Medical Adverse Event Studies

In May 2004, the results of The Canadian Adverse Events Study; a study of the incidence of adverse events among hospital patients in Canada, was published. It is the first Canadian study to provide a national estimate of the incidence of adverse events across a range of hospitals using methods comparable to those used in recent studies from other countries.

The overall incidence rate of adverse events of 7.5% suggest that, of the almost 2.5 million annual hospital admissions Canada, about 185,000 are associated with an adverse events and close to 70,000 of those are potentially preventable.

Patient safety is receiving growing attention in Canada. Numerous legal cases and media stories have highlighted the consequences of unintended adverse events. In 2002 the Canadian government budgeted $50 million over 5 years for the creation of the Canadian Patient Safety Institute, and many health care organizations have now initiated efforts to improve patient safety.

One important indicator of patient safety is the rate of adverse events among hospital patients. Adverse events are unintended injuries or complications that are caused by health care management, rather than by the patient’s underlying disease, and that lead to death, disability and the time of discharge or prolonged hospital stays. The study defines disability to mean a temporary impairment of function lasting up to a year, permanent impairment of function or death. The study found that 37%-51% of adverse events have been judged in retrospect to have been potentially preventable.

Hospital admissions with a most responsible diagnosis related to obstetrics or psychiatry were excluded. This is of significance as adverse events arising in the practice of obstetrics can result in greater economic loss claims.

Of particular note the study found that of the patients who experienced adverse events, 41.6% were judged to have 1 or more adverse events with a high preventability rating. In 15.3% of the patients, preventability was judged to be “virtually certain.” The sad finding of the study was that death was estimated to have occurred in 20.8% of those adverse events and 9% of these adverse events were judged to have been highly preventable. Preventable adverse events were similar across all hospital types, ranging from large community hospitals to small and teaching hospitals. Furthermore, 5.2% of the adverse events resulted in permanent disability, and 15.9% resulted in death.

The degree of disability required consideration of the patient’s potential for work and activities of daily living. The most common types of adverse events were related to surgical procedures, and the next most common were associated with drug or fluid-related events.

The study showed that an estimated 7.5% of patients admitted to acute care hospitals in Canada experienced 1 or more adverse events. 36.9% of these patients were judged to have highly preventable adverse events. It was estimated a small but significant proportion of patients died or experienced permanent disability as a result of their adverse events. The study found that in 2000, between 141,250 and 232,250 admissions to acute care hospitals in Canada were associated with an adverse event and that 9,250 to 23,750 deaths from adverse events could have been prevented.

Extrapolating the figures, found in the study, the Canadian Institute for Health Information stated that patients spend more than 1 million extra days in hospital being treated for injuries or complications in their care.

The high number of errors surprised Michael Decter, head of the Health Council of Canada. “We knew we had a problem, we didn’t know how big it was. Now that we know…, we’ve got a lot of work to do.”

One in 9 adults with health problems reported receiving the wrong medication or dose. The same number contacted an infection such as pneumonia while in hospital, the report said.

Figures on birth trauma were presented for the first time. One in 81 babies born vaginally suffers an injury, which can range from mild bruising to severe brain damage the report said.

In the United States, a recent study done by the HealthGrades Inc. of Colorado estimates that as many as 195,000 people a year could be dying in U.S. hospitals because of easily preventable errors. This estimate doubles previous figures. The HealthGrades Inc. said its data covers all 50 states and is more up-to-date than a 1999 study from the Institute of Medicine that said 98,000 people a year die from medical errors.

The HeathGrades Inc. study includes as mistakes, failure to rescue dying patients and the death of low-risk patients from infections. It said it found about 1.14 million “patient-safety incidents” occurred among the 37 million hospitalizations. Of the total deaths among patients who developed patient-safety incidents, 81 percent of these deaths were directly attributable to the incidents. In fact, approximately one in every four patients who were hospitalized and experienced a patient-safety incident died.

The U.S. government is trying to spearhead a move to get hospitals and clinics to use electronic databases and prescribing methods as an earlier study by the Institute of Medicine report said many deaths were due to medication prescribing errors or to errors in delivering medications.
The study concluded that if the Centres for Disease Control and Prevention’s annual list of leading causes of death included medical errors, it would show up as number six, ahead of diabetes, pneumonia, Alzheimer’s disease and renal disease.

An earlier and seminal study done by the Harvard Medical Practice Study Group determined that for every 8 potential medical malpractice claims, only 1 claim was actually filed.

This study (generally known as the Harvard study) commissioned by New York state in 1986, and released in 1990, showed that actual malpractice is relatively rare. Of the New York hospital cases examined, the incidence of adverse events, or injuries resulting from medical “interventions” or treatment, was 3.7 percent. The percentage of adverse events due to what the physician team characterized as “negligence” (not necessarily a legal definition) was 1 percent. However, only one in eight who suffered from an adverse event due to negligence filed a medical malpractice claim, and only one in 15 received compensation. Most adverse events resulted in only minimal and transient disability. This helps to explain why only a small percentage of patients who are injured as a result of negligence file medical malpractice claims. However, a significant portion (22 percent) of patients who did not file medical malpractice claim suffered moderate or greater incapacity.