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. Author manuscript; available in PMC: 2012 Sep 28.
Published in final edited form as: AIDS. 2007 Jul 31;21(12):1579–1589. doi: 10.1097/QAD.0b013e3281532b31

Table 5.

Multivariate analysis of duration of treatment regimen.

Base case
 With propensity
 With adherence
Hazard ratio P value Hazard ratio P value Hazard ratio P value
Nevirapine based 1.09 0.150 1.10 0.152 1.06 0.367
Single protease inhibitor based 1.16 0.002 1.16 0.002 1.16 0.003
Boosted protease inhibitor baseda 0.92 0.065 0.92 0.248 0.95 0.471
Triple nucleoside based 1.27 0.090 1.26 0.001 1.22 0.011
Other based 1.22 0.083 1.22 0.004 1.17 0.036
Current illicit drug use, compared with none 1.01 0.826 1.01 0.820 1.01 0.731
African-American, compared with Caucasian 0.95 0.111 0.95 0.128 0.99 0.700
Hispanic, compared with Caucasian 1.02 0.710 1.02 0.752 1.08 0.251
Other, compared with Caucasian 0.86 0.009 0.87 0.014 0.89 0.061
Baseline log RNA, per log unit 1.06 0.002 1.06 0.003 1.06 0.008
Baseline CD4 cell count, per 100 cells/μl 0.96 <0.001 0.96 <0.001 0.96 <0.001
Start in 1998, compared with ≤1997 1.04 0.397 1.04 0.367 1.06 0.192
Start in 1999, compared with ≤1997 1.31 <0.001 1.31 0.004 1.34 <0.001
Start in 2000, compared with ≤1997 1.55 <0.001 1.56 0.002 1.64 <0.001
Start in ≥2001, compared with ≤1997 2.19 <0.001 2.19 <0.001 2.35 <0.001
Stavudine/lamivudine backbone, compared with zidovudine/lamivudine 1.06 0.057 1.06 0.057 1.08 0.032
Other backbone, compared with zidovudine/lamivudine 1.19 <0.001 1.19 <0.001 1.20 <0.001
Propensity score NAb 1.01 0.976 NAb
Adherence 60–80%, compared with 80–100% NAc NAc 0.86 <0.001
Adherence 40–60%, compared with 80–100% 0.77 <0.001
Adherence 20–40%, compared with 80–100% 0.88 0.010
Adherence 0–20%, compared with 80–100% 1.01 0.942

Efavirenz-based therapy is the referent category. Positive numbers represent a greater hazard for changing regimens, and are therefore less favorable. Results from three different models are displayed; the first does not adjust for the likelihood of being prescribed efavirenz nor levels of adherence (Base case), the second uses propensity scores to adjust for confounding by treatment selection (With propensity), and the third adjusts for the level of medication regimen adherence (With adherence).

a

Subgroups of boosted protease inhibitor regimens not evaluated because no effect was apparent in the larger group.

b

Not applicable because analysis did not attempt to control for propensity.

c

Not applicable because analysis did not attempt to control for adherence.