Factors associated with response to a follow-up postal questionnaire in a cohort of American Indians

ObjectiveThe aim of the study was to collect pilot data on response rates to a follow-up postal questionnaire in a cohort of American Indians living in the Southwestern United States. We tested the effect of questionnaire length on response.MethodsCohort members were American Indian adults aged 18 and over who completed the baseline study visit. Study participants (N = 1587), cohort members who completed the baseline study visit during the first year of enrollment, were randomized into two groups to receive either an 18-page or 3-page follow-up postal questionnaire. Data were collected between October 2005 and March 2006.ResultsThe response rates after two questionnaire mailings and a reminder postcard were significantly higher for the short versus the long (56.2%, 48.1% p = < 0.01) questionnaire. Being female and being aged 50 or older were associated with returning a completed questionnaire. A reminder postcard and second mailing improved response by 11.7% and 13.4% respectively.ConclusionsThese results show that a postal questionnaire can be used in a cohort of American Indians living in the Southwest, but suggest that questionnaires should be short and repeat mailings are needed.