Attrition in Smoking Cessation Intervention Studies: A Systematic Review

Abstract

Withdrawal of participants from intervention studies has dire methodological and clinical consequences. Attrition rates in smoking cessation studies have been found to be particularly high. Identifying factors that contribute to attrition may inform strategies to address the problem and prevent its consequences. This systematic review had 2 objectives: to report attrition rates, and to identify factors that influence attrition of adult smokers participating in smoking cessation intervention studies. Inclusion criteria were (1) published between 1980 and 2015; (2) experimental or quasi-experimental design; (3) pharmacological, educational, or behavioural intervention; (4) target population of adult smokers; (5) examination of attrition rate; and (6) exploration of factors associated with attrition and/or of reasons given by participants for withdrawing. These criteria were met by 10 studies. Attrition rates ranged from 10.8% to 77%. A small number of demographic, clinical, behavioural, health, health-related beliefs, and logistical factors were related to attrition. The report of high attrition rates underlines the importance of incorporating strategies to minimize attrition in smoking cessation studies. Strategies to reduce attrition are proposed.