Drug-Disease Interaction
Another phenomenon responsible for adverse drug events is a drug-disease interaction. For example, renal failure or hepatic insufficiency can interfere with detoxification and excretion; ascites can alter the volume of distribution of hydrophilic drugs, while obesity has an altering effect on lipophilic drugs. Patients with advanced cognitive impairment may have increased sensitivity or paradoxical reactions to drugs with central nervous system or anticholinergic activities.
Optimal Prescribing
As with safety, effective drug therapy for older people is also far from optimal. Optimal drug prescribing should aim for a balance between overprescribing and underprescribing while keeping a safe environment in mind (i.e., monitoring for adverse drug reactions and reducing medication errors). More than 50% of outpatient prescriptions are without indication, while necessary drugs are withheld in the cases of about 55% of elderly outpatients and 25% of hospitalized elderly patients.13
Overprescribing refers not only to the use of multiple medications but also implies a lack of appropriateness in selection, dosing, or use of the medication. For example, the term “prescribing cascade” refers to adding a new medication to treat symptoms of an adverse drug event that is mistakenly assumed to be a separate new diagnosis. Potential consequences of overprescribing include adverse drug events, drug-drug interactions, decreased quality of life, and unnecessary costs. Common factors connected to overprescribing include, but are not limited to, advanced age, multiple comorbidities, multiple prescribers, poor record-keeping, and failure for healthcare providers to thoroughly review a patient’s medication regimen.
Underprescribing of medications to older people is also of concern. Underprescribing results from efforts to avoid complex medication regimens, fear for adverse events, problems with patient adherence to medications, and economic barriers. Underprescribing can result from the notion that older folks will not benefit from medications intended for primary or secondary prevention or for aggressive management of chronic conditions (e.g., angiotensin-converting enzyme inhibitors and beta blockers prescribed for congestive heart failure and after a myocardial infarction).
New Prescribing Initiatives
There have been new initiatives to emphasize optimal prescribing. The Joint Commission on Accreditation of Healthcare Organizations (JCAHO) mandates medication reconciliation across inpatient and outpatient practices. In 1999, the Centers for Medicare and Medicaid Services (CMS) expanded the drug use review policy for nursing home certification. Using specific criteria, surveyors and pharmacists must assess resident records for potentially inappropriate medication exposures and associated adverse drug reactions. The “Assessing Care for Vulnerable Elders” (ACOVE) initiative implemented use of quality indicators for prescribing appropriate medications, documentation, education, and medication monitoring. The White House Conference on Aging, held in December 2005, also addressed medication management issues in its resolution entitled “Optimize Medication Management Programs.”
Prescribing Principles
There are a few principles for prescribing that the clinician can keep in mind while caring for the older person. When starting therapy, the basic principle should be to start low and go slow. New complaints or worsening of an existing condition after a drug has been introduced should be scrutinized for the possibility of a drug-induced problem. When choosing treatment for a new medical condition, always consider non-pharmacologic approaches first.
Overprescribing can also be prevented by regularly reviewing a patient’s medication list each time a new medication is started or changed. It is important to know what other providers have prescribed and where prescriptions were filled. It is essential to maintain accurate records. In this regard, the use of electronic medical records can be both an advantage and a disadvantage. Inaccurate drug lists can be self-perpetuating when providers simply copy and paste these sections of the medical records. It is best if the patient can bring all medications, including those purchased over the counter, to the visit. Discontinue any medications that are deemed to be unnecessary after review.