Tuberculosis case finding and performance of symptom screening and rapid diagnostic tests in HIV-infected pregnant women in western Kenya

Abstract

Background: Tuberculosis (TB) during pregnancy in HIV-infected women is associated with poor maternal and infant outcomes. There are limited data on TB prevalence, optimal TB screening, and performance of rapid diagnostics in pregnant HIV-infected women. Methods: We conducted a cross-sectional study among HIV-infected pregnant women seeking antenatal care in western Kenya. Following a standardized questionnaire, sputum smear microscopy for acid-fast bacilli (AFB), mycobacterial liquid culture, GeneXpert MTB/RIF (Xpert), urine lipoarabinomannan (LAM), and tuberculin skin testing (TST) were performed. We determined prevalence and correlates of culture-confirmed pulmonary TB, and compared diagnostic performance of World Health Organization (WHO) symptom screening and rapid diagnostic tests to sputum culture. Results: Between July 2013 and July 2014, we enrolled 306 women. Among 288 women with a valid sputum culture result, 54% were on antiretroviral treatment, median CD4 cell count was 437 cell/mm3 (IQR 342-565), and prevalence of culture-confirmed pulmonary TB was 2.4% (CI 1.0-4.9%). Cough >2 weeks (p=0.04) and positive TST (>5mm, p=0.03) were associated with pulmonary TB. Women with TB were 23-fold (95% CI 4.4-116.6) more likely to report a household member with TB symptoms (p=0.002). WHO symptom screen (43%), AFB smear (0%), Xpert (43%) and LAM (0%) had low sensitivity but high specificity (81%, 99%, 99% and 95%, respectively) for pulmonary TB. Conclusion: HIV-infected pregnant women had appreciable prevalence of pulmonary TB despite modest immunosuppression. Current TB screening and diagnostic tools perform poorly in pregnant HIV-infected women. Adapted TB screening tools that include household member TB symptoms may be useful in this population.