A low response rate does not necessarily indicate non-response bias in gastroenterology survey research: a population-based study

Abstract

To estimate the potential for response bias in standard mailed questionnaires used in surveys of GI symptoms in a community. Validated self-report tools have been developed to measure functional gastrointestinal (GI) disorders but response rates in community surveys have been rapidly declining in many parts of the world. Whether a lower community response rate introduces significant response bias in GI survey research is unknown. A questionnaire was mailed to a total of 5,069 randomly selected subjects. The overall response rate was 52 %. A random sample of 723 of these subjects (428 responders and 295 non-responders, stratified by age and gender) was selected for medical record abstraction (including both inpatient and outpatient history). The odds for response increased in those with a higher body mass index (odds ratio (OR):1.02 [95 % CI: 1.01, 1.03]), more health care seeking behavior for non-GI problems (OR: 1.97 [95 % CI: 1.43, 2.72]), and for those who had responded to a previous survey (OR: 4.84 [95 % CI: 2.84, 8.26]). Responder status was not significantly associated with any GI symptoms or a diagnosis of GI or non-GI disease (with two exceptions, diverticulosis and skin disease). Despite a response rate of only 52 %, the results of a community-based GI survey do not appear to be impacted by non-response bias in a major way. A low survey response rate does not necessarily indicate non-response bias.