Pediatric Care Providers Often Misinterpret Tuberculin Skin Test Results

Pediatric health care providers in the United States might benefit from further training in diagnosing tuberculosis infection, according to Dr. Edward R. Carter and colleagues working at Madigan Army Medical Center in Tacoma, Wash., authors of the study "Interpretation of the Tuberculin Skin Test Reaction by Pediatric Providers," (Pediatric Infectious Disease Journal, 2002;21(3):200-203).

"The tuberculin (TB) skin test is widely used, but it is not easy to read," the researchers reported. "There are few data on how well pediatric care providers interpret the TB skin test or on the success of various methods used to read the skin test reaction."

A significant minority of pediatric care providers failed to correctly interpret a clearly positive tuberculin skin test result, Carter and coauthors found in a study of 57 people involved in pediatric care -- 16 pediatricians, 20 nurses, 13 residents, and 8 medical students. Each was asked to give a diagnosis for a child who developed a 15-mm skin induration in response to tuberculin injection. An induration of 10 mm or larger in children is considered a positive test result, the researchers noted.

Almost 20 percent of the study participants (10 of 57) interpreted the large induration as a negative test result, study data showed. Care providers who used the ballpoint pen method -- using a pen to draw a line from the edges of the arm to the edge of the induration, then measuring the gap between the lines -- performed significantly better than those who used other measurement techniques. However, only 18 of the 57 participants used the ballpoint pen technique.

"Many providers, regardless of professional training and experience, read a 15-mm TB skin test reaction as greater than or equal to 10 mm, but a significant minority interpreted it as negative," the authors concluded. "Specific instruction on use of the pen technique to read TB skin tests should be incorporated into medical training curriculums."

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