frequent than adverse events (Bates et al., 1995a; Bird and Loftus, 1976; Heinrich, 1931; Skiba, 1985), allow for a much faster buildup of such databases, even at the lowest levels of a national reporting system (e.g., a single hospital department, a primary care provider’s practice). Although To Err Is Human (Institute of Medicine, 2000) estimates the numbers of adverse events and associated fatalities to be very large nationwide, they are still infrequent at the lowest levels of the health care system and thus offer little insight into fundamental, frequently recurring underlying system factors on which to base the most efficacious safety improvements.

  • Mindfulness (Kaplan, 2002)/alertness—to maintain a certain level of alertness to danger, especially when the rates of actual injuries are already low within an organization. For those employed in work environments with a mature safety culture, it eventually becomes difficult to maintain a minimum level of risk awareness in the absence of clearly visible adverse events. A weekly or monthly reminder in the form of a near miss in that same work situation may serve to reinforce awareness of specific safety risks that continue to exist, as well as demonstrate informal recovery defenses in action. It may be necessary to publicize the details of such near misses to ensure that all front-line workers are alerted to the continuing risks.

The Causal Continuum Assumption

Since the 1930s (Heinrich, 1931), most safety experts have assumed (based on anecdotal evidence) or claimed that the causal factors of consequential accidents are similar to those of nonconsequential incidents or near misses. Yet this so-called causal continuum assumption has not yet been firmly established as a scientific fact in health care. To date, this relationship has been documented only in recent transportation safety research (Wright, 2002). The pattern of failure factors for near misses in the railway sector was, by and large, not statistically different from that for train accidents involving injuries and damages. The claim in the health care domain that addressing the causes of near misses will also aid in preventing actual adverse events and fatalities will have to based on more than anecdotal evidence if that claim is to be widely accepted and therefore worth acting upon.

Currently available databases could be used to test the causal continuum assumption in health care. In fact, in one study that evaluated this assumption in health care, the characteristics of near misses were found to be somewhat different from those of errors that resulted in harm (Bates et al., 1995a). In particular, for medication errors, near misses involving a modest overdose were more likely to result in harm than errors involving massive over-



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