You are leaving Medscape Education
Cancel Continue
Log in to save activities Your saved activities will show here so that you can easily access them whenever you're ready. Log in here CME & Education Log in to keep track of your credits.


How Common Are Inpatient Adverse Events?

  • Authors: News Author: Heidi Splete; CME Author: Charles P. Vega, MD
  • CME / ABIM MOC / CE Released: 3/3/2023
  • Valid for credit through: 3/3/2024, 11:59 PM EST
Start Activity

  • Credits Available

    Physicians - maximum of 0.25 AMA PRA Category 1 Credit(s)™

    ABIM Diplomates - maximum of 0.25 ABIM MOC points

    Nurses - 0.25 ANCC Contact Hour(s) (0 contact hours are in the area of pharmacology)

    Pharmacists - 0.25 Knowledge-based ACPE (0.025 CEUs)

    Physician Assistant - 0.25 AAPA hour(s) of Category I credit

    IPCE - 0.25 Interprofessional Continuing Education (IPCE) credit

    You Are Eligible For

    • Letter of Completion
    • ABIM MOC points

Target Audience and Goal Statement

This activity is intended for primary care physicians, hospitalists, nurses, pharmacists, physician assistants, and other members of the healthcare team who care for inpatients.

The goal of this activity is for learners to be better able to assess data regarding hospital safety in the United States.

Upon completion of this activity, participants will:

  • Assess historical rates of hospital adverse events
  • Analyze a large current study of adverse events in hospitals
  • Outline implications for the healthcare team


Medscape, LLC requires every individual in a position to control educational content to disclose all financial relationships with ineligible companies that have occurred within the past 24 months. Ineligible companies are organizations whose primary business is producing, marketing, selling, re-selling, or distributing healthcare products used by or on patients.

All relevant financial relationships for anyone with the ability to control the content of this educational activity are listed below and have been mitigated. Others involved in the planning of this activity have no relevant financial relationships.

News Author

  • Heidi Splete

    Freelance writer, Medscape


    Heidi Splete has no relevant financial relationships.

CME Author

  • Charles P. Vega, MD

    Health Sciences Clinical Professor of Family Medicine
    University of California, Irvine School of Medicine


    Charles P. Vega, MD, has the following relevant financial relationships:
    Consultant or advisor for: GlaxoSmithKline; Johnson & Johnson Pharmaceutical Research & Development, L.L.C.

Editor/Compliance Reviewer

  • Amanda Jett, PharmD, BCACP

    Associate Director, Accreditation and Compliance, Medscape, LLC


    Amanda Jett, PharmD, BCACP, has no relevant financial relationships.

Nurse Planner

  • Stephanie Corder, ND, RN, CHCP

    Associate Director, Accreditation and Compliance, Medscape, LLC


    Stephanie Corder, ND, RN, CHCP, has no relevant financial relationships.

Peer Reviewer

This activity has been peer reviewed and the reviewer has no relevant financial relationships.

Accreditation Statements


Interprofessional Continuing Education

In support of improving patient care, Medscape, LLC is jointly accredited with commendation by the Accreditation Council for Continuing Medical Education (ACCME), the Accreditation Council for Pharmacy Education (ACPE), and the American Nurses Credentialing Center (ANCC), to provide continuing education for the healthcare team.


This activity was planned by and for the healthcare team, and learners will receive 0.25 Interprofessional Continuing Education (IPCE) credit for learning and change.

    For Physicians

  • Medscape, LLC designates this enduring material for a maximum of 0.25 AMA PRA Category 1 Credit(s)™ . Physicians should claim only the credit commensurate with the extent of their participation in the activity.

    Successful completion of this CME activity, which includes participation in the evaluation component, enables the participant to earn up to 0.25 MOC points in the American Board of Internal Medicine’s (ABIM) Maintenance of Certification (MOC) program. Participants will earn MOC points equivalent to the amount of CME credits claimed for the activity. It is the CME activity provider’s responsibility to submit participant completion information to ACCME for the purpose of granting ABIM MOC credit.

    Contact This Provider

    For Nurses

  • Awarded 0.25 contact hour(s) of continuing nursing education for RNs and APNs; none of these credits is in the area of pharmacology.

    Contact This Provider

    For Pharmacists

  • Medscape designates this continuing education activity for 0.25 contact hour(s) (0.025 CEUs) (Universal Activity Number: JA0007105-0000-23-075-H01-P).

    Contact This Provider

  • For Physician Assistants

    Medscape, LLC has been authorized by the American Academy of PAs (AAPA) to award AAPA Category 1 CME credit for activities planned in accordance with AAPA CME Criteria. This activity is designated for 0.25 AAPA Category 1 CME credits. Approval is valid until 3/3/2024. PAs should only claim credit commensurate with the extent of their participation.

For questions regarding the content of this activity, contact the accredited provider for this CME/CE activity noted above. For technical assistance, contact [email protected]

Instructions for Participation and Credit

There are no fees for participating in or receiving credit for this online educational activity. For information on applicability and acceptance of continuing education credit for this activity, please consult your professional licensing board.

This activity is designed to be completed within the time designated on the title page; physicians should claim only those credits that reflect the time actually spent in the activity. To successfully earn credit, participants must complete the activity online during the valid credit period that is noted on the title page. To receive AMA PRA Category 1 Credit™, you must receive a minimum score of 70% on the post-test.

Follow these steps to earn CME/CE credit*:

  1. Read about the target audience, learning objectives, and author disclosures.
  2. Study the educational content online or print it out.
  3. Online, choose the best answer to each test question. To receive a certificate, you must receive a passing score as designated at the top of the test. We encourage you to complete the Activity Evaluation to provide feedback for future programming.

You may now view or print the certificate from your CME/CE Tracker. You may print the certificate, but you cannot alter it. Credits will be tallied in your CME/CE Tracker and archived for 6 years; at any point within this time period, you can print out the tally as well as the certificates from the CME/CE Tracker.

*The credit that you receive is based on your user profile.


How Common Are Inpatient Adverse Events?

Authors: News Author: Heidi Splete; CME Author: Charles P. Vega, MDFaculty and Disclosures

CME / ABIM MOC / CE Released: 3/3/2023

Valid for credit through: 3/3/2024, 11:59 PM EST


Clinical Context

Hospital safety and the health risks for adverse events (AEs) among inpatients have been the focus of countless hours and dollars spent over the past several decades, and the authors of the current study credit the Harvard Medical Practice Study (HMPS) as critical research that led to programs to improve hospital safety. This study examined AEs among inpatients in New York hospitals in 1984. Results of the study were published in 2 articles published in The New England Journal of Medicine.[1-2]

Researchers found an overall AE rate of 3.7 per 100 admissions; 28% of AEs were thought to be caused by negligence, and 16% of AEs led to death or disability.

Since then, multiple programs have been initiated to promote safe prescribing, reduce healthcare-acquired infections, and prevent errors related to surgery and procedures. These interventions are buttressed by technology that could hardly be imagined in the 1980s, but have we had influence in the rate of AEs in the hospital? The current study by Bates and colleagues uses a methodology similar to that employed in HMPS to find out.

Study Synopsis and Perspective

Nearly 25% of hospital admissions included at least 1 AE, as indicated from data from 2809 admissions at 11 hospitals.

The 1991 Harvard Medical Practice Study (HMPS),[1] which focused on medical injury and litigation, documented an AE rate of 3.7 events per 100 admissions; 28% of those events were attributed to negligence, wrote David W. Bates, MD, of Brigham and Women's Hospital, Boston, Massachusetts, and colleagues.

Although patient safety has changed significantly since 1991, documenting improvements has been challenging, the researchers said. Several reports have shown a decrease in healthcare-associated infections; however, other aspects of safety -- notably, adverse drug events, defined as injuries resulting from drugs taken -- are not easily measured and tracked, the researchers said.

"We have not had good estimates of how much harm is being caused by care in hospitals in an ongoing way that looked across all types of [AEs]," and the current review is therefore important, Bates said in an interview.

In a study recently published in The New England Journal of Medicine,[3] the researchers analyzed a random sample of 2809 hospital admissions from 11 hospitals in Massachusetts during the 2018 calendar year. The hospitals ranged in size from fewer than 100 beds to more than 700 beds; all patients were aged 18 years and older. A panel of 9 nurses reviewed the admissions records to identify potential AEs, and 8 physicians reviewed the AE summaries and either agreed or disagreed with the AE type. They ranked the severity of each event using a general severity scale into categories of significant, serious, life-threatening, or fatal.

Overall, at least 1 AE was identified in 23.6% of the hospital admissions. A total of 978 AEs were deemed to have occurred during the index admission, and 222 of these (22.7%) were deemed preventable. Among the preventable AEs, 19.7% were classified as serious, 3.3% as life-threatening, and 0.5% as fatal.

A total of 523 admissions (18.6%) involved at least 1 significant AE, defined as an event that caused unnecessary harm but from which recovery was rapid. A total of 211 admissions involved a serious AE, defined as harm resulting in substantial intervention or prolonged recovery; 34 included at least one life-threatening event; and 7 admissions involved a fatal AE.

A total of 191 admissions involved at least 1 AE deemed preventable. Of those, 29 involved at least 1 preventable AE that was serious, life-threatening, or fatal, the researchers wrote. Of the 7 deaths in the study population, 1 was deemed preventable.

The most common AEs were adverse drug events, which accounted for 39% of the AEs; surgical or other procedural events accounted for 30.4%; patient care events (including falls and pressure ulcers) accounted for 15%; and healthcare-associated infections accounted for 11.9%.

Overcoming Barriers to Better Safety

"The overall level of harm, with nearly 1 in 4 patients suffering an AE, was higher than I expected it might be," Bates told Medscape; however, techniques for identifying AEs have improved, and "it is easier to find them in electronic records than in paper records."

"Hospitals have many issues they are currently dealing with since COVID, and one issue is simply prioritization," Bates told Medscape, "but it is now possible to measure harm for all patients using electronic tools, and if hospitals know how much harm they are having in specific areas, they can make choices about which ones to focus on."

"We now have effective prevention strategies for most of the main kinds of harm," he said.

Generally, rates of harm are high because these strategies are not being used effectively, he said.

"In addition, there are new tools that can be used -- for example, to identify patients who are decompensating earlier," he noted.

As for additional research, some specific types of harm that have been resistant to interventions, such as pressure ulcers, deserve more attention, said Bates. "In addition, diagnostic errors appear to cause a great deal of harm, but we don't yet have good strategies for preventing these."

The study findings were limited by several factors, including the use of data from hospitals that might not represent hospitals at large and by the inclusion mainly of patients with private insurance, the researchers wrote. Other limitations include the likelihood that some AEs were missed, and the level of agreement on AEs between adjudicators was only fair.

Still, the findings serve as a reminder to healthcare professionals of the need for continued attention to improving patient safety, and measuring AEs remains a critical part of guiding these improvements, the researchers concluded.

Timely Reassessment and Opportunities to Improve

In the decades since the publication of the report, To Err Is Human, by the National Academies in 2000,[4] significant attention has been paid to improving patient safety during hospitalizations, and healthcare systems have increased in both system and disease complexity, said Suman Pal, MBBS, a specialist in hospital medicine at the University of New Mexico, Albuquerque, New Mexico, in an interview.

"Therefore, this study is important in reassessing the safety of inpatient care at the current time," he said.

"The findings of this study showing preventable [AEs] in approximately 7% of all admissions, while concerning, is not surprising, as it is consistent with other studies over time, as the authors have also noted in their discussion," said Pal.

The current findings "underscore the importance of continuous quality improvement efforts to increase the safety of patient care for hospitalized patients," he noted.

"The increasing complexity of medical care, fragmentation of healthcare, structural inequities of health systems, and more recent widespread public health challenges such as the COVID-19 pandemic have been, in my opinion, barriers to improving patient safety," Pal said.

"The use of innovation and an interdisciplinary approach to patient safety and quality improvement in hospital-based care, such as the use of machine learning to monitor trends and predict the individualized risk of harm, could be a potential way out" to help reduce barriers and improve safety, he said.

"Additional research is needed to understand the key drivers of preventable harm for hospitalized patients in the United States," said Pal. "When planning for change, keen attention must be paid to understanding how these [drivers] may differ for patients who have been historically marginalized or are otherwise underserved so as to not exacerbate healthcare inequities," he added.

The study was funded by the Controlled Risk Insurance Company and the Risk Management Foundation of the Harvard Medical Institutions. Bates owns stock options with AESOP, Clew, FeelBetter, Guided Clinical Solutions, MDClone, and ValeraHealth and has grants/contracts from IBM Watson and EarlySense. He has also served as a consultant for CDI Negev. Pal has disclosed no relevant financial relationships.

Study Highlights

  • The research was designed as a retrospective cohort study. Researchers selected 11 hospitals in Massachusetts to participate, with an oversampling of smaller hospitals.
  • The team evaluated admissions with discharges from 2018, and admissions for hospice, psychiatric care, treatment of addiction, and for observation only were excluded from evaluation.
  • 9 nurses formed the primary team examining electronic health records for AEs. Event categories included healthcare-associated infections, adverse drug events, surgical or procedural events, and patient-care events. The last category was defined by AEs related to nursing care, such as patient falls or pressure ulcers.
  • 8 physicians corroborated the AEs in the health record and also assessed whether the event was preventable.
  • Data were derived for 3 large hospitals and 8 smaller hospitals. The study assessed 2809 hospital admissions selected at random.
  • ≥ 1 AE occurred during 23.6% of admissions; 22.7% of these events were judged to have been preventable.
  • Among preventable events, 19.7% caused harm requiring intervention and/or prolonging recovery; 3.3% of preventable events were life-threatening, and 0.5% were fatal.
  • Patient variables associated with hospital admissions with an AE included older age, being a man, being Hispanic, and having Medicaid vs Medicare or private insurance. Asian American race was associated with a lower rate of hospital AEs.
  • The mean lengths of stay for patients with and without AEs were 9.3 and 4.2 days, respectively.
  • The most common category of AEs was adverse drug events (39% of all events), followed by surgical or procedural events (30.4%), patient care events (15%), and healthcare-associated infections (11.9%).
  • Although the percentage of life-threatening events was highest in the surgical/procedural domain, healthcare-associated infections were the events most often associated with mortality.
  • Of 968 total AEs, just 10 were related to diagnostic errors.
  • Larger hospitals had higher rates of AEs compared with smaller hospitals.

Clinical Implications

  • In HMPS, which gathered information on AEs in hospitals in 1984, there were 3.7 AEs per 100 admissions.
  • The current study by Bates and colleagues found at least 1 AE during 23.6% of admissions; 22.7% of these events were judged to have been preventable. The most common categories of AEs were adverse drug events and surgical or procedural events.
  • Implications for the healthcare team: To promote patient safety, the healthcare team should perform careful analyses of local rates of hospital AEs and the interventions used to prevent them.


Earn Credit

  • Print