative group. The difference was not statistically different. If it were, you would have to weigh that benefit against the 88% erectile dysfunction and 17% incontinence rates in the surgical group (2 -3 times higher than the non-operative group).

“The whole problem is selecting the ones which need to be operated on”

Manual handling techniques and back pain

Walking from the change rooms to the operating theatres, I go past a series of posters using drawings of animals in funny positions, extolling the virtues of manual handling techniques. Lifting with your knees, bending with your hips, twisting with your elbows, or whatever. And when I arrive in the operating rooms, I am regularly fascinated by the addition of yet another ingenious device to move a patient less than one metre from their bed to the operating table. Last week we used something that was basically a fully functioning hovercraft (here).

There are countless well-meaning guidelines (and rules) on how we should be moving objects (like this, and this) but do they help? I lift a lot of heavy things in awkward positions when I am working in the yard, but really only get back pain when I lie on my back for too long. I see Olympic weight lifters putting a fair bit of weight through their back without much back pain, and I know that the biggest predictors of back pain in the workplace are not physical factors (try this, this and this) but things like job satisfaction. What is the evidence that this advice, or these devices, actually work?

Why placebo surgery is ethical, and necessary

The research discussed in my previous post on placebo surgery for Parkinson’s disease sparked a rush of publications debating the ethics of placebo surgery, even before the results were released. One of these articles (here) gives a good overview of the ethics of placebo (sham) surgery controls, using one of the Parkinson’s trials as its case in point. The authors give both sides of the argument, but I disagree with two important points; points that lead them to conclude that placebo surgery is not necessary.

Placebo surgery #2: Surgery for Parkinson’s disease

In Parkinson’s disease, there is insufficient dopamine in parts of the brain. This chemical can be replaced in pill form, but with variable effect, and with some side effects. In the 1990’s many clinics were transplanting dopamine-producing cells from embryos into the brains of people with Parkinson’s disease. This procedure involved drilling holes in the skull, through which the cells were inserted. Animal studies showed that the cells could survive, and that the procedure could correct some of the movement disorders.  Open label trials (no placebo) of these transplants in humans showed that patients improved. This is the same evidence base for many operations performed today: a biological mechanism, supportive lab studies, and reports of patients that got better. Enter, the sham.

Placebo surgery #1: Surgery for angina

I will attempt to write a short note on every clinical study that has compared surgery to a placebo operation (sham surgery). The common thread is that while many patients improve after the real operation, many patients also improve after the sham operation, and in each example the real operation is no more effective than the sham surgery. This shows that when we see patients get better after we treat them, it is not necessarily due to the specific effect of our treatment. We (the doctors and the patients) perceive effectiveness by attributing cause and effect to the association we see. The difference between the perceived effect and the specific (real) effect is the placebo effect.

This study dates from 1959, and relates to a surgical procedure for angina that dates from 20 years before that: internal mammary artery ligation.

Lessons from history #2: Evidence based blood letting

Objections to evidence based medicine (a scientific approach to medicine) by doctors often sound like this:

“Practicing physicians are unwilling to hold their decisions in abeyance till their therapies received numerical approbation. Further, they are not prepared to discard therapies validated by both tradition and their own experience on account of somebody else's numbers.”

Things have not changed.

These quotes are from the early 1800’s and express the attitude of physicians at that time to studies such as the landmark paper in the American Journal of Medical Sciences from 1836. The article (by PCA Louis) systematically pooled data from many patients and used statistics to look at the effectiveness of blood letting for pneumonia (then standard practice). It found the treatment to be ineffective.*

Steroid injections for low back pain

The Cochrane review on injections for low back pain concludes: “There is insufficient evidence to support the use of injection therapy in subacute and chronic low-back pain”. The injections contain corticosteroid (‘steroids’, ‘cortisone’) mixed with local anaesthetic and are injected into the epidural region or the facet joints of the lumbar spine. The injections have been compared to placebo injections and to other treatments and, without going in to all the detail, they basically don’t work.

Prolotherapy: the illusion of effectiveness

Many of my blogs have a recurring theme: an intervention that sounds great (biologically plausible), has great early results, but on rigorous scientific testing is shown to be ineffective. Prolotherapy does not fit that mould, because I don’t even buy the biological argument in the first place. Prolotherapy involves the injection of irritant solutions in order to strengthen tissues and relieve pain. That makes about as much sense as homeopathy, or being struck on the head to relieve a headache.

The squeaky joint gets the oil: lubricants for osteoarthritis

Hyaluronic acid (HA) is the lubricant that normally oils your joints. In osteoarthritis of the knee, the joints are stiff and painful, and there is less of this lubricant in the joint. So why not inject HA directly into the joints (viscosupplementation)?  Talk about biological plausibility. To many people, this must be very appealing. We know this because people around the world have paid hundreds of millions of dollars to have this stuff injected into their knees. And yet the latest review of the research concludes that HA injections do not provide any significant benefit and may increase the risk of harm. So how do they conclude that, when so many individual studies show that it works? Because the studies are biased.