Sean Schafer


March 2012

Document Type


Degree Name



Dept. of Public Health and Preventive Medicine


Oregon Health & Science University


Surveillance of transmitted antiretroviral mutations detects emerging drug resistance, informs pre- and post-exposure prophylaxis, highlights HIV transmission from source cases already in care, and guides efforts to control resistance. We established a statewide surveillance system for transmitted antiretroviral resistance in Oregon that relies on laboratory reporting of nucleic acid sequences ascertained for clinical purposes. We evaluated reporting completeness and representativeness, compared Oregon to U.S. resistance estimates, and compared cases with transmitted resistance to newly-diagnosed cases without resistance. During 2007–2011, laboratories reported 49 percent (1,067/2,175) of expected tests, 73 percent (316/435) for 2011. Among 1,226 patients newly diagnosed with HIV during 2007–2011, resistance tests collected within 3 months of diagnosis were reported for 24.5 percent (300), and 39.6 percent during 2011 alone. We observed no significant differences among newly-diagnosed patients with and without reported resistance tests. Overall, 17.3 percent of newly-diagnosed cases had at least one resistance mutation for any of three classes; this was not significantly different from a 2006 U.S. survey. We also found that 12.3 percent had at least one nucleoside reverse transcriptase inhibitor mutation (NRTI); 5.7 percent had at least one non-nucleoside reverse transcriptase inhibitor (NNRTI) mutation, and 2.7 percent had at least one protease inhibitor (PI) mutation. The proportion of cases with NRTI resistance was twice the proportion reported by the earlier study (p<0.001); NNRTI and PI mutations were less frequent than expected, though not significantly so. We observed no significant differences among newly-diagnosed cases with and without evidence of resistance. This approach appears to accurately represent the proportion of newly infected cases with transmitted resistance and to have the potential to be replicable by other statewide HIV surveillance systems without substantial new costs.




School of Medicine



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