Last time we saw how I came to be diagnosed with osteoporosis while Saturn was conjunct Pluto in Capricorn in my 12th house. The process raised lots of questions so I began researching the disease and was shocked and angered by what I found. Not only has osteoporosis been redefined to expand the market for drugs, but the methods of diagnosis also involve dubious assumptions and statistical analysis. We’ll look at two of those methods here: the FRAX score and the DEXA scan.

Bones aren’t solid or rigid but have a honeycomb structure that constantly remakes itself, breaking down old bone and building new bone. This is called remodelling and about 10% of your skeleton may be destroyed and recreated at any one time. Bone remodelling relies on two types of cells: osteoclasts and osteoblasts.

Osteoclasts are a type of macrophage that form part of your immune system. While other macrophages hunt down bacteria and viruses and destroy them, the osteoclasts destroy old bone. They do this by dissolving and then reabsorbing small areas of bone tissue. Once the osteoclasts have done their job, the osteoblasts, a type of stem cell, move in and rebuild the new bone.

This metabolic process keeps your bones strong as long as it stays in balance and the osteoclasts don’t outpace the osteoblasts – i.e. bone building keeps up with bone breakdown. However, as you get older more bone is broken down than reformed so your bones will lose density as you age. This is a normal part of the aging process and there are many things you can do to help your bones remain strong.

Bones are strongest at about age 30 and after that will gradually lose density, depending on various factors including hormones. Women tend to lose bone faster than men, especially around the menopause, thanks to the drop in oestrogen. The rate of loss increases at menopause but settles down after ten years to a steady rate. In men, lower testosterone levels have a similar effect but the bone loss remains steady.

Osteoporosis is a ‘disease’ where the bones become weak and brittle because they’re breaking down too fast or not being rebuilt fast enough. The weaker your bones become, the more likely they are to break. There’s also an assumption that if you’re over 50 and you break a bone that you automatically have osteoporosis. But this doesn’t take into account the context of the fracture.

A fracture ‘caused’ by osteoporosis is called a fragility fracture. This is a break caused by a minor fall from a standing height or less that would normally not cause a fracture. Minor means with little or no force and is sometimes called a low-energy or low-trauma fracture. The most common fragility fractures are in the wrist, hip and spine.

But having low bone density doesn’t necessarily mean that you’ll have a fracture, just as having a fracture doesn’t necessarily mean you have osteoporosis.

The Journal of Internal Medicine published a paper in 2015 called Osteoporosis: the emperor has no clothes, which shows that most fractures in patients over 65 weren’t caused by osteoporosis. Most fractures are caused by falls and these happen most often in the elderly. That means increasing age may be a better predictor of fractures than bone density.

If you have impaired balance, you’re more likely to fall and more likely to break a bone. But even then, most falls don’t lead to fractures, even in the frail.

When I broke my wrist at age 49, the doctors at the fracture clinic didn’t think there was anything unusual about it. But the screening process for osteoporosis reclassified it as a fragility fracture because I had other risk factors (see previous post). While it’s true that the wrist tends to lose density faster than other bones so a wrist fracture may indicate increased bone loss. It’s also true that the wrist is naturally quite fragile, especially if you’re small and thin like me.

The fall that caused my fracture wasn’t minor either. Yes, I fell from a standing height but I also fell with some force and hit the ground hard, cracked my face open and needed stitches in my lip. I had been walking relatively fast at the time so also had a lot of momentum which threw me to the ground.

In other words, it wasn’t a minor trip. I didn’t fall because I’m frail and I didn’t lose my balance – I was knocked to the ground (by a dog!)

This is significant when we look at how the FRAX score is calculated. This is an online evaluation tool that takes into account various factors like age, height and weight, previous fracture in yourself and a parent, use of steroids, smoking, drinking, and rheumatoid arthritis. It provides an estimate of your 10-year risk of fracture based on the inputs.

However, it has been criticised for its modelling design and lack of transparency and the authors of Osteoporosis: the emperor has no clothes say it overdiagnoses osteoporosis. Based on FRAX at least 72% of white women over 65 and 93% over 75 would be recommended to take drugs for osteoporosis in the US. In the EU, these figures fall to 34% and 43% respectively because they calculate the risk differently.

The UK figures are similar to the US because it includes the metric for previous fractures. That means younger women with a lower absolute risk of fracture are more likely to be given drugs if they’ve had a previous fracture. While older women with a higher absolute risk but no previous fractures aren’t given drugs.

I tested this for myself and found it to be true. When you include previous fracture in the calculation, it gives me a risk score of 7.5%, just over the intervention threshold. When you remove previous fracture from the calculation, the score drops to 3.4%, putting me in the green ‘give lifestyle advice’ part of the graph:

Interestingly, it defines previous fracture as “a previous fracture in adult life occurring spontaneously, or a fracture arising from trauma which, in a healthy individual, would not have resulted in a fracture.”

In other words, I should never have been diagnosed with osteoporosis. I’m cured! 😂

This isn’t to say that my bones aren’t thinning – they are, and perhaps they’ve lost more density than they should have for someone my age. I had an early menopause which has effectively aged me prematurely. But even so, that doesn’t mean my bones are going to start spontaneously breaking for no good reason.

So what does the FRAX score really mean? Being given a risk percentage for fracture doesn’t mean it will happen – even if you fall. My FRAX score gives a 7.5% risk of fracture in the next ten years, which is actually quite low. It means I have a 92.5% chance of NOT having a fracture!

We see the same assumptions and issues with the DEXA (DXA) scan which is used in screening for osteoporosis, as well as other things.

The DEXA scan uses dual-energy X-ray absorptiometry to take high and low energy readings of the spine and hip. The low energy x-rays pass through soft tissue and the high energy x-rays pass through the bone as well, and the difference between these is used to calculate bone density (BMD). The result is given as a T-score and a Z-score which are expressed as a standard deviation from the average.

The T-score compares your bone density to the average BMD of a healthy person, i.e. someone young and pre-menopause at age 30. The Z-score compares your bone density to the average BMD of people in your age group and size. This is often used in younger patients who might develop what’s called secondary osteoporosis, caused by various diseases and medications.

A score of 0 means you have average bone density relative to the group you’re being compared to. For the T-score, a result of between -1 and -2.5 means you have osteopenia, which is below average BMD but not full osteoporosis. A result under -2.5 means you have osteoporosis in that bone. For the Z-score, a result of -1.5 and above is normal for your age group, and below -1.5 is flagged for further investigation.

It’s tempting to think that all this measurement and calculation gives an accurate reading of bone density. It looks impressive and ‘sciencey’ and gives a false sense of precision. But there are several problems with it.

The most obvious problem is in the definition of ‘average.’ The bone density of older women is judged against that of younger women who are seen as healthy. This automatically recasts older women as unhealthy or diseased if their bones fall below this average, which is highly likely since bones lose density so fast at menopause. But remember: this is normal – getting older isn’t a disease.

It’s also not possible to know what a person’s bone density was before they started losing density. In other words, how average was that person? DEXA scans have a tendency to overestimate the bone density of taller people and underestimate it in smaller people because they’re outside the average.

Aside from dodgy statistical assumptions, the machines themselves have to be calibrated properly and they often aren’t. Errors can occur if the patient isn’t positioned correctly on the machine, and multiple readings can produce totally different results. Elaine Mansfield discovered this when she had several scans weeks apart:

“Tests taken two weeks apart gave readings differing as much as 5.7%.”

This shouldn’t happen. There are also different kinds of scanners so your results may vary depending on the machine used. It’s all a bit hit and miss. Even walking around the room can change the result. In a post on What Doctors Don’t Tell You, Susan Ott, professor of medicine at the University of Washington in Seattle, says:

“A walk around the room causes the measurement to change by up to 6% [at the hip], which corresponds to six years of bone loss at the usual rate.”

The authors of Osteoporosis: the emperor has no clothes also criticise DEXA scans, saying they’re inherently inaccurate because of the way they interpret the results. The machines simplify the measurement and only take two components into account rather than three – bone mineral, fat, and soft tissue. These have different properties but the DEXA scan can only deal with two, so it relies on assumptions about fat vs soft tissue ratios. The margin of error can be 1 T-score either way:

“For example, a measured T-score of -2.5 (indicating osteoporosis) can reflect a true T-score of between -3.5 (clear osteoporosis) and -1.5 (slight osteopenia) without any possibility of knowing the true value for the individual. Therefore, even large individual changes in BMD, corresponding to those typically observed in clinical trials, may become irrelevant in terms of fracture prediction.”

This simplified measurement also can’t tell you anything about the quality of the bone. In an interesting article called Osteoporosis: the evolution of a diagnosis (Journal of Internal Medicine, 2015), the authors review the various ways bone loss has been defined over the years. They point out that fracture risk models, like FRAX and the DEXA scan, don’t take real bone strength into account:

“…DXA cannot be used to measure bone microstructure or quality, which are believed to influence fracture risk. Because DXA is a two-dimensional technique, it cannot be used to measure true volumetric BMD and bone size, or to separate trabecular from cortical bone.”

Overall, bone density measurement has poor predictive value for fractures. You can have osteoporosis but still have a low risk of fracture, and vice versa. In fact, loss of muscle strength may be a better indicator of potential fractures because it means you’re more likely to fall over.

In reality, osteoporosis is a risk factor, not a disease. But the pharmaceutical industry has a vested interest in identifying as many diseases as possible, as well as patients to treat. Money is poured into disease awareness campaigns and increased monitoring using scans and tests to create markets for treatments and drugs. A paper called Selling Sickness (BMJ, 2002), calls this ‘disease mongering.’

“Disease mongering can include turning ordinary ailments into medical problems, seeing mild symptoms as serious, treating personal problems as medical, seeing risks as diseases, and framing prevalence estimates to maximise potential markets.”

Osteoporosis is a good example of disease mongering where fears are whipped up to make it seem worse – like calling it a hidden killer. This approach to so-called healthcare can create unnecessary treatments and actual injury, as well as an unhealthy obsession with illness. The natural reduction in bone mass that occurs as you age has been medicalised and reframed as a disease, whereas:

“…for most healthy people, the risks of serious fractures are low and/or distant, and in absolute terms, long term preventative drug treatment offers small reductions in risk.”

Not only that, but the drugs themselves can be damaging and it’s not clear they even work. We’ll explore this next time in Bone of Contention: Osteoporosis Definition and Drugs…

Obviously, nothing in this post should be taken as medical or health advice and you should always do your own research and talk to your doctor or healthcare specialist (if you can find a good one!).

Images: Skeleton; Girl; Scan

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