Nosocomial TB Control Guidelines Debated; Will OSHA's Proposed Regulations Prevail?

Washington—Although the frightening resurgence of tuberculosis (TB) in the United States a decade ago has been followed by a welcome decline in incidence of infection, a debate continues about the need for regulatory measures to control the disease in hospitals and other health care facilities. While some experts see the decline as evidence that regulation is unnecessary, others say there is a need for an enforceable standard to protect health care workers and others from infection and prevent resurgence of the disease.

The ongoing debate was heightened this summer with two public hearings—in April and August—held by an ad hoc committee of the Institute of Medicine (IOM), chaired by Walter Hierholzer, MD, professor emeritus of internal medicine at Yale University.

The hearings were a response by the IOM to a congressional request to study to what extent health care workers are at greater risk from exposure to TB than others in the community. Congress was responding to complaints from health care institutions about proposed regulations by the Occupational Safety and Health Administration (OSHA) aimed at protecting health care workers who may be exposed to the disease. Some have described the measures as burdensome and, in light of the US decline in TB incidence, unnecessary.

In the late 1980s and early 1990s, considerable alarm over the increase in nosocomial TB prompted the Centers for Disease Control and Prevention (CDC) to issue two sets of guidelines for TB control in health care facilities. The first was published in 1990, followed by an expanded and revised version in 1994 (MMWR Morb Mortal Wkly Rep. 1994;43:1-132).

In 1997, in response to requests by organizations representing health care workers, OSHA issued proposed regulations that in essence would codify the CDC guidelines. The comment period has closed and OSHA is expected to issue the final notice before the end of the year.

At the IOM hearing in August, Keith Woeltje, MD, assistant professor of medicine at the Medical College of Georgia in Augusta, reviewed reports of the implementation of the guidelines in nine US hospitals. In general, he said, while compliance with the guidelines was low in 1992, after the first set was issued, by 1996 it had improved substantially.

For example, a survey by the CDC's Hospital Infections Program found that the percentage of TB isolation rooms meeting guidelines requirements went from 64% in 1992 to 96% in 1996. There was even a suggestion that nosocomial transmission of TB had been reduced, Woeltje said, adding that there is little question that implementing the guidelines can control TB outbreaks and will keep the risk of nosocomial TB low.

Noting the increase in compliance with CDC guidelines, Marilyn Field, PhD, the committee study director, suggested that perhaps the threat of pending federal regulations had encouraged it. What is clear, said committee member Robert Spear, PhD, is that the guidelines have become the standard of care. In that sense, they have the effect of law.

While nosocomial TB has been declining in this country, there is little question that health care workers are still at risk for the disease in their workplace. The risk varies with job category and is influenced by the age, ethnicity, and demographics of the workers. The risk is low and can be measured only approximately, Thomas Daniel, MD, professor emeritus, Case Western Reserve University School of Medicine, told the committee.

However, argued Jonathan Rosen, director of the Occupational Safety and Health Department, New York State Public Employees Federation, even if the risk is low, it is not zero. "If you work in a hospital where there are TB patients there is a greater risk than if you're working in a place that isn't likely to have TB," he said.

The OSHA proposal addresses this point. There's a significant risk from which workers need to be protected, and making the use of protective measures enforceable ensures compliance, Rosen said. "It is a mechanism that does not exist with voluntary guidelines."

The IOM committee expects to complete its report late this year or early in 2001, according to study director Field.

Chicago—Some researchers are saying that many physicians have been too lax in treating their hypertensive patients, accepting an insufficient reduction in blood pressure.

Speaking at a late summer press conference sponsored by Novartis Pharmaceuticals Corp in conjunction with the 18th Scientific Meeting of the International Society of Hypertension, George Bakris, MD, said recent research shows a need for aggressive treatment of hypertension.

He said too many physicians help their patients achieve lower blood pressure and then say, "Oh, it's better than you were, so let's leave it alone." "It's an attitude that needs to change," said Bakris, who is vice chair of the Department of Preventive Medicine at Rush Presbyterian–St Luke's Medical Center in Chicago.

The aggressive approach has just been endorsed by the National Kidney Foundation (NKF) with regard to patients with diabetes. In the September edition of the American Journal of Kidney Diseases, the NKF recommends that physicians lower the blood pressure of diabetic patients to less than 130/80 mm Hg—a reduction from the goal of less than 130/85 mm Hg recommended in the Sixth Report of the Joint National Committee on Detection, Evaluation, and Treatment of High Blood Pressure (JNC VI), issued by the National Institutes of Health (Am J Kidney Dis. 2000;36:646-661). The article was supported in part by an unrestricted educational grant from Novartis to the NKF.

The NKF developed its recommendations after results from several clinical trials showed marked benefits for aggressive blood pressure reduction.

In one study, the Hypertension Optimal Treatment (HOT) trial, 1501 diabetic patients were randomized to three diastolic blood pressure targets—less than 90 mm Hg, less than 85 mm Hg, and less than 80 mm Hg. The results showed that individuals in the lowest blood pressure group had the lowest rates of cardiovascular events (Lancet. 1998;351:1755-1762).

In another study, the United Kingdom Prospective Diabetes Study (UKPDS) 38, 1148 people with type 2 diabetes were randomized to achieve one of two blood pressure goals: less than 150/85 mm Hg or less than 180/105 mm Hg. Those who achieved the lower blood pressure had 32% fewer deaths, 44% fewer strokes, and 24% fewer diabetes-related complications (BMJ. 1998;317:703-713).

Joel D. Kopple, MD, president of the NKF, said physicians and patients need to recognize the importance of substantially reducing hypertension. "Physicians are going to have to be more aggressive in the management of blood pressure," Kopple said. "One of the ways to do this is to get patients to be participants in their treatment and to understand why their physicians are treating them in certain ways."

For nondiabetic patients, aggressive blood pressure reduction is also beneficial, said participants in the press conference. They also stressed that physicians ought to pay more attention to systolic blood pressure rather than the diastolic reading they've been taught to follow.

Stanley S. Franklin, MD, clinical professor of medicine at the University of California, Irvine, College of Medicine, said isolated systolic hypertension—ie, systolic blood pressure of 140 mm Hg or more and diastolic blood pressure of less than 90 mm Hg—is the most frequent form of uncontrolled hypertension in the United States, occurring in 65% of patients diagnosed as having hypertension. He noted that isolated systolic hypertension tends to occur in individuals over age 50, and it is in these people that most of the heart attacks, strokes and kidney disease occur.

Bakris added, "The message should be that systolic blood pressure is critically important and has been underappreciated for many years. There's no question, based on retrospective and prospective data, that aggressive reduction of systolic blood pressure can have a major impact on reducing cardiovascular events and risk."

Franklin and others have begun to focus on a relatively new concept, pulse pressure, to explain why isolated systolic hypertension is so risky. Pulse pressure is the difference between peak systolic blood pressure and diastolic blood pressure—a person with a blood pressure reading of 120/80 mm Hg has a pulse pressure of 40; if the pulse pressure is 60 or higher it signals that the patient is at increased risk. Franklin said that pulse pressure, which appears to be a marker for atherosclerosis, means physicians perhaps should be more concerned about a patient with a blood pressure reading of 170/70 mm Hg than about a patient whose blood pressure reading is 170/110 mm Hg.

Michael Weber, MD, immediate past president of the American Society of Hypertension, said, "Too often inexperienced physicians would see a patient with 170/70 mm Hg and say, ‘Well, 170 is not so good, but at least the patient's got a nice low diastolic to make up for it,' not realizing that this is a much worse situation than if the patient had 170/110 mm Hg. So that is a lesson we've got to get out to physicians, and it's been a slow lesson for them to absorb—because unfortunately, we were all educated that it was the diastolic pressure that was all-important."

Lifestyle changes—weight reduction, increased exercise, limiting alcohol and sodium intake—are usually the first treatment option that physicians give their patients. For persons with diabetes, drug therapy should be the first option, Bakris said.

If lifestyle changes don't work, then the JNC VI recommends single-drug therapy, using an initial low dosage of a drug that is slowly titrated upward to reach an optimal formulation that provides 24-hour efficacy with a once-daily dose, with at least 50% of the peak effect remaining at the end of the 24 hours.

But the researchers at the press conference said they would move aggressively into combination drug therapy if lifestyle changes aren't helping the patient reach the target blood pressure.

Kenneth A. Jamerson, MD, an associate professor of medicine at the University of Michigan Medical Center and a lead investigator for the HOT trial, said combination drug therapy was needed to achieve the lower blood pressure targets of the study.

"It was not important to us exactly what drug you used, but you needed to add a bunch of them together to achieve these very aggressive blood pressure goals," Jamerson said.

New guidelines to help physicians quickly diagnose and treat two related forms of heart disease have just been issued jointly by the American College of Cardiology (ACC) and the American Heart Association (AHA).

The guidelines concern unstable angina and non–ST segment elevation myocardial infarction (NSTEMI). Both conditions can appear identical in their early stages and cause people to head to the emergency department, but people with NSTEMI experience permanent myocardial injury, whereas in those with unstable angina, ischemia is not initially severe enough to cause irreversible damage.

The guidelines—which aim to help physicians distinguish between the two conditions and treat each appropriately—were developed by an expert panel of the ACC and the AHA and are based on the most recent scientific findings published in the Agency for Healthcare Research and Quality's evidence report on The Prediction of Risk for Patients with Unstable Angina. (Other guidelines, issued in June 1999, address chronic stable angina.)

The new guidelines recommend that a thorough clinical history and 12-lead electrocardiography remain the foundation of early diagnosis and assessment. But cardiac marker laboratory tests, which rapidly detect the presence of proteins released into the blood when heart muscle is damaged, are essential. Cardiac markers, especially troponin I and troponin T, can help determine whether a patient is having an MI and in estimating the risk of death and guiding therapy.

Unstable angina and NSTEMI, which account for about 1.4 million hospitalizations annually, develop when too little blood and oxygen reach heart tissue. This usually occurs because a thrombus intermittently (unstable angina) or completely (NSTEMI) occludes a coronary artery. A theory gaining favor among researchers suggests that inflammation of the endothelium may be the underlying cause of thrombus formation. According to this theory, the inflammation causes ruptures in the plaque that is found in coronary arteries.

To help inhibit the formation of coronary thrombi, the guidelines recommend using a triple antithrombotic therapy for patients who continue to have ischemia or who are scheduled for a revascularization procedure.

The triple therapy includes giving aspirin to all patients who can tolerate it, or an aspirin substitute such as clopidogrel or ticlopidine. The administration of glycoprotein IIb/IIIa inhibitors, including eptifibatide and tirofiban (or abciximab for up to 1 day in certain patients), is recommended. And the guidelines say that patients should receive an infusion of heparin or an injection of a low-molecular-weight version of heparin. Whether to give the drugs serially or concurrently depends on the patient's condition.

Eugene Braunwald, MD, chair of the expert panel and Distinguished Hersey Professor of Medicine and Faculty Dean for Academic Programs at Harvard Medical School, said publication of the updated guidelines is important.

"The landscape of therapy and diagnosis has changed substantially in 6 years, all for the better," Braunwald said in a press release. "These conditions affect an enormous number of people and represent ‘big-ticket' items for the health care system."

The guidelines also suggest which patients with unstable angina or NSTEMI should undergo a revascularization procedure, usually stenting. High-risk patients who, among other things, continue to show signs of myocardial ischemia even with medication, develop symptoms of heart failure, experience serious rhythm disturbances, or have certain other high-risk characteristics should use the interventional approach, the guidelines say.

"We see more clearly now who should have the aggressive approach," Braunwald said. "We don't say other patients shouldn't have it, but those at highest risk have to have it."

The full text of the guidelines appears in the September issue of the Journal of the American College of Cardiology and is available online, free to ACC members, at http://www.cardiosource.com. An executive summary appears in the September 5 issue of Circulation: Journal of the American Heart Association.