Enhanced TB Screening to Determine the Prevalence and Incidence of TB in Patients With HIV

new HIV clinic enrollees

All new enrollees to a Lusaka HIV clinic will receive a full TB work-up.

Otro: Comprehensive TB screening

All enrollees will receive a comprehensive TB screening regardless of symptom presentation.

Prevalence of undiagnosed TB in those with HIV.

Among the cohort of 400 new enrollees at the clinic, all will be tested for TB at the specified time points using enhanced TB screening. Initial diagnosis will use smear microscopy and culture. Chest X-ray will be performed on the second day of enrollment. Presumptive Diagnosis: As culture results will take several days or weeks to become available, a presumptive diagnosis will be made based on history and physical exam, symptoms, smear microscopy and chest radiography results. All patients who are smear-positive by at least one sample will be diagnosed with TB per national guidelines. Patients who are smear-negative or suspected of extra-pulmonary TB based on clinical or radiographic findings may be treated empirically for TB at the discretion of a clinical or medical officer. Sputum samples will also be sent for testing at the end of the study with the Xpert MTB/RIF assay.

Incidence of TB in a cohort of HIV clinic patients screened as 'TB negative'.

To account for patients who are censored prior to 12 months of follow-up, the incidence of TB will be calculated as a rate. Each patient will contribute follow-up time until they are censored, are diagnosed with TB, or have been in the study for 12 months. Patients who were diagnosed with TB at enrollment will not be included.

Performance of diagnostic measures

The performance of symptom screening, light microscopy, fluorescence microscopy, chest x-ray, and Xpert MTB/RIF assay compared to culture of sputum and other fluids in HIV-infected patients will be evaluated using data analysis methods.

Cost-effectiveness of each screening/diagnostic tool.

The primary outcomes of each diagnostic tool (or combination of diagnostic tools) that will be assessed are: cost per case diagnosed/detected, cost per patient cured, cost per case averted. For instance, the cost per case of active TB detected using the "null" or gold standard screening option will be calculated and compared to the cost per case of active TB detected using each of the other screening options.

Clinical outcomes

Clinical outcomes will be measured in a cohort of HIV-infected patients and TB/HIV co-infected patients during the first 12 months of HIV care including but not limited to mortality, immune recovery and development of other opportunistic infections.