Most HCWs decline treatment for latent TB

Reluctance can put patients at risk

Health care workers with positive TB skin tests frequently decline treatment for latent tuberculosis infection, putting themselves, their co-workers, and patients at risk, tuberculosis experts say.

As few as one-quarter to one-half of health care workers who meet the criteria for treatment may receive it, studies show.1 The consequences can be far reaching. In a 2003 case, a nurse with active TB exposed about 1,500 patients, including newborns in a nursery and maternity ward in New York City. Eleven years earlier, she had declined treatment for latent TB infection when she arrived at the hospital from the Philippines and registered a positive skin test result of 15 mm induration.

"As we've learned from the literature and our experience, a lot of health care workers think having a positive skin test is not due to infection but due to having [previous] BCG [vaccination]," says Cynthia Driver, DrPH, director of epidemiology with the TB Bureau of the New York City Depart-ment of Health and Mental Hygiene. "There's a need for greater understanding. In many cases, [the positive result] is due to infection."

Health care workers also may be reluctant to follow a nine-month regimen when they have no symptoms of disease. "In Florida, less than 30% of all people to whom we prescribe TB medications for latent TB infection ever complete the treatment," says David Ashkin, MD, FCCP, state TB controller.

Hospitals face increasing concerns about latent TB infection as the population of foreign-born workers rises. Health care workers mirror the larger community in their risk for TB disease, with foreign-born workers at significantly greater risk. In New York state, foreign-born health care workers had an incidence of TB disease of 17.5 per 100,000 in 2002 compared to two for U.S.-born workers, according to a study of TB among health care workers.2

In its report on the New York City nurse, the Centers for Disease Control and Prevention (CDC) urged employee health and infection control practitioners to improve adherence to treatment for latent TB infection among health care workers who work in high-risk settings.1

The use of Quantiferon-TB Gold also will provide stronger evidence of infection for those health care workers who had BCG vaccination, TB experts say.

Follow up positive TB screens

Screening employees for TB and tracking them to make sure they return to have the test read requires focus, perseverance, and resources. But the job isn't done until employee health practitioners have followed up on positive results, TB experts say.

"One of the biggest problems we see with tuberculosis, unfortunately, is missed opportunities," says Ashkin, a pulmonologist who also is medical executive director of A.G. Holley Hospital in Lantana, FL, the last remaining TB sanitarium.

Reports about health care workers with active TB serve as a wake-up call, he says. "These cases are usually signs that the systems we have in place aren't always working," he says.

First, employee health professionals need to ensure that health care workers follow up on positive results. In a Boston case, a surgical resident who worked in four hospitals received a positive skin test result in a pre-placement evaluation in June 2004 and was referred to the Boston Public Health Commission TB Clinic. She never showed up for her appointment.

By January 2005, she had respiratory symptoms that were diagnosed as pneumonia, according to a report in the Boston Globe. (The health commission and hospital declined to discuss the specifics of the case.) By June 2005, the surgical resident was diagnosed with tuberculosis.

As a result, about 5,000 patients and health care workers were tested for TB infection at Boston Medical Center, Cape Cod Hospital in Hyannis, Brockton (MA) Hospital, and the VA Boston Healthcare System, West Roxbury campus. In Boston, four patients and 13 health care workers had positive results that were tied to the exposure.

The U.S. Occupational Safety and Health Administration (OSHA), which does not have a standard related to tuberculosis, conducted inspections at the four hospitals and issued advisory letters to them. The other hospitals had relied on Boston Medical Center to conduct the TB screening, but had not ensured that the screening and follow up occurred, OSHA found. All hospitals have since changed their policies and procedures.

"There needs to be an emphasis on that complete process of follow-up of a positive skin test," says Anita Barry, MD, MPH, director of communicable disease control at the Boston Public Health Commission. That includes a chest X-ray, education of the health care worker and, when appropriate, a full discussion about the need for treatment for latent tuberculosis infection, she says.

Documentation of the TB test and follow-up is critical, says Barry. "It's like immunization," she says. "If you don't have documentation, it's like it never happened."

Even with BCG, a positive is a positive

BCG vaccination of foreign-born health care workers can be a complicating factor in the decision making about treatment of latent TB infection.

"BCG is the most commonly given vaccine in the world today," says Ashkin. "A lot of countries do a really, really good job of convincing their population that if they get BCG that they won't get tuberculosis. Most people who get BCG truly believe their PPD is not from tuberculosis but is secondary to BCG."

Yet in Morbidity and Mortality Weekly Report, CDC TB experts noted that BCG should not routinely be considered the reason for a positive TB skin test: "Because [health care workers] with a history of BCG are frequently from high TB prevalence countries, positive test results for M. tuberculosis infection in [health care workers] with previous BCG vaccination should be interpreted as representing infection with M. tuberculosis. Although BCG reduces the occurrence of severe forms of TB disease in children and overall might reduce the risk for progression from LTBI to TB disease, BCG is not thought to prevent M. tuberculosis infection. Test results for M. tuberculosis infection for [health care workers] with a history of BCG should be interpreted by using the same diagnostic cut points used for [health care workers] without a history of BCG vaccination."

The positive skin test reaction from BCG vaccination wanes after about five years, the report notes. The CDC issued updated guidelines on treatment for latent TB infection in 2000, countering previous recommendations that cautioned against treating people older than 35 years old. That limitation is not supported by scientific data, the CDC concluded.3

In the New York City case, which occurred in 2003, the Filipino nurse declined treatment for latent TB infection, citing her BCG vaccination. She also said that "most adults from the Philippines, where TB is endemic, have positive TST results and generally do not take treatment," according to the CDC report. She had an annual TB symptoms screen and one chest X-ray, all of which showed no sign of TB disease.1

In September 2003, she developed a cough, wheezing, and shortness of breath. When her chest X-ray was read as normal, she was treated for asthma. Her symptoms persisted for another two months, and she had a CT scan of her chest and a bronchoscopy. She was believed to have hypersensitivity pneumonitis until a biopsy confirmed the presence of M. tuberculosis. "Genotyping of the M. tuberculosis isolate did not match any pattern in the New York City or national databases," the CDC reported.

The hospital identified 32 co-workers, 613 infants, and 900 patients who were potentially exposed to the nurse. Only 227 infants and 216 maternity patients received medical evaluation — of those, five infants had a positive TB test (including one who had received BCG vaccination). Twenty-five of the co-workers had a previously positive TB skin test; they all declined treatment for latent TB infection. The other seven co-workers tested negative for TB infection.

Quantiferon produces clearer result

Quantiferon-TB Gold is a new tool that may convince health care workers that they have a true positive result and may influence their decisions about treatment, says Ashkin. "In anecdotal experience, it has been very helpful to me when I'm able to say, 'We have Quantiferon, here's the report, and you are truly positive.'"

After that positive result is conveyed, health care workers must make an informed decision about treatment and need adequate education, TB experts say. The CDC's updated TB guidelines state that after TB disease is excluded, health care workers "should be treated for LTBI unless medically contraindicated."4 However, health care workers who decline treatment should not be excluded from the workplace, CDC says.

Health care workers who otherwise are healthy are reluctant to take a nine-month regimen of isoniazid, the recommended treatment, which can cause liver toxicity. "We don't know what the overriding concern is among health care workers," says Sonal Munsiff, MD, director of New York City's Bureau of TB Control. "Is it the fear of toxicity or the belief that they don't have infection, that it's from BCG?"

A study of 297 health care workers with TB disease conducted by Munsiff, Driver, and others found that only 23% of those who met the criteria for latent TB infection received treatment. Health care workers at ambulatory facilities were less likely to have received the treatment.2

"Only 5% to 10% of the people infected with TB ever get active disease," says Ashkin. "You're asking people who are relatively well to take a medication. A lot of people are really reluctant to take it."

Of those who begin the treatment, many do not adhere to it. "I don't think we emphasize enough that you have to complete the therapy," says Ashkin. "If you don't complete it, you don't get the full benefit."

References

1. Centers for Disease Control and Prevention. Mycobacterium tuberculosis transmission in a newborn nursery and maternity ward — New York City, 2003. MMWR 2005; 54: 1,280-1,283.

2. Driver CR, Stricof RL, Granville K, et al. Tuberculosis in health care workers during declining tuberculosis incidence in New York state. Am J Infect Control 2005; 33:519-526.

3. Centers for Disease Control and Prevention. Targeted tuberculin testing and treatment of latent tuberculosis infection. MMWR 2000; 49(RR06):1-54.

4. Centers for Disease Control and Prevention. Guidelines for preventing the transmission of Mycobacterium tuberculosis in health care settings, 2005. MMWR 2005; 54(RR17):1-141.