Patient safety study provides first national estimate of adverse events in Canadian hospitals

This release is also available in French

The first national study of patient safety in Canadian hospitals estimates that 7.5 per cent of people hospitalized in Canada have experienced an adverse event as a result of their care.

"The Canadian Adverse Events Study: the incidence of adverse events in hospital patients in Canada", to be published in the May 25 edition of the Canadian Medical Association Journal, found that the overall rate of adverse events in 2000 was 7.5 per 100 patient admissions, not including pediatric, obstetric or psychiatric admissions. This rate suggests that 185,000 of the almost 2.5 million medical and surgical admissions in Canada in 2000 were associated with an adverse event – defined as an unintended injury or complication resulting in death, disability or prolonged hospital stay caused by health care management rather than the patient's underlying condition.

Researchers from seven Canadian universities, led by the University of Toronto (U of T) and the University of Calgary (U of C), analysed the adverse event rate after reviewing 3,745 adult patient charts, randomly selected from 20 acute care hospitals across five provinces (B.C., Alberta, Ontario, Quebec and Nova Scotia). The study also found that:

• the majority of adverse events resulted in temporary disability or prolonged hospital stay
• five per cent of patients who experienced adverse events were judged to have a permanent disability
• adverse events were associated with death in 1.6 per cent of patients admitted to acute care hospitals
• surgical care accounted for the largest number of adverse events
• close to 37 per cent of adverse events in the study were potentially preventable. Based on this, the researchers estimate there were 70,000 preventable adverse events across the country in 2000.

"Our study indicates that care in Canadian hospitals is safe for the vast majority of patients," says Prof. Ross Baker, PhD, principal investigator of the study and professor of health policy, management and evaluation at U of T. "However, certain patients are experiencing injuries and complications related to their care, some preventable. The good news is, this study gives hospitals a clearer picture of the scope and nature of this issue and will help them to determine why these problems are occurring and to develop strategies to address them."

"It would be a mistake to focus on the performance of individual health care providers when interpreting these findings," says Dr. Peter Norton, head of family medicine at U of C and co-principal investigator of the study. "We recommend that hospitals and health providers focus on system-wide changes – such as ensuring that medications don't look or sound alike – to reduce the number and likelihood of adverse events."

This research provides the first national estimate of adverse events across a range of teaching and community hospitals using methods comparable to recent studies in other countries. Those studies reported adverse events rates ranging from 2.9 per cent in the United States to 16.6 per cent in Australia. This variation is at least partly explained by differences in study methods.

The Canadian study also found that teaching hospitals had a higher rate of adverse events than other hospitals. The authors attribute this to several factors, including: patients with more complex illnesses may be treated in teaching hospitals; the complexity of care in teaching hospitals means patients may receive care from several care providers, thereby increasing the potential for adverse events relating to communication and coordination of care.

The study was jointly funded by the Canadian Institute for Health Information (CIHI) and the Canadian Institutes of Health Research (CIHR).

"As we all know, adverse events can have a devastating effect for everyone involved. But pointing fingers will not solve the challenges identified today," says CIHI's newly appointed board chair, Graham Scott. "The key here is to take this information, learn from it and use those lessons to ultimately make our health care safer."

"This study has been designed as a first step to help Canada's health care system better understand what adverse events are occurring in our hospitals," says CIHR president Dr. Alan Bernstein. "It will help decision makers plan interventions and improvements that can make hospitals more effective and safe. CIHR and its Institutes of Health Services and Policy Research, and Population and Public Health are dedicated to supporting innovative research and initiatives designed to improve health care services in the interest of improving the health and quality of life of all Canadians."

Initiatives already underway in Canada to address issues of patient safety and adverse events include the formation of the Canadian Patient Safety Institute (CPSI), established by the federal government to provide hospitals with information about how to make care safer.

"Every region of the country and every health profession will have a unique perspective on this landmark study and on the issue of patient safety," says CPSI chair Dr. John Wade. "However, the best long-term solutions will come from a truly national effort that brings together health providers, educators and the public in a spirit of collaboration and problem-solving. This is the approach the Canadian Patient Safety Institute will help make possible in Canada."

The national research team includes Virginia Flintoft, RN, MSc, Adalsteinn Brown, DPhil, and Drs. Ed Etchells and Philip Hébert at U of T; Drs. William Ghali and Maeve O'Beirne and Luz Palacios-Derflingher, MSc, at U of C; Dr. Sumit Majumdar at the University of Alberta; Dr. Sam Sheps at the University of British Columbia (UBC) and Dr. Robert Reid of UBC and the Group Health Cooperative, Seattle, WA; Régis Blais, PhD, at the Université de Montréal; Dr. Jafna Cox at Dalhousie University; and Robyn Tamblyn, PhD, at McGill University.

Backgrounder

Study design

• methods used in this study are based on a protocol from the Harvard Medical Practice Study of adverse events in New York State hospitals (1984)
• this protocol was modified and used in subsequent studies in Australia, the UK, New Zealand, Utah & Colorado, and Denmark
• investigators randomly selected one teaching, one large community and two small hospitals in each of five provinces: B.C., Alberta, Ontario, Quebec and Nova Scotia
• the study was designed to compare the rate of adverse events across types of hospitals and between medical and surgical care

Background

• this research paper reports on the first Canadian study to provide a national estimate of the incidence of adverse events
• health care management includes actions of individual hospital staff, broader systems and care processes
• adverse events are classified as being related to diagnostic errors, surgical procedures, fractures, anesthesia, medical procedures, drugs, clinical management and system error

Data collection

• 3,745 adult patient charts were reviewed, not including pediatric, obstetric or psychiatric charts
• nurse or health record professionals first reviewed all charts for evidence of any one of 18 criteria that are known to be associated with possible adverse events
• physician reviewers then looked at those charts with one or more of these criteria, and identified any unintended injuries or complications, and whether these resulted in death, disability at discharge, or a longer hospital stay
• the reviewers then determined the extent to which health care management, rather than the patient's disease, was responsible for the injury
• adverse events were those events where unintended injuries or complications resulted in death, disability or prolonged hospital stay and were caused by health care management
• physician reviewers also judged preventability of each adverse event
• the reviewers were trained together using a standard set of hospital charts and a training manual

Results

• the overall adverse event rate in Canadian acute care hospitals in 2000 was 7.5 per 100 patient admissions, not including pediatric, obstetric or psychiatric admissions. This rate suggests that, of the almost 2.5 million adult medical and surgical admissions in Canada in 2000, approximately 185,000 were associated with an adverse event.
• at the time these adverse events occurred, surgical services were responsible for the delivery of care 51 per cent of the time, medical services 45 per cent of the time and other types of professional services four per cent of the time
• 65 per cent of adverse events resulted in no physical impairment or disability or minimal and moderate impairment with recovery in 12 months or less
• five per cent of adverse events resulted in permanent disability
• 46 adverse events occurring in 40 people were associated with death, suggesting that 1.6 per cent of people hospitalized in Canadian hospitals in 2000 were judged to have suffered death associated with an adverse event
• physician reviewers estimated that each patient who experienced one or more adverse events spent an additional six days in hospital attributable to the adverse events (during the one-year time frame of the study)
• the study identifies that adverse events occur more frequently in teaching hospitals, even after adjustment for patients' disease status, and suggests the following factors to account for this finding: 1.teaching hospitals may receive patients at different points in their care (e.g., complex conditions requiring treatment not available in small or large community hospitals) 2.the complexity of care in teaching hospitals means that patients may receive care from several different providers, increasing the risk of adverse events related to communication and coordination of care
• the number of adverse events associated with death or permanent disability is similar in this study to the recent UK, New Zealand and Australian studies
• a third of the adverse events were associated with a surgical procedure with the adverse event occurring either during the operation or within a month following surgery
• a quarter of the adverse events were associated with a drug/fluid-related event

Recommendations

• the authors suggest that "efforts to improve medication safety and surgery are likely to play an important role in improving patient safety in Canada"
• the authors also suggest that that system changes will be necessary to improve safety in hospitals