infertR Documentation

Infertility after Spontaneous and Induced Abortion

Description

This is a matched case-control study dating from before the availability of conditional logistic regression.

Usage

infert

Format

1. Education 0 = 0-5 years
1 = 6-11 years
2 = 12+ years
2. age age in years of case
3. parity count
4. number of prior 0 = 0
induced abortions 1 = 1
2 = 2 or more
5. case status 1 = case
0 = control
6. number of prior 0 = 0
spontaneous abortions 1 = 1
2 = 2 or more
7. matched set number 1-83
8. stratum number 1-63

Note

One case with two prior spontaneous abortions and two prior induced abortions is omitted.

Source

Trichopoulos, D., Handanos, N., Danezis, J., Kalandidi, A., & Kalapothaki, V. (1976). Induced abortion and secondary infertility. British Journal of Obstetrics and Gynaecology, 83, 645–650. doi:10.1111/j.1471-0528.1976.tb00904.x.

Examples

require(stats)
model1 <- glm(case ~ spontaneous+induced, data = infert, family = binomial())
summary(model1)
## adjusted for other potential confounders:
summary(model2 <- glm(case ~ age+parity+education+spontaneous+induced,
                     data = infert, family = binomial()))
## Really should be analysed by conditional logistic regression
## which is in the survival package
if(require(survival)){
  model3 <- clogit(case ~ spontaneous+induced+strata(stratum), data = infert)
  print(summary(model3))
  detach()  # survival (conflicts)
}