More clinical studies are needed to address the challenges of appropriate prescribing of drugs to, and avoidance of drug interactions in elderly people. The issues are explored in a Series of two papers published in this week's edition of The Lancet.
Series co-ordinator Dr Anne Spinewine, Centre for Clinical Pharmacy, Université catholique de Louvain, Bruxelles, Belgium, and colleagues, say in the first paper that evidence suggests that the use of drugs in elderly people is often inappropriate, partly because of the complexities of the prescribing process, as well as other patient, provider, and health-system factors.
Elderly people can be overprescribed drugs -- ie given drugs for which they have no clinical need, given inappropriate drugs or underprescribed drugs which they need. One European study found that one in five elderly patients cared for at home had been prescribed at least one inappropriate drug. The authors discuss the psychometric properties of the instruments that can be used to detect inappropriate prescribing in older people, and they examine the relationship between inappropriate prescribing and poor health outcomes.
The paper also discusses various processes to optimise prescribing in elderly patients, including geriatric multidisciplinary team care, the involvement of pharmacists in patient care, and the importance of involving elderly patients and their expectations in the prescribing process.
The authors say: "The evidence is mixed and contradictory that inappropriate prescribing, defined by process measures, is associated with adverse patient outcomes…future studies that test the predictive validity of measures of inappropriate prescribing for elderly people are needed to better inform health policy."
In the second paper, which focuses on drug interactions, the authors say: "Drug therapy is essential when caring for elderly patients, but clearly it is a double-edged sword. Elderly patients are at high risk of having drug interactions, but the prevalence of these drug interactions is not well documented." An example of drug-drug interaction could be clarithromycin and warfarin, leading to an increased anticoagulant effect.
A European study of 1601 elderly outpatients living in six countries found that 46% of them had at least one potentially significant drug-drug interaction, and 10% of these interactions were regarded as severe. Another study reported that 37% of patients were taking drugs without their doctor's knowledge, while 6% were taking drugs not on their doctor's lists.
Many drug-drug interactions are well-documented, but their identification becomes increasingly difficult with patients taking many medications. For example, patients with five or more diseases and nine or more medications are difficult to assess. While each individual medication may be appropriate for the condition it was prescribed to treat, interactions can lead to unwanted side effects. The dangers of cascade interactions -- where a new drug is prescribed to treat the side-effect of a drug interaction misinterpreted as a new medical disorder -- are also discussed.
Use of drug databases, such as Lexi-comp, First Databank and Medispan -- can also help doctors predict and manage drug interactions. The authors say: "The greatest effect [of databases] is achieved by systems that proactively screen for interactions at the time of electronic prescribing."
A meta-analysis found that elderly patients usually have better outcomes when their care is managed by a multidisciplinary team consisting of a doctor (ideally a geriatrician), a nurse and a pharmacist. The authors conclude: "Modern drug development has produced a myriad of molecules, and elderly patients often many drugs to treat several diseases. However, one challenge in the real world use of drug therapy is to identify, manage, and prevent drug interactions that can potentially negate the beneficial effects of drugs.
"Computer-assisted drug interaction software can serve as a reference source, but any generated recommendations have to be tempered by a holistic, geriatric, multiprofessional approach that is team-based."
http://www.thelancet.com/webfiles/images/clusters/thelancet/press_office/Series.pdf
Journal
The Lancet