Time trends in drug resistant HIV-1 infections in the United Kingdom up to 2009: multicentre observational study
OBJECTIVE
To evaluate whether the prevalence of HIV-1 transmitted drug resistance has continued to decline in infections probably acquired within the United Kingdom.


DESIGN
Multicentre observational study.


SETTING
All UK public laboratories conducting tests for genotypic HIV resistance as a part of routine care.


PARTICIPANTS
14,584 patients infected with HIV-1 subtype B virus, who were first tested for resistance before receiving antiretroviral therapy between January 2002 and December 2009.


MAIN OUTCOME MEASURE
Prevalence of transmitted drug resistance, defined as one or more resistance mutations from the surveillance list recommended by the World Health Organization.


RESULTS
1654 (11.3%, 95% confidence interval 10.8% to 11.9%) patients had one or more mutations associated with transmitted HIV-1 drug resistance; prevalence was found to decline from 15.5% in 2002 to 9.6% in 2007, followed by a slight increase to 10.9% in 2009 (P=0.21). This later rise was mainly a result of increases in resistance to nucleos(t)ide reverse transcriptase inhibitors (from 5.4% in 2007 to 6.6% in 2009, P=0.24) and protease inhibitors (1.5% to 2.1%, P=0.12). Thymidine analogue mutations, including T215 revertants, remained the most frequent mutations associated with nucleos(t)ide reverse transcriptase inhibitors, despite a considerable fall in stavudine and zidovudine use between 2002 and 2009 (from 29.4% of drug regimens in 2002 to 0.8% in 2009, from 47.9% to 8.8%, respectively).


CONCLUSIONS
The previously observed decline in the prevalence of transmitted drug resistance in HIV-1 infections probably acquired in the UK seems to have stabilised. The continued high prevalence of thymidine analogue mutations suggests that the source of this resistance may be increasingly from patients who have not undergone antiretroviral therapy and who harbour resistant viruses. Testing of all newly diagnosed HIV-1 positive people should be continued.