The prevalence of many diseases is age related and several may co-exist in the same patient.
DISEASE PREVALENCE AND DRUG USE
IN THE ELDERLY
The prevalence of many diseases is age related and several may co-exist in the same patient. These include hypertension (Hawthorne, Greaves and Beevers, 1974), osteoarthrosis (Lawrence, 1977) and prostatic hypertrophy (Berry et al., 1984). Age-specific mortality rates for cardiovascular and cere-brovascular diseases, together with data for cancers, are shown in Table 42.1 (British Heart Foundation, 2000) and morbidity data in Table 42.2 (British Heart Foundation, 2001).
Cardiovascular
and cerebrovascular problems related to atheroma are the most common causes of
death in the elderly and are also a major source of suffering. Nevertheless, a
huge majority of old people have osteoarthrosis of the joints and the lower
limbs (Blackburn et al., 1994)
causing pain and disability without threatening life.
Several studies have examined the nature and preva-lence of medicines prescribed for old people living in the community. One of the best known is that by Cartwright and Smith (1988) which was based on a random sample of people aged 65 and over drawn from the electoral registers of 10 parliamentary constituencies in England. Information was obtained from 805 patients (78%) of the 1032 included in the original sample. Of these 805 patients, 60% had taken one or more prescribed medicines within the preceding 24 hours. Drugs for the diseases of heart and circulation were widely prescribed, and diuret-ics formed a therapeutic category in most widespread use. Diuretics were followed by analgesics, hypnotics, sedatives and anxiolytics, drugs for rheumatism and gout and then -adrenoceptor antagonists. Similar findings were recorded in two studies from Southamp-ton (Ridout Waters and George, 1986; Sullivan and George, 1996). A review by Jones and Poole (1998) confirmed the rising use of cardiovascular drugs amongst elderly people and widespread use of agents with an effect on the central nervous system. There was, however, some geographic variation in the use of medicines for musculo-skeletal and joint disease. By contrast, the use of drugs with an action on the central nervous system varies according to individual circumstances: psychotropic agents are used particu-larly in patients in residential nursing homes and in long-term care (McGrath and Jackson, 1996). A recent investigation, however, has shown that medication undertreatment is a problem of equivalent magni-tude to that of medication overuse in long-term care settings of elderly residents (Sloane et al., 2004). Overall, the use of prescription medications by older persons is increasing rapidly both to treat a large range of diseases as well as non-disease-specific symptoms.
Besides
prescribed medicines, elderly people as a group are high consumers of
non-prescription medi-cation. Indeed, it has been estimated that over 50% of
elderly people take one or more over the counter (OTC) preparations every day
(Chrischilles, Segar and Wallace, 1992b). Those OTCs most commonly taken are
oral analgesics, vitamins and tonics, but recently, the popularity of herbal
medicines has increased (Barnett, Denham and Francis, 2000). Women are
particularly likely to consume OTC medicines and some of these can interact
with prescription medicines to cause adverse events.
There
are two other features which are character-istic of drug therapy in the
elderly: long duration and polypharmacy. Drug treatment for older people is
often for chronic conditions, which means that once started, medicines tend to
be continued for 6 months or longer (Ridout Waters and George, 1986). This may
account for the increased rates of gastroin-testinal bleeding in patients
taking non-steroidal anti-inflammatory drugs (NSAIDs) (Langman et al., 1994). This latter problem
highlights the need for improve-ments in repeat prescribing and for regular
review of medication in the elderly.
There
are several legitimate reasons for polypharmacy in the elderly. First, as
indicated previously, the preva-lence of many diseases is age related and
several may co-exist in the same patient. Secondly, it may not be possible to
achieve an adequate therapeutic response from the use of a single drug. There
is an increas-ing promotion of therapeutic regimens, including two or more
drugs used in combination for the optimum management of a number of conditions
including diabetes, heart failure, hypertension and ischaemic heart disease
(Gurwitz, 2004). A third reason for giving more than one drug simultaneously is
to coun-teract or minimise the risk of side effects (type A adverse reaction)
occurring. The difficulty with this approach is that adverse drug effects may
be misinter-preted as a new medical condition and another drug is prescribed to
treat the observed effects leading to a ‘prescribing cascade’ (Rochon and
Gurwitz, 1997). Finally, patients are also being targeted by pharmaceu-tical
companies in the so-called direct-to-consumer advertising, which is likely to
have the effect of increasing polypharmacy in older people.
In
the study by Cartwright and Smith (1988), the average number of medicines
prescribed for the patient was 2.8, but many patients living in the community
received more than this. In an American telephone survey of
non-institutionalised ambulatory adults, the highest overall prevalence of
medication use was in those over 65 years, of whom 12% took at least 10
medications (including prescription, OTC and herbal treatments) during the
preceding week; and 23% of females and 19% of males had used five or more
prescription drugs over the same time (Kaufman et al., 2002). Such polypharmacy can cause confu-sion leading to
errors in medicine taking, particularly amongst those over the age of 85
(Parkin et al., 1976; Vestal, 1978).
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