Use of interactive telephone technology for longitudinal data collection in a large trial

We report here on the use of interactive telephone technology for collecting longitudinal data in a large randomized non-blinded parallel trial. Data were primarily collected via an automated interactive telephone system which enabled data to be downloaded by researchers periodically via a secure website. Alternative methods were used by some participants to provide data; here we analyze the demographic profiles of groups by preferred data provision, and consider the cost-effectiveness and efficiency of such a system. The automated telephone system was used to provide the majority of data obtained (75.7%), however the group preferring to use this system to provide the majority of their data was on the whole older, more likely to be married, university educated, higher income and white compared to participants preferring to submit their data via personal phone call or post. We conclude that interactive telephone technology provides a means by which large quantities of longitudinal data may be collected efficiently. Depending on the target population, however, considerable staff time may be required to manage attrition and consequent data loss, and alternative strategies should be considered to minimize this.