Use of a mixture model for the analysis of contraceptive-use duration among long-term users

This paper introduces a mixture model that combines proportional hazards regression with logistic regression for the analysis of survival data, and describes its parameter estimation via an expectation maximization algorithm. The mixture model is then applied to analyze the determinants of the timing of intrauterine device (IUD) discontinuation and long-term IUD use, utilizing 14 639 instances of IUD use by Chinese women. The results show that socio-economic and demographic characteristics of women have different influences on the acceleration or deceleration of the timing of stopping IUD use and on the likelihood of long-term IUD use.