Trends in Decline of Antiretroviral Resistance among ARV-Experienced Patients in the HIV Outpatient Study: 1999–2008

Table 2

Frequency of resistance mutations among ARV-experienced patients who had genotypic testing performed at viral load >1,000 copies/mL and while on ARVs, by year, the HIV Outpatient Study, 1999–2008.

Patient subgroup	1999	2004	2008	P trend*
	% [N]	% [N]	% [N]
Part A. Frequency of any resistance among all tested in the year—by patient subgroup
All patients tested	88.1[118]	81.7[164]	79.4 [63]	0.054
95% CI	(80.9, 93.4)	(74.9, 87.3)	(67.3, 88.5)
By type of ARV experience:
cART only	68.2[22]	75.9[54]	62.5% [24]	0.317
95% CI	(45.1, 86.1)	(62.4, 86.5)	(40.6, 81.2)
Mono-dual NRTI	93.2[88]	86.9[99]	87.9 [33]	0.066
95% CI	(85.8, 97.5)	(78.6, 92.8)	(71.8, 96.6)
TCE	94.5[55]	88.3[94]	93.8 [32]	0.426
95% CI	(84.9, 98.9)	(80.0, 94.0)	(79.2, 99.2)
Part B. Frequency of class-specific mutations—among all patients tested in the year
NRTI resistance	82.2[118]	73.8%[164]	66.7%[63]	0.096
95% CI	(74.1, 88.6)	(66.4, 80.3)	(53.7, 78.0)
NNRTI resistance	46.6[118]	65.2%[164]	55.6%[63]	0.165
95% CI	(37.4, 56.0)	(57.4, 72.5)	(42.5, 68.1)
PI resistance	65.2[118]	50.6%[164]	41.3%[63]	0.018
95% CI	(55.9, 73.8)	(42.7, 58.5)	(29.0, 54.4)
Triple-class resistance	33.9[118]	39.6%[164]	27.0%[63]	0.748
95% CI	(25.4, 43.2)	(32.1, 47.6)	(16.6, 39.6)
Part C. Frequency of class-specific mutations—among tested with prior ARV exposures
NRTI resistance	82.2[118]	73.8%[164]	66.7%[63]	0.094
95% CI	(74.1, 88.6)	(66.4, 80.3)	(53.7, 78.0)
NNRTI resistance	70.5[78]	75.8%[128]	68.1%[47]	0.384
95% CI	(59.1, 80.3)	(67.4, 82.9)	(52.9, 80.9)
PI resistance	71.4[105]	56.3%[144]	45.5%[55]	0.010
95% CI	(61.8, 79.8)	(47.7, 64.5)	(32.0, 59.4)
Triple-class resistance	65.5[55]	55.3%[94]	40.6%[32]	0.094
95% CI	(51.4, 77.8)	(44.7, 65.6)	(23.7, 59.4)

*Linear test for trend using annual estimates for entire period 1999–2008.
Numbers in square brackets indicate denominators (i.e., patients with eligible GT each year).
CI: confidence interval. GT: genotypic testing; cART: combination antiretroviral therapy; NRTI: nucleoside reverse transcriptase inhibitor; NNRTI: non-nucleoside reverse transcriptase inhibitor; PI: protease inhibitor; TCE: triple-class exposed.