Health care professionals are trained to be careful and competent at their job, and to ensure that they use resources effectively so that they can give care of the highest possible standard. But, given the complexity of health care and the high number of interventions that each patient may require as well as the number of health professionals that may be involved in carrying out these interventions, it is not surprising that errors and other problems occur, sometimes resulting in unintended injuries. Unfortunately, little attention has been given to the causes of clinical errors or to developing methods to prevent them. Leape (1994) has identified three main reasons as to why nurses and physicians have not developed more effective methods of error prevention. First, they may lack awareness of the severity of the problem. Second, most errors do not cause harm. Thirdly, the culture of clinical practice (i.e. to strive for error-free practice) makes it difficult for nurses and physicians to deal with human error when it does occur.
3.2 Nature and incidence of adverse events in medicine.
An adverse event is "an unintended injury that was caused by medical management and that resulted in measurable disability" (Hiatt et al., 1989). With the notable exception of the confidential enquiries and critical incident studies, there are relatively few studies which focus on the incidence of iatrogenic adverse events in the United Kingdom. So, most of the evidence on adverse events in medicine in this chapter will be drawn from studies carried out in the United States and Australia, particularly the Harvard Medical Practice Study (Hiatt et al., 1989) and the Quality in Australian Health Care Study (McL Wilson et al., 1995). Both studies uncovered significant number of adverse events in retrospective clinical reviews of medical records.
Chapter 3: Errors and adverse events in health care
To date, the Harvard Medical Practice Study is the most thorough and comprehensive investigation of adverse events in medicine that has been carried out. This study looked at a random sample of all discharge records (N= 30,429) in 1984 in 51 New York State hospitals according to pre-defined criteria which included death, increased length of stay, hospital re-admission, fever at discharge and complications requiring transfer to operating theatre or intensive therapy unit. It identified injuries sustained to patients during medical therapy and how many of them were the result of negligence. Of the 31,429 medical records examined, 1,133 (3.7 % of all cases) revealed an adverse event caused by medical treatment, 280 (27.6 %) of which were the result of negligence. When these findings are extrapolated to all patient discharges from New York Hospitals, the study concludes that for every 2.6 million patients discharged, 56,000 sustained injuries with minimal impairment, 13,500 with moderate impairment, 3,800 with permanent impairment, 2,500 with permanent and total disabilities and 13,400 with adverse events that caused death. The most common types of adverse events were found to be drug complications (19.4 %), wound infection (14 %) and technical complications. Risk factors included age, patients' condition, race, type of insurance and the hospital where care was given. There was a higher rate of adverse events in teaching hospitals, but lower rate of substandard care or negligence. This indicates that the rate of adverse incidents is influenced by severity of illness as well as the standard of care.
The Medical Practice study reveals that the incidence of adverse events is greater than is generally recognised. From the findings of the study, it was extrapolated that an estimated 1.3 million people each year in the United States received unintended injuries as a result of medical therapy (Leape et al, 1995). The study authors suggest that prevention methods should be directed at all adverse events and not just those that are negligent ( Leape et al., 1991).
A similar study was carried out in Australian hospitals (Quality in Australian Health Care Study, 1995), involving the retrospective clinical review of 14179 medical records according to 18 specific criteria (McL Wilson et al., 1995). The study reveals that 16.6 % (N= 2353) of admissions resulted in an adverse event, 51 % of which were considered preventable. This was considerably higher than the 3.7 % recorded in the Harvard Medical Practice Study. The authors of the Australian study argue that this may be because of the different focus of the two studies, the Harvard Medical Practice Study concentrating on negligence and the Quality in Australian Health Care Study on preventability. This may have influenced the level of reporting of adverse events. A second reason given for the higher incidence of adverse events in the Australian study was that the quality of medical records may have improved since the Harvard Medical Practice Study was carried out.
Thus, both studies indicate that adverse events are common in clinical practice and may lead to serious consequences for the patients. There were also many similarities in the findings of the two studies, particularly regarding the timing and nature of adverse events. If these figures are extrapolated to a British context, a medium sized hospital with 50,000 admissions per aimum would have between 2000 to 8000 adverse events per annum each leading either to patient injury or to a longer hospital stay (Vincent, 1997). In England alone, out of approximately 5 million admissions per annum, some 200,000 adverse events occur, with 50,000 being due to negligence (Vincent, 1997).
3.2.1 Confidential enquiries on adverse events in medicine.
In the United Kingdom, audit studies such as the confidential enquiry on maternal deaths (HMSO, 1986), the confidential enquiry into perioperative deaths (Buck et al., 1987), mortality associated with anaesthesia (Lunn and Mushin,
Chapter 3: Errors and adverse events in health care
department (Dearden and Rutherford, 1985) have yielded valuable information on the causes and incidence of adverse events and substandard care. All of these studies have indicated that a significant proportion of deaths and other adverse events to patients were avoidable and have also identified areas where the care is substandard. Staff shortages, lack of consultant involvement, inadequate supervision, inappropriate delegation of cases, deficient case notes, surgeons operating outside their specialties and failures of communication have all been found to be prominent contributing factors to deaths and injuries to patients.
Maxwell (1984) argues that the confidential enquiries have been highly influential in directing medical attention to perinatal and anaesthetics deaths. There is no doubt that lessons can be learnt firom these kinds of studies about the underlying causes of adverse events and how to reduce them. For instance, McDonald et al (1991) in their audit study of avoidable deaths fi-om surgical intervention have identified some of the avoidable factors of deaths such as surgeons' competence, pulmonary embolism and pneumonia. This has enabled them to institute measures such as reiteration of policy, improving line of communication, giving an insight into the surgeons' weaknesses and further training, using prophylactic heparin therapy to tackle the high pulmonary embolism rate, and emphasising the importance of physiotherapy to reduce the incidence of pneumonia, to prevent further mishaps or oversights. However, the confidential reports would have been strengthened if more data were provided on the denominators of the adverse events. For example, Nixon (1992) argues that although the "Report of the National Confidential Enquiry into Perioperative Deaths 1990" reported that there was 58 wound dehiscence and 54 anastomotic failures associated with perioperative deaths, no information was provided regarding the total number of cases and the number of patients who survived these complications. The low compliance in supplying information to the "inquiry" also reduces the validity of the report. Nixon (1992) reported that "one
fifth of requests for information were met with silence and a further fifth yielded incomplete data. Whether this represents simple apathy, active resistance , or an attempt to conceal is unknown".