Differential attrition in health behaviour change trials: A systematic review and meta-analysis

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Abstract

Abstract
Objective: Attrition is a common problem in health behaviour change (HBC) trials. When the degree of attrition differs between treatment conditions, then this is called differential attrition and is regarded as a major threat to internal validity. The primary research question of this study was: how often and to what degree does differential attrition occur in HBC trials?

Design: A systematic review and meta-analysis of a random selection of HBC trials (k = 60). We meta-analysed the relative attrition rates using a random-effects model and examined the relationship between the relative attrition rates and the potential moderators: the amount of human contact in delivery and the intensity of the intervention/control condition, the type of control condition, and the follow-up intensity and duration.

Main outcome measures: Relative attrition rates.

Results: The average attrition rate was 18% (SD = .15; M = .15) in the intervention and 17% (SD = .13; M = .13) in the control conditions. The estimated average relative attrition rate was 1.10 (95% CI: 1.01–1.20, p = .02), suggesting an overall higher attrition rate of 10% in the intervention conditions. This relative attrition rate was not related to any of the potential moderators.

Conclusion: There is indication of a slightly higher amount of attrition on average in the intervention conditions of HBC trials.
Original languageEnglish
Pages (from-to)122-134
Number of pages13
JournalPsychology & Health
Volume30
Issue number1
DOIs
Publication statusPublished - 2 Jan 2015

Keywords

  • differential attrition
  • internal validity
  • health behaviour change
  • RCT
  • bias
  • RANDOMIZED CLINICAL-TRIALS
  • PUBLICATION BIAS
  • DROPOUT RATES
  • RISK
  • INTERVENTIONS
  • OUTCOMES
  • SMOKING
  • DESIGN
  • REACH
  • FILL

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