Operating Characteristics of a Tuberculosis Screening Tool for People Living with HIV in Out-Patient HIV Care and Treatment Services, Rwanda

Background: The World Health Organization (WHO) 2010 guidelines for intensified tuberculosis (TB) case finding (ICF) among people living with HIV (PLHIV) includes a recommendation that PLHIV receive routine TB screening. Since 2005, the Rwandan Ministry of Health has been using a five-question screening tool. Our study objective was to assess the operating characteristics of the tool designed to identify PLHIV with presumptive TB as measured against a composite reference standard, including bacteriologically confirmed TB.

Methods: In a cross-sectional study, the TB screening tool was routinely administered at enrolment in outpatient HIV care and treatment services at seven public health facilities. From March to September 2011, study enrollees were examined for TB disease irrespective of TB screening outcome. The examination consisted of a chest radiograph (CXR), three sputum smears (SS), sputum culture (SC) and polymerase chain reaction line-probe assay (Hain test). PLHIV were classified as having "laboratory-confirmed TB" with positive results on SS for acid-fast bacilli, SC on Lowenstein-Jensen medium, or a Hain test.

Results: Overall, 1,767 patients were enrolled and screened of which; 1,017 (57.6%) were female, median age was 33 (IQR, 27-41), and median CD4+ cell count was 385 (IQR, 229-563) cells/mm3. Of the patients screened, 138 (7.8%) were diagnosed with TB of which; 125 (90.5%) were laboratory-confirmed pulmonary TB. Of 404 (22.9%) patients who screened positive and 1,363 (77.1%) who screened negative, 79 (19.5%) and 59 (4.3%), respectively, were diagnosed with TB. For laboratory-confirmed TB, the tool had a sensitivity of 54.4% (95% CI 45.3-63.3), specificity of 79.5% (95% CI 77.5-81.5), PPV of 16.8% and NPV of 95.8%.

Conclusion: TB prevalence among PLHIV newly enrolling into HIV care and treatment was 65 times greater than the overall population prevalence. However, the performance of the tool was poorer than the predicted performance of the WHO recommended TB screening questions.