Medication therapy is an integral element of health care interventions. In 2005, approximately 2.5 billion prescriptions were dispensed in the United States. Two-thirds of physician office visits result in a prescription. Medication use is often supported by “hard science” and evidence; clinical practice often shifts to the “soft science” of medicine, trying to understand patients, their histories, personalities, medication adherence, and a way to provide the best possible care.

Of the billions of prescriptions filled, it is estimated that half are taken improperly. Achieving a balance between “hard” and “soft” sciences—by providing evidence-based medication therapy that patients will adhere to—becomes paramount. This chapter explores patient adherence; provider’s considerations such as evidence, pharmacokinetics/pharmacodynamics, and safety; and health care system factors such as formulary systems/resources.

Discrepancies among documented medication therapy records and actual patient use of medications are common and occur with all classes of medications. Therefore, the first step for the provider in determining optimal medication therapy is to understand what medications the patient is actually taking and how they are taking them. The physician must also inquire in a nonjudgmental manner whether patients are taking any over-the-counter (OTC) medications, herbal, or vitamin products. Over 12% of the population take herbals on a yearly basis, but only 38.5% of these patients report this to their physician. Table 46-1 lists five concise steps to a medication review. To obtain an accurate medication history, the physician should start by asking open-ended questions; for example, “What medications are you taking?” This approach avoids the common mistake of assuming the patient is taking all their medications as prescribed. Although conducting an open-ended medication history may take more time up front, it may ultimately prevent over- or underprescribing and may also improve patient relationships. Polypharmacy is defined as the concurrent use of multiple medications or the prescribing of more medications than are clinically indicated. Polypharmacy can be minimized by a thorough medication regimen review.

Evaluation & Change

A thorough medication history and safety assessment begins to clarify many aspects of a patient’s medication regimen and, paired with evidence, can help the clinician make a solid patient-specific decision about a regimen. Evidence-based medicine (EBM) is defined as “the conscientious, explicit, and judicious use of the current best evidence in making decisions about the care of individual patients.” EBM entails obtaining the best external evidence to support clinical decisions and is, therefore, not restricted solely to randomized trials and meta-analysis.

It is critical to appreciate that EBM does not depend solely on the skills and aptitude of literature evaluation and application of data, but must also incorporate clinical experience. The most commonly reported barrier to practicing EBM is a lack of time. However, the goal of EBM is to provide appropriate allocation of effective and efficient care to all patients. Over 6 million references are estimated to be published in over 4000 journals in the National Library of Medicines database, MEDLINE. Slawson and Shaughnessy propose that the practitioner should approach this “information jungle” with a basic equation:

Relevance is directly proportional to its applicability to the physician’s practice. Relevance also includes a measure of the impact of change the information creates in the way one practices medicine. Validity relates to the intrinsic methodology, study design, and conclusions. Thus, by maximizing the principles of the usefulness equation, one may locate the best source of information. Tables 46-2 lists EBM-related web sites.

Formulary systems using evidence-based guidelines and principles have been developed by health care systems as a result of the information era in efforts to provide evidence-based, cost-effective medication management. Drug formularies may be defined as “a continuously revised list of medications that are readily available for use within an institution and reflect the current clinical judgment of the medical staff.” These systems provide an organized, evidence-based approach to care and have beneficial effects in improving the process of care, patient outcomes, promoting cost containment, cost-effective care, or both, and are recommended by the US Presidents’ Advisory Commission on Consumer Protection and Quality.

Evidence-based guidelines are an example of providing high “usefulness” in literature review and application. A guideline is defined by the Institute of Medicine as “systematically developed statement to assist physicians in patient decisions about appropriate health care for specific clinical circumstances.” Several types of evidence-based guidelines exist, and the strength of evidence varies. Evidence-based clinical practice guidelines incorporate recent literature regarding the effectiveness of therapy and clinical experience. Expert consensus guidelines may be the simplest type of guideline; however, limitations to this approach are inherent author bias and limited evidence-based sources. Outcomes-based guidelines incorporate measures of effectiveness to validate a positive impact on patient care.

The Cochrane Collaboration is an example of a system to provide sound clinical practice guidelines. Currently, the Cochrane Collaboration provides systematic reviews, maintains a registry of trials, and is a leading provider of evidence-based guidelines. Cochrane reviews may be located in the Cochrane Library, Cochrane Collaboration, or Cochrane Reviews’ Handbook at the following site: http://www.cochrane.org. In addition to the Cochrane Collaboration, many medical/ professional societies, health maintenance organizations, and the Agency for Health Care Policy and Research provide practice guidelines and Internet links to the guidelines.

As the demand for published, evidence-based guidelines grows, so does the need for outcomes-focused formularies that consider effectiveness, safety, and cost implications to practice. Drug formulary systems are fundamental tools of hospitals, health systems, and managed care organizations to designate preferred products and provide rational, cost-effective prescribing decisions. Traditional formulary decisions are based on comparative efficacy, safety, drug interactions, dosing, pharmacology, pharmacokinetics, and cost. Pharmacy and Therapeutics (P&T) Committees represent all major disciplines of practice and guide the formulary decision process with a goal of providing high-quality, safe, and cost-effective prescribing.

Medication Adherence

“Drugs don’t work in patients who don’t take them”—E. Coop, MD, former US Surgeon General. Poor adherence to medication is a national concern and a significant barrier in optimal medication management. Adherence to medication is defined as the extent to which a person’s behavior coincides with his medical advice. Medication nonadherence is estimated to result in 125,000 deaths/y in the United States and is responsible for 10% of hospital and 23% of nursing home admissions. The average rate of medication adherence is approximately 50% to 65%. There are no significant predictors of patient nonadherence and the reason why patients do not adhere to their regimen widely varies between patients and depends on the nature of the illness, patient’s involvement in the health care decisions, and gender.

Because it is difficult to predict patient adherence behavior, it is critical to identify barriers to adherence that may be controlled or modified. The most common reason for medication nonadherence is that the patient forgot. Other reasons include: other priorities, decision to omit dose, lack of information, and emotional factors. No one intervention has been proven to consistently improve adherence; therefore, a combination of interventions is often required.

1. 
   

   Do you ever forget to take your medications?

   
   
2. 
   

   Are you careless at times about taking your medications?

   
   
3. 
   

   When you are feeling better, do you sometimes stop taking your medications?

   
   
4. 
   

   Sometimes if you feel worse, do you stop taking your medications?