Modelling the rate of change in a longitudinal study with missing data, adjusting for contact attempts
Article first published online: 1 FEB 2011
Copyright © 2011 John Wiley & Sons, Ltd.
Statistics in Medicine
Volume 30, Issue 10, pages 1072–1089, 10 May 2011
How to Cite
Akacha, M. and Hutton, J. L. (2011), Modelling the rate of change in a longitudinal study with missing data, adjusting for contact attempts. Statist. Med., 30: 1072–1089. doi: 10.1002/sim.4165
- Issue published online: 12 APR 2011
- Article first published online: 1 FEB 2011
- Manuscript Accepted: 11 NOV 2010
- Manuscript Received: 19 MAY 2010
- contact attempts;
- longitudinal data;
- missing data;
- rate of improvement;
- selection models;
- sensitivity analysis
The Collaborative Ankle Support Trial (CAST) is a longitudinal trial of treatments for severe ankle sprains in which interest lies in the rate of improvement, the effectiveness of reminders and potentially informative missingness. A model is proposed for continuous longitudinal data with non-ignorable or informative missingness, taking into account the nature of attempts made to contact initial non-responders. The model combines a non-linear mixed model for the outcome model with logistic regression models for the reminder processes. A sensitivity analysis is used to contrast this model with the traditional selection model, where we adjust for missingness by modelling the missingness process.
The conclusions that recovery is slower, and less satisfactory with age and more rapid with below knee cast than with a tubular bandage do not alter materially across all models investigated. The results also suggest that phone calls are most effective in retrieving questionnaires. Copyright © 2011 John Wiley & Sons, Ltd.