Abstract

Background Randomised controlled trials often rely on questionnaires for follow-up.

Objective To compare response rates to an online and postal 12-month follow-up questionnaire on sexual health in female students who took part in a chlamydia screening trial.

Methods 1329 sexually active female students aged 16–27 were recruited from 12 universities and further education (FE) colleges. The 299 participants recruited between September 2004 and February 2005 were sent a postal questionnaire after 12 months. The 1030 participants recruited between March and December 2005 were contacted by email after 12 months and given a weblink to an online questionnaire.

Results The response rates to the 12-month questionnaire in the online and postal groups were 51% and 29% 4 weeks after follow-up commenced (RR 1.78 (1.47 to 2.14)) and 72% and 59% after 3 months. After adjusting for ethnicity, smoking, type of educational institution (university or FE college) and subject studied (health-related or not), the RR at 4 weeks was 1.88 (1.42 to 2.50). However, a prior telephone call to confirm contact details increased the response rate at 3 months in the postal group. In the online group, university students, those of white ethnicity and non-smokers had higher response rates at 4 weeks.

Conclusions In this young student population, an online questionnaire was quicker, cheaper and more efficient than a postal questionnaire. However, some FE college students did not have an email address. Telephone prompts and postal questionnaires were essential in obtaining a good response rate.