Polypharmacy and elderly patients

AORN Journal, March, 1999 by Pamala D. Larsen, Janice L. Hoot Martin

Polypharmacy, the concurrent use of multiple prescription or over-the-counter medications, is a growing problem in the United States. Although polypharmacy may occur in all age groups, it is a common occurrence in elderly people. A number of studies conducted during the past 10 years have revealed that patients age 65 and older use an average of two to six prescribed medications and one to 3.4 non-prescribed medications on a regular basis.(1) The problem of polypharmacy is so extensive that it was designated as the principal medication safety issue in the Healthy People 2000 document.(2)

DEFINING POLYPHARMACY

There is no generally accepted definition of polypharmacy except that it indicates use of multiple medications by a single patient. One researcher defines polypharmacy as excessive or unnecessary use of medications, and others consider it the prescription, administration, or use of more medications than are clinically indicated in a given patient.(3) For the purposes of this article, polypharmacy is defined as concurrent use of multiple medications by a single patient.

To date, little research has been conducted to determine the safety and efficacy of combining multiple medications in a single patient. Some researchers have suggested that research in pharmacology is not sophisticated enough at the present time to examine the effects of multiple medications taken at one time.(4) Others have referred to polypharmacy as an uncontrolled experiment. They suggest that a scientist in a laboratory would never combine eight to 10 different chemicals at random in a test tube without first preparing for the consequences. Thus, when an elderly patient is prescribed eight to 10 medications concurrently, it is impossible to predict the outcome.(5)

Reasons for polypharmacy. A number of factors contribute to an elderly patient taking multiple medications concurrently. With aging, the incidence of having at least one chronic disease or condition increases substantially. Eighty percent of individuals over the age of 65 have at least one chronic condition and 50% have more than one.(6) With chronic conditions, a number of different medications may be used to treat the diseases, and all prescribed medications may be justified; however, in the age of specialty medical practice, there usually are several physicians treating one patient. Patients can have multiple health care providers prescribing multiple medications for several conditions with little, if any, coordination of care or medications. It is no surprise that the older population alone consumes more than 30% of all prescription medications.(7)

A related factor in the development of polypharmacy is the health care provider who willingly writes multiple prescriptions because that is what the provider thinks the patient wants. Researchers have estimated that 75% of all visits to a physician result in a written prescription.(8) Little attention may be given to nonprescriptive methods of treatment, and both the patient and the care provider may not think the visit was "successful" unless a prescription was written.

Adverse medication reactions. In general, elderly patients are prescribed more medications than younger patients, particularly when hospitalized. Use of multiple medications predisposes elderly patients to adverse drug reactions (ADRs). The number of medications a patient takes has been shown to be the most consistent risk factor for ADRs.(9)

Researchers estimate that the potential for an ADR is

* 6% when patients take two medications,

* 50% when patients take five different medications, and

* 100% when patients take eight or more medications.(10)

Supporting the fact that ADRs are a common problem in elderly patients is the statistic that 20% to 25% of hospital admissions for individuals older than age 65 are the result of an ADR.(11) Table 1 lists categories of medications commonly prescribed to elderly patients. In particular, digoxin is one of the most widely used of all medications in elderly patients. Adverse reactions between digoxin and other medications occur with great frequency (Table 2).

Table 1

MEDICATIONS MOST COMMONLY ASSOCIATED WITH ADVERSE REACTIONS IN ELDERLY PATIENTS(1)

* Psychotropic medications (particularly the benzodiazepines)

* Antihypertensives (including diuretics)

* Nonsteroidal anti-inflammatory medications

* Systemic steroids

* Theophylline

* Warfarin

* Cimetidine

* Digoxin

NOTE

(1.) S Montamat, B Cusack, `Overcoming problems with polypharmacy and drug misuse in the elderly," Clinics in Geriatric Medicine 8 (February 1992) 145-156.

Table 2

MEDICATION INTERACTIONS WITH DIGOXIN(1)

* Amiodarone

* Antacids

* Choleslyromine

* Diltiazem

* Erythromycin

* Kaolin pectate

* Neomycin

* Para-aminosalicylic acid

* Quinidine

* Spironolactone

* Sulfasalazine

* Tetracycline

* Triamterene

* Verapamil

NOTE

(1.) J Lindenfeld, "Congestive heart failure," in Geriatric Medicine, ed R Schrier (Philadelphia: Sounders, 1990) 261; A Swonger, P Burbank, Drug Therapy in the Elderly (Boston: Jones & Bartlett, 1995) 220-225.