Osteoporosis is a condition in which the bones become less dense, changing the bone structure and making the bones more likely to break.

Bone mineral density is low in osteoporosis, making bones porous and brittle.¹

A bone mineral density test helps you and your doctor to measure the density of your bones and estimate how likely you are to get a fracture (broken bone) in the next ten years. Centres with expertise in SCI will ask you to have the density measured of your spine, hip and knee regions.

Healthy bone is constantly being broken down and reformed by the body’s cells in a process called bone remodeling. As a part of this process, the cells that breakdown bone tissue and the cells that create new bone, work to keep or increase the bone’s strength. Bones can adapt and change to the demands placed on them

After SCI, the cells that breakdown bone (osteoclasts) work over time, and the cells which build bone (osteoblasts) cannot keep pace, this results in thinning of the bone cortex and a lower number of bone cross struts and trabeculae. These changes in the bone decrease bone mineral density, usually areas rich in trabelcular bone are affected first and then the bone cortex.

Osteoporosis often affects people with SCI in a unique pattern called sublesional osteoporosis (‘sublesional’ means ‘below the level of injury’). Sublesional osteoporosis is a condition which involves:

• 

  X-ray image of a hip fracture.²

  Excessive bone resorption below the level of injury

• Low bone mineral density of the hip and or knee regions
• An increased risk of fracture

Bone tissues start to breakdown as early as the first few days after SCI. Among people with motor complete SCI, bone tissue resorption is highest between 3 and 6 months after injury and may continue for years. The rate of decline in bone density is less predictable in people with incomplete or non-traumatic SCI.

Osteoporosis is very common in people living with SCI long-term and increases the risk for fragility fractures.

Spinal cord injury can affect the body in a number of different ways that contribute to osteoporosis. These changes may include:

Changes to Body systems

Spinal cord injury affects many different systems in the body. Changes in the immune, hormone, circulatory, and nervous systems after SCI contribute to weaker bones after SCI. The role of these factors is not fully understood.

Fewer weight-bearing activities

Weight-bearing activities, like standing and walking, place forces through the bones of the legs and hips that stimulate the bones to become stronger. When a person spends less time standing and more time sitting, the bones experience fewer forces and adapt by becoming less dense and weaker.

Foods containing calcium and vitamin D help maintain bone strength.^3-6

Reduced muscle activity

Because muscles are connected to bones by tendons, the repeated pulling of muscles on bones during movement stimulates the bones to become stronger. When muscles become weak or paralyzed, the muscles atrophy and the muscles and bones nearby have fat deposited in them and there are not as many forces applied to the bones.

Lifestyle changes

Physical activity and nutritional habits can also influence the bones. After SCI, rates of physical activity, which can help to strengthen bone, are often lower than in people without SCI. In addition, changes in nutritional habits, such as reduced calcium and vitamin D intake can also contribute to low bone density after SCI.

Fragility fractures are very common after SCI. Individuals with these risk factors are more likely to experience a fracture after SCI. if you have more than 3 of the following fracture risk factors, please discuss them with your health care team.

Risk factors for fractures after SCI:

• Women
• Have a motor complete SCI (AIS A or AIS B, no movement of the legs)
• Paraplegia
• SCI for more than 10 years
• People less than 16 years of age at the time of the SCI onset
• People who consume more than 5 servings of alcohol per day
• Long term use of medications; specifically, anticonvulsants, heparin, or opioid medications
• Low weight for one’s height (a Body Mass Index (BMI) of less than 19)
• Low knee region bone mineral density
• Prior fragility fracture
• Family history of fracture

A DXA test is a non-invasive way to measure bone mineral density.⁸

Measuring and monitoring bone mineral density after SCI is an important part of managing bone health. These measurements allow health providers to diagnose osteoporosis, estimate your fracture risk and monitor changes in your bone density over time. There are several methods that are commonly used to measure different aspects of bone health.

A bone density test or DXA (Dual-Energy X-ray Absorptiometry) Test is an imaging modality that uses non-invasive x-ray technology to scan and measure bone mineral density. DXA is the most widely used tool for measuring bone mineral density and diagnosing osteoporosis.

Peripheral Quantitative Computed Tomography is another non-invasive imaging method that can be used to diagnose osteoporosis of the shin region. This type of scan measures cortical thickness and trabecular volumetric bone mineral density. However, it is most often used in research.

Vitamin D supplementation may have a role in osteoporosis prevention post-SCI.⁹

1. Adequate, but not too much Vitamin D intake

Vitamin D is a vitamin that has an essential role in maintaining bone health by increasing the absorption of calcium. After SCI, there are a number of different factors that may contribute to a vitamin D deficiency, including reduced exposure to sunlight, inadequate diet, and side effects from medications metabolized by the liver. Research evidence suggests that vitamin D supplements can help to maintain bone mineral density in the legs after SCI. Your health care team should measure and monitor your vitamin D serum level to ensure it remains in the optimal range.

There are currently no SCI guidelines on vitamin D intake. In Canada, the general recommendation for adults is to consume 600 IU of vitamin D each day or 800 IU each day for those older than 70 years. Osteoporosis Canada recommends that people with osteoporosis, multiple fractures, or conditions affecting vitamin D absorption should aim for 800-2000 IU each day. Intakes greater than 4000 IU per day are not recommended to prevent adverse effects associated with excessive levels of calcium due to its increased absorption by vitamin D.

2. Adequate, but not too much Calcium intake

Calcium is the main mineral in bone and is a common supplement used to treat women with osteoporosis after menopause. Current evidence suggests that calcium supplements alone do not reduce bone loss after SCI. However, calcium and vitamin D are used together to maintain bone density. Additionally, research suggests that high calcium intake achieved by using supplements may be linked to the development of coronary artery calcification (hardening of the heart arteries due to calcium build-up). Increasing calcium intake through food sources instead appeared to decrease this risk. As a result, dietary sources of calcium should be optimized first before considering supplementation.

There are currently no SCI guidelines on calcium intake. In Canada, the general recommendation for adults is to consume 1000-1200 mg of calcium each day or 1200 mg each day for those older than 70 years. Intakes greater than 2000-2500 mg per day are not recommended to prevent adverse effects such as bone pain and kidney stones. If you have stones in your bladder or kidney, calcium intake will need to be lower than that of your peers.

3. Drug Therapy

There are two main treatment approaches that can be taken to osteoporosis after SCI, depending on the length of time since the injury:

Early approaches

Bone loss happens at a faster rate during the first year after SCI, so treatments during this time focus on preventing the loss of bone mineral density by slowing the rate of bone loss. Early treatment may involve oral bisphosphonate medications, which are often started within the first 3 months after injury.

Later approaches

If sublesional osteoporosis occurs of the hip and knee regions (usually after the first year), later treatment seeks to keep or increase hip or knee region bone mineral density. Treatments during this period may include bisphosphonate medications, Denosumab, or Recombinant Parathyroid Hormone (PTH), supplements, and physical treatments. These treatments are based on the assumption that regional increases in bone density will result in a lower fracture risk.

Bisphosphonate medications are a family of drugs used to prevent the loss of bone mineral density. These drugs work by slowing the breakdown of bone or bone resorption. There are several drugs within this group, including Etidronate (Didrocal), Alendronate (Fosamax), Risedronate (Actonel), Clodronate (Bonefos, Clastion), and Tiludronate (Skelid). These drugs may be taken by mouth or through an intravenous (IV) line.

Bisphosphonate medications are often prescribed early after SCI to prevent declines in bone density during the first year. Research evidence has mostly supported that bisphosphonate medications help to reduce bone mineral density loss in the hip and knee regions during the first year after SCI. These medications appear to be more effective when given earlier after SCI.

Bisphosphonates are also used to treat existing bone loss after SCI. One research study has shown that Alendronate is effective for maintaining or increasing bone mineral density later after SCI.

Despite support from research, there are still many things about the use of bisphosphonates after SCI that we do not know, such as their long-term effects and what the best length of treatment is. Bisphosphonate medications may also have side effects (such as heartburn, stomach upset, racing heart, jaw or thigh pain), drug interactions, and specific instructions for use that should be discussed in detail with your health providers before taking the medications.

For more detailed information about bisphosphonate medications, see SCIRE Professional’s module on Bone Heath.

There are a number of physical treatment options that have been proposed for preventing and treating bone loss after SCI, however, the evidence does not support their regular use in treating bone loss after SCI.

FES can be applied to the leg muscles during assisted walking.¹¹

Functional electrical stimulation

Functional electrical stimulation (FES) is a treatment that applies electrical stimulation to the muscles during activities like standing, walking, or cycling. This treatment involves repeated pulling of the muscles on bones, which could help to strengthen the bones.

There is evidence suggesting that functional electrical stimulation cycling does not prevent bone loss in the lower leg early after SCI but may help to increase bone mineral density in stimulated areas of the leg during the later period after SCI. However, the stimulation needs to be ongoing or the benefits will be lost.

SCIRE Community provides additional detailed information about FES following SCI.

Electrical stimulation

Electrical stimulation to the muscles without functional activities may also be used. There is evidence suggesting that electrical stimulation can maintain or increase bone density over the stimulated areas. However, other studies have shown that the effects of electrical stimulation may return to baseline density within a few months after the treatment has ended.

Weight-bearing activities (standing and walking)

More research is needed to support weight-bearing activities for osteoporosis prevention.¹²

Weight-bearing activities are activities where the weight of the body is supported through the bones. Weight-bearing has long been considered to have an important role in bone health because it causes compression of the bones that may stimulate bone strengthening.

Weight-bearing treatments after SCI may include a variety of standing and walking activities, such as standing frames, braces, standing with functional electrical stimulation, and treadmill training.

Current evidence for weight-bearing activities for maintaining or improving bone health after SCI is inconclusive and needs further study.

Physical Activity

Physical activity is thought to improve bone health through a variety of processes that cause an increase in bone density. However, there is currently no evidence to support physical activity as a treatment for low bone density after SCI.

Therapies have been found to be ineffective:

Therapeutic ultrasound

Therapeutic ultrasound is a treatment that uses ultrasonic waves to provide energy to tissues deep within the body. Scientists have studied whether this treatment could provide stimulation to the bones to help prevent bone loss after SCI. However, current evidence suggests that therapeutic ultrasound is not effective for preventing bone loss after SCI.

Vibration exercise

Vibration exercise is a treatment that involves mechanical vibration of the body during resistance exercises. Current evidence suggests that vibration training is not effective for treating bone loss in the arms after SCI.

After SCI, low bone density implies an increased fracture risk. All of the current therapies are aimed at increasing bone mass and reducing your future risk of fracture.

Bisphosphonate medications are effective for preventing and treating bone loss after SCI and are usually started early after SCI onset. Non-drug physical treatments are not supported by current evidence for treating bone loss after SCI.

It is important to discuss any questions of concerns that you have about your treatment options in detail with your health providers to find the best management options for you. For a review of how we assess evidence at SCIRE Community and advice on making decisions, please see SCIRE Community Evidence.

Functional Electrical Stimulation (FES)

Astorino TA, Harness ET and Witzke KA. Effect of chronic activity-based therapy on bone mineral density and bone turnover in persons with spinal cord injury. Eur J Appl Physiol 2013; 113: 3027- 3037.

Bauman WA, Spungen AM. Disorders of carbohydrate and lipid metabolism in veterans with paraplegia or quadriplegia: A model of premature aging. Metabolism. 1994;43:749-56.

Bauman WA, Spungen AM. Coronary heart disease in individuals with spinal cord injury. Spinal Cord 2008;46:466-76.

Bauman WA, Morrison NG, Spungen AM. Vitamin D replacement therapy in persons with spinal cord injury. J Spinal Cord Med 2005;28:203-7.

Bauman WA, Spungen AM, Adkins RH, Kemp BJ. Metabolic and endocrine changes in persons aging with spinal cord injury. Assist Technol 1999c;11(2):88-96.

Bauman WA, Spungen AM, Zhong YG, Mobbs CV. Plasma leptin is directly related to body adiposity in subjects with spinal cord injury. Horm Metab Res 1997;28:732-6.

Bauman WA, Zhong YG, Schwartz E. Vitamin D deficiency in veterans with chronic spinal cord injury. Metabolism 1995;44:1612-6.

Bauman WA, Spungen AM, Raza M, Tothstein J, Zhang RL, Zhong YG, et al. Coronary artery disease: metabolic risk factors and latent disease in individuals with paraplegia. Mt Sinai J Med 1992;59:163-8.

Belanger M, Stein RB, Wheeler GD, Gordon T, Leduc B. Electrical stimulation: can it increase muscle strength and reverse osteopenia in spinal cord injured individuals? Arch Phys Med Rehabil 2000;8:1090-1098.

Cantorna MT, Vitamin D and its role in immunology: multiple sclerosis, and inflammatory bowel disease. Prog Biophys Mol Biol 2006;92:60-4.

Chain A, Koury JC, and Bezerra FF. Physical activity benefits bone density and bone-related hormones in adult men with cervical spinal cord injury. Eur J Appl Physiol 2012; 112: 3179-3186

Chen SC, Lai CH, Chan WP, Huang MH, Tsai HW, Chen JJ. Increases in bone mineral density after functional electrical stimulation cycling exercises in spinal cord injured patients. Disabil Rehabil 2005;27:1337-1341.

Cherniak EP, Levis S, Troen BR. Hypovitaminosis D: A stealthy epidemic that requires treatment. Geriatrics 2008;63:24-30.

Craven BC Robertson LA, McGillivray CF , and Adachi JD . Detection and treatment of sublesional osteoporosis after people with spinal cord injury Topics in SCI Rehabil 2009: 14(4):1-22.

Dudley-Javoroski S, Saha PK, Liang G, Li C, Gao Z, and Shields RK. High dose compressive loads attenuate bone mineral loss in humans with spinal cord injury. Osteoporos Int 2012; 23:2335- 2346.

Dudley-Javoroski S, and Shields RK. Active-resisted stance modulates regional bone mineral density in humans with spinal cord injury. Journal of Spinal Cord Medicine 2013; 36: 191-199.

Dudley-Javoroski S, and Shields RK. Asymmetric bone adaptations to soleus mechanical loading after spinal cord injury. J Musculoskelet Neuronal Interact. 2008;8:227-38.

Dudley-Javoroski S, and Shields RK. Does estimation and surveillance of mechanical loading interventions for bone loss after spinal cord injury. Phys Ther 2008; 88: 387-96.

Eser P, de Bruin ED, Telley I, Lechner HE, Knecht H, Stussi E. Effect of electrical stimulation-induced cycling on bone mineral density in spinal cord-injured patients. Eur J Clin Invest 2003;33:412-419.

Eser P, Frotzler A, Zehnder Y, Denoth J. Fracture threshold in the femur and tibia of people with spinal cord injury as determined by peripheral quantitative computed tomography. Arch Phys Med Rehabil. 2005;86:498-504.

Eser P, Schiessl H, Willnecker J. Bone loss and steady state after spinal cord injury: a cross-sectional study using pQCT. Journal of Musculoskeletal Neuronal Interactions 2004;4:197-198

Ford ES, Ajani UA, McGuire LC, Liu S. Concentrations of serum vitamin D and the metabolic syndrome among U.S. adults. Diabetes Care 2005;28:1228-30.

Frotzler A, Coupaud S, Perret C, Kakebeeke TH, Hunt KJ, Eser P. Effect of detraining on bone and muscle tissue in subjects with chronic spinal cord injury after a period of electrically-stimulated cycling: A small cohort study. Journal of Rehabilitation Medicine 2009; 41: 282-285.

Giangregorio LM, Hicks AL, Webber CE, Phillips SM, Craven BC, Bugaresti JM, et al. Body weight supported treadmill training in acute spinal cord injury: impact on muscle and bone. Spinal Cord 2005;43:649-657.

Giangregorio LM, Webber CE, Phillips SM, Hicks AL, Craven BC, Bugaresti JM, et al. Can body weight supported treadmill training increase bone mass and reverse muscle atrophy in individuals with chronic incomplete spinal cord injury? Appl Physiol Nutr Metab. 2006;31:283-291.

Heaney RP. Lessons for nutritional science from vitamin D. Am J Clin Nutr 1999;69:825-6

Holick MF. Vitamin D: Important for prevention of osteoporosis, cardiovascular heart disease, type I diabetes, autoimmune diseases, and some cancers. South Med J 2005;98:1024-7.

Hummel K, Craven BC, Giangregorio L. Serum 25(OH)D, PTH and correlates of suboptimal 25(OH)D levels in persons with chronic spinal cord injury. Spinal Cord 2012;50:812-6.

Mathieu C, Gysemans C, Giulietti A, Bouillon R. Vitamin D and diabetes. Diabetologia 2005;48:1247-57.

Melchiorri G, Andreoli A, Padura E, Sorge R, De Lorenzo A. Use of vibration exercise in spinal cord injury patients who regularly practice sport. Funct Neurol. 2007;22:151-154

Mohr T, Podenphant J, Biering-Sorensen F, Galbo H, Thamsborg G, Kjaer M. Increased bone mineral density after prolonged electrically induced cycle training of paralyzed limbs in spinal cord injured man. Calcif Tissue Int 1997;61:22-25.

Snijder MB, van Dam RM, Visser M, Deeq DJ, Dekker JM, Bouter LM, et al. Adiposity in relation to vitamin D status and parathyroid hormone levels: a population-based study in older men and women. J Clin Endocrinol Metab 2005;90:4119-23.

Warden SJ, Bennell KL, Matthews B, Brown DJ, McMeeken JM, Wark JD. Efficacy of low intensity pulsed ultrasound in the prevention of osteoporosis following spinal cord injury. Bone 2001;29:431-6.

Wortsman J, Matsuoka LY, Chen TC, Lu Z, Holick MF. Decreased bioavailability of vitamin D in obesity. Am J Clin Nutr 2000;72:690-3.

Zhou XJ, Vaziri ND, Segal JL, Winer RL, Eltorai I, Brunnemann BS. Effects of chronic spinal cord injury and pressure ulcer on 25(OH)-vitamin D levels. J Am Paraplegic Soc 1993;16:9-13

Image credits:

1. Osteoparoz by Aisha Huseynova. CC BY-SA 4.0, via Wikimedia Commons.
2. Cdm hip fracture 343 by Booyabazooka. CC BY-SA 3.0, via Wikimedia Commons.
3. Soy Beans by Jessica and Lon Binder. CC BY-NC-ND 2.0, via Flickr.
4. Steamed Kale by Laurel F. CC BY-SA 2.0, via Flickr.
5. Broccoli by Steffen Zahn. CC BY 2.0, via Flickr.
6. Shiitake Chinese Mushrooms by Artizone. CC BY-NC-ND 2.0, via Flickr.
7. Fracture by fahmionline, ID. CC BY 3.0 US, via The Noun Project.
8. Bone density machine by bwaters23. CC BY-NC-SA 2.0, via Flickr.
9. Vitamin D pills by Laura Dahl. CC BY-NC-ND 2.0, via Flickr.
10. Bone density by Eucalyp. [CC BY 3.0 US.
11. Functional Electrical Stimulation Therapy for walking ©MilosRPopovic, CC BY-SA 4.0.
12. Body weight-supported treadmill training with HAL Robot Suit exoskeleton by Oliver Jansen. CC BY-NC-ND 4.0.

Health claims are based on evidence from research.¹

All claims need evidence to support them. This is especially true in health care, where our decisions can have life-changing consequences. While there are many types of evidence, research is generally accepted to be the best source for evidence about health.

Research evidence is based on the findings of research studies that use scientific methods to seek answers to the questions we have about health and illness. Research evidence is sometimes comprised of the findings of just one study and at other times it is made up of the findings of hundreds of different studies.

There are many different sources of health information. We may hear about a friend’s experience, read a news article online, or simply listen to a doctor’s advice. However, this information may not always be as accurate as we believe.

Common problems with health information:

• All people can have conscious or unconscious beliefs that affect their judgments, even when those beliefs are not true. These biases can influence which treatments a doctor recommends or how a reporter writes about a treatment, in ways that might not be accurate.
• When we hear about another person’s experience with a treatment, we often assume that our experience would be the same, which is unlikely to be true – it takes very large groups of people to get an accurate picture of the effects of a treatment.
• We often make assumptions about the connections between a treatment and an outcome. However, unless strict controls are put in place, we cannot know for sure what actually caused an outcome. For example, it can be impossible to know if a medical treatment helped a person recover after an SCI, or if it was just the result of natural (spontaneous) recovery.

The importance of research evidence

Research evidence is important because the scientific methods used in well-designed research studies are more objective (unbiased) and accurate than conclusions based on other sources of evidence.

Some of these scientific methods may include:

The process of obtaining research evidence should be systematic and unbiased.³

• Using research techniques like blinding, control groups, and randomization to minimize bias.
• Studying large groups of people to identify patterns that may not be seen in smaller groups.
• Using special statistics to find out whether the findings could have simply been caused by chance.
• Providing a clear explanation about how the study was done, so you can think for yourself about how to interpret its findings. This also allows other researchers to repeat (replicate) the study to see if they get the same results.
• Requiring researchers to report any conflicts of interest (like if the authors have a financial interest in a product they are testing) to ensure that their research findings are independent of outside influences.
• Peer-reviewing a study to ensure it meets research standards before it is published.

There are many different types of research study designs. Below, we briefly outline the most common study designs used in SCI research.

The research design determines a study’s quality of evidence.⁴

Randomized controlled trials

In health research, the study design that provides the strongest evidence (as a single study) is called a randomized controlled trial, or RCT. RCTs are the most rigorous type of experimental study and can be used to determine whether a treatment actually caused the result.

RCTs are research experiments that place participants into at least two groups by chance, like the flip of a coin. One group (the experimental group) is given the treatment being tested and the other group (the control group) is given a comparison treatment or placebo. The two groups are then compared at the end of the study to see if they had different results.

Controlled trials without randomization (Prospective controlled trials)

In controlled trials without randomization, there is also an experimental group and a control group that are compared at the end of the study. However, unlike in RCTs, participants in these studies are not randomly assigned to their groups.

Because the groups are not randomly assigned, they may have additional differences that make a true comparison impossible. This type of study design is used when researchers cannot randomly assign participants into different groups.

Pre-post studies

Pre-post studies are one of the most common types of study designs used in SCI research. In this type of study, a group of people is tested before receiving a treatment and then afterwards. The difference between the “before” and “after” tests is thought to show the effects of the treatment.

Pre-post studies are used because they are often more convenient, ethical, and appropriate in a variety of different situations. However, because this study design does not control many of the factors that could affect the results of the study, it can be difficult to determine if changes in the results are caused by those other factors or the treatment itself.

Observational studies

Observational research involves observing what happens to a group of people over time when the researcher cannot control which participants receive which treatments. This type of research is used to observe connections and relationships between different factors.

Cohort studies are a type of observational study that follows up on or looks back on what happened to two (or more) comparable groups over time. The groups differ by an important characteristic, such as a health condition, risk factor, or treatment. The outcomes of the two groups are then compared to see how they differ over time.

Rats are often used in animal studies.⁵

Laboratory studies (animal studies)

Laboratory studies involving animals are usually done in an early stage of research to determine safety and if a treatment has potential before a risky procedure is used on people. Like human studies, there are strict ethical guidelines for performing studies involving animals. It is important to note that many treatments that are effective in animal studies are not effective in humans, so animal studies are considered introductory research that cannot simply be applied to humans as is.

Case studies and case series

Case studies describe the results of a treatment in a single individual (or case). Case studies are often used to communicate information when larger studies have not been done, or when it is difficult to do larger studies, like when a condition or treatment is extremely rare. A disadvantage of case studies is that because it is only based on one person, we do not know if the study’s conclusions also apply to other people. A case series is a study that includes multiple case studies.

Systematic reviews and Meta-analyses

Systematic reviews and meta-analyses summarize the findings of the research studies to answer specific research questions.⁶

Systematic reviews and meta-analyses combine the findings from all the studies on a topic together. This includes doing a systematic search for all the studies that address that topic, assessing the quality of each study, and interpreting the combined findings of all the studies together. Sometimes, systematic reviews may pool the data from different studies together and then analyze this grouped data. This is called a meta-analysis.

Systematic reviews and meta-analyses are considered the strongest form of research evidence to help with decision-making. These studies give greater context to the research and can weigh the findings of different studies against each other. However, systematic reviews and meta-analyses are only as strong as the studies they are based on, so they can still have some types of error.

Qualitative Research Designs

While the research methods listed above are most often used for making treatment decisions, qualitative research methods like interviews and focus groups provide other important knowledge. Qualitative research seeks to describe the qualities of something to develop a deeper understanding about it. For example, qualitative research may be used to describe the qualities of pain after SCI or the effect that it has on people’s daily lives.

Evidence quality can help us determine the value of research evidence in our treatment decisions. Higher quality evidence is usually weighed more heavily. However, lower quality evidence is still valuable when conclusions are made about a treatment, especially if there is no other research to help us understand it.

The quality of an experimental study is determined by how effectively the researchers reduce biases and errors in the study. Some of the features of high-quality experimental studies include:

Randomization

Randomization, control groups, blinding, and large numbers of participants help reduce biases and errors during data collection and analysis.⁷

Randomization is when study participants are randomly placed into the experimental group or the control group of a study. This is done to reduce biases in how participants are assigned to the groups within the study. Randomization means that all groups start off the same so they can be compared fairly at the end of the study.

Control groups

A control group is a group of participants in a study that receives an alternative treatment instead of the treatment being tested. This may be a placebo, a comparison treatment, or simply usual care (the care you would have if you were not in the study). At the end of the study, the control group is compared to the experimental group to see if they are different. Because the two groups only differ by which treatment they received, differences are thought to show the effects of the treatment.

Blinding

Blinding is when the type of treatment (experimental or control) that a participant receives is intentionally withheld from that person. The type of treatment may also be withheld from the researchers who are collecting information. This is called a double-blind experiment. Blinding is done to reduce the impact that people’s biases can have on how they report on something.

Large numbers of participants

When a study looks at a large group of participants, the people being tested are more likely to represent the general population and statistical analyses are more likely to be accurate. This allows the results of the study to be applied more accurately to real world situations.

When considering all the studies on a topic, the trends and comparisons between different studies can impact the relevance of the overall evidence.  Some factors to look at in a body of evidence include:

Number of research studies

The number of research studies published is important because each new study can validate, verify, or contradict the results of previous studies. If there are many studies on a specific topic with consistent results, the evidence is more likely to be reliable and be applicable to a more general population.

Consistency

Consistency is whether all the studies on a topic have similar results. When different studies produce opposing results and there is no explanation for the inconsistency, one should be cautious about making decisions using the evidence.

Doing research in populations with SCI is essential to improving treatment, rehabilitation, and management options for people with SCI, but there are some obstacles. Some research limitations unique to research in SCI populations include:

Low study participation

You may notice that many SCI studies have small sample sizes. SCI is not a common condition, so the number of people with SCI in a given location is often small. Even within that population, the level of injury and level of function will be very diverse. To make sure that this variation in injury types does not impact research results, studies often have strict participant criteria that require specific ranges for level of injury, level of function, time since injury, secondary health issues, medication use, etc. Also, people with SCI are more likely to have trouble accessing and maintaining participation in a study due to transportation, mobility, and ongoing health issues. All these factors contribute to the small sample sizes in studies of SCI and SCI treatments.

RCT challenges

Although RCTs are considered the gold standard for treatment research, they may not always be possible or ethical. There are ethical concerns over some of the strategies used in RCTs to reduce study bias when used for certain treatments. For example, randomizing participants to a non-treatment group in an exercise study, when it is commonly known that exercise is beneficial to health could be considered unethical. Invasive procedures such as surgeries are also difficult to study in RCTs because blinding participants might require a “sham” treatment (e.g. prepping the patient and making incisions but not doing the procedure). If a sham treatment is invasive and carries some risk, recruitment of willing participants in an already small participant pool becomes even more challenging. For the SCI population, it can be difficult to come up with a matched control group because of large variations in level of function and level of injury.

Although research provides the most reliable way of gathering information about a subject, research alone cannot tell us everything that we need to know about health. Some of the limitations of research as a form of evidence include:

Conducting and interpreting research are often challenging.⁹

• Conducting research is costly, challenging, and time-consuming. Only a small number of the questions we have will ever be answered directly through research.
• It is difficult to conduct high quality research. Even the most carefully designed studies can be faced with circumstances that create bias. Because of this, the majority of research studies do not provide strong evidence.
• Research can often be difficult and time-consuming to understand. This makes it challenging for everyone, including your health providers, to easily use research as a part of everyday decision-making.

Due to the limitations described above, many of the questions we have about treatments cannot be answered through research alone. Research is just one of many forms of evidence. Expert opinion, clinical consensus, and lived experience all have an important place in interpreting research evidence and making decisions when no high-quality research has been done.

Expert opinion

Expert opinion is a view or statement on a topic from an expert in the given field, based on clinical experiences or reasoning using foundational medical principles.

Clinical Consensus

Clinical consensus statements are written documents that include the recommendations of an organized group of experts on clinical issues.

Lived Experience

Friends and family may be a valuable source of health information.¹¹

Lived experience is the knowledge a person gains from direct, first-hand experience. There is value in understanding the impact and meaning of direct experiences for the development of research and treatments. Views of the same experience vary based on the person, their unique experience, and their environment.

Other sources of health information may include:

• Traditional or common practices
• Your personal experiences and reasoning
• The opinions and experiences of your family and friends

On top of the conclusions drawn from evidence other factors like potential risks and your preferences also need to be taken into account when deciding on treatment options for your health. Some questions to ask yourself before making a decision with the evidence can include:

1. Does this address your problem?
2. Based on the potential risks and benefits, is this suitable for you? (make a pros and cons list!)
3. Is this accessible for you? (finances, location, transportation)
4. How will this impact your life? (work, school, activities)
5. Do you have sufficient social, emotional, and physical supports? (family, friends, caregivers, other supports)
6. What are your personal preferences/goals?
7. What questions do you have?
8. What are the next steps that need to be taken?

For a list of included studies, please see the Reference List. For a review of how we assess evidence and advice on making decisions, refer to the SCIRE Community Evidence.

Want to learn more about research evidence?

Understanding Health Research. Useful Information. Available from: https://www.understandinghealthresearch.org/useful-information/.

Understanding Health Research. How to read a scientific paper. Available from: https://www.understandinghealthresearch.org/useful-information/how-to-read-a-scientific-paper-4.

Understanding Health Research. How science media stories work. Available from: https://www.understandinghealthresearch.org/useful-information/how-science-media-stories-work-3.

Cochrane Consumer Network. Available from: https://consumers.cochrane.org/.

Looking for more information about how SCIRE does its systematic reviews?

SCIRE Professional – Methods of Systematic Review. Available from: https://scireproject.com/about-scire-project/review-process-and-methodology/.

Foley, N. C., Bhogal, S. K., Teasell, R. W., Bureau, Y., & Speechley, M. R. (2006). Estimates of Quality and Reliability With the Physiotherapy Evidence-Based Database Scale to Assess the Methodology of Randomized Controlled Trials of Pharmacological and Nonpharmacological Interventions. Physical Therapy, 86(6), 817–824. https://doi.org/10.1093/ptj/86.6.817

Sackett, D. L., Straus, S. E., Richardson, W. S., Rosenberg, W., & Haynes, R. B. (2000). Evidence-Based Medicine: How to Practice and Teach EBM. Churchill Livingstone.

Sackett, D. L., Rosenberg, W. M. C., Gray, J. A. M., Haynes, R. B., & Richardson, W. S. (1996). Evidence based medicine: what it is and what it isn’t. BMJ, 312(7023), 71–72. https://doi.org/10.1136/bmj.312.7023.71

PEDro: http://www.pedro.fhs.usyd.edu.au/scale_item.html

Guyatt, G. H., Oxman, A. D., Kunz, R., Woodcock, J., Brozek, J., Helfand, M., Alonso-Coello, P., Glasziou, P., Jaeschke, R., Akl, E. A., Norris, S., Vist, G., Dahm, P., Shukla, V. K., Higgins, J., Falck-Ytter, Y., & Schünemann, H. J. (2011). GRADE guidelines: 7. Rating the quality of evidence—inconsistency. Journal of Clinical Epidemiology, 64(12), 1294–1302. https://doi.org/10.1016/j.jclinepi.2011.03.017

Martin Ginis, K. A., & Hicks, A. L. (2005). Exercise Research Issues in the Spinal Cord Injured Population. Exercise and Sport Sciences Reviews, 33(1). https://journals.lww.com/acsm-essr/fulltext/2005/01000/exercise_research_issues_in_the_spinal_cord.9.aspx

Zimmermann, G., Bolter, L., Sluka, R., Höller, Y., Bathke, A. C., Thomschewski, A., Leis, S., Lattanzi, S., Brigo, F., & Trinka, E. (2019). Sample sizes and statistical methods in interventional studies on individuals with spinal cord injury: A systematic review. Journal of Evidence-Based Medicine, 12(3), 200–208. https://doi.org/10.1111/jebm.12356

Tator, C. H. (2006). Review of treatment trials in human spinal cord injury: issues, difficulties, and recommendations. Neurosurgery, 59(5), 957–987. https://doi.org/10.1227/01.NEU.0000245591.16087.89

Ellis, C. (1992). Investigating subjectivity: Research on lived experience (Vol. 139). Sage.

Moberg, J., Oxman, A. D., Rosenbaum, S., Schünemann, H. J., Guyatt, G., Flottorp, S., Glenton, C., Lewin, S., Morelli, A., Rada, G., & Alonso-Coello, P. (2018). The GRADE Evidence to Decision (EtD) framework for health system and public health decisions. Health Research Policy and Systems, 16(1), 45. https://doi.org/10.1186/s12961-018-0320-2

Image credits:

1. Research ©luckey_sun, CC BY-SA 2.0
2. Brainstorming ©Icons8, CC0 1.0
3. Resorting to paper… #research# #proposal ©catherinecronin, CC BY-SA 2.0
4. Today’s reading #bigpicture by catherinecronin, CC BY-SA 2.0
5. A lab friend ©Anna Marchenkova, CC BY-SA 4.0
6. Library books ©timetrax23, CC BY-SA 2.0
7. Research Data Management ©janneke staaks, CC BY-NC 2.0
8. Magnifying glass ©kaosnoff, CC0 1.0
9. NCSR Researcher using Ubuntu ©Simos Xenitellis, CC BY-SA 4.0
10. Scientist ©H Alberto Gongora, CC BY 3.0 US
11. Image ©SCIRE