Estimate of Patient Harms in Hospital Care

A New, Evidence-based Estimate of Patient Harms Associated with Hospital Care |  Journal of Patient Safety: September 2013 | Review Article

This is a scathing review of the “adverse events” suffered by patients in hospitals. These are the  440,000 deaths each year from medical errors in the U.S.

The amount of new knowledge generated each year by clinical research that applies directly to patient care can easily overwhelm the individual physician trying to optimize the care of his patients.

Guidelines for physicians to optimize patient care are quickly out of date and can be biased by those who write the guidelines.

This rightful warning about guidelines was written in 2013,  2 1/2  years before the CDC opioid prescribing guidelines were created by a biased group of addiction specialists.  

The CDC guidelines are based on simplistic assumptions and corrupt data (that the CDC themselves admitted was flawed) to justify and establish arbitrary restrictions in an attempt to standardize (and thus control) the complexity of medicine.

The guidelines could end up just like the FDA classification of marijuana into Schedule I, a substance with “no known medical use”, is still officially enforced and prevented research. This classification is obviously incorrect, yet it remains set despite the massive body of evidence showing marijuana to have many medical uses and little harm.

If the overwhelming evidence of marijuana’s benefits cannot change the marijuana classification, how will the CDC guidelines every be adjusted when new evidence appears?

Furthermore, the lack of a well-integrated and comprehensive continuing education system in the health professions is a major contributing factor to knowledge and performance deficiencies at the individual and system level.

At the national level, our country is distinguished for its patchwork of medical care subsystems that can require patients to bounce around in a complex maze of providers as they seek effective and affordable care.

Because of increased production demands,

  • providers may be expected to give care in suboptimal working conditions,
  • with decreased staff, and
  • a shortage of physicians,
  • which leads to fatigue and burnout.

…should be no surprise that PAEs (preventable adverse events) that harm patients are frighteningly common in this highly technical, rapidly changing, and poorly integrated industry.

The picture is further complicated by a lack of transparency and limited accountability for errors that harm patients.

here are at least 3 time-based categories of PAEs (preventable adverse events) recognized in patients that are or have been hospitalized.

The broadest definition encompasses all unexpected and harmful experience that a patient encounters as a result of being in the care of a medical professional or system because high quality, evidence-based medical care was not delivered during hospitalization.

The harmful outcomes may be realized immediately, delayed for days or months, or even delayed many years.

An example of immediate harm is excess bleeding because of an overdose of an anticoagulant drug such as that which occurred to the twins born to Dennis Quaid and his wife.

An example of harm that is not apparent for weeks or months is infection with Hepatitis C virus as a result of contaminated chemotherapy equipment.

Harm that occurs years later is exemplified by a nearly lethal pneumococcal infection in a patient that had had a splenectomy many years ago, yet was never vaccinated against this infection risk as guidelines and prompts require


The approach to the problem of identifying and enumerating PAEs was 4-fold:

(1) distinguish types of Patient Adverse Events (PAEs) that may occur in hospitals,

(2) characterize preventability in the context of the Global Trigger Tool (GTT),

(3) search contemporary medical literature for the prevalence and severity of PAEs that have been enumerated by credible investigators based on medical records assessed by the GTT, and

(4) compare the studies found by the literature search.

According to the “IHI Global Trigger Tool for Measuring Adverse Events“:

The use of “triggers,” or clues, to identify adverse events (AEs) is an effective method for measuring the overall level of harm in a health care organization.

The IHI Global Trigger Tool for Measuring AEs provides instructions for conducting a retrospective review of patient records using triggers to identify possible AEs.

This tool includes a list of known AE triggers as well as instructions for selecting records, training information, and appendices with references and common questions.

Types of PAEs

The cause of PAEs in hospitals may be separated into these categories: 

  • Errors of commission,
  • Errors of omission,
  • Errors of communication,
  • Errors of context, and
  • Diagnostic errors

An error of commission is the easiest to detect in medical records.

This occurs when a mistaken action harms a patient either because it was the wrong action or it was the right action but performed improperly.

Errors of omission can be detected in medical records when an obvious action was necessary to heal the patient, yet it was not performed at all

Errors of omission because of failure to follow evidence-based guidelines are much more difficult to detect, partly because there are many complex guidelines and also because adverse consequences of failure to follow guidelines may be delayed until after discharge

Errors of communication can occur between 2 or more providers or between providers and patient.

Contextual errors occur when a physician fails to take into account unique constraints in a patient’s life that could bear on successful, postdischarge treatment

When would a doctor ever have time to discover these unique constraints in a patient’s life? 

It’s unrealistic to expect doctors to conduct a thorough questioning about all aspects of the patient’s life in 15 minutes.  Even after this lengthy “story” is entered in the EHR (Electronic Health Record),  most doctors are not even allocated the time to read a patient’s full medical record.

Because a patient’s medical record (EHR) is now electronically generated, they are overly long, rigidly formatted, and full of extraneous, irrelevant, and redundant data. (EHR systems are set up by and for managers, not the people actually doing the work)

For the next doctor, finding and reading a patient’s recorded lifestyle history might take quite a few of the 15 minutes allocated for an appointment. This is why many just ask patients the same questions over and over.

Preventability and the Global Trigger Tool

The prevailing view is that “preventability” of an adverse event links to the commission of an identifiable error that caused an adverse event. Adverse events that cannot be traced to a likely error should not be called “preventable.”

The portion of adverse events that are deemed preventable tends to be about 50% to 60%; however, recently, experts have postulated that virtually all adverse events they identified with the “GTT (Global Trigger Tool) are preventable.


Recent data from the 4 key studies provide a more comprehensive, evidence-based estimate of the number of lethal and serious medical errors than the one provided by the Institute of Medicine (IOM). These data are compiled in Table 2, and the studies are described below

All 4 studies (Table 2) have similar, 2-tier search methods to identify serious adverse events.

Preventabile Adverse Effects

The GTT (Global Trigger Tool), supplemented by other less comprehensive methods, was applied to medical records by experienced nonphysicians to identify possible adverse events, and then, physician reviewers determined which flags were associated with an adverse event.

However, the study populations were quite different:

One would expect the OIG studies of Medicare patients, who tend to have more comorbidity than the average hospitalized patient, to show the highest incidence of lethal PAEs.

One would expect the incidence of lethal adverse events in tertiary hospitals to be above the national average for all hospitalizations because more complex illnesses are treated there with longer hospital stays.

One would expect, as the original authors did, that the incidence data from North Carolina would be below the national average for lethal adverse events because of concerted efforts in that state to improve patient safety in hospitals compared with the average of other states in the United States


There has been no lack of contention about the prevalence of PAEs, which herein will be considered synonymous with medical errors that cause harm to patients; this does not include near misses that do not harm patients

Why is the present estimate of the number of lethal PAEs so much higher than the highest estimate (98,000) from the IOM?

the GTT is better able to identify adverse events than general reviews by physicians,

It is also possible that the frequency of preventable and lethal patient harms has increased from 1984 to 2002–2008 because of

  • the increased complexity of medical practice and technology,
  • the increased incidence of antibiotic-resistant bacteria,
  • overuse/misuse of medications,
  • an aging population,
  • and the movement of the medical industry toward higher productivity and expensive technology,
  • which encourages rapid patient flow and overuse of risky, invasive, revenue-generating procedures

There are important limitations to the 4 modern studies that must be considered

Premature deaths as a result of medical errors may occur many years after the hospital stay because the patient’s care was not optimal or did not follow guidelines

Lethal diagnostic errors have been estimated to affect 40,000 to 80,000 people per year including outpatients.

These are just the number of deadly diagnostic errors, which are only 1/10 to 1/5 of all possible deadly errors in hospitals.

Physicians have been indefensibly slow to adopt guidelines that would potentially prevent premature deaths or harm

Perhaps they could also be “indefensibly slow to adopt” the CDC guidelines?

In a study that broke past the wall of silence about discovery of medical errors that were missing from medical records, Weissman and colleagues found that 6 to 12 months after their discharge, patients could recall 3 times as many serious, preventable adverse events as were reflected in their medical records

A recent national survey showed that physicians often refuse to report a serious adverse event to anyone in authority. In the case of cardiologists, the highest nonreporting group of the specialties studied, nearly two-thirds of the respondents admitted that they had recently refused to report at least one serious medical error, of which they had first-hand knowledge, to anyone in authority.

It is reasonable to suspect that clear evidence of such unreported medical errors often did not find their way into the medical records of the patients who were harmed.

although it is probably an underestimate, a minimum estimate of a 2-fold increase in the medical record–based estimate is reasonable to compensate for the known absence of evidence in medical records of errors of commission and the inability of the GTT to detect errors of omission even when the evidence that guidelines were not followed may be present in the medical record

Note that the Weisman study suggests a factor of 3 (32/11) for undocumented evidence of serious PAEs caused during hospitalization, but here, we settle for a factor of 2.14

To this, one should add the estimated number of undetected diagnostic errors.

If we begin with the minimum estimate of 40,000 and assume that only half of these occur in hospitals, then the math looks like this: (210,000 × 2) + 20,000 ∼ 440,000 PAEs that contribute to the death of patients each year from care in hospitals.

This is roughly one-sixth of all deaths that occur in the United States each year. The problem of PAEs must emerge from behind the “Wall of Silence” and be addressed for the sake of prolonging the lives of Americans.

All evidence points to the need for much more patient involvement in identifying harmful events and participating in rigorous follow-up investigations to identify root causes


There was much debate after the IOM report about the accuracy of its estimates. In a sense, it does not matter whether the deaths of 100,000, 200,000 or 400,000 Americans each year are associated with PAEs in hospitals.

Any of the estimates demands assertive action on the part of providers, legislators, and people who will one day become patients.

Yet, the action and progress on patient safety is frustratingly slow; however, one must hope that the present, evidence-based estimate of 400,000+ deaths per year will foster an outcry for overdue changes and increased vigilance in medical care to address the problem of harm to patients who come to a hospital seeking only to be healed.  



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  1. Pingback: Letter to CDC: Need ICD Code for Medical Errors | EDS Info (Ehlers-Danlos Syndrome)

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