Among 228 patients admitted to the medical unit of a Boston teaching hospital, the patient-reported adverse event rate was nearly 9 per 100 admissions. Serious injuries were uncommon, but two thirds were judged preventable. In addition, 4% of patients experienced near misses. Few patient-reported incidents were identified in the medical record, and none were submitted by clinicians to the hospital's incident-reporting system. Patients were more likely to report preventable adverse events and close calls if they had more drug allergies.
The incidence of patient-reported adverse events in this population is generally similar in magnitude to chart review studies of adverse events among patients in acute care hospitals reported elsewhere. The Medical Practice Study found a rate of 3.7 adverse events per 100 admissions.22
A replication of this study in Colorado and Utah found similar results (2.9%),23
but studies in Great Britain and Australia found higher rates (11.7% and 16.6%).24,25
Although U.S. rates have generally been lower than the 9% rate reported here, these other investigators used a more restrictive definition of adverse events, requiring death, disability, or extended hospitalization.26,27
A significant limitation of these studies is the ascertainment of adverse events based on chart review alone. Many adverse events are not recorded in the medical record, a finding attributed to variable standards for documentation, clinician unawareness or oversight, and concern about liability exposure.28,29
Studies of hospital incident reports elicited from medical house officers showed that as many as half of the reports were not found in the medical record.16,17,30
A study of adverse drug events that compared chart review, computerized detection, and spontaneous reporting found little overlap between the types of events detected.31
An inpatient study that relied on both chart review and clinician queries reported higher adverse event rates than chart review alone.20
In addition, a study in ambulatory care showed that chart review detected fewer than 11% of adverse drug events.13
Overall, these data have 2 implications: the true underlying rate of adverse events is higher than that detected by any single approach, and patient contact represents an important detection approach, at least outside the hospital.
Our study suggests that patient reports represent a valuable source of events inside the hospital as well. In addition, the lack of documentation for many patient-reported adverse events in our study suggests that patient reports represent a reservoir of incidents that were unaccounted for in previous inpatient studies.
We found that patients on multiple medications were more likely to report adverse events. This finding is consistent with studies that document the prominence of adverse drug events among medical inpatients,20,22
and the link between adverse drug events and polypharmacy in the nursing home and primary care settings.13,32
The association between error reporting and multiple drug allergies suggests an increased vulnerability and perhaps vigilance in this group.
Our study has several limitations, including its relatively small sample size, and the fact that it comes from a single site. The unit, which included a small geriatric service, may overrepresent community-dwelling elderly patients compared with an unselected population. We did not enroll patients who were admitted and discharged during the same weekend; this may bias our results if such patients were more or less prone to harm than other inpatients. Ascertainment of adverse events, near misses, and errors relied on the judgment of experienced clinicians, but the data from chart review and patient reports were often limited and in many cases made it difficult to understand or evaluate patients' complaints. In addition, because our interview questions elicited information about “injuries,” we did not collect information about the psychologic that harm the patient may have experienced. Excluding patients on contact precautions may have decreased the observed adverse event rate, as recent data suggest these patients are at a higher risk of adverse events than other patients.33
We did not review all charts for adverse events routinely, so we cannot assess the underlying adverse event rate. Incident classification was retrospective, which did not permit clarification of incidents from patients or clinicians other than the reports elicited by the interviewer. To address these potential problems, reviewers offered generally conservative assessments, excluding events that were difficult to interpret or not credible and produced blinded ratings that were highly reliable.
The results of this study offer some guarded optimism about the prospect for productive partnerships between clinicians and hospitalized patients to create safer health care. Many patients and their families are able to identify errors and injuries during or shortly after the hospitalization, providing a potentially useful source of information that could inform clinical care and guide improvement initiatives. Patients may also be able to identify conditions, such as poor staffing, that increase the risk of harm. This study also adds credibility to “best practice” recommendations proposed by organizations such as the American Hospital Association and National Patient Safety Foundation that call for patient participation in preventing medical errors. Finally, patient reports about the attitudes and behaviors of staff may offer insights into the safety culture of the organization.
Additional studies are needed in order to understand the role that patients can play in promoting safe care. Many of the most basic questions remain unanswered. How can we elicit patient incident reports efficiently and confidentially, and use the information to advance safety? Will this information affect the patient-clinician relationship, or increase the risk of malpractice litigation? How can we work with patients at greatest risk of harm, as those at extremes of age, carrying the greatest burden of comorbid illness, with the most drugs, interventions, and allergies, may be least able to participate in safety prevention? Which interventions are most suitable for patients to play a role?
Many patients are aware of errors and iatrogenic injuries that affect their own care. Engaging patients as partners with clinicians in efforts to identify and prevent medical errors offers a promising strategy to advance patient safety.