Prevalence of clinically relevant resistance to first line drugs (Stanford HIVdb) by antiretroviral class between 2007 and 2011.

<p>NRTI: nucleoside reverse transcriptase inhibitors (abacavir, emtricitabine, lamivudine and tenofovir); NNRTI: non-nucleoside reverse transcriptase inhibitors (efavirenz and nevirapine); PI: protease inhibitors (atazanavir, darunavir and lopinavir). * p value for Chi-square test for trend.</p>