The demography of the UK population is changing. Currently, one fifth of the UK population is 60 years or older. Increasing age is associated with changes in pharmacokinetics and pharmacodynamics, affecting the absorption, distribution, metabolism and excretion of drugs [7]. The altered physiology of old age is related to reduced total body water, reduced lean body mass and body fat, reduced serum albumin and altered protein binding, reduced liver phase one metabolism, reduced renal plasma flow, reduced glomerular filtration rate and renal clearance.
A meta-analysis identified that around 20% of people over 70 take five or more drugs [8]. These drugs are usually prescribed for co-morbidities resulting from musculoskeletal, cardiovascular, gastrointestinal, neurological and urological disorders. Polypharmacy is associated with increases in drug-drug interactions, adverse drug reactions, disease-drug interactions and food-drug interactions. There is also an increase in prevalence of falls [9], hospital admission rates, lengths of hospital stay, readmission rates and mortality rate. Associated problems include medication administration errors and poor compliance.
Adverse drug reactions can either singly or in combination precipitate an emergency department visit. They include confusion, electrolyte disorders, gait disorder and falls, postural hypotension and falls, gastrointestinal bleeding, incontinence, hypothermia and constipation [7].
In our study, 82 patients prescribed five or more prescription medications had the potential for adverse drug reactions. However, our study design does not allow for correlation of polypharmacy with the presenting complaint, as data were collected retrospectively and also because for any given presentation there may be the coexistence of multiple factors contributing to the presentation. The study highlights the emergency department as a place where potential drug interactions can be identified in high-risk elderly attenders.
The emergency department provides an environment in which polypharmacy can be identified, including its role in precipitating hospital attendance, leading to corrective action being initiated, particularly in patients being sent home [10]. In the current climate of bed shortages, emergency department gridlock and admission avoidance schemes, the presence of a, ED pharmacist would be of potential benefit to the process of identification of drug interactions [11, 12]. Furthermore, rational prescribing for the elderly should be guided by consensus criteria, such as those developed in the US by Delphic methodology [13]. These essentially involve listing potentially inappropriate medications, where the risks of administration may outweigh the benefits of administration.
In our own population, we suggest more effective surveillance of prescription medication in elderly attenders to the ED, and the need for mechanisms to detect the need for, and achieve, corrective action where indicated.
Potential strategies Box 1
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Medication review for all ED attenders, aided by dedicated ED pharmacist sessions
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IT-based solutions to highlight potential drug interactions: electronic prescribing support systems
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Effective prescription monitoring in the community
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Targeted feedback to general practitioners to consider reducing prescription medication via care of elderly liaison health visitor
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Effective case management of chronic disease in the community
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Awareness of risk-inducing prescriptions (box 2)
Examples of drugs that pose a particular risk for older people Box 2
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Long term non-steroidal anti-inflammatory drugs
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Long-acting benzodiazepines, e.g. diazepam
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Anti-cholinergic drugs
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Tricyclic antidepressants
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Doxazosin
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Metoclopramide