Original ArticlesProportion of Hospital Deaths Associated with Adverse Events
Introduction
The death of a patient in the hospital is a medical outcome of particular transcendence. Some hospital deaths are assumed to occur because of inadequate care, and are thus considered potentially preventable 1, 2. This, together with the fact that death is easy to define, has made analyses of hospital death useful in identifying deficiencies in the quality of care 1, 3, 4, 5, 6, 7, 8.
Problems with the quality of care are sometimes manifested as adverse events (AE), defined as undesired complications that arise from health care received during the hospital stay. The frequency and repercussions of AE, including the possible relationship between AE and the quality of care, have been analyzed in some detail 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19. The Harvard Medical Practice Study [10]estimated that 3.7% of all hospitalized patients experience at least one relevant AE. Although some AE are believed to be inevitable, there is evidence to suggest that many can be avoided 1, 2, 19, 20, 21.
The relationship between AE and death has been investigated only for certain types of events, and in particular groups of patients 1, 5, 6, 10, 22, 23, 24, 25. However, there appear to be no overall analyses of all AE as risk factors for death in a large sample of patients who died in the hospital. Knowledge of the magnitude of the association between AE and mortality, and of the proportion of the hospitalized population exposed to AE, would allow the proportion of potentially avoidable deaths to be assessed more accurately. Clinicians and health care managers should find this information useful to assess the potential impact of programs focused on the prevention of mortality from AE.
The objective of this study was to determine the fraction of hospital deaths associated with AE. We examined this relation for all AE, and for different categories of AE.
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Patients and methods
We used a paired (1:1) case-control design. The case group initially comprised all 529 consecutive deaths of patients older than 14 years at the University of Granada Hospital (Granada, Spain), an 800-bed, teaching tertiary care center, from January 1, 1990, to January 1, 1991. During this 1-year period there were a total of 14,150 admissions (death rate of 3.74%), and a total of 10,037 surgical interventions were performed. Because we were unable to obtain medical records for five patients,
Results
In the 524 hospital deaths studied, 299 patients (57.1%) experienced a total of 906 AE. In the control patients, 225 (42.9%) experienced a total of 576 AE. Table 1 shows the distribution of AE in the case and control groups, and Fig. 1 shows the numbers of subjects who experienced at least one AE. Except for administrative AE, the number of events was significantly higher in cases than in controls.
The distribution of cases and controls according to sex, age, and potentially confounding or
Discussion
Despite the limitations of our study design, our data suggest a relationship between the burden of AE experienced by a patient and the risk of hospital death.
Unlike the Harvard study [10], the present study was not designed to investigate negligence. The purpose of this study was not to demonstrate a causal link between the occurrence of AE and intrahospital death. Consequently, it was not our intention to provide a precise estimate of how many intrahospital deaths could be avoided by
Acknowledgements
This work was supported by Grant No. AP91-26198701 from the Spanish Ministry of Education and Science through the Teaching and Research Staff Training Program and by Grant No. 96/1688 from the Fund for Health Research (Spanish Ministry of Health). We thank Karen Shashok for translating the original manuscript into English.
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