A dedication to safety is a critically important responsibility of any industry.7
However, when providing air transportation or selling kitchen appliances, consumer safety is generally limited to considerations of the risks related to using the service or product, whereas, improving consumer safety in medicine requires assessing, and often balancing, the potential harm of inappropriate non-intervention (errors of omission), as well as inappropriate or unsafe intervention (errors of commission) (Fig. 1). In this way, medicine has more in common with the military or law enforcement, in that the risks of friendly fire and intervening too early or too much must be weighed against the risks of enemy fire and intervening too slowly or insufficiently.
Although iatrogenic adverse events are sometimes talked about as if they are synonymous with medical errors, increasing a patient's risk of iatrogenic adverse events will often be the right thing to do.21–23
For example, underuse of thrombolytics, anti-platelet agents, and anticoagulants are common causes of preventable morbidity and mortality.15,33,34
However, appropriate use of these medications clearly and substantially increases iatrogenic adverse events even when done optimally. Of course, misapplications or mishaps in the use of medical interventions can result in iatrogenic injuries that are truly appalling.7,12
Therefore, discussions and considerations of adverse events, patient safety, and medical errors must always consider the appropriateness of medical intervention at the time the decision was made,23,35
to try and avoid second-guessing influenced by hindsight and omission bias.25
To our knowledge, our study is the first systematic examination of the balance between substantive errors of omission versus commission using a detailed peer evaluation of both the inpatient and outpatient medical record. We found that the vast majority of medical errors noted by trained reviewers were related to errors of omission. This finding was consistent across a variety of conditions and was equally true when limiting review to those errors that were felt to be the most serious. Many experts have decried the inadequacies of our health care system for taking care of those with chronic illnesses,15,36
and insufficient care for people with chronic illness was particularly prominent in our study. For example, there were over 3 times more substantive errors of omission related to diabetes care than there were errors of commission related to all conditions combined in the entire patient sample.
Some previous research has examined errors of omission and commission in the inpatient setting17,20,29
or using explicit review criteria.31,37
Although anecdotes of mishaps causing iatrogenic complications tend to be highlighted in most discussions of medical errors, a careful reading of past studies reveals that our results are not that dissimilar from results found in inpatient settings. Evaluations of inpatient errors have consistently found that at least half of major adverse events reportedly resulting from medical errors were related to underuse.17,20,29
For example, the Utah–Colorado Study (UTCOS) found that for inpatient care, excluding adverse events related to neonatal care and patient falls, permanent disability and death were almost 3 times more likely to be caused by underuse errors than overuse/misuse errors.17
Still, our study found an even greater preponderance of underuse errors than previous studies, and we believe that there are several potential reasons for this finding. First, most previous studies mainly or solely examined errors in hospital care, where errors of commission might be relatively more common.17,20,29
Second, most previous studies sampled adverse events and then worked backward to find errors. Such retrospective, unblinded reviews may overestimate errors of commission because even experts are highly subject to hindsight and omission bias.1–5,24,38
On the other hand, it also seems likely that the occurrence of adverse events might increase documentation of otherwise undetectable overuse/misuse errors. Third, the number of errors of omission may have increased since the studies conducted in the 1980s and the early 1990s. As the number of treatments known to produce benefit has increased and cost containment efforts have favored less use, the percentage of errors resulting from undertreatment may also have increased. For example, using an explicit review instrument, McGlynn et al.31
found that patients failed to receive nearly 50% of indicated care.
Our findings are limited to 12 VA health care facilities, and therefore our estimates of underuse versus overuse/misuse should not be overly generalized to other settings. However, we think it likely that the general finding is not limited to VA facilities. Indeed, both overall quality and receipt of recommended care have generally been reported to be as good or better in VA than in other sectors of the US health care system.39–41
A more major and inherent limitation of our study is its reliance on the medical record. Medical errors are frequently not identifiable from the medical record;18,42,43
however, most of the albeit limited information on this topic has not found major differences in the types of errors found in the medical record versus patient or medical personnel reports.18,42,44
In addition, the VA medical record system has been found to be fairly reliable in accessing quality.45
Still, it may be that overuse/misuse errors are much more difficult to detect by medical record review than underuse errors and quality related to technical skill (such as how well a procedure or surgery is performed) is virtually impossible to glean from the medical record. Therefore, our results must be qualified as only pertaining to the types of medical errors that can be detected from medical record review.
What are the implications of our findings? These results clearly show that the attention given to patient safety is well deserved, but also suggests that some portrayals of the nature of the problem may be misleading. A detailed understanding of the overall incidence and importance of errors of omission versus commission can be critical when trying to improve the effectiveness, efficiency, and safety of health care.23,46–48
Many of the system solutions being pursued by patient safety and human factors experts7,15
clearly have the promise of substantially reducing both types of errors and our findings create a stronger case for such safety systems. For example, improving communication between providers, enhancing information availability, and the use of electronic alerts, reminders, and order entry7,15,22
all have direct relevance to reducing errors of commission and
errors of omission. However, we risk overlooking important opportunities for designing these systems to optimally improve patient safety if we fail to understand the incidence and full importance of errors of omission.
Further, some proposed safety interventions either directly or indirectly present risks of increasing underuse (such as redundancy systems, compulsory order renewals, mandatory referrals, drug interaction alerts, and pre-authorization). In such instances, our appropriate abhorrence for iatrogenic injuries can lead us to bad decisions if we fail to reflect upon the incidence and relative importance of errors of omission versus commission for the specific situation under consideration. This is another instance in which health care can learn from safety efforts in other industries.49–52
For example, when 4 people died in a British rail accident in 2000, the rail authority reduced maximum allowable rail speeds, which was felt to subsequently contribute to substantial reductions in rail travel—resulting in increased auto deaths, economic losses, and pollution.52
Similarly, an intemperate response to tragic iatrogenic blunders can do more harm than good or result in the diversion of scarce resources from more important, and fixable, health care problems. For example, tunnel vision in trying to eliminate drug-drug interactions could lead to “safety systems” that inadvertently increase patient injury. One of us (R. H.) recently received a pharmacy alert warning that one of his patients was on both aspirin and lisinopril (which have a known drug–drug interaction). However, the risk of aspirin–ACE–inhibitor interactions (though possible with high doses of salicylates) is trivial compared to the thousands of major adverse events and deaths occurring each year resulting from underuse of these medications.15,34,53–55
Even very small reductions in the use of these life-saving medications in response to such well-meaning alerts would far outweigh any potential benefits.
In summary, we found that over 95% of medical errors identified in a review of patients' medical records were caused by patients receiving too little medical care. These results are limited to errors that can be detected by medical record review; nonetheless, they clearly demonstrate that patient safety and quality improvement efforts must carefully reflect upon transgressions related to those things we do and those things we fail to do. Although deserved attention has been directed to iatrogenic harm resulting from medical blunders, research to date suggests that underuse of needed treatments is probably the greatest risk to patient safety.