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Trends in adverse events over time: why are we not improving?
  1. Kaveh G Shojania1,
  2. Eric J Thomas2
  1. 1Sunnybrook Health Sciences Center, University of Toronto Centre for Patient Safety, Toronto, Ontario, Canada
  2. 2Memorial Hermann Center for Healthcare Quality and Safety, University of Texas at Houston, Houston, Texas, USA
  1. Correspondence to Dr Kaveh G Shojania, Sunnybrook Health Sciences Centre, University of Toronto Centre for Patient Safety, Room H468, 2075 Bayview Avenue, Toronto, ON, Canada M4N 3M5; kaveh.shojania{at}

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Trends in adverse events over time: why are we not improving?

With widespread interest and investments in patient safety in the 13 years following the US Institute of Medicine report To Err is Human,1 the question has understandably arisen: have we decreased medical harm? One widely cited study showed no significant reductions in either the overall rate of harm or the rate of preventable harm in 10 US hospitals chosen on the basis of patient safety activities.2 A second US study,3 though not focused on temporal trends, reported that one third of patients suffered harm from their medical care at three tertiary care hospitals recognised for their efforts in improving patient safety. Given that previous major studies reported adverse event rates in the range of 3–16%,4–10 progress seems sorely lacking.

Adding to this distressing picture, Baines et al11 report in this issue of the journal that the adverse event rate among hospitalised patients in the Netherlands increased from 4.1% in 2004 to 6.2% in 2008. Somewhat reassuringly, preventable adverse rate did not change. The increase in non-preventable adverse rates may reflect better documentation in medical records as a result of interest in patient safety, with the stable rate of preventable events suggesting that safety has not actually worsened. Nonetheless, the main message of this study11 and the two previous ones2 ,3 remains: sustained attention to patient safety has failed to produce widespread reductions in rates of harm medical care.

Why has patient safety not improved?

First, while patient safety and healthcare quality have certainly received substantial attention for more than 10 years now, the actual investments in patient safety still pale beside investments in traditional biomedical research. The US National Institute of Health has a budget of approximately $30 billion,12 roughly 60 times that of the US Agency for Healthcare Research and Quality.13

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