TB in health care workers lower than U.S. rates

Expert: Measure benefits before you intervene

TB rates among the nation’s health care workers are similar to TB rates among other groups of employed people, and lower than the national average, says Amy Curtis, PhD, MPH, an epidemiologist at the Centers for Disease Control’s Division of TB Elimination’s surveillance branch.

That was one of the findings about TB and health care workers presented at a conference held last December in Washington, DC, titled "Tuberculosis Infection Control in the 21st Century," which was jointly sponsored by the American Thoracic Society, the American College of Chest Physicians, and the Infectious Disease Society of America.

"We found TB rates are similar among all employed persons and lower than the U.S. average," says Curtis. "We know there have been outbreaks in the past at health care facilities, but as a group, health care workers don’t have extraordinarily high rates."

Those data haven’t been adjusted yet for gender and country of origin, she adds, but even after the effect of such factors has been taken into account, the rates aren’t expected to change dramatically. Moreover, TB rates per 100,000 health care workers have been falling steadily in recent years, says Curtis: from 5.4 in 1994, to 4.9 in 1995, to 4.5 in 1997, to 4.6 in 1998.

Risk-analysis tools can help make sound decisions about the effectiveness of measures aimed at protecting health care workers against TB, says George Gray, PhD, deputy director of the Center for Risk Analysis and faculty member of the School of Public Health at Harvard University. Gray also spoke at the December conference.

"There are very few risks which you can elim inate altogether," he says. Since resources are finite, risks and interventions must somehow be prioritized, he adds. "And there are lots of instances in this country where we make investments that aren’t as efficient as other decisions we could be making instead." Too often, such decisions are based on anecdotal evidence, politics, or emotion. The kind of risk analysis Gray practices ranks the costs of interventions by the price of each year of life they save. Environmental regulations rank among the most costly, he says; interventions aimed at protecting workers on the job are generally a much better bargain.

Another factor to consider are countervailing risks — a second set of risks that are engendered, sometimes unwittingly, by trying to protect people against a first set.

One example is the recent drive to force airplane passengers to purchase a separate seat for their young children. If proponents of the separate-seat law prevail, a certain percentage of potential flyers will decide to save money by driving instead; the decision to travel by car, in turn, will place the travelers into a much higher-risk category than flying.

His conference audience brought up an example from the world of TB control, he adds. Respirators designed to offer greater protection against TB can, because of their cumbersome qualities, increase the likelihood of needlesticks and other accidents to those who are wearing them. "People understand the general notion of risk analysis, but they’re not following through and thinking about these things in a formal way," adds Gray. "Doing a formal risk analysis helps you make a stronger case when there’s a case to be made."