Figure 1.
Distribution of final HIV-1 RNA and CD4 cell counts.
(A) Final HIV-1 RNA and (B) final CD4 cell counts by calendar year for 1,814 unique patients tested for both parameters at least once from 1999 through 2011. The number of individuals each year ranged from 575 in 1999 to 854 in 2011. The HIV-1 RNA lower limit of quantitation was 50 copies/mL from 1-1-99 to 10-17-02, 75 copies/mL from 10-18-02 to 3-4-08 and 40 copies/mL from 3-5-08 to 12-31-11.
Figure 2.
Annual and monthly means of HIV-1 RNA and CD4 cell counts.
(A) Annual log10-transformed HIV-1 RNA means and CD4 cell count geometric means calculated from each patient's final values by calendar year. (B) Monthly log10 HIV-1 RNA means and (C) CD4 cell count geometric means calculated from all testing in a given month which represented 21–24% of that year's number of patients (575 persons in 1999 to 854 in 2011). Two-limit Tobit, censored regression models were used to estimate the true mean log10 HIV-1 RNA values by month and year. CD4 cell counts of 0 were assigned the value of 1 cell/µL.