Low Yield of Chest Radiography in General Inpatients and Outpatients with "Positive PPD" Results in a Country with Low Prevalence of TB.

Rationale And Objectives: The purpose of this study was to assess the frequency and spectrum of abnormalities on routine screening chest radiographs among inpatients and outpatients with "positive purified protein derivative (PPD)" in a large tertiary care academic medical center in a country with low prevalence of tuberculosis (TB).

Materials And Methods: The reports of all chest radiographs of general inpatients and outpatients referred for positive PPD (2010-2014) were evaluated for the frequency of evidence of active or latent TB and the spectrum of imaging findings. The results of additional chest radiographs and computed tomography scans were recorded, as were additional relevant clinical histories and symptoms.

Results: Of the 2518 patients who underwent chest radiography for positive PPD, the radiographs were normal in 91.3%. The vast majority of the abnormal radiographs demonstrated findings consistent with old tuberculous disease. There were three cases (0.1%) of active TB, all of which were either recent immigrants from an endemic area or had other relevant histories or clinical symptoms suggestive of the disease.

Conclusions: Universal chest radiography in general inpatient and outpatient populations referred for positive PPD is of low yield for detecting active disease in a country with low prevalence of TB.