Impact of Length or Relevance of Questionnaires on Attrition in Online Trials:Randomized Controlled Trial

McCambridge, Jim, Kalaitzaki, Eleftheria, White, Ian R, Khadjesari, Zarnie ORCID: https://orcid.org/0000-0002-2958-9555, Murray, Elizabeth, Linke, Stuart, Thompson, Simon G, Godfrey, Christine and Wallace, Paul (2011) Impact of Length or Relevance of Questionnaires on Attrition in Online Trials:Randomized Controlled Trial. Journal of Medical Internet Research, 13 (4). ISSN 1439-4456

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Abstract

BACKGROUND: There has been limited study of factors influencing response rates and attrition in online research. Online experiments were nested within the pilot (study 1, n = 3780) and main trial (study 2, n = 2667) phases of an evaluation of a Web-based intervention for hazardous drinkers: the Down Your Drink randomized controlled trial (DYD-RCT).  OBJECTIVES: The objective was to determine whether differences in the length and relevance of questionnaires can impact upon loss to follow-up in online trials.  METHODS: A randomized controlled trial design was used. All participants who consented to enter DYD-RCT and completed the primary outcome questionnaires were randomized to complete one of four secondary outcome questionnaires at baseline and at follow-up. These questionnaires varied in length (additional 23 or 34 versus 10 items) and relevance (alcohol problems versus mental health). The outcome measure was the proportion of participants who completed follow-up at each of two follow-up intervals: study 1 after 1 and 3 months and study 2 after 3 and 12 months.  RESULTS: At all four follow-up intervals there were no significant effects of additional questionnaire length on follow-up. Randomization to the less relevant questionnaire resulted in significantly lower rates of follow-up in two of the four assessments made (absolute difference of 4%, 95% confidence interval [CI] 0%-8%, in both study 1 after 1 month and in study 2 after 12 months). A post hoc pooled analysis across all four follow-up intervals found this effect of marginal statistical significance (unadjusted difference, 3%, range 1%-5%, P = .01; difference adjusted for prespecified covariates, 3%, range 0%-5%, P = .05).  CONCLUSIONS: Apparently minor differences in study design decisions may have a measurable impact on attrition in trials. Further investigation is warranted of the impact of the relevance of outcome measures on follow-up rates and, more broadly, of the consequences of what we ask participants to do when we invite them to take part in research studies.  TRIAL REGISTRATION: ISRCTN Register 31070347; http://www.controlled-trials.com/ISRCTN31070347/31070347 Archived by WebCite at (http://www.webcitation.org/62cpeyYaY).

Item Type: Article
Uncontrolled Keywords: sdg 3 - good health and well-being ,/dk/atira/pure/sustainabledevelopmentgoals/good_health_and_well_being
Faculty \ School: Faculty of Medicine and Health Sciences > School of Health Sciences
Depositing User: Pure Connector
Date Deposited: 09 Apr 2018 15:30
Last Modified: 24 Sep 2022 03:24
URI: https://ueaeprints.uea.ac.uk/id/eprint/66711
DOI: 10.2196/jmir.1733

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