Drug-Related Visits to the Emergency Department: How Big Is the Problem?

Payal Patel, Pharm.D., Peter J. Zed, Pharm.D.


Pharmacotherapy. 2002;22(7) 

In This Article


Drug-related visits to the emergency department constitute a significant problem that contributes to overall pressures on our health care system. Although published information regarding this situation is limited, the studies we reviewed provide guidance for the future. One of the prospective studies indicated that as many as 28% of emergency department visits were considered drug related, and 70% of these were preventable.[18,26] The retrospective studies indicated that the estimated frequency of drug-related visits was as low as 0.86% but as high as 10.6%. Such a wide range may be explained by the heterogeneous study objectives, design, and definitions of drug-related visit used in each review. Regardless of study design, hospital admissions of patients who visited the emergency department with a drug-related problem were estimated to be 8.6-24.2% and were associated with increased costs to our health care system.

Female gender and increasing age appeared to be the factors associated with the greatest number of drug-related visits to an emergency department. Drug classes often implicated in these visits were nonsteroidal antiinflammatory agents, anticonvulsants, antidiabetic drugs (insulin and oral hypoglycemics), antibiotics, respiratory agents, hormones, central nervous system drugs, and cardiovascular drugs. Common drug-related problems resulting in emergency department visits were adverse drug reactions, noncompliance, and inappropriate prescribing.

Until recently, the only available literature describing drug-related problems and emergency department visits or hospital admissions were retrospective chart reviews. Eight studies in this review were retrospective and involved over 700,000 patients. The primary methodologic limitation of these studies is their design. Retrospective studies may underestimate the true frequency of drug-related visits to emergency departments because important information may be missing (e.g., nonrecorded facts) or inaccurately documented. The nature of an emergency department visit and the drug-related association often are difficult to determine from a retrospective review. Another common flaw of retrospective analysis is the lack of a drug expert who prospectively collects and assesses pertinent data (e.g., complete drug history). Most of the studies we reviewed relied on a single investigator to analyze the data captured from routine chart information, which may decrease the validity of the results.

Another limitation of many of the studies is that the definition of a drug-related event varied from study to study. Most did not involve a consistent systematic approach, such as using the eight widely accepted categories for drug-related problems listed earlier.[1] Only one retrospective[20] and one prospective study[26] used these categories. Many studies evaluated only some of the listed drug-related problems, most commonly adverse drug reactions and noncompliance. Thus, the reported frequency of drug-related visits to emergency departments may have been further underestimated. Also, intentional overdose would not constitute a drug-related problem according to the eight categories.[1] Therefore, a few studies that included overdose secondary to intentional ingestion and abuse may have overestimated the true frequency of drug-related visits to the emergency department.[16,27]

A limitation of all of the studies was the lack of evaluation of complementary and alternative medicines as a cause of drug-related visits to the emergency department. Increased administration and misadministration of complementary and alternative medicine has contributed to drug-related problems. Failure to address this situation, especially in more recent studies, has resulted in underestimating its contribution to the problem.

The frequency of drug-related visits to an emergency department was much higher in one prospective study[26] than in the others, which simply may reflect improved prospective study methods, use of a comprehensive definition of drug-related problem, and involvement of experts in identifying drug-related problems. Therefore, it makes sense to involve pharmacists in patient care to help identify and resolve drug-related problems and prevent their recurrence.

Many drug-related problems resulting in emergency department visits can be prevented. Two studies reviewed -- one retrospective[18] and one prospective[26] -- estimated that 70% of all drug-related emergency department visits were preventable. Data provided by the prospective study[26] revealed that patient noncompliance accounted for 46% of preventable visits, and inappropriate prescribing and monitoring accounted for 44%. If these problems could be avoided, 90% of preventable drug-related visits would not occur.

Of interest, one retrospective study[19] reported that 70% of patients had a good understanding of drug administration, and even fewer -- only about 30% -- had a good understanding of potential adverse effects and drug interactions. Pharmacists can improve patient education on these specific aspects of drug therapy in an attempt to decrease preventable drug-related visits to the emergency department. One possible way to accomplish this is to have stronger relationships between the patient's primary health care providers, such as the family physician and the community pharmacist. Transferring relevant patient information by hospital physicians and pharmacists to family physicians and community pharmacists when a patient is discharged may facilitate closer monitoring of the patient, improve patient education, and reinforce patient compliance through visits or phone calls. Identifying patients who are most likely to be at risk and are taking drugs most often associated with drug-related problems may be a good starting point.


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