from laboratory results, medication orders, information on vital signs, drug levels, and text reports to identify patients experiencing possible adverse drug events. Pharmacists then follow up on high-risk patients. Patient monitoring could be further improved through the incorporation of linked pharmacy and laboratory data into electronic order entry and real-time decision-support technologies, although issues concerning alert mechanisms must be resolved if this potential is to be realized (Schiff et al., 2003). In addition, recognition of the benefits of the pharmacist’s involvement in medication monitoring is extending beyond the inpatient setting to home health care, nursing homes, and community care (Knowlton and Penna, 2003).

It should be noted that susceptibility to adverse reactions is greatly increased in patients with multiple health conditions taking multiple medications. This is a growing problem for the elderly and others with chronic illnesses receiving care from several clinicians who may fail to coordinate medication treatment. On average, Medicare enrollees with chronic conditions are seen by eight different physicians or other providers during the course of a single year (Anderson and Knickman, 2001). Studies of medication errors among the elderly (Gurwitz et al., 2003, 2005) found that in both hospital and ambulatory care settings, monitoring errors were attributable to inadequate laboratory monitoring of drug therapies, or to a delayed response or failure to respond to signs and symptoms of drug toxicity (36 percent) or laboratory evidence of drug toxicity (37 percent) (Gurwitz et al., 2003, 2005). The most common preventable adverse effects from these monitoring errors were electrolyte/renal, gastrointestinal tract, hemorrhagic, and metabolic/endocrine events. Patient adherence was a contributing factor in 20 percent of the cases studied (Gurwitz et al., 2003). Another study of four primary care practices found that 25 percent of patients experienced an adverse drug event over a 3-month period (13 percent of these events were serious, 39 percent were preventable, and 6 percent were both serious and preventable) (Gandhi et al., 2003). The events were attributed to poor communication—the physician’s failure to respond to symptoms reported by the patient or the patient’s failure to report symptoms to the physician.

Using the methods noted above, the overarching goal of monitoring is the early detection of a downturn in a patient’s health status or the occurrence of an adverse event and the initiation of activities to restore the patient’s health (IOM, 2004b). Drugs may cause adverse effects in patients for a variety of reasons. For example, a drug may be highly potent and toxic at therapeutic doses, a drug may interact in an unforeseen way with another drug or a food product, a patient may have a particular sensitivity to a drug, a wrong drug or improper dosage may be administered, or a drug may be improperly manufactured (Noah and Brushwood, 2000). The signs and symptoms of an adverse reaction may be unpredictable (e.g., a skin



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