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.
Introduction
According to the Centers for Disease Control and Prevention, there were 9557 cases of active tuberculosis (TB) (a rate of three cases per 100,000 persons) reported in the United States during 2015, representing a 1.6% increase compared to the prior year. However, the number of TB deaths reported annually continues to decrease every year (11% from 2013 to 2014), with a 71% decrease in the annual death rate since 1992. The case rate among foreign-born persons is approximately 13 times higher than among U.S.-born persons (15.1 vs 1.2 cases per 100,000 persons) .
In countries with low TB prevalence such as the United States, about 90% of new cases of TB arise from reactivation of dormant foci of infection . Consequently, treatment of latent tuberculosis infection (LTBI) is a major component of the national strategy for eliminating the disease in the United States . Purified protein derivative (PPD), also known as tuberculin skin test, is the most common means of detecting prior TB infection. For those who test positively, the American Thoracic Society and the Centers for Disease Control and Prevention recommend routine screening chest radiography to exclude clinically active TB or to detect evidence of old healed disease to assess reactivation risk .
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Materials and Methods
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Results
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Table 1
Demographic Information and Clinical Symptoms
Characteristics Mean ± Standard Deviation (Range) Age (y) 42 ± 15(18–93) Gender Female 1539/2518(61.1) Male 979//2518(38.9) Any clinical symptoms 138/251(5.5) Cough 54/138(39.1) Fever 19/138(13.8) Night sweats 12/138(8.7) Hemoptysis 9/138(6.5) Unintended weight loss 9/138(6.5)
Continuous variables are displayed as mean ± standard deviation (range); categorical variables are displayed as numerator over denominator (%).
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Discussion
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Conclusion
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References
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