Table 2.
Potential risk factors associated with the timing of ARV regimen change, possibly right-censored. Coefficient and associated standard error estimates from four estimators are presented: Weibull, Cox’s proportional hazards model, and log-rank estimators
| Weibull | Cox | Log-rank | ||||
|---|---|---|---|---|---|---|
| Covariable | Est. | SE | Est. | SE | Est. | SE |
| HIV-1 RNA at BL | −0.271 | 0.290 | 0.223 | 0.200 | −0.497 | 0.330 |
| HIV-1 RNA at VF* | −0.310 | 0.166 | 0.218 | 0.116 | −0.419 | 0.224 |
| Time to VF | −0.300 | 0.179 | 0.132 | 0.124 | −0.298 | 0.192 |
| CD4 cell count | 0.663 | 0.269 | −0.414 | 0.182 | 0.628 | 0.274 |
| CD8 cell count | −0.079 | 0.150 | 0.069 | 0.103 | −0.024 | 0.182 |
| Weight | 0.043 | 0.216 | −0.050 | 0.148 | 0.010 | 0.270 |
| Age | 0.135 | 0.172 | −0.060 | 0.119 | 0.111 | 0.211 |
| Gender | −0.121 | 0.451 | 0.037 | 0.316 | 0.015 | 0.565 |
| Drug Use | −0.659 | 0.449 | 0.355 | 0.307 | −0.767 | 0.552 |
| Race | ||||||
| White | – | – | – | – | – | – |
| Black | −0.846 | 0.395 | 0.514 | 0.272 | −1.010 | 0.437 |
| Hispanic and others | 0.052 | 0.519 | −0.002 | 0.357 | 0.145 | 0.594 |
NOTE: Abbreviations used: baseline (BL), virological failure (VF), coefficient estimate (Est.), standard error estimate (SE). In the case of HIV-1 RNA endpoint, we do not include HIV-1 RNA at VF in the PS model (cf. Li et al., 2012). When HIV-1 RNA is removed from the model, coefficient estimates are similar to those presented above.