Please can you give a brief introduction to osteoporosis?
Osteoporosis is defined as a reduction in bone mass coupled with micro-architectural deterioration of bone tissue which predisposes to fractures. Osteoporosis manifests through an increased risk of fracture, and age-related fractures are a major public health problem.
The lifetime risk from aged 50 years of an osteoporosis-related fracture in women approaches 1 in 2 and in men approaches 1 in 5. The major fracture sites affected are the hip, spine, distal forearm and proximal humerus. Many fractures throughout the skeleton can be linked to low bone mass and a corresponding increase in skeletal fragility.
Fractures typically occur more in women than in men at all ages over 50, and they account for an annual cost to the UK of around £2.1 billion each year.
Who is most at risk of osteoporosis?
The major risk factors for osteoporosis are:
Reduced Body Mass Index (BMI) – thinness
Heavy alcohol consumption
Low calcium intake
Vitamin D insufficiency
Estrogen deficiency at the time of the menopause
The major risk factors that can be used to identify those who are likely to have an increased risk of fracture are summarized in the World Health Organization (WHO) risk assessment tool called FRAX, and in addition to age and gender they include:
Body Mass Index
A previous history of fracture
A family history of fracture
Secondary osteoporosis attributable to diseases such as rheumatoid arthritis
Very heavy alcohol consumption
On the basis of these factors the FRAX tool assigns a ten year risk of hip fracture, or of any osteoporotic fracture, and characterizes whether a person has such a high risk of these fractures that treatment is warranted, whether there is such a low risk that treatment should not be required, or whether there is an intermediate risk at which bone density measurement will assist in clinical decision making. Once the bone density is done, a new ten year risk is computed which gives a yes or no to treatment as a clinical decision.
How many people does osteoporosis affect?
Osteoporosis itself, defined as low bone density on a DEXA scan, affects 22.8% of all post-menopausal women in the UK, and it affects a substantially lower proportion of men.
The reason that osteoporosis is a public health problem is that the associated fractures affect around 1 in 2 women and 1 in 5 men throughout their lifetime from age 50 years.
What is osteoporosis screening?
At present there is no approved mass screening program for osteoporosis in Europe. In some of the analyses undertaken in North America, measurements of bone density above age 65 in women have been sanctioned as helpful for clinical decision making. That is the closest worldwide that we’ve come to a mass screening program.
Historically in the UK we have used, since 2000, the Royal College of Physicians guidelines for evaluation and treatment of osteoporosis, which suggests opportunistic use of DEXA scanning for individuals who might be at risk of fracture, for example those who have had a previous fracture, those who have a family history and so on, in whom a low bone density value would influence a clinical decision. So this opportunistic use of bone mineral measurement is sometimes referred to as opportunistic screening.
With the advent of FRAX in 2008 there has been a review by the National Osteoporosis Guidelines Group (NOGG), summarized in a BMJ editorial that I wrote in August of this year, on risk assessment in osteoporosis. The review suggests that a clinical risk factor assessment should be undertaken for all individuals above the age of 50, and bone density measurements should be utilized for those whose clinical risk factor score suggests DEXA scanning will influence clinical treatment.
The National Osteoporosis Guidelines Group (NOGG) has provided a lovely nomogram for targeting treatment at those who are at a particularly high risk. This is still not a mass screening program but it is a risk assessment system for osteoporosis that we in the UK ought to be undertaking in primary and secondary care.
Why is osteoporosis screening important?
Well, we should treat osteoporosis as we treat any chronic disease: in cardiovascular disease we assess risk factors and intervene with statins, in stroke we assess blood pressure and intervene for those at the highest end of the blood pressure distribution, for osteoporosis we ought to assess fracture risk and intervene for those at the highest risk of fracture.
Can osteoporosis screening help to reduce future fractures?
After age and gender and independently of bone density, the biggest single risk for a future fracture is whether you’ve had a fracture in the past. If we look at all of the future fractures that are going to arise, 50% of them will arise in the 20% of women who have had a previous fracture. That shows the power of secondary prevention - targeting treatment at those who have already had symptoms of the disease in question, a previous fracture.
So, there is a huge amount of interest internationally in secondary fracture prevention – targeting risk assessment and treatment at those who have already sustained a previous fracture. A programme recently introduced by the International Osteoporosis Foundation, of which I am chair of the Scientific Committee, is called Capture the Fracture. It entails promoting Fracture Liaison Services (FLS), which are health care systems linking a series of processes which identify people who have had a previous fracture, arrange risk assessment via clinical risk factors and bone density measurement, communicate that risk to primary care practitioners and permit appropriate treatment for those at the highest risk.
This system for secondary fracture prevention within Capture the Fracture will be housed on an international website containing 13 criteria for best practice that set the global quality standard for FLS implementation. The 13 criteria will be launched in the spring of next year along with a position paper. This will provide a basis for secondary prevention throughout Europe and worldwide.
How many people are currently screened for osteoporosis and do you think this number should be increased?
At the present time, if we were to take as an indicator a health authority of around 100,000 people in the UK, we estimate that there is a need for 1,000 DEXA scans for clinical indications there. Broadly speaking we have the capacity to undertake that number of scans but the extent to which they are utilized, particularly in primary care, is very variable throughout the country. And so there is a huge job to be done in terms of standardizing risk assessment and treatment using the FRAX and NOGG algorithms.
Why do you think the current screening rates are so variable?
Because there hasn’t been a large scale education program that tells all of the practitioners engaged in all of the different areas of healthcare exactly how to assess risk and treat. It is a knowledge gap, not a practical or financial gap.
There isn’t an undercapacity of DEXA scanners in the UK, there are plenty of DEXA scanners available. The undercapacity is theunder-utilization of the existing available resource (DEXA) and an underutilitilization of existing FRAX risk assessment tools.
This was described with the advent of FRAX in 2008, and already the FRAX website receives a massive number of hits each week so it is clearly gaining in momentum, but it is the widespread utilization of treatment guidance that is important.
In fact,the European Council on Osteoporosis will again release in the spring of next year a new version of our European guidelines on osteoporosis assessment and treatment which will espouse this FRAX and NOGG approach.
Would you like to make any further comments?
Thirty years ago when I first started research into osteoporosis it was considered an inevitable consequence of ageing, rather like grey hair or thin skin. Over those thirty years there has been a complete step change in our approach to the disorder:
We now know its burden
We understand its causes
We understand how to measure
We have a massive array of treatments which interfere with all sorts of different steps in the bone turnover cycle and lead to an improvement in bone density and a reduction in fracture
The major challenge facing us now is using that information in cost-effective strategies to reduce the burden of fractures in the future. Those strategies should be applied throughout the life course and in the entire population as well as in those at the highest risk.
For the entire population our research shows that it is never too early to start preventing osteoporosis – right from the start with pregnant women by improving her nutrition and vitamin D status we can optimize the bone health of the baby she is carrying. Through childhood and youth we can maximize exercise, dietary intake of calcium and vitamin D, and avoidance of tobacco.
In mid-life we can continue with a healthy lifestyle and appropriately treat secondary causes of osteoporosis. Later in life we can assess risk and intervene where most appropriate. This combined strategy ought to reduce the fracture burden in future generations, and indeed we are already seeing age-adjusted hip fracture rates throughout the western world beginning to plateau and decline.
Where can readers find more information?
About Professor Cyrus Cooper MA, DM, FRCP, FFPH, FMedSci
Cyrus Cooper is Professor of Rheumatology and Director of the MRC Lifecourse Epidemiology Unit; Vice-Dean of the Faculty of Medicine at the University of Southampton; and Professor of Musculoskeletal Science at the University of Oxford.
He leads an internationally competitive programme of research into the epidemiology of musculoskeletal disorders, most notably osteoporosis. His key research contributions have been:
Discovery of the developmental influences which contribute to the risk of osteoporosis and hip fracture in late adulthood;
Demonstration that maternal vitamin D insufficiency is associated with sub-optimal bone mineral accrual in childhood;
Characterisation of the definition and incidence rates of vertebral fractures;
Leadership of large pragmatic randomised controlled trials of calcium and vitamin D supplementation in the elderly as immediate preventative strategies against hip fracture.
He is Chairman of the Committee of Scientific Advisors, International Osteoporosis Foundation; Chair of the MRC Population Health Sciences Research Network; Associate Director of Research at the University of Southampton Medical School; and Associate Editor of Osteoporosis International.
He has published extensively (over 550 research papers) on osteoporosis and rheumatic disorders and pioneered clinical studies on the developmental origins of peak bone mass.