EATG » Study demonstrates mortality benefit of Xpert TB assay in HIV patients

Study demonstrates mortality benefit of Xpert TB assay in HIV patients

Patients newly diagnosed with advanced HIV in Malawi who were screened for tuberculosis with the Xpert MTB/RIF assay had significantly lower rates of 12-month, all-cause mortality than patients who were screened with light-emitting diode fluorescence microscopy, according to recent data from the CHEPETSA trial.

“These findings suggest that, in settings with poor existing health infrastructure, screening for TB with a high-sensitivity test at the point of HIV diagnosis may save lives among those with highest risk of mortality,” Lucky G. Ngwira, PhD fellow from the Malawi Liverpool Trust Clinical Research Program and Liver School of Tropical Medicine, and colleagues wrote in Clinical Infectious Diseases.

Previous studies have shown that the Xpert MTB/RIF assay (Cepheid) improves same-day diagnosis and shortens the amount of time to treatment; however, a mortality benefit has not been established, according to the researchers. To investigate this, Ngwira and colleagues randomly assigned 12 clinics in Malawi in a 1:1 ratio to perform point-of-care TB testing with the Xpert MTB/RIF assay or light-emitting diode fluorescence microscopy (LED FM) among patients newly diagnosed with HIV who presented with TB symptoms. The primary outcome was the incidence of all-cause mortality within the first year of HIV diagnosis.

Overall, 1,001 study participants were enrolled in the Xpert MTB/RIF arm and 841 were enrolled in the LED FM arm. More than 2% of participants who were screened with the Xpert MTB/RIF assay and 1.2% of those screened with LED FM were diagnosed with prevalent TB.

In the overall population, there was a 22% reduction in all-cause mortality among participants screened with the Xpert MTB/RIF assay at 12 months, although the researchers said this finding was not significant. There was, however, a significant reduction among participants with advanced HIV. In this population, the Xpert MTB/RIF assay was associated with a 57% reduction in all-cause mortality (RR = 0.43; 95% CI, 0.22-0.87). Additional subgroup analyses showed that all-cause mortality was 60% lower among patients aged 35 years or younger and 42% lower among men in the Xpert MTB/RIF group vs. the LED FM group.

The researchers highlighted certain limitations to the study that they said should be considered while interpreting the findings. These limitations include the lack of knowledge on specific causes of death and a low sample size. They also noted that point-of-care TB testing in the clinics required substantial investments and infrastructure development to implement and maintain solar electrical supply, staff training and other equipment and diagnostic supplies.

“Our results may therefore not fully generalize to settings in which investments are not possible,” they wrote. “Decisions about scale-up of this intervention should balance challenges in implementation and the lack of an observed benefit in the population as a whole against the need to prevent deaths among the highest-risk patients.”

Ngwira LG, et al. Clin Infect Dis. 2018;doi:10.1093/cid/ciy590.

By Stephanie Viguers

News categories: Tuberculosis, Diagnostics