Factors influencing the response to postal questionnaire surveys about respiratory symptoms

Response rates to postal questionnaires have been falling in recent years. To examine factors affecting the response to five postal respiratory questionnaire surveys. Cross sectional study. General practice. Five surveys were conducted in all adults registered with two UK general practices using an ECRHQ-based questionnaire, with two reminders at 4-week intervals. Response rates declined over time (1993 - 71.2%; 1995 - 70.5%; 1999 - 65.5%; 2001 - 65.3%; 2004 - 46.9%). Age and gender of non-responders were available for 2001 and 2004: responders were older (mean 48.8 years vs 37.6, p