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Streamlined form nets at-risk kids
By asking two simple questions, student health staffers at a Virginia university have found an easy way to zero in on the college students who are most likely to be TB skin test-positive.
By requiring skin tests only of those who said they’d been in contact with someone who has active TB, or those who identified themselves as having been born in a country where TB is endemic, the school found they could pick up 80%-90% of all tuberculin skin-test reactors, says Betty Anne Johnson, MD, PhD, director of student health at Virginia Commonwealth University (VCU) in Richmond.
The school hasn’t always enjoyed such a streamlined approach to the prickly subject of TB skin testing. Until recently, VCU required all new freshman to have a TB skin test. "We wanted to change that to something more efficient, because we felt we were placing a lot of skin tests unnecessarily," Johnson says.
The question was how to narrow the field, without missing lots of latently infected kids. Asking about every risk factor named in revised federal guidelines on targeted testing seemed overly broad, notes Johnson. "I didn’t know how many intravenous drug abusers I might find on campus," she says, alluding to one risk factor. "Nor did I know how many HIV-positive students I might find. And should I be asking about whether students traveled back and forth across the U.S./Mexican border? I simply didn’t know."
At the same time, limiting the questions to those appropriate for screening younger children seemed too narrow, since college-age kids have had considerably more experience than their younger siblings.
Vetting the questions
So Johnson, along with Virginia’s TB control officer, Ram Koppaka, MD, decided to test their questions. For three years, they collected answers to 33 questions in a health history filled out by 5,382 entering freshmen. Next, they correlated the replies with results of the school’s universal skin-testing program.
Country of origin proved to be "overwhelmingly the best predictor" for whether students would be skin test-positive or not, Johnson says. "We decided to include the question about contacts because we felt that issue was simply too important to ignore," she adds.
But figuring out how to ask the country-of-origin question got sticky, Koppaka and Johnson soon discovered. Each time a foreign-born student turned up, the two had to look up TB rates in the pertinent country. Koppaka came up with the idea of creating a list of only those countries with low risk for TB. To make the cut, a country needed a TB incidence rate of less than 15/100,000; had to be politically stable; and had to have seen a consistent decrease in TB rates over the past 20 years.
Using that list, it was simple to identify students who came from some other, presumably higher-risk setting. "That simplified things enormously," says Johnson.
Not surprisingly, the new arrangement has trimmed student health’s skin-testing workload enormously. Family physicians do the work of filling out answers to the two key questions as they complete the rest of the health history, leaving student health to place and read the skin-tests when indicated — thus making sure the procedure is done properly by someone with plenty of experience.
Other colleges and universities can adopt the same streamlined strategy, Johnson says. To come up with their own screening questions, she suggest that they do an abbreviated version of the same experiment she and Koppaka carried out — that is, compare a single semester’s worth of skin-test results from everyone to answers to a list of potential questions. That way, the schools would be sure to identify questions pertinent to their own school, which might have a slightly different of risk factors from VCU.
Schools often go one of three ways
Though Johnson is in the midst of conducting a survey on the subject, there are no data on how most colleges handle the challenge of TB screening. But since she and Koppaka recently wrote the revised TB screening guidelines for the American College Health Association guidelines, Johnson gets plenty of calls from schools on the subject. From the callers’ questions, she surmises that most places now take one of three approaches — either they make everyone get skin tested (so no one feels they’ve been subjected to "discrimination"); they don’t make anyone get tested; or they make only "international students" submit to the procedure.
Making everyone get tested is obviously a waste of time. But the opposite tack — testing no one — is hardly an improvement, Johnson says, given that two college students (one in Alabama, the other in Colorado) actually have died of TB during the past year.
Perhaps surprisingly, testing only "international" students misses the mark as well, she adds. "International students are those who are here on temporary visas, so they’re easy for the office of international studies to identify," Johnson says. But using that term, instead of "foreign-born," misses naturalized citizens and permanent residents.
When she and Koppaka compared skin-test results from "foreign-born" students with results from the smaller subset of "international" kids, they found that the "international" students only accounted for 40% of skin test positives.
To find out more about VCU’s TB skin-testing program, or to read about a peer-counseling program designed to enhance completion rates of prevention therapy among the latently infected, go to VCU’s web site, at http://ush1.ush.vcu.edu/tb.