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In light of the importance of drug therapy in clinical disease, nonadherence has become a major public health problem. Nonadherence is estimated at ~40%, with some studies showing that it may be as high as 75%.1-3 In terms of cost, nonadherence rivals that of cancer, Alzheimer's disease, and diabetes.4 It results in reduced efficacy or disease deterioration, with detrimental effects on patient health and quality of life, as well as increased morbidity and mortality.
Nonadherence is a precursor to increased drug expenditures. The average monthly cost of drugs prescribed for nonadherent patients is almost 3 times higher than the cost of drugs for those patients who adhere to their drug regimen.3,5 Studies have shown that $11 billion is spent annually servicing poor therapeutic outcomes associated with nonadherence.2,5
Reasons for Nonadherence
All patients should be screened for medication adherence. Patients with the highest risk for nonadherence are as follows6,7:
One study revealed that 59% of the elderly on long-term therapy make >1 errors when taking their medications, with 26% making a potentially serious error and 66% of these errors being errors of omission.8-10 Many elderly patients who omit medications do so deliberately. Many think that they do not need the medication or that the dose is too strong.
A large percentage of patients, especially the elderly, lack basic information about their medications. Many are not informed about the drug name, purpose, dosage schedule, duration of therapy, side effects, and adverse consequences (eg, what happens if they stop taking the medication).
In a Seattle, Wash, study, only 44% of patients using prescription drugs could recall a pharmacist instructing them on the drugs' use, whereas 80% recalled that their physician had done so. Only 52% reported that their physician had instructed them about possible side effects, and only 30% reported receiving this information from their pharmacist.3,11
Nonadherence-induced disease deterioration has been observed in patients with hypertension, diabetes, seizures, and HIV, as well as in patients who have had an acute myocardial infarction (AMI).
A study by Newby and colleagues12 showed that long-term adherence to secondary- prevention therapies for coronary artery disease (CAD) remains poor. Nearly 50% of the patients with CAD in the 7- year study admitted that they did not consistently take -blockers, lipid-lowering therapy, aspirin, or angiotensin-converting enzyme inhibitors. The study also revealed that nonadherence was greater among people with the highest risk of poor outcomes, who could benefit from increased medication adherence.
The results of 2 other studies showed that nonadherence to medications is common among recent AMI patients and in patients with diabetes, resulting in higher mortality. Nonadherence in the AMI study resulted in an almost fourfold increase in the death rate in the first year after hospital discharge.13 The diabetes study showed almost a twofold increase in mortality following nonadherence.14
A study by Chapman and associates15 showed that, within 3 months of starting both antihypertensive and lipid-lowering therapies, less than half of the patients were taking both medications as prescribed.
Nonadherence actually increases the patient's risk of receiving additional unnecessary medications. Nonadherence and the disease deterioration it causes can lead to the following6:
Because polypharmacy can result in nonadherence, a patient's drug regimen should be assessed periodically, and the following questions should be asked16:
In order to increase medication adherence, cost needs to be considered. Researchers in Canada17 looked at 290 chronically ill patients discharged from the hospital. The investigators discovered that drug cost was the primary reason given for nonadherence to their drug treatment.
Physicians and pharmacists need to inquire about patients' ability to afford the medications prescribed. The following questions may provide important information18:
Physicians and pharmacists must function as teachers, motivators, and persuaders. Indeed, these health care professionals are asking patients to take medications for chronic disease for decades. Communication is among the most important factors in order for patients to adhere to their drug regimens.
Many elderly patients suffer from poor hearing, vision, and joint mobility. Patients should be asked to repeat information they are told to make sure that they understand. Studies have demonstrated that, if patients know why they are taking a medication, they will be more adherent and less likely to have another medication prescribed.6,19,20 Patients with arthritis should be asked whether they can open containers with a childproof cap.
Dr. Dutcher is a clinical pharmacist for B&B Clinical Consultants, Punta Gorda, Fla.
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