How many people seek medical care for problems related to their use of medications?

About 11 to 15 of every 1,000 Americans visit a health care provider because of adverse drug effects in a given year, representing about three to four of every 1,000 patient visits during 1995 to 2001. The total number of visits to treat adverse drug events increased from 2.9 million in 1995 to 4.3 million visits in 2001.

Why is this important?

Adverse drug events (ADEs) are injuries resulting from the use of medications, whether due to side effects of the drug or to human errors or failures in health care delivery. Many ADEs are minor or temporary, but those that prompt individuals to seek medical care represent potentially more serious events.

Several recent studies provide clues to the occurrence and preventability of ADEs among patients in the community (outside of hospitals).

• One-quarter of the adult patients of four primary care practices experienced an ADE; 11 percent were judged preventable because of prescribing errors. Another 28 percent were considered ameliorable (the severity or duration of symptoms could have been reduced) with better communication between physicians and patients (Gandhi et al. 2003; Weingart et al. 2005).
• ADEs were detected in the records of about 5 percent of Medicare patients at one large multispecialty practice; 28 percent were judged preventable because of errors in prescribing or monitoring or patient nonadherence to the prescription (Gurwitz et al. 2003). The cost of treating preventable ADEs was estimated at $1,983 per case (Field et al. 2005).
• Among patients discharged home from one hospital, 11 percent had an ADE following their hospitalization; 27 percent of the ADEs were deemed preventable and another 33 percent ameliorable (Forster et al. 2005).

Findings

Community-dwelling individuals in the U.S. made ambulatory care visits for the treatment of adverse drug events (VADEs) at a rate of 3.3 to 4.0 per 1,000 visits, or 10.9 to 15.3 per 1,000 population during 1995–2001 (Zhan et al. 2005).

• These rates translate to 2.9 million visits in 1995 and 4.3 million visits in 2001, a significant increase. Most of these visits (80%) were made to physicians' offices or hospital outpatient clinics. One of five visits (20%) was made to a hospital emergency department, including those that resulted in admission to the hospital.
• Compared with visit rates among adults ages 25–44, visit rates were about one-third to one-half as frequent among children ages 0–15 and two to six times more frequent among elderly adults ages 65–74 during 2001. Higher rates among the elderly may reflect both greater use of medications and greater physiological vulnerability to side effects.

Implications

Rates of VADEs offer insight into the scope of potentially serious adverse drug events that occur in the community. Factors that may precipitate ADEs include changes in medications, changes in a patient's metabolism, interactions among multiple prescriptions, inadequate patient education, inadequate monitoring of high-risk drugs, and gaps in coordination of care (Forster 2006).

Assuming that previous studies of ADEs in ambulatory care (Gandhi et al. 2003; Gurwitz et al. 2003) can be generalized to this data, then 11 percent to 28 percent of the 4.3 million VADEs in 2001 might have been prevented with improved systems of care and better patient education, yielding an estimate of 473,000 to 1.2 million potentially preventable VADEs annually. Assuming that the average cost of treating a preventable ADE is $1,983 (Field et al. 2005), the potential cost-savings that could be achieved by reducing VADEs would be $946 million to $2.4 billion.

Improvement Ideas and Resources

The Institute of Medicine recently recommended that health care providers adopt patient-information and decision-support tools to prevent medication errors and associated preventable adverse drug events. The IOM also noted the importance of fostering a "safety culture" within the organization and implementing medication safety practices "within the context of an overall quality improvement program" (IOM 2006). Specifically, the IOM stated that providers should be able to:

• Access comprehensive reference information concerning medications and related health data at the point of care.
• Communicate patient-specific medication-related information (such as lists of current medications) in an interoperable format.
• Assess the safety of medication use through active monitoring and use these monitoring data to inform the implementation of prevention strategies.
• Write prescriptions electronically by 2010 (and all pharmacies should be able to receive them electronically by 2010).
• Subject prescriptions to evidence-based, current clinical decision support, such as "intelligent" alerts about dangerous drug interactions.
• Have the appropriate competencies for each step of the medication use process, which might be facilitated through multidisciplinary teams to manage patients with complex conditions when appropriate.
• Make effective use of well-designed technologies appropriate to ambulatory care, such as decision support capabilities to prevent prescribing errors.

The IOM noted the importance of fostering a "safety culture" within the organization and implementing medication safety practices "within the context of an overall quality improvement program" (IOM 2006).

An online Physician Practice Patient Safety Assessment tool has been developed by the Health Research and Educational Trust, the Institute for Safe Medication Practices, and the Medical Group Management Association to help physician offices develop and maintain patient safety practices (Pittman 2006). Additional resources for physicians are available from the American Academy of Family Physicians, the American Academy of Pediatrics, and the American College of Physicians.

Measure:

The denominators were based on the estimated total number of visits to physicians' offices, emergency rooms, and hospital outpatient clinics and U.S. Census Bureau estimates of the civilian noninstitutionalized population. The numerator represents the number of ambulatory visits made by community-dwelling individuals for treatment of an adverse drug event (ADE). ADEs were identified based on ICD-9-CM codes for External Causes and Injury (E-codes) E930-E947, excluding codes for adverse effects due to bacterial vaccine and other vaccine and biological substances and adverse reactions to heroin and methadone. The National Center for Health Statistics "assigns E-Codes based on the verbatim description of the causes of injuries recorded on visit records" by participating physicians' offices. The increase in the total number of visits was statistically significant, but the trends in visit rates were not (Zhan et al. 2005).

Limitations:

Adverse drug events may be underreported in the data source used in the analysis.

Source:

Rates were compiled by researchers at the Agency for Healthcare Research and Quality (Zhan et al. 2005) using the National Ambulatory Medical Care Survey and the National Hospital Ambulatory Medical Care Survey, which collect encounter data on patient visits during a randomly assigned one-week period from a sample of physicians offices and a randomly assigned four-week period from a sample of hospital outpatient clinics and emergency departments. Data are representative of the U.S. civilian, noninstitutionalized population.

References:

* Indicates source of data used in the chart(s).Field, T. S., B. H. Gilman, S. Subramanian et al. 2005. The Costs Associated with Adverse Drug Events Among Older Adults in the Ambulatory Setting. Medical Care 43 (12): 1171–6.

Forster, A. J. 2006. Can You Prevent Adverse Drug Events after Hospital Discharge? Canadian Medical Association Journal 174 (7): 921–2.

Forster, A. J., H. J. Murff, J. F. Peterson et al. 2005. Adverse Drug Events Occurring Following Hospital Discharge. Journal of General Internal Medicine 20 (4): 317–23.

Galt, K. A., E. C. Rich, W. Taylor et al. 2003. Interventions to Improve Medication Safety in Primary Care Practice. National Ambulatory Primary Care Research & Education Conference on Patient Safety, September 18–19, 2003, Chicago, Ill.: Primary Care Organizations Consortium.

Gandhi, T. K., S. N. Weingart, J. Borus et al. 2003. Adverse Drug Events in Ambulatory Care. New England Journal of Medicine 348 (16): 1556–64.

Gurwitz, J. H., T. S. Field, L. R. Harrold et al. 2003. Incidence and Preventability of Adverse Drug Events Among Older Persons in the Ambulatory Setting. Journal of the American Medical Association 289 (9): 1107–16.

IOM (Institute of Medicine). 2006. Preventing Medication Errors. Washington: National Academy Press.

Pittman, M. A. 2006. Improving Care in Physician Offices. Hospitals and Health Networks Online (Oct.).

Royal, S., L. Smeaton, A. J. Avery et al. 2006. Interventions in Primary Care to Reduce Medication Related Adverse Events and Hospital Admissions: Systematic Review and Meta-Analysis. Quality & Safety in Health Care 15 (1): 23–31.

Weingart, S. N., T. K. Gandhi, A. C. Seger et al. 2005. Patient-Reported Medication Symptoms in Primary Care. Archives of Internal Medicine 165 (2): 234–40.

* Zhan, C., I. Arispe, E. Kelley et al. 2005. Ambulatory Care Visits for Treating Adverse Drug Effects in the United States, 1995–2001. Joint Commission Journal on Quality and Patient Safety 31 (7): 372–8.