Analysis Shows Cost-Effectiveness of Screening Immigrants for Latent TB Infection

Screening and treating immigrants from developing countries for dormant TB infections would prevent thousands of cases and save tens of millions of dollars, according to a new study.

The number of US TB cases has been dropping, but immigrants account for a growing proportion of them. Of the nearly 16,000 US cases last year, about half were in foreign-born persons -- up 27 percent from a decade earlier.

Potential immigrants now get a chest X-ray to detect active TB; those who are sick are required to get treatment. The Institute of Medicine has recommended that a skin test for inactive, or latent, infections also be given to those from countries where TB is common. The new study looked at whether such a practice would be cost-effective.

The study, "Global Drug-Resistance Patterns and the Management of Latent Tuberculosis Infection in Immigrants to the United States," was published in the New England Journal of Medicine (2002;347(23)1850-1859). Using immigration figures from 2000, researchers in New York calculated all the costs of screening and treating immigrants when they enter the country. They compared that to the cost of treating the active TB cases that would eventually arise if nothing were done. They estimated that screening and treating dormant infections for a single year would prevent 9,000-10,000 active TB cases and save $60 million to $90 million.

"This is a wake-up call that, yes, tuberculosis is a preventable disease," said Dr. Lee B. Reichman, executive director of the New Jersey Medical School National Tuberculosis Center. The challenge, he said, is to get doctors to recognize this and test and treat their patients for latent TB. If screening of immigrants is adopted, "then we can really make a dent in the tuberculosis problem," Reichman said.

The study also compared different antibiotics, taking into account drug resistance in each country or region. Researcher Dr. Kamran Khan, now at St. Michael's Hospital at the University of Toronto, said this information can be used to tailor treatment for immigrants.

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