3 | Risk factors for falls and fall-related injuries in seniors

The previous chapter presented the epidemiology of fall-related injuries among seniors in Canada. This chapter examines current knowledge about fall risks. The information presented here was summarized from several well-known guidelines and systematic reviews of the literature on risk factors and best practices for the prevention of falls and fall-related injuries among seniors.

Review of current knowledge

The following sources were used:

• A best practices guide for the prevention of falls among seniors living in the community, Federal/Provincial/ Territorial Ministers Responsible for Seniors (2001);²⁶
• the Rand Report (2002) more recently cited as Interventions for the prevention of falls in older adults: Systematic review and meta-analysis of randomized clinical trials, (2004);²⁷
• the Cochrane Review: Interventions for preventing falls in elderly people (2001);²⁸ the Cochrane Review: Population-based interventions for the prevention of fall-related injuries in older people (2005);²⁹
• the American Geriatrics Society's Guideline for the prevention of falls in older persons, (2001);³⁰ and
• additional findings, highlighting Canadian studies published after the reviews.

The review conducted for the Best practices guide of the F/P/T Ministers Responsible for Seniors screened 674 studies, ultimately reviewing 34 that evaluated fall prevention interventions designed to reduce falls or fall-related injuries among community-dwelling seniors.

The Rand Report screened 774 articles, rejecting all but 34, which contributed data to the meta-analysis. The Rand Corporation also funded a report summarizing published research on causal factors for falls, collating data from 16 studies.

The American Geriatrics Society (AGS) Guideline is one of the most adopted guidelines, prepared in collaboration with the British Geriatrics Society and the American Academy of Orthopaedic Surgeons. This guideline outlines recommended practice and establishes the strength of the recommendations based on the evidence in the research literature.

The Cochrane Review (2001) focused on randomized control trials and included 40 studies involving interventions with seniors in community, facility and acute care settings that measured falls or fall-related injuries as an outcome. The 2005 Cochrane Review reviewed five studies that reported changes in medically treated fall-related injuries among older people following the implementation of a controlled population-based intervention.

Risk factors - complex and interactive

Falls result from a complex interaction of risk factors. As the number of risk factors increases, the higher the risk of falling and of being injured. For example, one study showed that only 27% of people living in the community, with no risk factor or only one, had a fall. The figure rose to 78% for those with four or more risk factors.³¹

Over the past 20 years or so, researchers have assessed risk factors and grouped them in various ways to facilitate comparisons in research studies. Typically, risk factors have been grouped into two main categories - intrinsic factors that lie within the individual and include both demographic and health factors, and extrinsic factors that lie within either the physical or socio-economic environment. However, a more recent model for categorizing risk factors better captures the interrelationships between behaviours and other risk factors. The four categories of risk factors in this model are biological and medical, behavioural, environmental, and socio-economic. (See Appendix A for a list of the risk factors in all of these categories).

3.1 Biological and medical risk factors

Biological and medical risk factors fall along a continuum from effects of healthy aging to pathological conditions. Normal aging inevitably brings physical, cognitive and affective changes which may contribute to the risk of falls, including sensory, musculoskeletal, neurological, and metabolic changes. Gender is also a key factor as women fall more often than men and sustain more injuries when they fall. Advanced age is associated with higher rates of falls. Seniors over 80 years of age are the most likely to fall and be injured. However, it is not age per se that increases the risk of falls - it is the co-morbidity of aging related to changes.

• Muscle weakness and reduced physical fitness, particularly to the lower body, are one of the most common intrinsic risk factors for falling. A panel of the American Geriatrics Society, British Geriatrics Society and American Academy of Orthopaedic Surgeons³² found it to be the most important risk factor, increasing risk of a fall by four to five times. A loss of muscle strength, balance, flexibility and coordination can contribute to difficulty accomplishing activities of daily living. Related balance and gait disorders also have been shown to be closely linked to falls, creating a three-fold increase in the risk of falling. A recent Canadian study of veterans and their caregivers confirmed these findings.³³

• Impaired control of balance and gait is a factor leading to instability and falls.³⁴ In particular, age-related changes in the neural, sensory and musculoskeletal systems can lead to impaired ability to maintain upright stance or react to a sudden loss of balance (e.g., a slip, trip or push).³⁵ Balancing reactions that involve rapidly taking a step or reaching to grasp an object for support play a critical role in preventing falls, but the ability to execute these reactions effectively can be impaired even in relatively young and healthy seniors.³⁶ Neurologic disorders such as Parkinson's disease or hemiparesis due to stroke can exacerbate these difficulties.³⁷

• Vision changes can contribute to falls. Those with visual deficits such as reduced acuity or contrast sensitivity, declined accommodation to light and darkness, or altered depth perception are two and a half times more likely to have a fall.³⁸ Visual deficits such as myopia, ulcerative scars, corneal pathology, cataracts or complications from cataract surgery and glare intolerance are also thought to increase the risk of falling. People may also experience problems with new glasses, particularly multi-focal lenses that distort depth perception.³⁹

• Chronic illness has been associated with an increased risk of falling. Arthritis is a major contributor (osteoarthritis being the most common form), increasing the risk of a fall by 2.4 times.⁴⁰ Senior women experience more arthritis than men (58% vs. 42%, CCHS 2003). Other chronic illnesses such as stroke and Parkinson's disease increase the risk of falls. Hypotension (low blood pressure) affects 15% of all seniors and has been associated with as many as 20% of all falls.⁴¹ Osteoporosis, characterized by low bone mass and the deterioration of bone tissue, does not affect the risk of falling per se, but does increase the risk of fractures from a fall, particularly those of the hip, spine and wrist. Other chronic conditions frequently implicated in falls include urinary incontinence and cardiovascular conditions including arrhythmias.

• Physical disability can increase the risk of falls. Physical disabilities linked to aging include gait disorders, diminished touch and sensation in limbs and feet, hearing loss, poor balance, dizziness, postural hypotension, sore feet and other feet problems, and injuries from a previous fall.

• Acute illness may be responsible for between 10% to 20% of falls.⁴³ One example is acute infection. A Canadian study found that anti-infective medications were highly associated with fall-related hospital admissions, strongly suggesting that people with acute infectious disease are at a high risk for falls and injuries as a result of weakness, fatigue or dizziness.⁴⁴ Even the short periods of immobility often associated with an acute illness are known to contribute to reduced bone density and muscle mass.

• Cognitive impairment, such as confusion due to dementia and delirium, can also increase the risk of a fall. The Rand researchers reported an increased risk of 1.8 times for persons with cognitive impairment.⁴⁵ The Canadian study of veterans and caregivers also found that worsening memory was associated with more frequent falling.⁴⁶

• Depression has been reported by many researchers as having a relationship to falls, but such studies are often retrospective and the depression could well result from the fall, rather than be a causal or risk factor.⁴⁷

3.2 Behavioural risk factors

• A history of previous falls is one of the best predictors of a future fall. Any previous fall increases the risk for another fall threefold.⁴⁸ A previous fall may reduce mobility in older people, resulting in loss of strength, balance and reflexes. Feelings of fear and helplessness may also ensue, further adding to restrictions on activity and participation and reduced quality of life.⁴⁹

• Risk-taking behaviour as a factor associated with falls has not been studied scientifically. The risk associated with participation in activities is influenced by individual, behavioural and situational factors. For example, an older adult's vision and strength, awareness of the environment, and protective behaviours, such as using a handrail, influence the risk of falls.⁵⁰ Risk behaviours may include climbing, reaching, or bending while performing activities of daily living.⁵¹ Reviews of cases presenting in the emergency department have shown that many falls result from seniors climbing ladders, standing on unsteady chairs, and even participating in vigorous sports such as skiing or tennis. Many seniors report that their fall occurred when they were rushing, not paying attention or not using mobility devices prescribed for them such as a cane or walker.⁵²

• Certain medications and multiple prescriptions are a significant factor in many falls. Older people tend to take more drugs than younger people and, with age, they develop altered mechanisms for digesting and metabolizing drugs. Both the half-life and the active levels of a given dose increase with age, making the cumulative effects of medication use unpredictable. Medications can affect one's risk of falling in several ways. They can affect alertness, judgment, and coordination. Certain drugs increase postural hypotension - a significant drop in blood pressure with a change in position (lie to sit or stand) - resulting in dizziness. Drugs can also alter the balance mechanism and the ability to recognize and adapt to obstacles. Finally, drugs may impair mobility by causing increased stiffness or weakness.⁵³

• Polypharmacy, defined as taking five or more prescribed medications, is shown to be a significant factor in many falls.⁵⁴ The variety of prescription medications is increasing and they are used in greater numbers and in new combinations. Drug-herb interactions may also be implicated in falls as supplements, herbs and vitamins can react with each other or with prescription medications.⁵⁵ The effects of various drug combinations are not yet clearly understood, especially the possible risks for falls in elderly individuals.

• Benzodiazepines, such as alprazolam (Xanax) and diazepam (Valium), are often prescribed to treat sleep problems and anxiety. Even the use of short-acting benzodiazepines has a greater association with falls and hip fractures.⁵⁶

• Patients taking psychotropic medications, such as paroxetine (Paxil) and sertraline (Zoloft) prescribed for depression, appear to have about a two-fold increased risk of falls and fractures, compared with individuals not taking these drugs. Some studies have also found that use of nonsteroidal anti-inflammatory drugs is associated with falling. However, current evidence suggests that diuretics, in general, do not cause falls and that thiazide diuretics may help prevent fractures by slowing the development of osteoporosis.⁵⁷

• The risks associated with anticoagulant therapy, especially the risk of falls-related injury, are greater in the elderly. A fall may result in head trauma but go undiagnosed because patients are confused, do not remember falling, or fail to report the fall. This is especially risky in patients on anticoagulant therapy since a fall with head trauma may result in bleeding in the brain. Blunt head trauma may cause behavioural and neurologic abnormalities and may be a sign of bleeding in the brain or brain cavity.⁵⁸

• Excessive alcohol has been shown to be a factor in increased rates of falling. Consumption of 14 or more drinks per week is associated with an increased risk of falls in older adults.⁵⁹ Cross-sectional studies may fail to identify this risk of heavier drinking, perhaps because older adults at risk for falls decrease their alcohol use over time or because heavier drinkers at risk for falls tend not to enroll in studies. Alcohol may also interact with certain drugs to increase the risk of falls by producing changes in awareness, balance and gait. Alcohol used in moderation has not been associated with increased fall rates.⁶⁰

• Footwear, clothing and handbags can contribute to falls, although clear research evidence is lacking. Footwear that fits poorly, has worn soles, is not laced or buckled when worn, or is of an unusual heel height for the individual, can contribute to falls. As people age, their height and posture change and long dressing gowns or trousers, which may have fit well at one time, can cause tripping hazards resulting in a fall and related injury.⁶¹ Many older people report falling or sustaining a fall-related injury, as a result of carrying an object such as a handbag, laundry basket or grocery bag.⁶² Suspected mechanisms relate to altered balance, altered recovery mechanisms upon a trip or stumble, and altered means of protection as the senior lands on the ground or floor.⁶³ Holding an object, for example, has been shown to impede ability to recover balance as it prevents one from rapidly grasping a handrail or other object for support.⁶⁴

• Inactivity and inadequate diet may be important factors in both falls and related injuries. Again, while clear research evidence is lacking, people who are hospitalized 19 days or more have been shown to have an increased risk of a fall.⁶⁵ Undoubtedly, inactivity will result in reduced muscle mass, decreased bone density and poor balance. Dietary relationships to falls are less clear. However, adequate protein, essential vitamins and water are believed to be essential for optimum health. If deficiencies do exist, it is reasonable to expect that weakness, poor fall recovery and increased injury will ensue. Bone health is affected by intakes of vitamin D and calcium and deficiencies in these two nutrients have been associated with increased risk of fracture from a fall.

• Fear of falling has been identified relatively recently as a risk factor in the fall prevention literature. Fear of falling is widespread and has been reported as the most common fear of older adults.⁶⁶ It is an important aspect to consider, particularly for those who develop fear after having fallen.⁶⁷ Fear of falling is reported by a significant number of older persons.⁶⁸ Specific fears vary but often include fear of falling again, being hurt or hospitalized, not being able to get up after a fall, social embarrassment, loss of independence, and having to move from home.⁶⁹
  
  Fear can positively motivate some seniors to take precautions against falls and can lead to gait adaptations that increase stability.⁷⁰ For others, fear can lead to a decline in overall quality of life and increase the risk of falls through a reduction in the activities needed to maintain self-esteem, confidence, strength and balance.⁷¹ In addition, fear can lead to maladaptive changes in balance control (e.g., "stiffening") that may increase the risk of falling.⁷² People who are fearful of falling also tend to lack confidence in their ability to prevent or manage falls, which increases the risk of falling again.⁷³
  
  Fear, as it affects client compliance with fall prevention strategies, is discussed in Chapter 4, Section 5 of this report.

3.3 Environmental risk factors

Between 25% and 75% of falls in older people involve an environmental component.⁷⁴ While individual levels of risk have not been established for many of these factors, researchers and clinicians have recognized a number of hazards in the home and public environment that contribute to falls and related injuries. These factors interact with other risk factors, such as poor vision or balance, to compound fall-related risk for seniors.

• Stairs can be problematic - hazardous characteristics include uneven or excessively high or narrow steps, slippery surfaces, unmarked edges, discontinuous or poorly-fitted handrails, and inadequate or excessive lighting. A recent Canadian study examined stairs which seniors said they found difficult to use. Unsafe features identified most frequently were: no contrast markings for stair edges, non-uniform risers, stair dimensions that differ from the recommended seven-inch maximum height or rise and eleven-inch minimum run (toe to heel allowance), open risers and lack of handrails.⁷⁵ Handrails that are securely mounted at an appropriate height and shaped correctly allow a functional grip to be established.⁷⁶ Stair surfaces and floors that are slippery, excessively patterned, glare-producing or uneven also have been implicated in falls.⁷⁷

• Factors in and around the home that contribute to falls include: loose or uneven rugs; absence of night lights; an absence of accessible light switches at room entrances; hazardous shower stalls; baths or toilets; lack of grab bars or handrails; appliance cords or other obstacles in walking routes; items stored in high cupboards; and low furniture such as beds or chairs. Outside the home hazards can be found in such features as garden paths and walks that are cracked or slippery from rain, snow or moss. Entrance stairs and poor night lighting can also pose risks. Even pets can be a tripping hazard.⁷⁸

• Factors in the public environment can also trigger falls. A Canadian study found that 65% of falls among seniors occurred outdoors while walking on a familiar route.⁷⁹ Poor building design and inadequate maintenance of buildings can also contribute to falls. Most problematic are cracked or uneven sidewalks, unmarked obstacles, slippery surfaces, poor lighting and lengthy distances to sitting areas and public restrooms.

• Fall hazards in long-term care settings and hospitals also have been identified. Factors include chair and bed heights, floor surfaces, lighting and lack of rest areas. Many falls occur as people arise from bed. Apart from the dizziness sometimes associated with rising too quickly, the physical structure of the bed itself may be a factor. For example, when bed rails are in the lowered position and a person is moving to a standing position, space is lacking under the bed for proper footing and balance. It is logical to conclude that this may be a factor explaining why so many institutional falls occur in and around the bed.

• Assistive devices can promote independence and mobility and may prevent falls if properly used and safely maintained. However, cane tips can become worn, making them unsafe. Walkers with wheels or wheelchairs may lack a functioning locking mechanism posing a hazard. Moreover, the use of canes and walkers can interfere with the ability to maintain balance in certain situations, and the demands of using these devices can be excessive for older adults.⁸⁰ Having an assistive device does not necessarily guarantee its use. Many older people see such aids as symbols of their old age and advanced frailty, and they may be reluctant to use them because of this stigma.⁸¹

3.4 Socio-economic risk factors

• Income, education, housing and social connectedness are recognized social determinants of health but a limited body of research exists on the relationship between falls and these determinants. A recent Canadian study of veterans found that financial strain was an independent predictor of both falls and injurious falls, particularly among the caregivers of veterans.⁸²

It has been suggested that, because a relationship exists between income, education and housing and certain chronic health conditions, poor health may be the link between these factors and the increased risk of falling. For example, the group most affected by low income is women age 75 and over who live alone. These women may not be able to afford home modifications or assistive devices, attend fitness programs or have access to fall prevention information, all of which would help reduce falls.

Summary

Literature and guidelines report that falls result from a complex interaction of risk factors and, as the number of risk factors increases, the higher the risk of falling and of being injured. Biological and medical, behavioural, environmental, and socio-economic risk factors interact and compound. Normal aging inevitably brings physical, cognitive and affective changes which may contribute to the risk of falls. Gender is also a key factor as women fall more often than men and sustain more injuries when they fall. Advanced age is associated with higher rates of falls and fall injuries.

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