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.
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 language | English |
|---|---|
| Pages (from-to) | 122-134 |
| Number of pages | 13 |
| Journal | Psychology & Health |
| Volume | 30 |
| Issue number | 1 |
| DOIs | |
| Publication status | Published - 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