npde (version 2.0)

virload: Simulated HIV viral loads in HIV patients

Description

This is simulated data, based on real data obtained in a phase II clinical trial supported by the French Agency for AIDS Research, the COPHAR 3-ANRS 134 trial (Goujard et al., 2010). The original study included 35 patients, who received a once daily dose containing atazanavir (300 mg), ritonavir (100 mg), tenofovir disoproxil (245 mg) and emtricitabine (200 mg) during 24 weeks. Viral loads were measured 6 times over a treatment period of 24 weeks (day 0, 28, 56, 84, 112, 168).

The datasets were generated in a simulation study designed to evaluate the new method proposed to handle BQL data (Nguyen et al., 2011). Data was simulated using a simple bi-exponential HIV dynamic model describing the two-phase decline of viral load during anti-retroviral treatment.

The virload data frame has 300 rows and 4 columns of data. The dataset was then censored at two different LOQ levels (LOQ=20 or 50~copies/mL) to generate two datasets containing different proportions of BQL data, creating the data frames virload20 andvirload50 respectively.

Usage

virload

Format

This data frame contains the following columns:

ID

an ordered factor with levels 1, ..., 50 identifying the subject on whom the observation was made. The ordering is by Time at which the observation was made.

Time

time since the beginning of the study (days).

Log_VL

logarithm (base 10) of the viral load (copies/L).

cens

indicator variable (cens=1 for censored data, cens=0 for observed data)

ipred

individual predictions)

Source

Goujard, C., Barrail-Train, A., Duval, X., Nembot, G., Panhard, X., Savic, R., Descamps, D., Vrijens, B., Taburet, A., Mentre, F., and the ANRS 134 study group (2010). Virological response to atazanavir, ritonavir and tenofovir/emtricitabine: relation to individual pharmacokinetic parameters and adherence measured by medication events monitoring system (MEMS) in naive HIV-infected patients (ANRS134 trial). International AIDS Society 2010, Abstr WEPE0094. Nguyen, T., Comets, E., Mentre, F. (2010). Prediction discrepancies (pd) for evaluation of models with data under limit of quantification. 20th meeting of the population approach group in Europe (PAGE), Athens, Greece. Abstr 2182.

Examples

data(virload)
str(virload)
data(virload50)

#Plotting the data
plot(Log_VL~Time,data=virload,xlab="Time (d)",ylab="Viral loads, base 10 logarithmic scale  (cp/mL)")
plot(Log_VL~Time,data=virload50,xlab="Time (d)",ylab="Viral loads, base 10 logarithmic scale  (cp/mL)")