You can safely skip the LDH and save thousands
UR study calls for eliminating routine LDH tests
When Walter Reed Medical Center removed routine lactate dehydrogenase (LDH) tests from its rule out myocardial infarction (MI) protocols, the Washington, DC, military hospital saved nearly $47,000 the first year with no adverse effect on patients.1 The protocol change was made after a utilization review study concluded LDH testing did not add clinically useful data in diagnosing patients for MI.
LDH tests cost $7.77 at Walter Reed, but a non-military hospital would pay between $11 and $20 for the extra step. During the study, researchers examined 200 patients with one or more abnormal cardiac isoenzyme finding. They also surveyed 100 hospitals and found that 66% still routinely perform the LDH test as part of their heart attack protocol despite the fact that national guidelines have recommended against routine LDH testing since 1990.
When the Walter Reed staff began reviewing blood tests given to patients, they noticed that LDH tests were being performed routinely on all patients to rule out acute myocardial infarction (AMI) but that the information was not being used, says Capt. Daniel C. Randall, MD, of the U.S. Army Medical Corps. Formerly with Walter Reed, Randall is now stationed at Madigan Army Medical Center in Tacoma, WA. Guidelines endorsed by the American Heart Association, the American College of Physicians, and the American College of Cardiology have recommended against administering LDH tests unless patients experience chest pain for more than 24 hours and creatine kinase isoenzyme-MB (CK-MB) enzyme tests are negative.2
"We knew that was a very small subset of patients. We looked back over a year to determine how many patients had LDH drawn and how many were positive," says Randall.
Randall, and his co-researcher, Lt. Col. David L. Jones, MD, studied other blood tests given to patients and determined that in every single test when the LDH enzyme showed positive, the patient also had a positive CK-MB test. So the LDH test was removed from the heart attack protocol at Walter Reed.
"We said it was still available for the doctors to use, but we didn’t stress it," Randall says. During the next year, only 14 LDH tests were performed, and none were positive. The previous year, 6,177 tests had been performed at a cost of $47,000.
In addition to cutting the annual expenditure for LDH tests by 99%, the change in protocol allowed the laboratory staff to provide a faster turnaround for other tests, Randall adds.
After the utilization review project at Walter Reed, Randall and Jones made scripted telephone calls to 50 hospitals, mostly military and teaching hospitals. They asked if the hospitals were still automatically using the LDH test for heart attack patients. Out of 50 hospitals called, 32 responded positively. The researchers called an additional 50 hospitals, randomly chosen from the American Hospital Association guide. Of those, 34 were still using the LDH tests on a routine basis. Overall, 66% of hospitals surveyed were still automatically using the LDH test. Nearly three-quarters of hospitals affiliated with medical schools were still using the test; 62% not affiliated with medical schools routinely used the tests.
"My assertion, which is supported by the utilization review study, is that the LDH test is not needed. If the CK-MB test is positive, the patient almost certainly had a heart attack, and another test is not needed," Randall says.
LDH levels in the blood increase only after 24 to 48 hours following a heart attack, but they remain elevated for 72 to 144 hours. "Most patients don’t wait three or four days to come in to the hospital if they have chest pain. Hospitals should screen out those patients whose pain started during admission and use that information to determine what tests are needed," Randall says.
A positive LDH test can indicate pneumonia, a blood clot in the lung, or other conditions, Randall says. Other studies have shown that a person is three times more likely to have a false-positive elevated LDH than a true-positive LDH test, he adds.
Not only does this test waste resources, says Randall, but there are new tests out there, such as the troponin test, that are more sensitive and more specific an indicator as to whether a person has a heart attack.
References
1. Randall DC, Jones DL. Eliminating unnecessary lactate dehydrogenase testing: A utilization review study and national survey. Arch Inter Med 1997; 157:1,441-1,444.
2. Gunnar RM, Passmania ER, Bourdillon PD, et al. Guidelines for the early management of patients with acute myocardial infarction: A report of the American College of Cardiology/American Heart Association Task Force on Assessment of Diagnostic and Therapeutic Cardiovascular Procedures (Subcommittee to Develop Guidelines for Early Management of Patients with Acute Myocardial Infarction). J Am Coll Cardiol 1990; 16:249-292.
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