The NICOLA questionnaire trial (NICOLA-QT): a randomised trial of the effect of timing and mode of delivery on the completion and return of a self-assessment questionnaire

Background NICOLA-QT is designed to detect the optimal time and delivery method for giving a self-assessment questionnaire to participants, seeking to overcome the low response rates associated with these. The outline has been registered as SWAT-2. NICOLA-QT is embedded in the NICOLA cohort study, which is recruiting 8,500 people over 50 years of age in Northern Ireland and follow them into old age, making a comprehensive assessment of their health, lifestyles and their decision making.