Table 1.
Baseline Characteristics of Patients Switched to Second-line Antiretroviral Therapy (2003–2008) With and Without Available Samples for Genotyping and/or Drug Concentrations
| Characteristic | Patients With Samples, No. (%) (n = 122) | Patients Without Samples, No. (%) (n = 295) |
|---|---|---|
| Program | ||
| Community | 95 (77.9) | 117 (39.7) |
| Workplace | 27 (22.1) | 178 (60.3) |
| Age at switch, y, median (IQR) | 36 (31–44) | 40 (35–48) |
| Sex, male | 60 (49.2) | 210 (71.2) |
| Transfers into program on ART | 40/112 (32.8) | 80/265 (30.2) |
| Reason for switch | ||
| Failure | 93/111 (83.8) | 214/261 (82.0) |
| Nonadherence | 5 (4.5) | 10/261 (3.8) |
| Other | 13 (11.7) | 37/261 (14.2) |
| Year of switch | ||
| ≤2005 | 17 (13.9) | 37 (12.5) |
| 2006–2007 | 34 (27.9) | 107 (36.3) |
| 2008 | 71 (58.2) | 151 (51.2) |
| Reported nonadherence, first-line ART | 16 (13.1) | 46 (15.6) |
| VL <400 copies/mL, first-line ART | 61/98 (62.2) | 177/243 (72.8) |
| Days on first-line ART, median (IQR) | 545 (311–810) | 601 (393–907) |
| Duration of viremia | ||
| <12 mo | 54/119 (45.4) | 123/293 (42.0) |
| ≥12 mo | 65/119 (54.6) | 170/293 (58.0) |
| NNRTI preswitch | ||
| EFV | 78 (63.9) | 220 (74.6) |
| NVP | 44 (36.1) | 75 (25.4) |
| NRTIs preswitch | ||
| ZDV + 3TC | 44 (36.1) | 182 (61.7) |
| d4T + 3TC | 75 (61.5) | 111 (37.6) |
| Other | 3 (2.5) | 2 (0.6) |
| Switch: bPI plus | ||
| ZDV/ddI | 59 (48.4) | 67 (22.7) |
| ABC/ddI | 36 (29.5) | 171 (58.0) |
| TDF/FTC | 9 (7.4) | 13 (4.4) |
| Other | 18 (14.7) | 44 (14.9) |
| CD4 count, cells/µL, median (IQR) | 177 (77–263) | 176 (102–257) |
| Log10 VL, median (IQR) | 4.3 (3.8–4.7) | 4.5 (4.0–4.9) |
| Subtherapeutic first-line ART preswitch | 44/80 (55) | |
| HIV subtype (n = 115) | ||
| A | 1 (0.9) | |
| B | 2 (1.7) | |
| C | 112 (97.4) | |
| Resistance mutations | ||
| No major DRM | 26 (22.6) | |
| Any NNRTI mutation | 85 (73.9) | |
| Any NRTI mutation | 80 (69.6) | |
| NRTI, other than M184V/I | 42 (36.5) | |
| NRTI cross-resistance mutations | 19 (16.5) | |
| Two-class resistance | 76 (66.1)a | |
Abbreviations: 3TC, lamivudine; ABC, abacavir; ART, antiretroviral therapy; bPI, ritonavir-boosted protease inhibitor; d4T, stavudine; ddI, didanosine; DRM, drug resistance mutation; EFV, efavirenz; FTC, emtricitabine; HIV, human immunodeficiency virus; IQR, interquartile range; NNRTI, nonnucleoside reverse transcriptase inhibitor; NRTI, nucleoside reverse transcriptase inhibitor; NVP, nevirapine; TDF, tenofovir; VL, viral load; ZDV, zidovudine.
a In 36 of 76 patients, dual class resistance was on the basis of NNRTI mutations and M184V/I alone.