Abdominal Ultrasound for the Diagnosis of Tuberculosis Among Human Immunodeficiency Virus-Positive Inpatients With World Health Organization Danger Signs

Abstract

Background: Studies of the value of abdominal ultrasound for diagnosing human immunodeficiency virus (HIV)-associated tuberculosis have major limitations.

Methods: We conducted a prospective study of HIV-positive inpatients with cough and World Health Organization danger signs. The reference standard was positive Mycobacterium tuberculosis culture from any site. Participants had at least 2 sputa and 1 blood specimen sent for mycobacterial cultures. Standardized data capture sheets were used for ultrasound reports. A blinded radiologist interpreted chest radiographs, categorized as "likely", "possible", and "unlikely" for HIV-associated tuberculosis.

Results: We enrolled 377 participants: 249 women, median age 35 years, 201 with tuberculosis, and median CD4 count 75 cells/µL. The following abdominal ultrasound findings independently predicted tuberculosis: lymph node long-axis ≥10 mm (adjusted odds ratio [aOR], 4.76; 95% confidence interval [CI], 2.41-9.38), splenic hypoechoic lesions (aOR, 3.45; 95% CI, 1.91-6.24), and abdominal/pleural/pericardial effusions (aOR, 1.95; 95% CI, 1.16-3.29). Presence of ≥1 of these 3 features had a sensitivity of 76.4% (95% CI, 69.8-82.3), a specificity of 68.6% (95% CI, 61.1-75.4), and a c-statistic of 0.784 (95% CI, 0.739-0.830). The sensitivity and specificity of chest radiograph assessed as likely tuberculosis was 55.2% (95% CI, 47.2-62.9) and 83.9% (95% CI, 77.0-89.4), respectively.

Conclusions: Three features of tuberculosis on abdominal ultrasound independently predicted tuberculosis with moderate diagnostic performance in seriously ill HIV-positive inpatients. Abdominal ultrasound was more sensitive but less specific than chest radiograph for diagnosing tuberculosis in this patient population.

Keywords: HIV; WHO algorithm; abdominal ultrasound; inpatients; tuberculosis diagnosis.

Figures

Figure 1.

Venn diagram depicting numbers of participants with ultrasound features significantly associated with culture-positive tuberculosis on multivariable logistic regression. Values in parenthesis represent number of participants with culture-positive tuberculosis for each category.

Figure 2.

C-statistic for the model including multivariable adjusted ultrasound features (long-axis lymph node length ≥10 mm, splenic hypoechoic lesions, splenic enlargement ≥110 mm, and fluid present in either abdominal/pleural/cardiac sites) for the diagnosis of culture-positive tuberculosis among 366 participants.

Figure 3.

Venn diagram of the yield of abdominal ultrasound features (long-axis lymph node length ≥10 mm, splenic hypoechoic lesions, splenic enlargement ≥110 mm, and fluid present in either abdominal/pleural/cardiac sites) and chest radiograph (CXR) assessment of “likely” tuberculosis using the reference standard of culture-positive tuberculosis in the 314 participants who had an abdominal ultrasound performed and chest radiograph assessment done.