Medical illnesses are more important than medications as risk factors of falls in older community dwellers? A cross-sectional study

Abstract

Background: previous studies have confirmed the contribution of various medications towards falls in the older population. Recently questions were raised as to whether the chronic illnesses or drug use was more important.

Objective: we attempt to test the hypothesis that underlying medical illnesses are the cause of falls rather than medications.

Design: cross-sectional.Setting: urban community in Hong Kong.Subjects: 4,000 ambulatory community-dwelling men and women aged 65 years or over.

Methods: demographic data, fall history in the previous 12 months, medical diagnoses, current medications and self-rated health were recorded. Body measurements and neuromuscular function tests were performed. Medical diagnoses and their corresponding medications were tested simultaneously in a multivariate model.

Results: 789 (19.7%) subjects reported at least one fall and 235 (5.9%) experienced two or more falls. After adjustment for age and sex, medications associated with any falls were aspirin, diabetic drugs, nitrates, NSAIDs, and paracetamol, and those associated with recurrent falls were calcium channel blockers, diabetic drugs, nitrates, NSAIDs, aspirin and statins. Only anti-diabetics and nitrate showed moderate and borderline significance in multivariate analyses for recurrent and any falls respectively (OR 2.9, P = 0.01; OR 1.5, P = 0.027). Other medications failed to show significant relationship with falls, while eye diseases, heart diseases and musculoskeletal pain showed variable associations.

Conclusion: The apparent association between many medications and falls was mediated through the underlying medical diagnoses and neuromuscular impairment. Anti-diabetics agents were associated with falls.

Introduction

About 18–32% of community dwelling older persons fall each year, resulting in significant mortality, morbidity, fear of falling and restrictions in physical activities [1–8]. Medications, in particular antihypertensives and sedatives, have often been cited as one of the major causes for these falls [3, 4, 7, 9, 10]. Other associated risk factors found were physical disabilities, poor vision, cognitive impairment, and presence of certain conditions such as depression, stroke and cardiovascular diseases [1, 2, 5, 6, 10]. Few studies, however, have attempted to compare the relative importance of medications and their indications in causing falls. We attempt to test the hypothesis that underlying medical illnesses are the cause of falls rather than the medications among functionally independent community-dwelling older individuals.

Methods

A total of 4,000 community-dwelling men and women aged 65 years or over were invited to attend a health check carried out in the School of Public Health of The Chinese University of Hong Kong between August 2001 and December 2003. Invitation was by placing recruitment notices in community centres for the elderly and in housing estates. Talks were given at these centres explaining the purpose, procedures and investigations to be carried out. Only volunteers who could walk independently either with or without aids were included. Those with a history of bilateral hip fractures were excluded. The example was stratified so that approximately 33% were in each of the age groups: 65–69, 70–74 and 75 and over. The study was approved by the Clinical Research Ethics Committee of the Chinese University of Hong Kong. All subjects gave written consent prior to data collection.

A questionnaire containing information regarding demographics, socioeconomic status, smoking habit, alcohol intake, self-rated health, daily physical activity level, cognitive function, history of falls in the past 12 months, medical history and current medications was administered by research assistants trained in both data collection and specific physical measurements used in the health check.

The presence or absence of diseases was based on the subjects’ report of diagnoses as told by their doctors, and counter-checked by their medications. Subjects brought all their current medications to the centre for inspection and ascertainment on the day of the health check. Self-rated health was graded by each subject on a scale of 1–5, with 1 = excellent and 5 = poor. Physical activity level was assessed using the Physical Activity Scale of the Elderly (PASE). This is a 12-item scale measuring the average number of hours per day spent in leisure, household and occupational physical activities over the previous 7-day period. The activity weight for each item was determined based on the amount of energy expended, and each item score was calculated by multiplying the activity weight by activity daily frequency. A summary score of all the items reflect the daily physical activity level [11]. Cognitive function was assessed using the Mini-Mental State Examination (MMSE) [12].

The following physical measurements were performed for each subject: height, weight and stride length in a usual-paced 6-m walk. Body weight was measured, with subjects wearing a light gown, by the Physician Balance Beam Scale (Healthometer, IL, USA). Height was measured by the Holtain Harpenden stadiometre (Holtain Ltd, Crosswell, UK). Stride length was calculated by dividing the distance with the number of steps taken during the 6-m walk.

A fall was defined as any unexpected loss of balance resulting in coming to rest on the ground or floor. Recurrent fallers were defined as those subjects with two or more falls in the past year.

Statistical methods

Statistical analysis was performed using SPSS version 11.5. Multiple logistic regression analysis was used to calculate age and sex adjusted odds ratios for all variables. Variables with P<0.05 were chosen to be entered into the final model for each of the significant medications. Fallers (fell at least once) were compared with non-fallers, and recurrent fallers (fell at least twice) were compared with those with one or no falls. A P value of <0.05 was taken as statistically significant. Significance was stratified into three levels in the final models.

Results

Baseline characteristics of 4,000 subjects were listed in Table 1.

Falls

Among 4,000 older men and women, 789 (19.7%) reported having at least one fall in the previous 12 months. Among those, 235 (5.9% of 4,000) had more than one fall.

Association between falls and medications

Table 2 summarizes the age- and sex-adjusted odds ratios of various medications in relation to falls and recurrent falls. Use of aspirin, calcium channel blockers, anti-diabetics (including sulphonylureas, biguanide and insulin), nitrates, non-steroidal anti-inflammatory drugs (NSAIDs) and statins was associated with an increased risk of recurrent falls. Aspirin, anti-diabetics, nitrates, NSAIDs and paracetamol use was associated with increased risk of any number of falls. Psychotropic drugs including benzodiazepines, antidepressants and antipsychotics were not significantly associated with either any or recurrent falls.

Table 3 summarizes the age- and sex-adjusted odds ratios of other factors that may contribute to falls and recurrent falls, including medical diagnoses, cognitive function, social factors, physical activity score, self-rated health and physical measurements. Factors significantly associated with recurrent falls include the following: diabetes, eye diseases (cataract and/or glaucoma), heart diseases (history of myocardial infarction, angina and congestive heart failure), lower body musculoskeletal pain (low back pain, hip and knee pain), self-rated health and average stride length. The same variables, apart from the addition of a history of stroke, were associated with any falls in the previous year.

Tables 4 summarizes the multivariate models demonstrating the association between each medication and falls with adjustment to significant non-drug factors. Female sex, heart diseases and shorter stride length were highly associated with falls history (P<0.005). Eye disease was moderately associated with falls in the nitrates model (P = 0.009), while lower body musculoskeletal pain, previous stroke and eye disease were slightly associated with falls in all medication models. The only medication with any significant association with any falls was nitrate, showing borderline significance (OR 1.489, P = 0.027).

Table 5 summarizes multivariate models on recurrent falls. Female sex and shorter stride length were again strongly associated with recurrent falls. Eye disease was moderately associated while heart diseases and lower musculoskeletal pain showed a slight association. Among medications, only anti-diabetics showed a moderate association (OR 2.9, P = 0.01).

Discussion

Previous studies have demonstrated the relationship between falls and various types of medications. Few had addressed the possible confounding effect of the underlying medical illnesses. When we studied medications together with their indications and other significant non-drug risk factors, we found that most of the medications failed to demonstrate association with falls. This suggests that underlying medical illnesses and non-drug factors, rather than medications, were responsible for falls in functionally independent community-dwelling older persons.

We found shorter stride length to be a good indicator of falls. It is a measurement of balance, gait and muscular power. Changes in stride length have been associated with reductions in falls after fall intervention [13]. It is easy to measure, requires no special equipment and can be done in virtually any setting. Its value as a falls risk assessment tool is worthy of further examination.

Female sex has often been associated with increased falls [1, 5, 9, 14]. This association persisted after adjustment for all the other significant factors for falls in our study including stride length, a surrogate for neuromuscular function and stature, and remained as the strongest predictor. Whether it is due to recall bias difference between the two genders as suggested previously [15], or there are other gender specific risk factors yet unknown will need to be answered in a prospective study.

Increase in age was not associated with increased falls amongst our subjects after adjustment for underlying medical illnesses, medications, visual impairment and stride length. The relative high physical independence and good health of our cohort may have contributed to this finding. In a frailer population, the effect of age on falls could have been more prominent.

Our study had shown that heart diseases were associated with falls, while medications used in these diseases were not. Subjects with cardiovascular diseases are more prone to cerebral white matter disease, which has been found to be related to gait and balance impairments and falls in high-functioning older persons [16, 17].

Anti-diabetic medications were found to be related to recurrent falls, but being diabetic was not. Diabetes on treatment had been found to be an independent risk factor of falls [18, 19], though the association was less robust among those on oral agents when compared with insulin-treated diabetics [20]. Our cohort contained a significant proportion of diabetic subjects not on drug treatment (25.7%), allowing direct comparison between those with and without anti-diabetics. Our findings suggest that being on anti-diabetics or having diabetes requiring drug control could be a risk factor for falls. More advanced diabetes or hypoglycaemic side effects of drugs could be the cause of falls among older diabetics.

Limitations

We were unable to find any correlation between the use of psychotropic medications and falls. This could be explained by the fact that very few of our subjects (3.5%) were on these agents and the prevalence of these medications was much lower among our subjects than in western studies [4, 10]. Adverse effect of medications could also have been masked by our cohort being relatively healthy and mobile.

Being retrospective in nature, our results were subject to recall bias [15, 21]. We also had difficulties in determining whether a specific medication was actually being taken around the time of falls, especially if it was a take-as-required medication or one that had been newly prescribed sometime within the previous 12 months.

Conclusion

The association between medications and falls appears to be due to the underlying diseases and non-drug factors rather than due to the medications themselves. Female sex, shorter stride length and heart diseases are strong risk factors for falls. Anti-diabetic drugs are strongly associated with falls. How these factors affect falls and why females and those with heart diseases are more prone to falls will be the topics for further prospective studies.

Key points

• Chronic medical conditions were often more important than medications in causing falls in high-functioning community-dwelling older individuals.

• Cardiovascular disease, lower back and leg pain were all more associated with falls than medications used for these conditions.

• Diabetic drugs are associated with falls after adjustment for other chronic medications, short stride length and visual impairments.

Declaration of conflicts of interest

None.

Acknowledgements

The study was jointly funded by the Research Grant Council of Hong Kong and by grant 5R01 AR049439-02 from the National Institute of Health.

References