As previously discussed, there is a trend towards increased hospitalisation due to falls and fall-related injuries, and falls continue to account for significant mortality in older people. (37, 59) Understanding the risk factors which predict injurious falls in older people who fall, may assist in targeting falls prevention interventions to “at risk” individuals and groups. Many of the community based observational studies discussed above have also examined the risk predictors for all injurious falls, minor injury falls and severe injury falls. In general, the risk predictors for injurious falls are similar to those seen for all falls and are discussed in more detail below.
A range of community based prospective cohort studies have demonstrated that impairments in mobility and balance, function, cognition, certain medications and comorbidities along with situational factors and accumulation of risk factors, contribute to increased risk of any injurious falls. (19, 60-63) In a Canadian community population, O’Loughlin et al. found that the following factors were associated with a 2-fold increased risk of having an injurious fall when adjusted for age: increasing number of days of limited activity (OR 2.2; 95% C.I. 1.4 – 3.6), previous stroke (OR 2.4; 95% C.I. 1.3 – 4.5) and being involved in 10 or more activities in the previous week (OR 2.1; 95% C.I. 1.1 – 3.8). (19) Respiratory disease was also
associated with increased risk of having an injurious fall (OR 1.7; 95% C.I. 1.1 – 2.8). Use of heart medications (OR 0.5; 95% C.I. 0.3 – 0.9) and being involved in 2 or more activities in the previous week (OR 0.5; 95% C.I. 0.3 – 0.8) were protective. This suggests that both limited activity and high levels of activity increase the risk of injurious falls, but that a certain level of activity is required to reduce the risk of injurious falls. Koski et al. reported on risk factors for injurious falls in a Finnish community based cohort of males and females. (63)
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Over 2 years of follow-up, gait impairment, described as path deviation (which constituted 1 of 6 measures of gait), was associated with injurious falls (OR 1.8; 95% C.I.1.0 – 3.3). (63) In males, gait impairment was strongly associated with injurious falls (OR 3.5; 95% C.I. 1.4 – 8.8). The use of digoxin was associated with a non-significant increased risk of injurious falls (OR 2.2; 95% C.I. 0.9 – 5.7). In females, short step length had the strongest association with injurious falls (OR 32.1; 95% C.I. 2.4 – 43.8). The use of calcium channel blockers was associated with a 2.5-fold increased risk of having an injurious fall (OR 2.5; 95% C.I. 1.2 – 5.2), and the use of medication for peripheral vascular disease showed a non-significant trend to increasing the risk of an injurious fall (OR 3.7; 95% C.I. 0.8 – 17.6).
The risk profile for falls resulting in minor injuries is similar to that seen for all injurious falls. Nevitt et al. described a significant association between turning around or reaching and injurious falls (OR 3.5; 95% CI 1.7 – 7.3). (25) There were weaker associations with
injurious falls and slower reaction time, reduced grip strength, falls whilst using stairs or steps and being of White racial background. In the Finnish study mentioned above path deviation and the use of calcium channel blockers were associated with minor falls. (63) In males, gait disturbance and the use of calcium channel blockers were also associated with increased risk minor injurious falls. Females had a similar risk profile with path deviation, use of calcium channel blockers and the additional use of anti-inflammatories increasing the risk of minor injurious falls.
Major or serious injurious falls are falls resulting in the requirement for medical
interventions, E.D. attendance or hospitalisation. Nevitt et al. found in their multivariate analysis that having had a previous fall with a fracture, slower trail making B test (a test of cognition) and being of White racial background were all associated with increased risk of a
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major injurious fall. (25) In another prospective U.S. cohort study, Tinetti et al. reported that cognitive impairment (MMSE <26), being female, having at least 2 chronic conditions, balance and gait score <12/22 (Tinetti score) and body mass index <22 kg/m2 were associated
with increased risk of serious injurious falls in multivariate analysis. (60) In the Finnish prospective cohort study by Koski et al., absence of Achilles reflex, reduced sternal pain sensation and use of long-acting benzodiazepines were all strongly associated with injurious falls, and 2- to 3-fold increased risk of falling and sustaining a major injury. (63) Tinetti et al. also looked at the circumstances of the fall to identify situational issues which may be
associated with serious injurious falls. (61) This study found that falls on stairs, whilst performing displacing activities, and falls from at least body height, approximately doubled the risk of injurious falls. In addition, this study found that increasing numbers of
predisposing risk factors was significantly associated with a linear trend to increased risk of falling (p<0.0001).
We can again examine the differences in risk factors for injurious falls between the sexes, and between those who are independent and those termed disabled. Cohort studies in the United States and Finland have found different rates and risk factors for injurious falls between the sexes. Tinetti et al. reported that females were more likely to sustain a fracture than males however there was no difference in the likelihood of having a fall. (61) In addition, in the subgroup who had recurrent falls, females had a 1.9-fold increased risk of sustaining a serious injury in the adjusted model (OR 1.9; 95% C.I. 1.1 – 3.1) compared to males. In the Finnish study, in males, the risk of major injurious falls was increased 4-fold by absence of
quadriceps tendon reflex (OR 4.8; 95% C.I. 1.15 – 19.6). (63) There was a non-significant trend to increased risk of falls in those with gait disturbance and digoxin use. In females, the use of long-acting benzodiazepines increased the risk of major injurious falls (OR 4.0; 95%
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C.I. 1.25 – 12.5). There was a non-significant increased risk with foot deformities, short step length and the use of calcium channel blockers. In a second study Koski et al. also reported on the risk of major injurious falls in those who were independent, based on their ability to perform activities of daily living (ADLs), including domestic chores. (62) The presence of peripheral neuropathy was associated with a 2-fold increased risk of major injurious falls and insomnia was associated with a 4-fold increased risk. In those who were categorised as disabled, having 2 or more deficits in ADLs, being divorced, widowed or unmarried, low body mass index, impaired gait, poor distant visual acuity and the use of long-acting benzodiazepines were all associated with sustaining a major injurious fall.
1.5.2 Emergency Department based studies – characteristics of fallers and risk factors