Part 5: Understanding Relative Risk and Absolute Risk…Relatively Speaking, It’s Absolutely Crazy!

Authors: Kimberly Zambito, MD, Orthopaedic Surgeon and Owner of Qualis Os www.qualisos.com Nick Birch FRCS (Orth), Consultant Spine and Bone Health Specialist and owner of OsteoscanUK www.osteoscanuk.com Do you remember the scene: Alec Guiness as Obi One Kenobi in the bar on Tatooine telling the inquisitive Imperial war troopers that “there is nothing to see here. Move on.” He was using a Jedi Mind trick. Have you ever wondered about the use of similar Jedi mind tricks in medical research? Seriously, statistics can seem like Jedi mind tricks depending on how numbers are presented or manipulated. Many of our clients and blog readers have requested information about understanding “risk” as it pertains to results in research studies. In keeping with the Star Wars theme, the Force is Strong with our readers. Thank you for the inspiration. Risk and Odds “Risk” is the likelihood of something “bad” happening or a loss resulting from a particular action, decision, event, or situation. It involves uncertainty about the future and can apply to various areas such as finance, safety, business, and for readers of this blog, bone health. There are three key aspects to risk : Likelihood (Probability): How likely it is that an event will occur? Impact (Consequence): How severe is the outcome likely to be if it did occur? Exposure: What is the extent to which someone or something is vulnerable to that risk? An everyday example of each is: In finance, how likely am I to lose money if I invest in a risky venture? What will the impact be on my family and me if I lose all my savings and get into a lot of debt? Am I particularly exposed to the risk of financial ruin because I don’t know enough about stock markets or have been misinformed about a particular investment? The term “odds” is often used instead of “risk” e.g. “Doctor, what are the odds that I will break my hip if I trip and fall?” However, “Odds” refer to the probability of an event occurring versus the probability of an event not occurring. It is not the same as risk. A bone health example would be: Odds = Hip fracture occurs versus Hip fracture does not occur Using the same scenario, an example of risk might be: Risk = Chance of hip fracture versus All possible outcomes (no fracture, fracture anywhere, death) Let’s look at a hypothetical example of a randomized controlled trial of hip fractures during adventure trips in the Grand Canyon, specifically, hip fractures sustained while tightrope walking across the Grand Canyon versus bungee jumping from a hot air balloon in the Grand Canyon.

Authors: Kimberly Zambito, MD, Orthopaedic Surgeon and Owner of Qualis Os www.qualisos.com Dr Nick Birch FRCS (Orth), Consultant Spine and Bone Health Specialist www.osteoscanuk.com Andrew Bush, MD, Orthopaedic Surgeon www.centralcarolinaortho.com For decades doctors have known that fracture rates increase as people get older, the primary reason being impaired bone density and bone toughness. As a result, in the 1990s there was a big push to develop screening tools to predict future fracture risk and allow earlier intervention to prevent fractures if a person’s risk was high. Many methods have been developed over the years including FRAX, Q-Fracture, the Osteoporosis Self-Assessment Tool (OST), DXA T- and Z-scores, and more recently REMS T-scores, Z-scores and Fragility Scores. The simplest of these tools is the OST which uses a formula based on gender, age and weight to estimate whether a person has osteoporosis and by inference, whether their fracture risk is elevated. By definition this tool is age dependent. However, it turns out not to be particularly helpful in predicting future fracture risk as osteoporosis by itself only accounts for about a third of fragility (low trauma) fractures. A more complicated prediction tool is FRAX which was originally developed in Sheffield, England in the 1990s. It was later adopted by the World Health Organisation as their official fracture prediction device, and it is now the most commonly used screening tool for fragility fracture risk. FRAX works by comparing a person’s characteristics to information about fracture rates in a very large database that matches their age, weight, gender, country of origin and a variety of clinical features. The fracture data from the database was recorded when FRAX was developed and from this matching process a risk profile is generated. Importantly, that data has not been updated in the years since it was first collected and given the change in lifestyles and wellness characteristics that have emerged since the 1990s, it is no longer certain that the matching process used by FRAX is accurate in relation to the current population and FRAX may now be systematically over-estimating future fracture risk. The clinical risk factors (CRF) in FRAX include a past history of a fracture, history of a parental hip fracture, current use of steroid medication, current smoking and / or heavy drinking plus whether a person has a range of other medical conditions that might lead to impaired bone health e.g. malabsorption in the gut, thyroid disease, long-term liver or kidney disease, diabetes and rheumatoid arthritis. Each CRF adds a certain level of risk to the estimate of how likely a future fracture is. So, a person would reasonably expect to have a low FRAX risk if they remain healthy and active even in to their 70s and 80s. Not so! It turns out that FRAX is highly age dependent which means that however healthy you are, your risk when using FRAX to estimate fracture risk inexorably increases as you age. Initially, FRAX was derived to determine fracture risk without input from diagnostic densitometry (DXA). Subsequently, an algorithm was developed that allowed DXA-derived BMD values, or T-scores, for the hip to be included in the fracture risk estimate (REMS-derived BMD values cannot currently be used in FRAX calculations). This goes some way to improve the estimate as it uses real data from the person being assessed rather than just comparing that person to broad categories of physiological features. Trabecular Bone Score (TBS) is a DXA method that was developed to estimate bone toughness in the spine and TBS values can now be included in FRAX as well. The addition of these values increases the accuracy of fracture risk prediction via FRAX, but the age bias remains. This blog focuses on how increasing age affects FRAX generated fracture risk, irrespective of how healthy you are, and how this might lead to medical decision-making that might not make much sense. Let’s explore the use of FRAX in prediction of fragility fracture risk. FRAX can be found on the internet at https://frax.shef.ac.uk/FRAX/ .

I’m Active, Eat Right, and Have Never Broken a Bone…Why is my Fragility Score Yellow or Red?!?!?!

I’m Active, Eat Right, and Have Never Broken a Bone…Why is my Fragility Score Yellow or Red?!?!?!

Fall Prevention Week is September 23-27, 2024 . It coincides with the beginning of Autumn or Fall…how very punny. Falls are not funny though. Whenever a patient tells me they had a “bad” fall from a standing height, it sometimes indicates that they are in denial of their bone health. There are no “bad” falls from a standing height. There are falls that break bones and falls that do not break bones. Most of the resources on this website focus on technology to measure bone density and bone quality. While both components of bone are related to fracture risk, we cannot forget the importance of fall prevention. This blog post is not about high-impact injuries that result in broken bones, it is about preventing fractures resulting from a fall from a standing or sitting position. Why are these low energy falls such a big deal? These falls have the potential to become significant life changing events , especially if a fall results in a fracture. A history of fracture can increase the risk of subsequent fractures: Prior rib fracture can increase risk of vertebral body fractures by 2.3- fold Prior vertebral fracture can increase risk of subsequent vertebral fractures by 9.1-fold; new hip fracture by 7.1- fold; and wrist fracture by 2.3- fold Prior shoulder fracture can increase risk of new wrist fracture by 5-fold; new vertebral body fracture by 10-fold; and new hip fracture by 18-fold Prior wrist fracture can increase risk of vertebral body fracture by 37% The Center for Disease Control has estimated the rate of death from falls increased 30% from 2007 to 2016. If this rate continues to increase, there will be an estimated 7 deaths each hour related to falls. Falls can occur for many reasons, no matter your age. When younger people fall intact protective mechanisms may lead to a fall on an outstretched hand, resulting in a hand or wrist fracture. Older people have compromised protective mechanisms which may lead to a fall on their side, resulting in a hip fracture, or even a head injury. The CDC and National Council for Aging are excellent resources for learning about fall prevention. You can find a questionnaire to check your risk for falling here . While this information about falls may seem scary at first, it can empower you to talk to your health care provider about fall prevention. There are a number of simple in-office fall assessment tools available through your doctor or physical therapist. Ask about having your balance assessed. If your primary care doctor or orthopaedic surgeon are not able to assess you, ask for an assessment with a physical therapist. Here are some safety tips for you or for loved ones at home: Ask your loved one if they are concerned about falling. Be gentle and compassionate. God willing, we will all grow older, and most likely weaker. Notice if they are holding on to furniture or walls to move about the house, or have difficulty getting out of a chair. Discuss current health conditions. Have a list of current medications. Sometimes medications can make people dizzy, weak, or affect eyesight. Ask about their last eye exam and if they needed updated glasses. Do a home safety check. You can get a home safety checklist at the website listed above. Ask about fluid and food intake. Dehydration and low blood sugar can cause dizziness and lead to falls. Let’s not forget about pets. 66.4% of falls associated with cats and 31.3% of falls associated with dogs are from tripping over the animal Among people hospitalized for falls over pets, 79.9% were fractures 8.8% of pet-related injuries were caused by people tripping over a pet toy or food bowl Journal of Safety Research 2010 and WebMD 2010 Here are a few tips to consider: Walk the dog, don’t let the dog walk you Dog obedience training Clean food and water spills that can cause slip and falls Clear floors of pet toys and leashes Avoid bending over to pet an animal Crate your dog or put the dog outside when expecting company Be aware of your limitations and consider risk assessment before doing something you may consider stupid after sustaining an injury. If you have never tried ice-skating and you have decided that you want to try it as an older adult, you may consider doing a risk assessment. That assessment may go something like this: If I fall and break my wrist, will I be able to work and continue to earn money to pay my bills? If I broke my ankle, who will drive me around? For me, the answer is learning to ice-skate at my age is not worth the risk of a fracture. There are other activities I enjoy doing. Many patients have asked about skiing. If you have enjoyed skiing your entire life and you desire to continue this activity, do a risk assessment of the type of skiing you want to do. You may decide to stay away from black diamonds. You may decide you will be better off on green or blue slopes. You can still enjoy the activity as you age with some adjustments. At some point, you may decide that the activity no longer gives you the joy it did previously and you move on to something else. Situational awareness or mindfulness in the moment is key to fall prevention. Whenever a patient comes to me for treatment of a fracture, I ask about how the fracture occurred. Typically, the answer is related to a fall. I follow with, “How did you fall?”. A story unfolds. Many times the story involves doing too much at once, not paying attention, or not turning on a light at night and tripping on something. Slow down. Have a night light for those night-time trips to the bathroom. Avoid carrying 15 grocery bags into the house at one time. Carry 3-4 and make multiple trips. Being in the moment prevents falls. In summary, there are a number of reasons why a person may fall. Reasons may include medications or interactions of medications that cause dizziness; poor eyesight; muscular weakness, dehydration, low blood sugar, a cluttered home, lack of mindfulness, pets, and not knowing limitations. The CDC and the National Council on Aging are great resources to get started with assessing your risk or your loved one’s risk for falling. Each source provides tips for preventing falls. If you have experienced falls, please share that information with your doctor, physical therapist, or loved one. There is no shame in asking for help to prevent a fall. If you have a loved one who has fallen, please do not shame them. Treat them with the kindness and compassion you want for yourself. Respect their dignity. Preventing a fall is preventing a fracture.

Why Is My Doctor Trying to Scare the $h!t Out of Me?

Bone Health is Connected to Overall Health

Guest blog by Nick Birch, FRCS (Orth)

I recently received a question: why is my T score going up and my fragility score getting worse? This is a great question. Let's take this step by step. First let's address the T-score. When tracking bone health over time, we must evaluate the actual numbers for Bone Mineral Density (BMD), not T-score. The T-score is a nice way to get an overall picture of your BMD compared to a 30-year-old white female. It is easy to get sucked into comparing T-scores, as we have all been conditioned to look at T-scores. However, T-scores represent standard deviations on a graph, and they represent a range of numbers and not absolute values of BMD. Therefore, tracking bone density over time can only be done by comparing BMD values in g/cm 2 and expressing those changes as percentages compared to baseline and compared to the result immediately prior. There are several factors that cause the BMD and therefore T-scores to change including age, levels of activity, nutrition and build. In post-menopausal women, there is a natural reduction of BMD and T scores over time which can be slowed, and in some cases reversed, with attention to good nutritional balance and lots of impact and resistance exercise. These changes usually occur slowly and are often not detectable on DXA scans in under several years because the Least Significant Change (LSC) is 5-6% which is not sensitive enough to measure a few percentage points difference. REMS can detect such changes, usually at yearly intervals. Changes in BMD caused by increases or decreases in weight and thus Body Mass Index (BMI) occur more quickly, and these changes can often be detected by REMS over a period of months rather than years. If the change is sufficiently large, DXA will be able to detect it in similar timeframes. For simplicity, let’s say BMD in 2022 was 0.983 g/cm 2 . Then in 2024, BMD was 0.899 g/cm 2 . The change in BMD is calculated as follows: 0.899 - 0.983 = -0.084 This demonstrates a decrease BMD (g/cm 2 ) over 2 years. To find the percent change, divide -0.084 by the original BMD (g/cm 2 ) -0.084 ÷ 0.983 = -0.085 This indicates there was an 8.5% decrease in BMD (g/cm 2 ). Remember to take into consideration the LSC which are different for DXA and REMS. A generally accepted LSC for DXA is 5-6% . So, if the change in BMD over time is less than 5-6%, it is not necessarily a real change when measure by DXA. If the change is greater than 5-6%, it does represent a real change. LSC for REMS is 0.88-1.05% (0.88% for hip and 1.05% for spine) meaning it can detect smaller changes, often in shorter timeframes. In the example provided above, there was a real change in BMD, as 8.5% is greater than 5-6% for DXA and 0.88-1.05% for REMS. Fragility Score is an adimensional number from 0-100. The lower the score, the better. FS reflects the micro-architecture of the bone. The AI in REMS technology compares the acquired spectra from the patient to a reference database. If the patient’s spectra match the spectra of individuals who have fractured, the patient will be in the RED. If the patient’s spectra match the spectra of individuals in the database who did not fracture, then the patient will be in the GREEN. YELLOW indicates some individuals fracture, and some did not. There is a natural increase in FS over time which is in the range of 1.5 – 2.0% per year in post-menopausal women. If the difference in FS over, for instance three years, is 4-5, that change may be inconsequential, considering the LSC and the expected change with age. Remember, you are more than your T-scores or Z-scores. Knowledge brings empowerment and peace of mind.