Recently, Dr. Michael Laposata, pathologist-in-chief and director of laboratory medicine at Vanderbilt University Hospital, wrote that "medical error from incorrect laboratory test selection and result interpretation is rapidly becoming a more serious problem as the test menu becomes larger and more complex." In support of this are a number of studies, which are described below.
Lab test errors common according to survey of internists, medical specialists, and emergency physicians
In a survey of general internists, medical specialists, and emergency physicians, respondents were asked to describe cases involving diagnostic error. Analysis of the 583 cases reported revealed that errors occurred most frequently in the testing phase defined as failure to order, report, and follow-up laboratory results (44%).
-Schiff G, Hasan O, Kim S, Abrams R, Cosby K, Lambert B, Elstein AS, Hasler S, Kabongo M, Krosnjar N, Odwazny R, Wisniewski M, McNutt R. Diagnostic error in medicine.
Arch Intern Med 2009; 169 (20): 1881-7.
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Inappropriate utilization of lab tests is common
Inappropriate utilization of laboratory testing is common and "estimated to range from 10% to 50% of the volume encountered in hospital laboratories." In the article, Dr. Kent Lewandrowski, Director of the Clinical Research Laboratory at Massachusetts General Hospital, cited the following benefits of improved utilization of lab tests:
- Reduced financial cost
- Reduction of false-positive test results
- Reduction of iatrogenic anemia
- Decreased hospital length of stay
- Elimination of unneccessary follow-up tests or procedures
-Lewandrowski K. Managing utilization of new diagnostic tests.
Clin Leadersh Manag Rev 2003; 17(6): 318-24.
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Review of D-dimer use in hospitalized patients shows that clinicians often use the test incorrectly
The authors indicate that the D-dimer test is often elevated in hospital inpatients who do not have venous thromboembolism yet clinicians commonly overlook this fact. Among the conditions associated with elevated levels include infection, inflammation, cancer, surgeyr, trauma, ischemic heart diseas,e and stroke. The authors also report misuse of the test in disseminated intravascular coagulation (DIC).
-Thachil J, Fitzmaurice D, Toh C. Appropriate use of D-dimer in hospital patients.
Am J Med 2010; 123 (1): 17-19.
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Study finds that most determinations of the PT and aPTT are not clinically indicated
In a study examining the ordering patterns and clinical indications for the prothrombin time (PT) and activated partial thromboplastin time (aPTT), researchers found that over 80% of all admitted patients had these tests ordered. "At least 70% of these tests were not clinically indicated," costing over $60,000 per year.
-Erban S, Kinman J, Schwartz J. Routine use of the prothrombin and partial thromboplastin times.
JAMA 1989; 262: 2428-2432.
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Harvard study reveals that diagnostic errors are a major cause of adverse events
In the Harvard Medical Practice Study, diagnostic errors were common, accounting for 17% of adverse events.
-Leape L, Brennan T, Laird N. The nature of the adverse events in hospitalized patients: results from the Harvard Medical Practice study II.
N Engl J Med 1991; 324: 377–84.
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Study of residents finds that nearly half of urinalysis orders on newly admitted patients had no clinical indication
In a study investigating the indications that led residents to order urinalysis on newly admitted patients, researchers found no clinical indication in 669 of 1341 patients (49.9%). Among the indications deemed to be appropriate included urinary tract symptoms, elevated BUN or creatinine, fever, sepsis, decreased albumin, edema, abdominal or back pain, volume depletion, abnormal sodium level, metabolic acidosis, and chronic illness.
-Kroenke K, Hanley J, Copley J et al. Improving house staff ordering of three common laboratory tests: reductions in test ordering need not result in underutilization.
Med Care 1987; 25: 928-935.
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Hyponatremia frequently incorrectly diagnosed, leading to significant management errors
In a study evaluating the assessment and management of severe hyponatremia in a large teaching hospital, incorrect diagnoses were found in 42% of patients and significant management errors in 33%. Among patients with management errors, a significant percentage died (41%).
-Huda M, Boyd A, Skagen K, Wile D, van Heyningen C, Watson I, Wong S, Gill G. Investigation and management of severe hyponatraemia in a hospital setting.
Postgrad Med J 2006; 82: 216-9.
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Incorrect interpretation of laboratory test results is a major cause of missed or delayed diagnoses according to a review of malpractice claims
In a study investigating missed and delayed diagnoses in the ambulatory setting, Gandhi and colleagues reviewed 307 closed malpractice claims. Notable findings included the following:
- Of the 307 claims, 181 (59%) involved diagnostic errors.
- Fifty-nine percent of these errors led to significant adverse outcomes and 30% were associated with death.
- Failure to order appropriate diagnostic or laboratory tests accounted for 55% of the breakdowns in care.
- Thirty-seven percent of the errors were related to incorrect interpretation of diagnostic or laboratory tests.
-Gandhi T, Kachalia A, Thomas E, Puopolo A, Yoon C, Brennan T, et al. Missed and delayed diagnoses in the ambulatory setting: a study of closed malpractice claims.
Ann Intern Med 2006; 145: 488–96.
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Many physicians could benefit from education about tests included in routine stool examinations
In a study to better understand physician practices regarding the diagnosis of acute diarrhea, researchers found that many physicians "could benefit from education to improve their knowledge about tests included in routine stool examinations." Among the notable findings were that 28% of physicians were uncertain if routine stool culture testing included tests for E. coli 0157:H7. Forty percent were unsure if routine testing was able to detect Yersinia or Vibio species.
Hennessy T, Marcus R, Deneen V, Reddy S, Vugia D, Townes J, Bardsley M, Swerdlow D, Angulo F. Survey of physician diagnostic practices for patients with acute diarrhea: clinical and public health implications.
Clin Infect Dis 2004; 38 Suppl 3: S203-11.
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Incorrect ordering of lab tests is a major cause of error in family medicine offices
In a survey of 243 clinicians, investigators determined the types of testing errors which occurred in family medicine offices. Survey participants submitted 590 event reports with 966 testing process errors. Errors related to implementation of tests (17.9%) and test ordering (12.9%) were common. Although patients were unharmed in 54% of events, 18% resulted in some harm with harm status unknown for 28%.
-From Hickner J, Graham D, Elder N, Brandt E, Emsermann C, Dovey S, Phillips R. Testing process errors and their harms and consequences reported from family medicine practices: a study of the American Academy of Family Physicians National Research Network.
Qual Saf Health Care 2008; 17(3):194-200.
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Physicians in practice for fewer years order more tests
In one study, 48 family physicians were asked to complete a questionnaire about their use of laboratory tests. Five clinical vignettes were presented, and physicians were asked to select the most appopriate lab tests for further evaluation. The researchers noted that "physicians practicing less than 10 years ordered more tests."
-Salloum S, Franssen E. Laboratory investigations in general practice.
Can Fam Physician 1993; 39: 1055-61.
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Failure to order appropriate tests and incorrect interpretation among the most frequent errors in the Emergency Department
In a review of 122 closed malpractice claims involving patients complaining of a missed or delayed diagnosis in the Emergency Department, failure to order appropriate diagnostic tests (58% of errors) and incorrect interpretation (37%) were among the most frequent errors.
-Kachalia A, Gandhi T, Pupolo A, Yoon C, Thomas E, Griffey R, et al. Missed and delayed diagnoses in the emergency department: a study of closed malpractice claims from 4 liability insurers.
Ann Emerg Med 2007; 49: 196–205.
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Anemia is often not evaluated properly by physicians
In a study looking at the diagnosis and treatment of anemia in medical inpatients, researchers found numerous errors in the evaluation of anemia. In approximately 25% of cases, anemia was not recognized. In about 20%, anemia was recognized but not evaluated or treated. The authors also noted that "physicians ignored or misused information from the complete blood cell count and smear description and exmained the smear themselves in fewer than one in 10 anemic patients. Not all of the missed cases of anemia were mild, expected from the patient's illness, or unimportant to the patient's care."
-Self, K, Conrady M, Eichner E. Failure to diagnose anemia in medical inpatients.
Am J Med 1986; 81: 786-90.
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HPV tests are often inappropriately used
Recently, researchers surveyed clinicians who provide cervical cancer screening about their knowledge and use of HPV testing. "Although many U.S. clinicians reported using HPV tests according to guidelines, many also reported inappropriate use."
Irwin K, Montaño D, Kasprzyk D, Carlin L, Freeman C, Barnes R, Jain N, Christian J, Wolters C. Cervical cancer screening, abnormal cytology management, and counseling practices in the United States.
Obstetrics & Gynecology 2006; 108 (2): 397-409.
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Recognition and evaluation of macrocytosis is variable in the outpatient setting
In a study of over 3800 adult outpatients, 138 (3.7%) were found to have an elevated MCV. Fifty-five of these 138 patients had no further evaluation to determine the cause of the elevated MCV. Among those who did receive further evaluation, errors were common. For example, the authors noted that, among patients thought to have alcohol-induced macrocytosis, nince "had other causes for this finding."
-Wymer A, Becker D. Recognition and evaluation of red blood cell macrocytosis in the primary care setting.
J Gen Intern Med 1990; 5(3):264-5.
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Many patients with a positive ANA test are incorrectly diagnosed
In a study of patients referred to an autoimmune disease center, misdiagnosis of autoimmune disease by primary care physicians was common. "Of those referred with SLE, 76 (29%) were seropositive for antinuclear antibodies but did not have autoimmune disease." In many cases, ANA positive patients who were incorrectly diagnosed with autoimmune disease were treated with high-dose corticosteroid therapy. The authors concluded that "many patients with a postiive antinuclear antibody test are incorrectly given a diagnosis of SLE."
-Narain S, Richards H, Satoh M, Sarmiento M, Davidson R, Shuster J, Sobel E, Hahn P, Reeves W. Diagnostic accuracy for lupus and other systemic autoimmune diseases in the community setting.
Arch Intern Med 2004; 164(22): 2435-41.
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Misdiagnosis of pheochromocytoma is common
In a review of patients with either preoperative or pathologic diagnosis of pheochromocytoma, the overdiagnosis rate was 23%. Among the most common causes of overdiagnosis was misinterpretation of biochemical test results. Overdiagnosis had serious consequences with some patients undergoing unneccessary therapy, including surgical removal of the adrenal gland.
-Yu R, Nissen N, Chopra P, Dhall D, Phillips E, Wei M. Diagnosis and treatment of pheochromocytoma in an academic hospital from 1997 to 2007.
Am J Med 2009; 122(1): 85-95.
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High proportion of serum digoxin level measurements in hospitalized patients are inappropriate
In a study of 162 inpatients who had serum digoxin levels measured, only 16% had an appropriate indication for measurement. The authors concluded that "a high proportion of digoxin levels were inappropriate, particularly among inpatients."
-Cañas F, Tanasijevic M, Ma'luf N, Bates D. Evaluating the Appropriateness of Digoxin Level Monitoring.
Arch Intern Med 1999; 159: 363-368.
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Serum antiepileptic drug level are often measured when indications are lacking
In a study of 330 inpatients in whom antiepileptic drug levels were measured, researchers found that most determinations lacked an appropriate indication (73%). Among those that had an appropriate indication, half were not sampled correctly. The authors concluded that "efforts to decrease inappropriate monitoring may result in substantial cost reductions without missing important clinical results."
-Schoenenberger R, Tanasijevic M, Jha A, Bates D. Appropriateness of antiepileptic drug level monitoring.
JAMA 1995; 274(20): 1622-1626.