Association between falls in elderly women and chronic diseases and drug use: cross sectional study
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Abstract
Objective To assess the associations between having had a fall and chronic diseases and drug use in elderly women.
Design Cross sectional survey, using data from the British women's heart and health study.
Setting General practices in 23 towns in Great Britain.
Participants 4050 women aged 60-79 years.
Main outcome measure Whether women had had falls in the previous 12 months.
Results
The prevalence of falling increased with increasing numbers of
simultaneously occurring chronic diseases. However, no such relation
with falling was found in the fully adjusted data for the number of
drugs used. Circulatory disease, chronic obstructive pulmonary disease,
depression, and arthritis were all associated with an increased odds of
falling. The fully adjusted, population attributable risk of falling
associated with having at least one chronic disease was 32.2% (95%
confidence interval 19.6% to 42.8%). Only two classes of drugs
(hypnotics and anxiolytics, and antidepressants) were independently
associated with an increased odds of falling. Each class was associated
with an increase of about 50% in the odds of falling, and each had a
population attributable risk of < 5%.
Conclusion Chronic diseases and multiple pathology are more important predictors of falling than polypharmacy.
Introduction
Falls
among elderly people are common and are associated with increased
morbidity, disability, social isolation, and a lower quality of life and
with early entry into residential care in this group.1
A number of chronic diseases are associated with a higher risk of
falling, as are several classes of drugs, particularly tranquillisers
and antidepressants.1-3
However, few studies have assessed the independent associations of a
range of risk factors in a single study group. We aimed to assess the
independent associations of chronic diseases and drug use and the risk
of falls in a group of women aged 60-79 years and living in the
community.
Methods
Participants
The
women were participants in the British women's heart and health study.
Full details of the selection of participants and measurements taken
have been reported in previous studies.4-6
We used the British regional heart study framework to randomly select
women aged 60-79 from general practice lists in 23 towns in England,
Scotland, and Wales. No women were excluded from the study, and all 7166
women in the age range, regardless of whether they normally lived in
private accommodation, a residential home, or a nursing home, and
irrespective of medical conditions, were invited to participate.
Transport to examination centres was offered to immobile and frail
women. Invitations were sent to the women, and two reminders were sent
to non-responders. A total of 4286 women (60% of those invited)
participated. Baseline data (from a self completed questionnaire,
interviews by a research nurse, physical examination, and review of
primary care medical records) were collected between April 1999 and
March 2001.
Assessment of falls
In
the self completed questionnaire participants were asked whether they
had had a fall in the previous 12 months, how many times they had
fallen, and whether they had received medical attention for any falls.
No specific definition of a fall was given in these questions. As in
other studies, we defined frequent falling as at least two falls in the
previous 12 months.7
Assessment of chronic diseases
We
collated details of clinical diagnoses of each of the women's chronic
diseases, together with the dates of first diagnosis, from a combination
of review of primary care medical records, interviews by a research
nurse, and the participants' responses to the questionnaire.4-6
Coronary heart disease was defined as any previous diagnosis of
myocardial infarction or angina. Circulatory disease was defined as any
diagnosis of myocardial infarction, angina, stroke, transient ischaemic
attack, aortic artery disease, or peripheral artery disease. Chronic
obstructive pulmonary disease included asthma and chronic bronchitis,
and eye disease included cataracts and glaucoma.
Assessment of current drug use
Participants
were asked to bring all their current medicines to the clinic visit,
and at the research nurse's interview a full drug history was taken.
Drugs were coded according to the British National Formulary:
hypnotics and anxiolytics (drugs in section 4.1); antidepressants (4.3);
any central nervous system drugs (4.1 to 4.11); analgesics (4.7 and
10.1.1); cardiovascular system drugs (2.1 to 2.12); endocrine system
drugs (6.1 to 6.7); and respiratory system drugs (3.1 to 3.3).8
In analysing the data on analgesic drugs we did a sensitivity analysis
in which non-steroidal anti-inflammatory drugs were not included in the
definition (only drugs in section 4.7 were included). The results of
this sensitivity analysis did not differ significantly from the results
presented here.
Other measurements
We
measured blood pressure with a Dinamap 1846SX vital signs monitor (GE
Clinical Services, Northampton). We took two measurements in succession,
with a 1 minute interval, on the right arm, with the participant seated
and the arm supported on a cushion at chest level. Participants were
then asked to stand, with their arms relaxed and at their sides, and two
standing measurements were taken. The mean of the two measurements was
used in all analyses. Postural hypotension was defined as a reduction
between sitting and standing of ≥ 20 mm Hg in systolic blood pressure or
≥ 10 mm Hg in diastolic pressure.9 We also assessed the association of low standing blood pressure (systolic ≤ 100 mm Hg or diastolic ≤ 60 mm Hg) with falls.
We
derived two measures of alcohol consumption from the questionnaire
data: regular daily consumption (or consumption on most days) of any
alcohol; and heavy drinking, defined as ≥ 14 units of alcohol a week.
Social class was derived, in the case of married women, from the longest
held occupation of the husband or, in single women, from her own
longest held occupation. Social class was defined according to the
registrar general's classification.
Statistical analysis
We
used multiple logistic regression to assess associations with falls. Of
the 4286 women who participated 425 could not be assigned an adult
social class. These women were likely to have been married to unemployed
men, and as their risk factor profiles were similar to those of women
in social class V they were allocated to this group, as in previous
analyses.5
Sensitivity analyses in which these women were excluded showed no
significant difference in the findings. There were a few missing data
for each of the other variables, and the multivariable analyses were
conducted on the 3742 women (92%) with complete data on all the
variables that were included in the final fully adjusted model. These
3742 women did not differ from the women without complete data in age or
in the prevalence of any falls, frequent falls, or falls where the
women received medical attention (P > 0.4 for all variables). We
estimated population attributable risks of falling for risk factors from
the fully adjusted logistic regression models, using maximum likelihood
estimates as proposed by Greenland and Drescher.10
In all analyses we used robust standard errors, which take into account
the clustering effects in each town, to calculate 95% confidence
intervals. We used Stata version 8.0 (StataCorp, College Station, TX,
2002) for all statistical analyses.
Results
Of
the 4286 participants 4050 (94%) provided data on falls. There were no
differences between the women who provided these data and the other
women in age, prevalence of any chronic diseases, drug use, or
socioeconomic position (P > 0.15 for all variables). Of the 4050
women 686 had fallen at least once in the previous 12 months, giving a
prevalence of 16.9% (95% confidence interval 15.8% to 18.1%). The
prevalence of frequent falling was 7.0% (6.2% to 7.8%) and of falls
where medical attention was given was 6.8% (6.0% to 7.6%).
Women
who had fallen at least once in the previous 12 months were older than
women who had not fallen and were more likely to have chronic diseases,
more likely to be taking drugs, and had a higher body mass index (table 1).
Postural hypotension and low standing blood pressure were not
associated with falling. The women who had fallen had a lower mean
haemoglobin concentration, and this inverse association remained even
when data were adjusted for social class, body mass index, chronic
diseases, and each class of drug used. The fully adjusted odds ratio of
any falls for an increase in haemoglobin concentration of one standard
deviation was 0.90 (0.81 to 0.99). Very few of the women had anaemia: no
women had a haemoglobin concentration below 80 g/l, 15 had a
concentration below 100 g/l, and 222 (5.5%) had a concentration below
120 g/l. Alcohol consumption was not related to falling. In the 12
months before the women's baseline examination 55 women (1.28%) had had a
fractured hip (15 women) or wrist (44 women). Women who had had a fall
in the previous 12 months were much more likely to have had a fracture
than the women who hadn't had a fall (table 1).
Characteristics
of women who had had no fall or at least one fall in the previous 12
months. Values are percentage of women (95% confidence interval),
adjusted for age, except where otherwise indicated
Drug use and falls
Just
over 70% (2887) of the women were taking at least one drug, and 622
(15.4%) were taking five or more drugs. There was a strong linear
association between the number of drugs that women took and whether they
had had a fall (figure).
However, the association was not significant when the data were
adjusted for chronic diseases and other potential confounding factors.
The crude odds ratio for a fall in the previous 12 months for each
additional drug taken was 1.14 (1.10 to 1.19), but the fully adjusted
odds ratio was 1.01 (0.96 to 1.06). Linear associations between frequent
falls and falls receiving medical attention and the number of drugs
taken were similar, with the fully adjusted models showing no
significant associations. Use of hypnotics or anxiolytics and use of
antidepressants were associated with an increased odds of falling, even
with adjustment for chronic disease status (including ever having had a
diagnosis of depression) and other potential confounding factors (table 2).
In the fully adjusted analyses analgesics, cardiovascular system drugs,
endocrine system drugs, and respiratory disease drugs were not
independently associated with having had a fall (table 2).
Prevalence
of falls in the previous 12 months and number of drugs taken (crude
data and fully adjusted for age, each chronic disease, body mass index,
alcohol consumption, haemoglobin concentration, and social class)
Relation between drug use and falls in previous 12 months in 3742 UK women aged 60-79 years. Values are crude or fully adjusted* odds ratios (95% confidence interval)
Chronic disease and falls
Nearly
three quarters (2961) of the women had at least one chronic disease.
There was a marked linear trend of increasing odds of falling with
increasing number of chronic diseases (figure).
This association remained even after adjustment for drug use and other
potential confounding factors. The crude odds ratio for any fall in the
previous 12 months for each additional simultaneously occurring disease
was 1.46 (1.36 to 1.56), and the fully adjusted odds ratio was 1.37
(1.25 to 1.49). We found similar linear trends for the association
between increasing numbers of simultaneously occurring chronic diseases
and frequent falls and treated falls, and these associations remained
significant in the fully adjusted models.
Prevalence
of falls in the previous 12 months and number of simultaneous chronic
diseases (crude data and fully adjusted for age, each drug taken, body
mass index, alcohol consumption, haemoglobin concentration, and social
class)
Circulatory
disease, chronic obstructive pulmonary disease, depression, and
arthritis were each associated with a higher odds of falling, even with
adjustment for drug use and other potential confounding factors (table 3).
The population attributable risk of having had at least one fall in the
previous 12 months, estimated from the fully adjusted models, was 6.2%
(2.0% to 10.0%) for coronary heart disease, 6.2% (1.6% to 10.5%) for
circulatory disease, 8.0% (3.3% to 12.4%) for chronic obstructive
pulmonary disease, 9.4% (5.4% to 13.3%) for depression, and 17.4% (10.4%
to 23.9%) for arthritis. The fully adjusted odds ratio of having had a
fall in the previous 12 months associated with having at least one of
the chronic diseases in table 3
was 1.81 (1.42 to 2.31), and the population attributable risk was 32.2%
(19.6% to 42.8%). When we stratified the analyses by the year in which
the participant's disease was first diagnosed, we found positive
associations between falls and diseases diagnosed before (including up
to 10 years before) the year in which the women had a fall.
Relation
between diagnoses of chronic diseases and falls in previous 12 months
in 3742 UK women aged 60-79 years. Values are crude or fully adjusted* odds ratios (95% confidence interval)
Effects of combined multiple pathology and polypharmacy
When
number of drugs taken and number of chronic diseases were included in
the same regression model they combined multiplicatively. The odds ratio
for a fall for each additional chronic disease, adjusted for number of
drugs taken, was 1.39 (1.29 to 1.51), and that for each additional drug
taken, adjusted for number of chronic diseases, was 1.05 (1.01 to 1.09).
There was no strong evidence of a statistical interaction between
number of drugs and number of chronic diseases (P = 0.16) and no
evidence of statistical interactions between any of the individual
chronic diseases and their relevant treatment (P > 0.15 for all
diseases).
Discussion
The
risk of falling rose with the number of drugs taken and the number of
chronic diseases each woman had, but the association was stronger for
multiple pathology than for polypharmacy and remained in the fully
adjusted analyses. The population attributable risk of falling
associated with having any chronic disease was much higher (32%) than
that associated with use of psychotropic drugs (between 2% and 5%). Thus
in public health terms targeting prevention and control of chronic
diseases rather than polypharmacy may be a more useful strategy for
preventing falls in elderly people. Factors commonly supposed to be
associated with falls, such as postural hypotension, alcohol
consumption, and reduced physiological reserve (as shown by low forced
expiratory volume in 1 second) were not associated with falls in this
study.11,12
Contrary to evidence in previous reviews that risk factors differ for
single falls, frequent falling, and treated falls, we found similar risk
factor profiles for the different types of fall.13,14
Limitations of the study
Our response rate (60%) is moderate but consistent with other large contemporary epidemiological surveys.15
As reported previously our respondents were slightly younger than
non-respondents and were less likely to have a primary care medical
record of stroke or diabetes, although the prevalence of coronary heart
disease and cancer did not vary between respondents and non-respondents.4
Because chronic diseases are associated with falling we may have
underestimated the prevalence of falls. The associations of chronic
diseases and drug use with falling would only be exaggerated if the
associations among non-respondents were in the opposite direction to the
associations among responders or if they were non-existent, both of
which are unlikely.
Our study is cross sectional and
may therefore be susceptible to reverse causality. With respect to the
effects of antidepressants and hypnotics or anxiolytics, it is possible
that having had a fall may lead to anxiety or depression and therefore
treatment for these conditions. However, assessing the association
between drug use and the prevalence of falling is relevant, because the
plausible mechanism by which central nervous system drugs result in
falls is related to their contemporary use.16
That there was an association between falls and number of chronic
diseases among women whose diagnosis had been made before the year of
the fall indicates that these associations are not due to reverse
causality.
We could not assess the effect of all the
major chronic diseases that affect this age group. In particular we did
not collect information on cognitive function. However, that the
participants were able to complete a detailed health questionnaire
suggested that few if any women had severe dementia. Elderly people may
under-report falls.17
Any such misclassification is likely to be non-systematic and would
therefore dilute the associations. We used a crude indicator of the
severity of falls: whether the participant had had medical attention.
Although having received medical attention may indicate a greater
severity of fall, it also reflects sociodemographic and personal factors
that influence the likelihood of getting medical care after a fall.
Implications
As in other studies, our results show an association between the number of psychotropic drugs taken and the risk of falling.3,7
Although the population attributable risk of falling associated with
these drugs was small, they may be an important cause of morbidity in
people using them. Trials have shown that gradual withdrawal of
psychotropic drugs is feasible among elderly people and is associated
with a decreased risk of falling.18
Chronic
diseases may increase the risk of falls through direct effects of the
disease and indirect effects, such as reduced physical activity, muscle
weakness, and poor balance. Perhaps because observational research has
focused more on drug use than chronic diseases, the effect of specific
chronic diseases on the risk of falling has not been the main focus of
controlled trials of interventions to prevent falls, although the
inclusion of exercises specifically aimed at reducing falls as well as
at improving cardiovascular fitness in cardiac rehabilitation programmes
has been recommended.19 Chronic diseases and multiple pathology, rather than polypharmacy, may be the most important predictors of falling.
Notes
Acknowledgments:
The British women's heart and health study is co-directed by SE, Peter
Whincup, Goya Wannamethee, and DAL. We thank Carol Bedford, Alison
Emerton, Nicola Frecknall, Karen Jones, Mark Taylor, and Katherine
Wornell for collecting and entering data, all the general practitioners
and their staff who supported data collection, and the women who
participated in the study.
Contributors:
All authors developed the study's aim and design and managed its data.
DAL undertook the initial analysis and coordinated the writing of the
paper. All authors contributed to the final version. DAL will act as
guarantor for the paper.
Funding:
The British women's heart and health study is funded by the Department
of Health. DAL is funded by a Medical Research Council and Department of
Health training fellowship.
Competing interests: None declared.
Ethical
approval: Local ethics committees approved the study, and 99.4% of
participants gave written informed consent for their medical records to
be available.
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