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Mountains in the clouds: patient safety research
  1. David W Bates
  1. Professor David W Bates, Brigham and Women’s Hospital, Boston, Massachusetts, USA; dbates{at}

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Do you see yonder cloud that’s almost in shape of a camel?

By th’ mass and ‘tis, like a camel indeed.

Methinks it is like a weasel.

It is backed like a weasel.

Or like a whale.

Very like a whale.

William Shakespeare, Hamlet, Prince of Denmark (Hamlet and Polonius, Act III, ii)1

It is becoming increasingly clear that patient safety represents an important issue globally, and the amount of research on patient safety is skyrocketing.23 Despite this, it is not clear how big the problem of patient safety really is—different studies have produced different results. For example, the estimates of deaths attributed to errors in the USA have been hugely variable, and hotly debated.4 But whenever studies which use multiple modalities to find injuries are done, it seems as if each modality turns up multiple injuries, with little overlap between those found with one modality and another, so that the bottom line point estimate clearly depends on the techniques used,56 and the true estimate may be higher than many people have realised. Furthermore, with technical advances such as intravenous “smart pumps”, which have a black-box capability to track interventions, whole new sets of errors can be found.7 The net outcome has been that sorting out how big an issue safety really is, has been like looking at mountains in the clouds—it is hard to tell where one thing begins and another ends, and reasonable observers may …

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  • Competing interests: None declared.

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