Table 3. Influence of selected characteristics of ANRS 1220 Primo-CI cohort participants on the CD4+ cell count at seroconversion and its slope, as estimated from the linear mixed model.
| Effect | Coefficient (95% CI) | P |
|---|---|---|
| Fixed effect | ||
| Square-root CD4+ cell count intercept | ||
| Baseline | 12.035 (11.358 to 12.712) | < 0.001a |
| CD4+ cell count at cohort inclusion (per 1 cell/μL increase) | 0.020 (0.019 to 0.021) | < 0.001a |
| Time from HIV seroconversion to cohort inclusion (per one-year increase) | 0.973 (0.672 to 1.273) | < 0.001a |
| Square-root CD4+ cell count slope (cells/μL decrease per year) | ||
| Baseline | −0.676 (−0.972 to −0.379) | < 0.001a |
| CD4+ cell count at cohort inclusion (per 1 cell/μL increase) | −0.001 (−0.001 to −0.000) | 0.009a |
| Time from HIV seroconversion to cohort inclusion (per one-year increase) | −0.065 (−0.186 to 0.056) | 0.292a |
| Random effect | ||
| Intercept variance | 2.007 (1.390 to 2.898) | < 0.001b |
| Slope variance | 0.525 (0.394 to 0.701) | |
| Covariance between intercept and slope | −0.165 (−0.430 to 0.101) |
CI: confidence interval; HIV: human immunodeficiency virus.
a Wald test.
b The likelihood ratio test rejected the null hypothesis that all coefficients were simultaneously equal to 0.
Note: The following variables: age at seroconversion, gender, CD4+ cell count at cohort inclusion and time from seroconversion to cohort inclusion, were initially included in the multivariable analysis. We used a backward stepwise selection procedure in the final model to retain only those covariates significantly associated (P < 0.05) with the intercept and slope.