Chapter 3. Patient Safety

The Institute of Medicine defined patient safety in its 1999 report, To Err Is Human, as freedom from accidental injury due to medical care or medical errors.¹ In 1999, the IOM published To Err Is Human: Building a Safer Health System, which called for a national effort to reduce medical errors and improve patient safety. Central to this effort is the ability to measure and track patient safety events.

Measuring patient safety is complicated by difficulties assessing and ensuring the systematic reporting of medical errors and patient safety events. All too often, patient safety event reporting systems are laborious and cumbersome. Health care providers may also fear that if they participate in the analysis of medical errors or patient care processes, the findings may be used against them in court or harm their professional reputations. Many factors limit the ability to aggregate data in sufficient numbers to rapidly identify prevalent risks and hazards in the delivery of patient care, their underlying causes, and practices that are most effective in mitigating them. These include difficulties aggregating and sharing data confidentially across facilities or State lines.

Despite these limitations, a clear picture of patient safety is emerging. Progress has been made in recent years in raising awareness, developing event reporting systems, and establishing national data collection standards. Examining patient safety using a combination of administrative data, chart abstraction, and patient surveys allows a more robust understanding of what is improving and what is not. Still, data remain incomplete for a comprehensive national assessment of patient safety.²

Importance

Mortality

Type of statistic	Number
Number of Americans who die each year from medical errors (1999 est.)	44,000-98,0001
Number of Americans who die in the hospital each year due to 18 types of medical injuries (2000 est.)	at least 32,0003

Cost

Type of statistic	Number
Cost attributable to medical errors (in lost income, disability, and health care costs) (1999 est.)	$17 billion-$29 billion1
Annual cost attributable to surgical errors (2008 est.)	$1.47 billion4

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Measures

This year's chapter highlights three core measures and nine additional measures related to surgical complications, other complications of hospital care, and complications of medications:

Core measures:

• Postoperative care composite: pneumonia or venous thromboembolic event.
• Appropriate timing of antibiotics among surgical patients.
• Adverse events associated with central venous catheters (CVCs).
• Potentially inappropriate prescription medications for adults age 65 and over.

Additional noncore measures include:

• Catheter-associated urinary tract infections (UTIs).
• Accidental puncture or laceration.
• Postoperative wound separation in abdominopelvic-surgery patients (reclosure).
• Iatrogenic pneumothorax.
• Deaths following complications of care.
• Deaths in low-mortality diagnosis-related groups (DRGs).
• Adverse drug events in the hospital.
• Any hospital complication.

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Findings

Surgical Care

Adverse health events can occur during episodes of care, especially during and soon after surgery. Although some events may be related to a patient's underlying condition, many of them can be avoided if appropriate care is provided.

Postoperative Care Composite: Pneumonia or Venous Thromboembolic Event

Complications after surgery may include, but are not limited to, pneumonia and blood clots.

Figure 3.1. Composite measure: Adult surgery patients with postoperative complications (postoperative pneumonia or venous thromboembolic event), 2004-2006

Source: Centers for Medicare & Medicaid Services, Medicare Patient Safety Monitoring System, 2004-2006.
Denominator: Adult hospitalized Medicare patients having major surgery and meeting specific criteria for each measure.
Note: Postoperative care complications included in this composite are postoperative pneumonia and venous thromboembolic event (blood clot). Note that this composite changed from 2004 to 2005 with the alteration of the complications of UTIs being changed to catheter-associated UTIs. Catheter-associated UTIs was removed from this composite for 2006 data. Sensitivity analysis carried out on the composite shows that this change does not significantly alter the composite estimate.

• In 2006, 2.7% of Medicare surgical patients had postoperative pneumonia or a thromboembolic event. The change from the 2004 figure (3.0%) was not statistically significant (Figure 3.1).

Catheter-Associated Urinary Tract Infections

The urinary tract is a common site of health care-associated infection. Catheter use and specific comorbid conditions can increase the risk of developing a UTI. Approximately 40% of all health care-associated infections are attributed to catheter-associated UTIs.⁵

Figure 3.2. Adult surgery patients with postoperative catheter-associated urinary tract infection, overall* and by selected comorbid conditions, 2006

*The overall rate uses a different denominator from the condition-specific rate denominators that are based on the numbers of patients who have a specific condition.
Key: CHF = congestive heart failure.
Source: Centers for Medicare & Medicaid Services, Medicare Patient Safety Monitoring System, 2006.
Denominator: Adult hospitalized Medicare patients having major surgery and meeting specific criteria for each measure.
Note: The overall rate also includes health conditions in condition categories not shown in the figure (e.g., chronic obstructive pulmonary disease, smoking, and corticosteroids). Patients may be counted as having one or more conditions concurrent with a UTI.

• In 2006, the total percentage of surgical patients with catheter-associated UTIs was 5.4% (Figure 3.2).
• In 2006, patients with renal disease, cerebrovascular disease, and congestive heart failure or pulmonary edema had the highest rates of catheter-associated UTIs among the conditions analyzed (Figure 3.2).

Appropriate Timing of Antibiotics Among Surgical Patients

Infections acquired during hospital care (nosocomial infections) are one of the most serious safety concerns. A common health care-associated infection is a wound infection following surgery. Hospitals can reduce the risk of wound infection after surgery by making sure patients get the right antibiotics at the right time on the day of their surgery.

Research shows that surgery patients who get antibiotics within the hour before their operation are less likely to get wound infections. Getting an antibiotic earlier or after surgery begins is not as effective. However, taking these antibiotics for more than 24 hours after routine surgery is usually not necessary and can increase the risk of side effects, such as stomachaches, serious types of diarrhea, and antibiotic resistance. Among adult Medicare patients having surgery, the National Healthcare Quality Report tracks receipt of antibiotics within 1 hour prior to surgical incision, discontinuation of antibiotics within 24 hours after end of surgery, and a composite of these two measures.

Figure 3.3. Adult surgery patients who received appropriate timing of antibiotics: Overall composite and two components, 2005 and 2006

Source: Centers for Medicare & Medicaid Services, Quality Improvement Organization Program, 2005 and 2006.
Denominator: Hospitalized patients having surgery.
Note: Beginning in 2005, the data collection method changed from the abstraction of randomly selected medical records for Medicare beneficiaries to the receipt of hospital self-reported data for all payer types.

• In 2006, 84.5% of adult patients having surgery received antibiotics within 1 hour of surgery, and 77.1% had their antibiotics stopped within 24 hours of surgery (Figure 3.3).
• Appropriate timing of antibiotics received by adult patients having surgery improved significantly between 2005 (75.2%) and 2006 (80.9%), both overall and for the two components of the composite measure.

Figure 3.4. State variation: Adult surgery patients who received appropriate timing of antibiotics, 2006

Key: Above average = appropriate timing of prophylactic antibiotics is significantly above the all States average in 2006. Below average = appropriate timing of prophylactic antibiotics is significantly below the all States average in 2006.
Source: Centers for Medicare & Medicaid Services, Medicare Quality Improvement Organization Program,, 2006.
Denominator: Hospitalized patients having surgery.
Note: "All States average" is the average of all responding States (52 in this case, including the District of Columbia and Puerto Rico), which is a separate figure from the national average.

• Variation was seen among States in the overall timing of prophylactic antibiotics (Figure 3.4). In 2006, the all States average was 80.9% and ranged from 65.1% to 91.6%.
• Twenty-three Statesⁱ were significantly above the all States average in 2006, with a combined average rate of 85.5%.
• Twenty-four Statesⁱⁱ the District of Columbia, and Puerto Rico were significantly below the all States average in 2006, with a combined average rate of 76.8%.

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ⁱ The States were Connecticut, Delaware, Iowa, Maine, Maryland, Massachusetts, Michigan, Minnesota, Missouri, Montana, Nebraska, New Hampshire, New Jersey, North Carolina, North Dakota, Oklahoma, Rhode Island, South Carolina, South Dakota, Vermont, Virginia, West Virginia, and Wisconsin.
ⁱⁱ The States were Alabama, Alaska, Arizona, Arkansas, California, Colorado, Georgia, Hawaii, Illinois, Indiana, Kansas, Kentucky, Louisiana, Mississippi, Nevada, New Mexico, New York, Ohio, Oregon, Pennsylvania, Tennessee, Texas, Utah, and Wyoming.

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Accidental Puncture or Laceration

Adverse events, including the nicking or cutting of bodily organs and blood vessels, are possible during any operation or procedure. This may be especially true in emergent situations, when, according to an expert panel review,⁶ some of these occurrences are not preventable. Puncture or laceration can lead to serious complications.⁶

Figure 3.5. Accidental puncture or laceration during procedure per 1,000 discharges, adults age 18 and over, 1994, 1997, and 2000-2005

Source: Agency for Healthcare Research and Quality, Healthcare Cost and Utilization Project, Nationwide Inpatient Sample, 1994, 1997, and 2000-2005.
Note: Rates are adjusted by age, gender, age-gender interactions, comorbidities, and DRG clusters.

• From 1994 to 2005, the rate of accidental puncture or laceration during procedure increased from 3.5 to 4.5 per 1,000 hospital discharges of adults age 18 and over (Figure 3.5).
• From 2000 to 2005, the rate of accidental puncture or laceration during procedure increased significantly from 4.0 to 4.5 per 1,000 hospital discharges of adults age 18 and over.

Postoperative Wound Separation in Abdominopelvic-Surgery Patients (Reclosure)

Possible complications of abdominal and pelvic surgery include wound separation or rupture, which involves all layers of the abdominal wall and requires surgical reclosure. This can occur within 30 days of the procedure, typically between days 5 and 8. Separation is more likely to occur if wound infection is present and can lead to prolonged hospitalization and death.⁶

Figure 3.6. Reclosure of postoperative abdominal wound separation per 1,000 abdominopelvic-surgery hospital discharges, adults age 18 and over, 1994, 1997, and 2000-2005

Source: Agency for Healthcare Research and Quality, Healthcare Cost and Utilization Project, Nationwide Inpatient Sample, 1994, 1997, and 2000-2005.
Note: Rates are adjusted by age, gender, age-gender interactions, comorbidities, and DRG clusters.

• From 1994 to 2005, the rate of postoperative abdominal wound separation decreased from 3.2 to 2.8 per 1,000 abdominopelvic surgery discharges in adults age 18 and over (Figure 3.6).

Other Complications of Hospital Care

Besides surgery, other types of care delivered in hospitals can place patients at risk for injury or death.

Adverse Events Associated With Central Venous Catheters

Patients who require a CVC to be inserted into the great vessels leading to the heart tend to be severely ill. However, the placement and use of these catheters can result in infections and other complications.

Figure 3.7. Bloodstream infections or mechanical adverse events among central venous catheter placements: Overall composite and two components, 2004-2006

Source: Centers for Medicare & Medicaid Services, Medicare Patient Safety Monitoring System, 2004-2006.
Denominator: Adult hospitalized Medicare patients with CVC placement.
Note: Mechanical adverse events include allergic reaction, tamponade, perforation, pneumothorax, hematoma, shearing off of the catheter, air embolism, misplaced catheter, thrombosis or embolism, knotting of the pulmonary artery catheter, and certain other events.

• From 2004 to 2006, there were significant increases in the percentage of CVC placements with associated complications overall (Figure 3.7).
• The percentage of CVC placements with associated bloodstream infection and mechanical adverse events increased significantly between 2004 and 2006.

Iatrogenic Pneumothorax

Iatrogenic pneumothorax is a partial or complete collapse of a lung due to an accumulation of air in the pleural space (between the lungs and the chest wall) and is caused by medical care. This condition can be life threatening.^6-7

Figure 3.8. Iatrogenic pneumothorax per 1,000 hospital discharges, adults age 18 and over, 2001-2005

Source: Agency for Healthcare Research and Quality, Healthcare Cost and Utilization Project, State Inpatient Databases, 2001-2005.
Note: Rates are adjusted by age, gender, age-gender interactions, comorbidities, and DRG clusters.

• From 2001 to 2005, the rate of iatrogenic pneumothorax decreased from 0.70 to 0.65 per 1,000 hospital discharges of adults age 18 and over (Figure 3.8).

Deaths Following Complications of Care

Many complications that arise during hospital stays cannot be prevented. However, rapid identification and aggressive treatment of complications may prevent these complications from leading to death. Deaths following complications of care, also called "failure to rescue," is an indicator that tracks deaths among patients whose hospitalizations are complicated by pneumonia, thromboembolic event, sepsis, acute renal failure, gastrointestinal bleeding or acute ulcers, shock, or cardiac arrest.⁶

Figure 3.9. Deaths per 1,000 discharges with complications potentially resulting from care (failure to rescue), adults ages 18-74, 1994, 1997, and 2000-2005

Source: Agency for Healthcare Research and Quality, Healthcare Cost and Utilization Project, Nationwide Inpatient Sample, 1994, 1997, and 2000-2005.
Denominator: Patients ages 18-74 years from U.S. community hospitals whose hospitalizations are complicated by pneumonia, thromboembolic event, sepsis, acute renal failure, gastrointestinal bleeding or acute ulcer, shock, or cardiac arrest.
Notes: Rates are adjusted for age, gender, comorbidities, and DRGs.

• From 1994 to 2005, the rate of deaths following complications of care declined from 161.1 to 120.4 per 1,000 admissions of adults ages 18-74 (Figure 3.9).
• The rate of deaths following complications of care decreased significantly from 2000 to 2005 (153.4 to 120.4 per 1,000 admissions).

Deaths in Low-Mortality Diagnosis-Related Groups

When in-hospital deaths of patients admitted for low-risk illnesses or procedures occur, health care errors are more likely responsible than in deaths of patients with high-risk illnesses.^6-7

Figure 3.10. Deaths per 1,000 admissions in low-mortality diagnosis-related groups, adults age 18 and over, 1994, 1997, and 2000-2005

Source: Agency for Healthcare Research and Quality, Healthcare Cost and Utilization Project, Nationwide Inpatient Sample, 1994, 1997, and 2000-2005.
Notes: All estimates shown in Figure 3.10 used version 3.1 of the AHRQ Patient Safety Indicators software (go to the Measure Specifications appendix for details). Rates not risk adjusted.

• From 1994 to 2005, the rate of deaths in low-mortality DRGs decreased from 0.69 to 0.51 per 1,000 admissions of adults age 18 and over (Figure 3.10).
• Between 2000 and 2005, there was no significant change in the rate of deaths in low-mortality DRGs per 1,000 admissions of adults age 18 and over.

Complications of Medications

Complications of medications are common safety problems. Some, but not all, adverse drug events may be related to misuse of medication. However, prescribing medications that are inappropriate for a specific population may increase the risk of adverse drug events.

Adverse Drug Events in the Hospital

Some medications used in hospitals can cause serious complications. The Medicare Patient Safety Monitoring System tracks a number of adverse drug events, including serious bleeding associated with intravenous heparin, low-molecular-weight heparin, or warfarin and hypoglycemia associated with insulin or oral hypoglycemics.

Figure 3.11. Hospital patients with adverse drug events, 2004-2006

Source: Centers for Medicare & Medicaid Services, Medicare Patient Safety Monitoring System, 2004-2006.
Denominator: Adult hospitalized Medicare patients receiving specified medication.

• In 2006, adverse drug events in the hospital related to some frequently used medications ranged from 5.2% of Medicare patients who received low-molecular-weight heparin to 15.5% of Medicare patients who received intravenous heparin (Figure 3.11).
• The rates of adverse events associated with low-molecular-weight heparin and warfarin decreased significantly between 2004 and 2006.
• The rates of adverse events associated with insulin and other hypoglycemics increased significantly between 2004 and 2006.

Potentially Inappropriate Prescription Medications for Adults Age 65 and Over

Some drugs are considered potentially harmful for older patients but nevertheless were prescribed to them.^{8, iii}

Figure 3.12. Adults age 65 and over who received potentially inappropriate prescription medications in the calendar year, 1996, 1998, and 2000-2005

Source: Agency for Healthcare Research and Quality, Medical Expenditure Panel Survey, 1996, 1998, and 2002-2005.
Reference population: Civilian noninstitutionalized population age 65 and over.
Note: Prescription medications received include all prescribed medications initially purchased or otherwise obtained, as well as any refills.

• From 1996 to 2005, the percentage of older patients who reported purchasing at least 1 of 33 inappropriate drugs decreased significantly, from 21.3% to 17.7% (Figure 3.12).
• There was no significant difference between 2000 and 2005 in the receipt of potentially inappropriate drugs by older patients for both the 33 drugs that should often or always be avoided and the 11 drugs that should always be avoided.
• The receipt of the 11 drugs that should always be avoided remained relatively stable over the 1996-2005 period at about 3%.

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ⁱⁱⁱ Eleven drugs that should always be avoided for older patients include barbiturates, flurazepam, meprobamate, chlorpropamide, meperidine, pentazocine, trimethobenzamide, belladonna alkaloids, dicyclomine, hyoscyamine, and propantheline. Twenty-two drugs that should often be avoided for older patients include carisoprodol, chlorzoxazone, cyclobenzaprine, metaxalone, methocarbamol, amitriptyline, chlordiazepoxide, diazepam, doxepin, indomethacin, dipyridamole, ticlopidine, methyldopa, reserpine, disopyramide, oxybutynin, chlorpheniramine, cyproheptadine, diphenhydramine, hydroxyzine, promethazine, and propoxyphene.

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Any Hospital Complication

Examining specific adverse events is helpful for targeting quality improvement activities. A complementary approach is to study a broad panel of patient safety events. Such an approach provides a better understanding of the overall prevalence of adverse events.

The Medicare Patient Safety Monitoring System affords an opportunity to examine hospital adverse events in aggregate. Not all adverse events are captured by the system, but a large number can be. These include adverse events associated with CVCs, femoral artery puncture for angiographic procedures, and hip-and knee-joint replacements; postoperative pneumonia, venous thromboembolic, and cardiac events; infections with methicillin-resistant Staphylococcus aureus (MRSA) and vancomycin-resistant Enterococcus; adverse drug events; hospital-acquired pressure ulcers; catheter-associated UTIs; inhospital patient falls; and contrast nephropathies associated with catheter angiography.

Figure 3.13. Adult hospitalized Medicare patients with one or more adverse events, 2005 and 2006

Source:Centers for Medicare & Medicaid Services, Medicare Patient Safety Monitoring System, 2005 and 2006.

• In 2005 and 2006, approximately one out of seven adult hospitalized Medicare patients experienced one or more of the adverse events tracked by the Medicare Patient Safety Monitoring System (Figure 3.13).

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Future Directions

In response to the IOM's report on patient safety, the President signed the Patient Safety and Quality Improvement Act of 2005 (Patient Safety Act) to spur the development of voluntary, provider-driven initiatives to improve the quality, safety, and outcomes of patient care. The act addresses many of the current barriers to improving patient care.

The Patient Safety Act provides for voluntary formation of Patient Safety Organizations (PSOs), which can be public or private organizations. PSOs will collect, aggregate, and analyze information regarding the quality and safety of care delivered in any health care setting. To allow standardized data collection, the Secretary of Health and Human Services (HHS) requested that the Agency for Healthcare Research and Quality (AHRQ) coordinate the development of common definitions and reporting formats (Common Formats) for patient safety events. These Common Formats support data aggregation, analysis, and learning throughout the improvement cycle.

AHRQ issued Common Formats in August 2008 as Version 0.1 Beta. AHRQ's initial Common Formats address patient safety event reporting (the first stage in the improvement cycle) in the hospital inpatient setting. In the future, AHRQ will develop Common Formats to address the remaining three phases of the improvement cycle (root cause analysis, implementation of improvement action, and evaluation of effectiveness). AHRQ has contracted with the National Quality Forum, a nonprofit organization focused on health care quality, to assist in gathering and analyzing feedback on the Common Formats. AHRQ plans to issue updates and revisions based on user input and, over time, to release Common Formats that address patient safety in other settings.

AHRQ is also working with patients to improve reporting of patient safety events, because patients see problems that busy providers may not notice. Measures from Hospital CAHPS® (Consumer Assessment of Healthcare Providers and Systems) are beginning to capture patient perceptions of problems with medications and transitions of care, but more work is critically needed.

Health care-associated infections (HAIs) are the most common complication of hospital care, and preventing them requires a multipronged approach. HHS supports a number of initiatives to reduce HAIs. AHRQ is summarizing effective quality improvement strategies for preventing HAIs, training patient safety officers to implement these strategies, and partnering with hospitals to improve infection safety. The Centers for Disease Control and Prevention's National Healthcare Safety Network (NHSN) collects surveillance information on the rate of HAIs and information on health care practices from nearly 2,000 hospitals in 49 States. Hospitals using NHSN for data collection and prevention efforts decreased their rates of central line-associated bloodstream infections by 40 to 50% during the last decade among patients in intensive care units. In most intensive care units, rates also decreased 50% for the subset of central line-associated bloodstream infections associated with methicillin-resistant Staphylococcus aureus. HHS is working to establish national targets for HAI reduction and helping to coordinate HHS-supported efforts to achieve these goals.

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References

1. Kohn LT, Corrigan JM, Donaldson MS, eds. Institute of Medicine. Committee on Quality of Health Care in America. To err is human: building a safer health system. Washington, DC: National Academies Press; 1999.

2. Aspden P, Corrigan JM, Wolcott J, et al., eds. Institute of Medicine. Committee on Data Standards for Patient Safety. Patient safety: achieving a new standard of care. Washington, DC: National Academies Press; 2004.

3. Zhan C, Miller MR. Excess length of stay, charges, and mortality attributable to medical injuries during hospitalization. JAMA 2003 Oct 8;290(14):1868-74.

4. Encinosa WE, Hellinger FJ. The impact of medical errors on ninety-day costs and outcomes: an examination of surgical patients. Health Serv Res 2008 Jul 25 [Epub ahead of print]. Available at: http://www3.interscience.wiley.com/cgibin/fulltext/120855828/HTMLSTART.

5. Tambyah PA, Maki DG. Catheter-associated urinary tract infection is rarely symptomatic: a prospective study of 1497 catheterized patients. Arch Intern Med 2000;160:678-82.

6. AHRQ Quality Indicators. Guide to Patient Safety Indicators. Rockville, MD: Agency for Healthcare Research and Quality; March 2003. Version 3.1. Available at: http://www.qualityindicators.ahrq.gov/psi_download.htm.

7. Rivard PE, Elway AR, Loveland S, et al. Applying patient safety indicators (PSIs) across health care systems: achieving data comparability. Available at: http://www.ahrq.gov/downloads/pub/advances/vol2/rivard.pdf [Plugin Software Help]. Accessed June 27, 2008.

8. Zhan C, Sangl J, Bierman AS, et al. Potentially inappropriate medication use in the community-dwelling elderly: findings from the 1996 Medical Expenditure Panel Survey. JAMA. 2001 Dec 12;286(22):2823-29.

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