Patient Safety and Quality

One percent of Americans visit doctors each year to manage health problems caused by medication

Adverse drug effects (ADEs), harm, or injury resulting from the use of medications remain a significant threat to patient safety in the United States, concludes a study by researchers at the Agency for Healthcare Research and Quality. Chunliu Zhan, M.D., Ph.D., other AHRQ researchers, and colleagues at the National Center for Health Statistics, calculated that about one ambulatory care visit is made per 100 people each year to treat ADEs serious enough to require care. This totals 3 to 4 million visits for ADES (VADEs) made each year in the United States. In 2001, there were 4.3 million VADEs in the United States, averaging 15 visits per 1,000 people. VADE rates at physician offices, hospital outpatient departments, and hospital emergency departments were 3.7, 3.4, and 7.3 per 1,000 visits, respectively.

From 1995 to 2001, there was an upward trend in the total number of VADEs, due to population growth. However, the increases in VADEs per 1,000 visits and per 1,000 people were not statistically significant. VADEs were lower in children younger than 15, higher in older adults (aged 65 to 74 years) than in adults aged 25 to 44, and were more frequent in females than in males. These findings were based on analysis of National Ambulatory Medical Care Survey and National Hospital Ambulatory Medical Care Survey data.

The researchers calculated the number of visits to physician offices, hospital outpatient departments, and emergency departments in which ADEs were identified as the cause of injury in the E-codes (diagnostic codes of external causes and injury). This approach offers an alternative way to estimate national prevalence of ADEs and the burden of ADEs to the health care system. The researchers suggest these survey data and E-codes also offer a potential ADE measure for the annual National Healthcare Quality Report, for which no ADE measure is currently available.

See "Ambulatory care visits for treating adverse drug effects in the United States, 1995-2001," by Dr. Zhan, Irma Arispe, Ph.D., Edward Kelley, Ph.D., and others, in the July 2005 Journal on Quality and Patient Safety 31(7), pp. 372-378. Reprints (AHRQ Publication No. 05-R067) are available from the AHRQ Publications Clearinghouse.

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