The U.S. Centers for Disease Control and Prevention recommends that individuals who have a positive PPD test undergo chest radiography to exclude a diagnosis of TB.
"We chose to look into the subject because we do so many screening chest x-rays for positive PPD, and they are nearly always negative," said Dr. Adam Jacobi, an assistant professor of radiology at Mount Sinai Hospital. New York City has one of the highest TB rates in the country, he noted.
"In the few instances where there was something suspicious, we were surprised that clinicians cared more about the clinical scenario -- i.e., not coughing -- than the x-ray appearance," he said in an interview with AuntMinnie.com. "We also wanted to see how many downstream tests were recommended based on the chest x-ray."
Of the 904 cases reviewed, not a single case of confirmed active TB was identified. Active TB could not be excluded based on chest x-ray alone in four patients, but all sputum cultures that were obtained in these individuals were negative. Granulomas were present in 26 patients. No cavitary lesions were identified. A single case of lung cancer was identified, and follow-up exams were recommended in 30 patients.
"We do not feel the screening-positive PPD chest x-ray should be done away with, but we did want to open a dialogue for discussion," Jacobi said. "We also plan to look similarly into the yield of the preoperative chest x-ray."