A parallel-group prospective cohort study among adult persons living with HIV/AIDS to study the effect of a new TB diagnostic test, Xpert MTB/RIF on: 1) TB case detection; 2) time to TB diagnosis and TB treatment; 3) presumptive TB patient drop-out from the TB diagnostic "cascade" before starting TB treatment; and 4) loss to follow-up after initiation of TB treatment.
The Centre for Infectious Disease Research in Zambia (CIDRZ) in collaboration with the Zambian National TB Program (NTP) and the Ministry of Health (MOH) will provide near point-of-care Xpert testing at a high-volume anti-retroviral treatment (ART) clinic in Lusaka, Zambia. A total 892 study participants will be enrolled into two parallel cohorts-an "Xpert" and a "standard of care" (SOC) cohort over a 7-month period. The Xpert cohort will enrol participants at the health centre implementing Xpert. The SOC cohort will enrol participants from one health centre offering the standard of care (sputum smear microscopy plus clinical evaluation). A parallel-group prospective cohort study will be conducted by following participants in one cohort from each site for 210 days from the time of sputum submission, allowing sufficient person-time to observe all outcomes of interest, including completion of a standard course of ATT as well as patient drop-out and loss to follow-up. A systematic facility assessment survey using an adapted version of the WHO Service Availability and Readiness Assessment tool will be conducted. Key informants will be interviewed.
Study Type
OBSERVATIONAL
Enrollment
776
The Xpert MTB/RIF assay is a nucleic acid amplification (NAA) test that uses a disposable cartridge with the GeneXpert Instrument System
Chelstone and Chilenje Health Centres
Lusaka, Zambia
Culture-positive patient drop-out before accessing treatment
For both cohorts, the proportion of patients not started on TB treatment by 210 days post-enrolment will be assessed.
Time frame: From study enrolment through confirmed drop out date at or before 210-days post enrollment
Time to TB treatment
Time frame: time in days from study enrolment to initiation of anti-TB therapy (ATT) (through 210 days post-enrolment)
Percentage of participants who receive TB treatment within 14 days of enrolment (effect of Xpert on the accuracy of TB diagnosis)
sensitivity of empirical TB diagnosis and treatment will be defined as the percentage of participants who received TB treatment within 14 days of enrolment among all those with a positive culture but negative or unavailable result for SM (for the SOC cohort), or negative or unavailable SM plus Xpert (for the Xpert cohort)
Time frame: study enrolment to 14 days of enrolment
Percentage of participants who did not receive TB treatment 14 days post-enrolment (effect of Xpert on the accuracy of TB diagnosis)
the specificity of empirical treatment will be defined as the percentage of participants who did not receive TB treatment 14 days post-enrolment among all those with a negative culture and negative or unavailable result for SM (in the SOC cohort), or negative or unavailable result for SM plus Xpert (in the Xpert cohort)
Time frame: study enrolment to 14 days of enrolment
Time to TB Diagnosis
The World Health Organization definition of a TB case will be used
Time frame: average of 28 days
Number of TB patients lost to follow-up
Time frame: The number of patients will be measured as time in days from study enrolment to confirmed drop out (confirmed as failure noted at 3 and 6 month chart review)
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