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Spotlight On... Adverse Events

Patients admitted to the hospital generally expect that the medical care they receive will improve their health, not worsen it. Unfortunately, that isn't always the case. In some instances, patients are harmed as a result of their medical treatment. For example, a patient may contract an infection associated with the use of a catheter or experience a surgical complication. According to an  OIG report, these types of events - termed "adverse events" - affect a significant portion of Medicare beneficiaries.

More Than One in Four Medicare Beneficiaries Experience Some Degree of Harm While Hospitalized

Prompted by the Tax Relief and Health Care Act of 2006, OIG conducted a thorough examination of the issue of adverse events. Perhaps the most noteworthy outcome is a  report describing the incidence rate of these events. Though others have attempted this challenging task previously,  estimates of this rate varied widely. Using a random sample of Medicare beneficiaries discharged from hospitals during a 1-month period,  OIG found that 13.5 percent experienced adverse events and that for 1.5 percent of beneficiaries, these adverse events contributed to their deaths. An additional 13.5 percent of beneficiaries in the sample experienced temporary harm as a result of their medical care, bringing the total percentage of beneficiaries experiencing instances of care-related harm to 27 percent. Nearly half (44 percent) of these adverse or temporary harm events were preventable.

While these statistics are troubling on their own, the prevalence of these events has wider impact. OIG determined that the costs to Medicare associated with adverse and temporary harm events totaled an estimated $324 million for 1 month alone. This would equate to an estimated $4.4 billion per year.

In light of these findings, OIG recommended that the Agency for Healthcare Research and Quality (AHRQ) and the Centers for Medicare & Medicaid Services (CMS) broaden their patient safety efforts to include all types of adverse events and advance efforts to identify these events. In addition, CMS should provide further incentives for hospitals to reduce the incidence of adverse events.

Reporting Systems To Track Adverse Events Exist but Often Miss Events and Opportunities for Improvement

In addition to studying the frequency of adverse events, OIG examined adverse event reporting systems. Hospitals are required to track and analyze patient harm as a requirement of participating in Medicare, and in fact, all the hospitals in OIG's sample had such a system in place.

Yet, OIG found that hospital staff did not report 86 percent of events to incident reporting systems. Previous  explanations for low reporting levels include the following: (1) staff do not have time, (2) staff fear punitive action, and (3) staff do not believe that reports will lead to improvement. However, this report found that the low level of reporting is also due partly to hospital staffs' lack of understanding as to what constitutes patient harm. Therefore, OIG recommended that AHRQ and CMS develop a list of potentially reportable events to assist hospital staff.

In addition, there is no comprehensive national reporting system for adverse events, and only half of States have systems. These  State reporting systems vary greatly, with differences in what constitutes an adverse event, what information must be recorded, how that information is used, and whether information about the event is  publicly disclosed. Across the board, however, OIG found that States with systems often require reporting for only a small subset of events. Just 12 percent of the temporary harm or adverse events that occurred in hospitals met State requirements for reporting; in other words, only 35 of the events in the sample were required to be reported to the State reporting systems. Hospitals actually reported just three of these events, all in Pennsylvania. Many of the events not reported as required involved serious harm, including six patient deaths.

Finally,  another OIG report found that when the Medicare program receives reports of alleged serious adverse events, it often misses opportunities to promote patient safety in its responses. More detailed information can be found in the report.

OIG Will Continue To Examine Adverse Events

OIG plans to continue exploring the complex yet vitally important issue of adverse events, looking beyond hospitals to other medical settings. One study underway is examining the frequency of adverse events in nursing homes, the factors that contributed to those events, and their costs to Medicare.


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Office of Inspector General, U.S. Department of Health and Human Services | 330 Independence Avenue, SW, Washington, DC 20201