Tuberculosis infection among people taking corticosteroid pills may be underestimated, new research suggests. Current guidelines for what constitutes a positive TB skin test among corticosteroid pill users may not be identifying all those who are infected, according to findings published in the European Respiratory Journal.

Previous research has shown that people who take corticosteroid pills, such as Prednisone, and have inhaled the TB bacteria, have an eight times higher risk of the bacteria becoming active than people who are not taking the drugs.

However, an examination of more than 7,300 people in the US National Health and Nutrition Examination Survey found this was not the case. The survey, a series of studies designed to assess the health and nutritional status of adults and children in the United States, is unique in that it combines interviews and physical examinations.