of adverse events. It is important to appreciate that when an adverse event occurs, we may be quick to judge or to blame the actions or omissions of individuals, but careful inquiry usually shows that deficiencies in our systems are also at fault. We have learnt much from other industries in this respect. Investigation of major disasters such as the Chernobyl nuclear explosion, the Space Shuttle Challenger crash, and the Paddington rail accident identified ‘violations of procedure’ or problems resulting from actions or omissions by people at the scene. However, further analysis of these events revealed ‘latent conditions’21 further upstream in the process, which allowed these violations to occur and have such a devastating effect. ‘Latent conditions’ are often a result of gradual and unintentional erosion of safety‐enhancing processes because of other pressures: for example, cutting training budgets to reduce costs. Further in the background are often deeply ingrained cultural and organizational issues, some of which may be elusive and difficult to resolve. Of course, it is very well to learn about the underlying causes of these non‐healthcare‐related disasters, but the question that most clinicians will ask at this stage is how they are relevant to us. Although healthcare is similar to these industries in some respects, such as the high level of inherent risks and the presence of well‐meaning and dedicated staff, it is very different in others, such as diversity, often non‐centralized administration, uncertainty, and unpredictability.
Human error
Human error is not easy to define, as boundaries are often blurred between the actions or inactions of individuals and the deficiencies of the systems in which they work. However, it is important to define and classify different sorts of errors in medicine, largely because this may help us learn from incidents. We can think about errors in medicine in relation to the clinical processes involved – for example, prescribing errors or diagnostic errors – but perhaps it is also useful to look at the underlying psychological themes. In his analysis of different types of error, Reason22 divided them into two broad types of error: slips and lapses. These are errors of action and mistakes that are, broadly speaking, faults of knowledge or planning. He also discusses violations that, as distinct from errors, are intentional acts that, for one reason or another, deviate from the usual or expected course of action.
Table 11.1 International adverse events studies, showing data for older patients.
Sources: Mills6; Brennan, et al.7; Wilson, et al.8; Thomas, et al.9; Vincent, Neale, and Woloshynowych10; Davis, et al.11; Baker, et al.12; Forster, et al.13; Michel, et al.14; Sari, et al.15; Sousa, et al.16; Rafter, et al.17; Nilsson, et al.18
| Study | Year | No. of subjects | No. (proportion, %) of elderly subjects | Definition of elderly (years) | Overall adverse event rate (%) | Incidence in elderly (%) | Incidence in young (%) | Difference |
|---|---|---|---|---|---|---|---|---|
| California (Mills) | 1977 | 20,864 | 3826 (18.34%) | ≥65 | 4.65 | 7.22±0.82 | 4.07±0.30 | p < 0.05 |
| Harvard (Brennan) | 1991 | 30,121 | 4980 (16.53%) | ≥65 | 3.7 | Standardized for DRG 5.7±0.6 | 2.6±0.2 (16–44 yrs) | p < 0.0001 |
| Australia (Wilson) | 1995 | 14,210 | 3945 (27.76%) | ≥65 | 16.6 | 23.3 | Mean 13.75 | Not given |
| Utah and Colorado (Thomas) | 2000 | 15,000 | Not stated | ≥65 | 2.9±0.2 | All adverse events 5.29±0.37 | All adverse events 2.80±0.18 | p = 0.001 |
| UK (Vincent) | 2001 | 1014 | 342 (33.73%) | ≥65 | 10.8 | 18.13 (62/342) | 7.25 (48/662) | p < 0.001 |
| New Zealand (Davis) | 2002 | 6579 | 1967 (29.9%) | ≥65 | 11.2 | 17.6 (346/1967) | 10.93 (504/4612) | Not given |
| Canada (Ross‐Baker) | 2004 | 3745 | Not stated | Not stated | 7.5 | Mean age of patient with adverse events 64.9 (SD 16.7) vs. 62.0 (SD 18.4) yrs, p = 0.016 | ||
| Ottawa (Forster) | 2004 | 502 | 126 (25.1%) | >72 | 12.7 | 22.22 (28/126) | 9.57 (36/376) | p < 0.001 |
| France (Michel) | 2007 | 8754 | Not stated | Not stated | 6.6 per 1000 days of hospitalization | Mean age of those experiencing adverse events = 63 yrs, 61.7 yrs for those who did not (p = 0.5) | ||
| UK (Sari) | 2007 | 1006 | 332 (33.0%) | ≥75 | 8.7 | 13.5 (95% CI 9.8–17.2) | 6.2 (95% CI 4.4–8.0) | p < 0.001 |
| Portugal (Sousa) | 2014 | 1669 | Not stated | >65 | 11.1 | 19.3 (59% of adverse events in >65 years) | 8.2 | Not stated |
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