Systematic review and meta analysis of differential attrition between active and control arms in randomized controlled trials of lifestyle interventions in chronic disease.

BACKGROUND

Attrition is a major obstacle for lifestyle interventions sustained for the medium-to-long term and can have significant consequences on the internal validity of a trial. When the degree of attrition differs between active and control arms this is termed differential attrition and is an important consideration during initial stages of trial planning.

OBJECTIVES

The primary research question of this study was: what is the differential attrition between treatment arms in lifestyle interventions for prevalent chronic diseases?

METHODS

We performed a systematic review and meta-analysis of 23 studies involving a lifestyle intervention component in cohorts with chronic diseases. The search accessed three databases: Scopus, Medline Ovid and Web of Science. Attrition between treatment arms was analysed using a random-effects model and examined the relationship between the relative attrition and potential moderators, such as time to final follow-up, time to first follow-up, type of disease, type of control, type of intervention and length of treatment.

RESULTS

The pooled risk ratio was 1.00 (95% CI 0.97 - 1.03) and only one study fell outside this range. A univariable association was described between the pooled risk ration and length (years) to final follow-up, which did not remain in the multivariable model.

CONCLUSIONS

Ultimately, we found no evidence of differential attrition in medium-to-long term lifestyle intervention studies for chronic disease, increasing confidence in conducting such studies with minimal potential of attrition bias.

TRIAL REGISTRATION

PROSPERO registration number CRD42018084495 .