title: Including the questionnaire with an invitation letter did not improve a telephone survey's response rate.
abstract: OBJECTIVE
  To determine whether including the study questionnaire with a letter of invitation improves the response rate in a telephone-based survey.
  
  
  METHODS
  This randomized controlled trial was part of a larger study to assess patient preferences for novel and controversial treatments for inflammatory bowel disease at Royal Prince Alfred Hospital, a tertiary referral teaching hospital in Sydney, Australia.
  
  
  RESULTS
  Of 270 eligible patients, 124 (46%) were randomized to receive the questionnaire plus invitation whereas 146 (54%) were in the control group receiving a letter of invitation only. The consent rate was 26% for those receiving the questionnaire and 36% for the control group. The odds ratio for consent to participate among those sent the questionnaire to those not sent the questionnaire was 0.63 (95% CI=0.37-1.07).
  
  
  CONCLUSIONS
  This study found that the advance mailing of a questionnaire to potential participants in a telephone survey reduced the likelihood of their participation.
authors.affiliation: Surgical Outcomes Research Centre, Sydney South West Area Health Service & University of Sydney, Australia.
authors.forename: Christopher M
authors.initials: CM
authors.lastname: Byrne
authors.forename: James D
authors.initials: JD
authors.lastname: Harrison
authors.forename: Jane M
authors.initials: JM
authors.lastname: Young
authors.forename: Warwick S
authors.initials: WS
authors.lastname: Selby
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Solomon
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001294:Attitude to Health; D015709:Correspondence as Topic; D006801:Humans; D015212:Inflammatory Bowel Diseases / Q000628:therapy*; D008875:Middle Aged; D010349:Patient Compliance; D017060:Patient Satisfaction; D018579:Patient Selection; D011177:Postal Service; D011795:Surveys and Questionnaires; D013689:Telephone