Analysis of transmitted drug resistance in Spain in the years 2007-2010 documents a decline in mutations to the non-nucleoside drug class.

We have studied transmitted drug resistance (TDR) in 1.864 antiretroviral-naïve patients entering CoRIS (Spain) during 2007-2010. An overall 8.58% TDR was observed (3.92%, nucleoside reverse transcriptase inhibitors (NRTIs); 3.86%, non-nucleoside reverse transcriptase inhibitors (NNRTIs); 2.31%, protease inhibitors), with a significant decreasing trend over time for NNRTIs (5.53%, 2007; 2.45%, 2010; p for trend = 0.044). Non-B subtype prevalence was 15.93%, with a significant increase (11.95%, 2007; 18.14%, 2010; p for trend = 0.018), mainly related to immigration. Having no formal education increased the risk of TDR to NNRTIs (OR, 7.26), and carrying a non-B subtype reduced the risk of TDR to NRTIs (OR, 0.27). These findings may have important implications for treatment guidelines and laboratory testing recommendations.