TABLE 3.

Examples of Quality of Chronic Health Care in the United States

Health Care Servicea	Sample Description	Data Source	Quality of Care	Referencea
ASTHMA
Adult asthma
	Adults ≥18 years old in a group of 393 adults and children diagnosed with asthma, from a sample of 2,024 patients of 135 providers	Medical records from physicians’ offices, community health centers, and hospital outpatient facilities sampled from Maryland Medicaid claims data, 1988	For each type of clinical setting, the study reports the average percentage of technical quality indicators for adult asthma that were not met. Each of the averages was located in the 40%–45% range. Between 5% and 35% of care was inappropriate.	(Starfield et al. 1994)
Childhood asthma
	Children <18 years old in a group of 393 adults and children diagnosed with asthma, from a sample of 2,024 patients of 135 providers	Same as above	For each type of clinical setting, the study reports the average percentage of technical quality indicators for childhood asthma that were not met. Each of the averages was located in the 30%–40% range. Between 0% and 20% of care was inappropriate.	(Starfield et al. 1994)
DIABETES MELLITUS
Dilated eye examination to screen for retinopathy
Annual dilated eye examination starting at time of diagnosis of non-insulin-dependent diabetes mellitus (NIDDM) and 5 years after diagnosis of insulin-dependent diabetes mellitus (IDDM).	2,392 adults ≥18 years old with IDDM (124 patients), NIDDM treated with insulin (922 patients), and NIDDM not treated with insulin (1,346 patients) from a sample of 84,572 people representative of the U.S. civilian, noninstitutionalized population	National Health Interview Survey, 1989	49% had a dilated eye examination in the prior year; 66% had an examination in the prior 2 years; 61% and 57% of patients at high risk of vision loss because of a history of retinopathy or of long duration of diabetes, respectively, had an examination in the prior year.	(Brechner et al. 1993)
Any eye examination (including nondilated) to screen for retinopathy
Dilated eye examination is recommended, as described above, but any eye examination is also reported to determine whether there was any effort to assess for retinopathy.	Same as above	Same as above	61% had an eye examination in the prior year; 79% had an examination in the prior 2 years.	(Brechner et al. 1993)
Eye exam by ophthalmologist
Dilated eye examination is recommended, as described above, but an examination by an ophthalmologist serves as a proxy for a dilated eye examination.	97,388 Medicare patients ≥65 years old diagnosed with diabetes mellitus	All Medicare claims data (Parts A and B) from 3 states (Alabama, Iowa, Maryland), submitted from 7/1/90–6/30/91	54% did not have an examination by an ophthalmologist during the prior year.	(Weiner et al. 1995)
Hemoglobin A1C
Hemoglobin A1C (or glycosylated hemoglobin) is a blood test that reflects the metabolic control of diabetes. The test should be performed at least once a year for diabetics.	Same as above	Same as above	84% did not receive a hemoglobin A1C test during the prior year.	(Weiner et al. 1995)
Cholesterol screening
It is recommended that total cholesterol should be measured at least once a year for diabetics.	97,388 Medicare patients ≥65 years old diagnosed with diabetes mellitus	All Medicare claims data (Parts A and B) from 3 states (Alabama, Iowa, Maryland), submitted from 7/1/90–6/30/91	45% did not receive blood cholesterol screening during the prior year.	(Weiner et al. 1995)
Diabetes mellitus
	368 adults ≥18 years old diagnosed with diabetes, from a sample of 2,024 patients of 135 providers	Medical records from physician offices, community health centers, and hospital outpatient facilities sampled from Maryland Medicaid claims data, 1988	For each clinical setting, the study reports the average percentage of technical quality indicators for diabetes that were not met. Each average was located in the 40%–60% range.	(Starfield et al. 1994)
HYPERTENSION
Treatment for hypertension
Hypertension (or high blood pressure) is a leading risk factor for coronary heart disease, congestive heart failure, stroke, ruptured aortic aneurysm, renal disease, and retinopathy, all of which contribute to high morbidity and mortality (U.S. Preventive Services Task Force 1989). This was reiterated in 1996 (U.S. Preventive Services Task Force 1996).	246 patients >30 years old with chronic uncomplicated hypertension	Medical records for patients from 4 group practices in Massachusetts, 11/1/85–10/31/87	41%–54% of patients had their hypertension controlled (mean blood pressure <150/90).	(Udvarhelyi et al. 1991)
Treatment for hypertension
Same as above	Nationally representative sample of U.S. adults with hypertension (sample size not available)	National Health and Nutrition Examination Survey III, 1988–91	55% of people with hypertension had blood pressure under control (blood pressure <160/95 on one occasion and reported currently taking antihypertensive medications); 21% when using strict criteria (blood pressure <140/90 and reported currently taking antihypertensive medications).	(Joint National Committee on Detection 1993)
Treatment for hypertension
Same as above	8,697 adults ≥18 years old diagnosed with hypertension from a sample of 36,610 people representative of the U.S.	NHIS, 1990	89% of adults with hypertension received advice from a physician about controlling hypertension (i.e., taking antihypertensive medication, decreasing salt intake, losing weight, or exercising); 80% reported taking at least one action to control hypertension.	(CDC 1994b)
Treatment for hypertension
Same as above	593 adults ≥18 years old diagnosed with hypertension, from a sample of 2,024 patients of 135 providers	Medical records from physician offices, community health centers, and hospital outpatient facilities sampled from Maryland Medicaid claims data, 1988	For each type of clinical setting, the study reports the average percentage of technical quality indicators for hypertension that were not met. Each average was located in the 40%–55% range.	(Starfield et al. 1994)
DEPRESSION
Depression: treatment
There is no evidence that minor tranquilizers are effective for depression, but there is evidence that antidepressant medications are effective for depression.	634 patients with current depressive disorder or depressive symptoms from a sample of 22,399 adult patients who visited 1 large HMO and several multispecialty, mixed-group practices in each city during the study period	Medical Outcomes Study in 3 cities (Boston, Chicago, Los Angeles); questionnaires completed 2/86–10/86; phone interviews completed 5/86–12/86	19% of patients were treated with minor tranquilizers; 12% were treated with antidepressant medications; 11% were treated with a combination of minor tranquilizers and antidepressant medications; 59% received neither.	(Wells et al. 1994a)
Depression: treatment
Same as above	1,198 patients hospitalized with depression, representative of all Medicare elderly patients hospitalized in general medical hospitals with a discharge diagnosis of depression	Medical records for Medicare patients from 297 hospitals in 5 states (California, Florida, Indiana, Pennsylvania, Texas), 7/1/85-6/30/86	33% of patients discharged with antidepressants had doses below recommended level.	(Wells et al. 1994b)
Depression: admission
Appropriate reasons for admission include depression, medical condition meriting acute care, comorbid major psychiatric disorder, or medical reasons precluding outpatient care for depression.	Same as above	Same as above	93% were admitted for clearly or possibly appropriate reasons, and 7% were admitted for inappropriate reasons.	(Wells et al. 1993)
Depression: admission assessment
	Same as above	Same as above	As part of admission assessment, 23% of patients did not have adequate psychological assessment, 26% did not have cognitive assessment, 50% did not have assessment of psychosis, 19% did not have documentation of psychiatric history, 47% did not document whether patient had a history of suicide attempts or ideation, 24% did not have documentation of prior or current medication use, and 45% did not have documentation that heart sounds were examined. Mean number of components of neurologic examination (assessments of pupils, deep tendon reflexes and gait) performed was 1.4.	(Wells et al. 1993)
Depression: diagnosis and treatment
	64 patients with major depression from a sample of 2,592 consecutive primary care patients 18–65 years old who attended one of the study clinics	Patient surveys and interviews, physician surveys, and computerized pharmacy records from 3 primary care clinics of Group Health Cooperative of Puget Sound in Washington	Among patients with major depression who received antidepressant medications, 78% received dosages within the recommended ranges.	(Simon and VonKorff 1995)
MENTAL/ADDICTIVE DISORDER
Mental or addicitve disorder
	People with mental or addictive disorder from a sample of 20,291 adults ≥18 years old	National Institute of Mental Health's Epidemiologic Catchment Area study interviews, 1980–85	29% of people with any mental or addictive disorder received some professional or voluntary mental health service during the prior 12 months, as did 32% of people with any disorder except substance use, 37% of people with any mental disorder with comorbid substance use, 24% of people with substance use (e.g., alcohol), 64% of people with schizophrenia, 46% of people with any affective disorder (e.g., depression), 33% of people with any anxiety disorder (e.g., obsessive-compulsive), 70% of people with somatization, 31% of people with antisocial personality disorder, and 17% of people with severe cognitive impairment.	(Regier et al. 1993)
HYSTERECTOMY
Hysterectomy
Hysterectomy is the surgical removal of the uterus.	642 women ≥20 years old who underwent nonemergency, nononcologic hysterectomies	Medical records for patients from 7 managed care organizations, 8/1/89–7/31/90	16% of hysterectomies were inappropriate, 25% were equivocal, and 58% were appropriate.	(Bernstein et al. 1993b)
BREAST CANCER
Breast cancer: treatment
	199 women 50–69 years old and 175 women ≥70 years old, with adenocarcinoma of the breast, receiving primary cancer managagement at a participating hospital	Medical records from 7 hospitals in southern California, for women with breast cancer diagnosed in 1980–82	67% of women ≥70 years old received appropriate treatment, compared with 83% of women 50–69 years old. When controlling for comorbidity, hospital, and cancer stage, a difference in appropriateness related to age persisted.	(Greenfield et al. 1987)
CARDIAC DISEASE
Coronary artery disease: coronary angiography
Coronary angiography is a method for evaluating coronary artery anatomy to determine whether a patient is a candidate for coronary artery bypass graft surgery or percutaneous transluminal coronary angioplasty.	352 patients who met explicitly defined criteria for necessity of coronary angiography, from among 1,350 positive exercise stress tests in a randomly selected sample of 5,850 stress tests	Medical records from 4 teaching hospitals (3 public, 1 private) in Los Angeles, and patient telephone interviews (with 243 of the 352 patients), 1/1/90–6/30/91	43% of patients received coronary angiography within 3 months of the positive exercise stress test; 56% received coronary angiography within 12 months of the positive test.	(Laouri et al. 1997)
Coronary artery disease: coronary angiography
Same as above	Random sample of 1,335 patients who had coronary angiography	Medical records from 15 nonfederal hospitals providing coronary angiography in New York, selected through a stratified random sample (for location, volume of coronary angiography, and authorization to perform coronary artery bypass graft surgery), 1990	4% of coronary angiographies were inappropriate, 20% were equivocal, and 76% were appropriate.	(Bernstein et al. 1993a)
Coronary artery disease: coronary angiography
Same as above	Random sample of 1,677 cases of coronary angiography	Medicare physician claims data and medical records from 3 sites selected from 13 sites in 8 states (Arizona, California, Colorado, Iowa, Massachusetts, Montana, Pennsylvania, South Carolina), 1981	17% of coronary angiographies were inappropriate, 9% were equivocal, and 74% were appropriate.	(Chassin et al. 1987)
Coronary artery disease: coronary artery bypass graft (CABG)
In CABG surgery, damaged blood vessels supplying the heart are replaced with vessels from elsewhere in the body.	Stratified, random sample of 386 patients who underwent CABG surgery in the 3 hospitals	Medical records from 3 hospitals (excluding Veterans Administration or governmental hospitals and specialty hospitals) selected through a stratified random sample (for size and teaching status) in a western state as part of the National Institutes of Health Consensus Development Program, 1979, 1980, and 1982	14% of CABG surgeries were inappropriate, 30% were equivocal, and 56% were appropriate.	(Winslow et al. 1988)
Coronary artery disease: CABG
Same as above	Random sample of 1,156 patients who had isolated CABG surgery	Medical records for patients from 12 Academic Medical Center Consortium hospitals in 10 states (California, Iowa, Louisiana, Maryland, Massachusetts, Minnesota, New Hampshire, New York, North Carolina, Pennsylvania), 1990	1.6% of CABG surgeries were inappropriate, 7% were equivocal, and 92% were appropriate.	(Leape et al. 1996)
Coronary artery disease: CABG
Same as above	Random sample of 1,338 patients who had isolated CABG surgery	Medical records from 15 nonfederal hospitals providing CABG procedure in New York, selected through a stratified random sample (for location and volume of CABG operations), 1990	2.4% of CABG surgeries were inappropriate, 7% were equivocal, and 91% were appropriate.	(Leape et al. 1993)
Coronary artery disease: percutaneous transluminal coronary angioplasty (PTCA)
PTCA uses a miniature balloon catheter to decrease stenosis (blockage) in blood vessels supplying the heart.	Random sample of 1,306 patients who had PTCA	Medical records from 15 nonfederal hospitals providing PTCA in New York, selected through a stratified random sample (for location and volume of PTCA), 1990	4% of PTCAs were inappropriate, 38% were equivocal, and 58% were appropriate.	(Hilborne et al. 1993)
Heart attack: treatment with aspirin
Aspirin is an effective, inexpensive, and safe treatment for a heart attack. Aspirin therapy reduces short-term mortality in patients with suspected heart attack by 23%. Aspirin should not be given to patients with certain conditions (e.g., hemorrhagic stroke, gastrointestinal bleeding).	7,917 Medicare patients ≥65 years old, hospitalized with heart attack who were “ideal” candidates for treatment with aspirin with no possible contraindications to aspirin therapy	Medical records for Medicare beneficiaries who were hospitalized in 4 states (Alabama, Connecticut, Iowa, Wisconsin), as part of the Cooperative Cardiovascular Project Pilot, 6/1/92–2/28/93	64% received aspirin within the first 2 days of hospitalization.	(Krumholz et al. 1995)
Heart attack: treatment with aspirin
Same as above	5,490 Medicare patients ≥65 years old, hospitalized with heart attack who were alive at discharge and who had no contraindications to aspirin therapy	Some as above	76% were discharged with instructions to take aspirin. Patients who were prescribed aspirin at discharge had a 6-month mortality rate of 8.4%, compared with 17% for patients not prescribed aspirin.	(Krumholz et al. 1996)
Heart attack: treatment with aspirin
Same as above	7,486 patients who were “ideal” candidates for treatment with aspirin during initial hospitalization from a sample of 16,124 Medicare patients hospitalized with a principal diagnosis of heart attack; 5,841 patients who were alive at discharge and who were “ideal” candidates for treatment with aspirin prior to or at time of discharge, from the same sample	Same as above	83% received aspirin during hospitalization; 77% received aspirin prior to or at time of discharge.	(Ellerbeck et al. 1995)
Heart attack: treatment with aspirin
Same as above	187 patients with confirmed heart attack who were alive at discharge and who had no contraindications to aspirin therapy from a sample of 300 Medicare patients ≥65 years old hospitalized with a principal diagnosis of heart attack	Medicare mortality data issued by the Health Care Financing Administration (HCFA) and medical records for Medicare patients from 6 hospitals in Connecticut, as part of the Medicare Hospital Information Project, 10/1/88–9/30/91	73% received aspirin at time of discharge.	(Meehan et al. 1995)
Heart attack: treatment with thrombolytics
Thrombolytics are medications that break down some of the acute blockage in the blood vessels that causes a heart attack, thereby reducing infarct size and limiting left ventricular dysfunction. Thrombolytics have been shown to reduce post-AMI mortality by as much as 25%, though they should not be given to patients with certain conditions (e.g., recent hemorrhagic stroke)	1,105 patients who were “ideal” candidates for treatment with thrombolytic agents from a sample of 16,124 Medicare patients hospitalized with a principal diagnosis of heart attack.	Medical records for Medicare beneficiaries who were hospitalized in 4 states (Alabama, Connecticut, Iowa, Wisconsin), as part of the Cooperative Cardiovascular Project Pilot, 6/1/92–2/28/93	70% received thrombolytics during hospitalization.	(Ellerbeck et al. 1995)
Heart attack: treatment with thrombolytics
Same as above	68 patients with confirmed heart attack who had no contraindications to thrombolytic therapy and who had electrocardiographic indications for thrombolytic therapy from a sample of 300 Medicare patients ≥65 years old hospitalized with a principal diagnosis of heart attack	Medicare mortality data issued by HCFA and medical records for Medicare patients from 6 hospitals in Connecticut, as part of the Medicare Hospital Information Project, 10/1/88–9/30/91	43% received thrombolytics during hospitalization.	(Meehan et al. 1995)
Heart attack: treatment with heparin
Heparin is beneficial to patients with heart attack though heparin should not be given to patients with certain conditions (e.g., bleeding disorders, stroke).	9,857 patients who were “ideal” candidates for treatment with heparin from a sample of 16,124 Medicare patients hospitalized with a principal diagnosis of heart attack	Medical records for Medicare beneficiaries who were hospitalized in 4 states (Alabama, Connecticut, Iowa, Wisconsin), as part of the Cooperative Cardiovascular Project Pilot, 6/1/92–2/28/93	69% received heparin during hospitalization.	(Ellerbeck et al. 1995)
Heart attack: treatment with intravenous nitroglycerin
Intravenous nitroglycerin is beneficial to patients with heart attack who have persistent chest pain, although intravenous nitroglycerin should not be given to patients with certain conditions (e.g., shock or hypotension on admission).	1,754 patients who were “ideal” candidates for treatment with intravenous nitroglycerin from a sample of 16,124 Medicare patients hospitalized with a principal diagnosis of heart attack	Same as above	74% received intravenous nitroglycerin during hospitalization.	(Ellerbeck et al. 1995)
Heart attack: avoidance of calcium channel blockers for patients with a contraindication
Calcium channel blockers should not be given to patients with certain conditions (e.g., low left ventricular ejection fraction, evidence of shock or pulmonary edema during hospitalization).	785 patients with clear contraindication to calcium channel blockers from a sample of 16,124 Medicare patients hospitalized with a principal diagnosis of heart attack	Same as above	21% who were ineligible for calcium channel blockers received them.	(Ellerbeck et al. 1995)
Heart attack: smoking cessation advice for smokers
Smokers with coronary artery disease who stop smoking have a better prognosis than those who keep smoking; at the time of heart attack, these smokers are most susceptible to advice about cessation of smoking.	1,691 smokers who were “ideal” candidates for smoking cessation advice from a sample of 16,124 Medicare patients hospitalized with a principal diagnosis of heart attack	Same as above	28% received smoking cessation advice prior to or at time of discharge.	(Ellerbeck et al. 1995)
Heart attack: treatment with angiotensin-converting enzyme (ACE) inhibitors
ACE inhibitors can reduce post-AMI mortality in patients with left ventricular dysfunction, although ACE inhibitors should not be given to patients with certain conditions (e.g., aortic stenosis).	1,473 patients who were “ideal” candidates for treatment with ACE inhibitors from a sample of 16,124 Medicare patients hospitalized with a principal diagnosis of heart attack	Same as above	59% received ACE inhibitors prior to or at time of discharge.	(Ellerbeck et al. 1995)
Heart attack: beta blocker therapy
Beta blocker therapy can reduce post-AMI mortality by as much as 25%, although beta blockers should not be given to patients with certain conditions (e.g., low left ventricular ejection fraction, pulmonary edema).	2,976 patients who were “ideal” candidates for treatment with beta blockers from a sample of 16,124 Medicare patients hospitalized with a principal diagnosis of heart attack	Same as above	45% received beta blockers prior to or at time of discharge.	(Ellerbeck et al. 1995)
Heart attack: beta blocker therapy
Same as above	3,737 Medicare patients ≥65 years old with principal diagnosis of heart attack who were eligible for treatment with beta blockers, from a statewide cohort of 5,332 people who had survived a heart attack for at least 30 days and who had prescription drug coverage	New Jersey Medicare hospital admissions and enrollment data, 1986–92; New Jersey Medicaid drug utilization and enrollment files, 1986–91; New Jersey Program of Pharmacy Assistance for the Aged and Disabled drug utilization data, 1986–91	21% received beta blockers within 90 days of discharge; adjusted mortality rate for patients with treatment was 43% less than that of patients without treatment.	(Soumerai et al. 1997)
Heart attack: beta blocker therapy
Same as above	104 patients with confirmed heart attack who were alive at discharge and who had no contraindications to beta blockers from a sample of 300 Medicare patients ≥65 years old hospitalized with a principal diagnosis of heart attack	Medicare mortality data issued by HCFA and medical records for Medicare patients from 6 hospitals in Connecticut, as part of the Medicare Hospital Information Project, 10/1/88–9/30/91	41% received beta blockers at time of discharge.	(Meehan et al. 1995)
Heart attack: permanent cardiac pacemaker
Pacemakers help regularize abnormal heart rates and rhythms.	Medicare patients who underwent a total of 382 pacemaker implantations	Medical records from 6 university teaching hospitals, 11 university-affiliated hospitals, and 13 community hospitals in Philadelphia County, 1/1/83–6/30/83	20% of pacemaker implantations were inappropriate, 36% were equivocal, and 44% were appropriate.	(Greenspan et al. 1988)
Heart attack: hospital care
Care for heart attack	1,437 patients hospitalized with acute myocardial infarction from a nationally representative sample of 7,156 patients hospitalized with any of 5 conditions (congestive heart failure, acute myocardial infarction, pneumonia, stroke, hip fracture) (Draper et al. 1990)	Medical records for Medicare patients from 297 hospitals in 5 states (California, Florida, Indiana, Pennsylvania, Texas), 7/1/85–6/30/86	64%–68% of patients with acute myocardial infarction received appropriate components of care (e.g., documentation of examination of jugular veins and alcoholism or smoking habits).	(Kahn et al. 1990)
Congestive heart failure: hospital care
Care for congestive heart failure	1,465 patients hospitalized with congestive heart failure from a nationally representative sample of 7,156 patients hospitalized with any of 5 conditions (congestive heart failure, acute myocardial infarction, pneumonia, stroke, hip fracture) (Draper et al. 1990)	Same as above	66%–97% of patients with congestive heart failure received appropriate components of care (e.g., documentation of past surgery and lung examination on day 2; blood pressure readings; electrocardiogram; serum potassium level; oxygen therapy or intubation for hypoxic patients).	(Kahn et al. 1990)
Stroke: hospital care
Care for stroke	1,442 patients hospitalized with stroke from a nationally representative sample of 7,156 patients hospitalized with any of 5 conditions (congestive heart failure, acute myocardial infarction, pneumonia, stroke, hip fracture) (Draper et al. 1990)	Same as above	38%–94% of patients with stroke received appropriate components of care (e.g., documentation of previous stroke and gag reflex; blood pressure readings; electrocardiogram; serum potassium level).	(Kahn et al. 1990)
CAROTID ARTERIES
Carotid endarterectomy
Carotid endarterectomy is a procedure that opens up stenotic (blocked) carotid arteries (which supply blood to the brain).	Random sample of 1,302 cases of carotid endarterectomy	Medicare physician claims data and medical records from 3 sites selected from 13 sites in 8 states (Arizona, California, Colorado, Iowa, Massachusetts, Montana, Pennsylvania, South Carolina), 1981	32% of carotid endarterectomies were inappropriate, 32% were equivocal, and 35% were appropriate.	(Chassin et al. 1987)
GASTROINTESTINAL DISEASE
Upper gastrointestinal tract endoscopy
Endoscopy enables visualization of the gastrointestinal tract, and permits biopsy and brush cytologic examination.	Random sample of 1,585 cases of upper gastrointestinal tract endoscopy	Same as above	17% of upper gastrointestinal tract endoscopies were inappropriate, 11% were equivocal, and 72% were appropriate.	(Chassin et al. 1987)
CATARACTS
Cataract surgery
Cataract surgery is a commonly performed surgery in adults ≥65 years old. Cataract surgery should not be performed in people with certain conditions (e.g., macular degeneration or diabetic retinopathy).	1,020 patients who underwent a total of 1,139 cataract surgeries	Medical records for patients from 10 academic medical centers, 1990	2% of cataract surgeries were inappropriate, 7% were equivocal, and 91% were appropriate.	(Tobacman et al. 1996)
HIV/AIDS
Relation between hospital experience and mortality from AIDS
	300 patients diagnosed with acquired immunodeficiency syndrome (AIDS)	Case records of the Massachusetts AIDS Surveillance Program and billing records from 40 hospitals, medical records for patients from 22 of the 40 hospitals, and data tapes from the Massachusetts Rate Setting Commission, 1/1/87–12/31/88	Patients in low-experience hospitals were 2.16 times more likely to die (2.92 when controlling for characteristics potentially associated with mortality) during an AIDS admission, compared with those in high-experience hospitals.
Relation between physician experience and mortality from AIDS
	125 primary care physicians’ clinical experiences treating 403 adult male patients with AIDS	Group Health HIV/AIDS Surveillance Database, Group Health's Utilization Management/Cost Management Information System, and physician personnel records, 1984–94	Patients of physicians with the least experience survived 14 months after AIDS diagnosis compared with 26 months for patients of physicians with the most experience.	(Kitahata et al. 1996)
NEONATAL MORTALITY
Relation between physician experience and neonatal mortality
	53,229 births classified as likely neonatal intensive care unit (NICU) admissions from a sample of 473,209 births (singletons only) in 1990	California birth certificate and infant death file for all nonfederal hospitals, California Office of Statewide Health Planning and Development (OSHPD) discharge abstracts, California Perinatal Dispatch Centers’ neonatal transport data, and OSHPD hospital data, 1990	Infants born in hospitals with an average NICU census ≥20 patients per day had lower risk-adjusted mortality than those born in hospitals without an NICU (odds ratio = 0.74; confidence interval = 0.58–0.95; P= .02).	(Phibbs et al. 1996)
PREVENTABLE DEATHS
Evaluation of preventable deaths
	182 patients who died in hospitals from stroke, pneumonia, or heart attack	Medical records for patients from 12 hospitals, 1985	14% of deaths resulted from inadequate diagnosis or treatment and could have been prevented.	(Dubois and Brook 1988)
ADVERSE EVENTS
Adverse events
An adverse event is an injury that is caused by medical management rather than the underlying disease and that prolongs hospitalization, produces a disability at discharge, or both.	30,121 medical records from a weighted sample of 31,429 records of hospitalized patients from a population of 2,671,863 nonpsychiatric discharged patients	51 randomly selected acute care, nonpsychiatric hospitals in New York, 1984	There were 1,133 adverse events and 280 negligent events during 1984 admissions, representing a 3.7% statewide incidence rate of adverse events, and a 1.0% statewide incidence rate of adverse events due to negligence.	(Brennan et al. 1991)
Adverse drug events
Same as above	4,031 adult admissions to a stratified random sample of 11 medical and surgical units in two hospitals.	Medical records and reports of hospital staff for 2 tertiary care hospitals in Boston, 2/93–7/93	There were 1.8 preventable adverse drugs events (ADEs) per 100 admissions (adjusted rate), of which 20% were life threatening, 43% were serious, and 37% were significant. There were an additional 5.5 potential ADEs per 100 admissions (adjusted rate).	(Bates et al. 1995)

^aIf a description in the first column has no citation, it is covered by the citation in the reference column.

^bWe contacted the authors of some of the articles to clarify details related to the sample and to the data analysis.