Thall {pubh}

RCT on the treatment of epilepsy.

Description

Randomised control trial of an antiepilectic drug (prograbide), in which the number of seizures of 59 patients at baseline and other four follow-up visits were recorded.

Usage

Thall

Format

A tibble with 59 rows and 8 variables:

id

Subject ID.

treat

Treatment, factor with levels "Control" and "Prograbide".

base

Number of seizures at baseline.

age

Age in years at baseline.

y1

Number of seizures at year one follow-up.

y2

Number of seizures at year two follow-up.

y3

Number of seizures at year three follow-up.

y4

Number of seizures at year four follow-up.

Source

Thall, PF and Vail, SC (1990) Some covariance models for longitudinal count data with over-dispersion. Biometrics, 46: 657-671.

Stukel, TA (1993) Comparison of methods for the analysis of longitudinal data. Statistics Med 12: 1339-1351.

Shoukri, MM and Chaudhary, MA (2007) Analysis of correlated data with SAS and R. Third Edition. Chapman & Hall/CRC.

Examples

data(Thall)

c1 <- cbind(Thall[, c(1:5)], count = Thall$y1)[, c(1:4, 6)]
c2 <- cbind(Thall[, c(1:4, 6)], count = Thall$y2)[, c(1:4, 6)]
c3 <- cbind(Thall[, c(1:4, 7)], count = Thall$y3)[, c(1:4, 6)]
c4 <- cbind(Thall[, c(1:4, 8)], count = Thall$y3)[, c(1:4, 6)]
epilepsy <- rbind(c1, c2, c3, c4)

require(lme4, quietly = TRUE)
model_glmer <- glmer(count ~ treat + base + I(age - mean(age, na.rm = TRUE)) +
  (1 | id), data = epilepsy, family = poisson)
glm_coef(model_glmer, labels = c(
  "Treatment (Prograbide/Control)",
  "Baseline count", "Age (years)"
))