poster: Comparison of the cavidi exavir reverse transciptase assay to hivrna among antiretroviral patients in Malawi
M Hosseinipour, S Phiri, A Cachafeiro, D Namakwa, S Gama, G. Joaki, C Kanyama, I Hoffman S Fiscus
Objectives: As antiretroviral programs expand in developing countries, the need for inexpensive methods of monitoring response to therapy is of increasing importance. Cavidi Exavir Reverse Transcriptase (RT) Assay is a low tech, less expensive assay that is commercially available and may serve as HIVRNA surrogate for antiretroviral patients in resource limited settings.
Methods: A prospective observation study enrolled adult patients seeking antiretroviral therapy in the Lighthouse HIV Clinic at Lilongwe Central Hospital in Malawi between January 2003 and July 2003 and followed through December 2004. Patients received quarterly laboratory assessments of HIVRNA. Exavir RT assay was performed on a subset of samples to determine performance compared with HIVRNA. Log transformed HIVRNA (<400=lower limit detection) and Exavir RT results (<200=lower limit of detection) were compared using linear correlation.
Results: A total of 152 timepoints for 102 subjects were evaluated using both the Exavir RT assay and HIVRNA (95 baseline, 3 month 3, 20 month 6, 17 month 9, 17 month12). Correlation coefficient of log transformed results was 0.91 (Figure 1). 70% of test results differed by < 0.5 log. Of those differing by >0.5 log according to RNA level, >100K, 26%; 10K-100K 33%, 1K-10K 75%. 17/24 (70%) of undetectable specimens for HIVRNA were also undetectable on the Exavir RT assay or were below 515 copies.
Conclusions: The Cavidi Exavir RT assay correlates well with HIVRNA and may serve as a substitute for HIVRNA in resource limited settings.
Recommendations: Further evaluation of this technology is warranted in clinical settings.