- Did You Know?
Safety hazards and everyday probabilities.
1. Transfusion—Allain JP. Transfusion risks of yesterday and of today. Transfus Clin Biol. 2003;10:1-5. [go to pubmed]
2. Coin flips—Probability = 0.5 raised to the power of 20.
3. Airline—From 1992-2002 annual numbers of passenger deaths on US commercial flights ranged from zero to a high of 324 deaths per million passenger enplanements. The median value was 2.4 deaths per million, with an inter-quartile range of 6-14. [Available at: http://www.ntsb.gov/aviation/Table3.htm].
4. Anesthesia—Lagasse RS. Anesthesia safety: model or myth? a review of the published literature and analysis of current original data. Anesthesiology. 2002;97:1609-1617. [go to pubmed]
5. Automobile—Approximately 42,000 deaths annually in US due to motor vehicles; approximately 225 million registered vehicles in United States. Since 225 million is reasonably close to the total population of the United States, the mortality rate attributable to motor vehicles does not change substantially if one uses number of citizens as the denominator. Note that we used persons in the denominator rather than vehicle miles traveled in order to make the ratio analogous to mortality rates in health care, where we use deaths per numbers of patient admissions or operations, not total hospital days. Similarly, the aviation statistics presented here reflect deaths per passenger enplanements, not hours of flight time.
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6. Preventable deaths—Two major studies reported that 2.9%-3.7% of all hospitalized patients experience an adverse event (AE), with 6.6%-13.6% followed by death. The Institute of Medicine’s well-known statistic of 44,000-98,000 deaths per year comes from using these two estimates (6.6% and 13.6%), projected over the roughly 30 million hospitalizations in the United States each year. A more recent study specifically assessed the preventability of deaths among hospitalized patients. This study found that multiple reviewers judged 6% of deaths as probably or definitely preventable. Using this result produces estimates of 115 and 302 death per million opportunities (annual hospital admissions in US), depending on whether one chooses upper or lower bounds of the ranges for the AE rate (2.9%-3.7%) and the proportion of AEs followed by death (6.6%-13.6 %). The figure shows 208 deaths per million, the average of these upper and lower bounds.
Hayward RA, Hofer TP. Estimating hospital deaths due to medical errors: preventability is in the eye of the reviewer. JAMA. 2001;286:415-420. [go to pubmed]