Table 3.
Linear Regression Estimates Evaluating the Association Between Plasma Ritonavir Trough Concentrations and Changes in Lipid Parameters Over 48 and 96 Weeks
| Parameter | LDL |
TG |
Non-HDL |
||||||
|---|---|---|---|---|---|---|---|---|---|
| Estimate (95% CI) | P Value | Estimate (95% CI) | P Value | Estimate (95% CI) | P Value | ||||
| Associations with change to week 48, mg/dL | |||||||||
| Intercept | 3.78 | (−0.02 to 7.57) | … | 15.85 | (5.17–26.52) | … | 8.21 | (4.10–12.31) | … |
| RTV C24 (per 1 log [ng/mL])a | 0.51 | (−1.58 to 2.61) | .63 | 1.71 | (−4.25 to 7.68) | .57 | 0.99 | (−1.30 to 3.28) | .40 |
| Test for PI-specific association (2 df) | P = .09 | P = .23 | P = .10 | ||||||
| Associations with change to week 96, mg/dL | |||||||||
| Intercept | 4.23 | (0.30–8.16) | … | 17.45 | (6.18–28.73) | … | 8.87 | (4.54–13.20) | … |
| RTV C24 (per 1 log [ng/mL])a | −0.15 | (−2.28 to 1.99) | .89 | −0.14 | (−6.36 to 6.08) | .97 | −0.25 | (−2.63 to 2.14) | .84 |
| Test for PI-specific association (2 df) | P = .53 | P = .35 | P = .22 | ||||||
Estimates (mg/dL) are from simple linear regression analysis of RTV C24 on change from baseline to the given week for each lipid parameter. RTV C24 values (on the natural log scale) were centered on the group mean for modeling, so the intercept estimate represents the average lipid change from baseline for an average (geometric mean) RTV C24 of approximately 55 ng/mL. The test for a PI-specific association is a 2-df F test for nonzero treatment group main (intercept) and interaction (RTV C24 × treatment) coefficients.
Abbreviations: C24, plasma trough concentration; CI, confidence interval; df, degrees of freedom; HDL, high-density lipoprotein; LDL, low-density lipoprotein; PI, protease inhibitor; RTV, ritonavir; TG, triglycerides.
a Estimate represents the estimated difference in the lipid change from baseline to given week for each 1-log (natural) difference in RTV C24; note that 1 log is approximately the difference between the first and third quartiles of observed RTV C24 in the A5257 study.