Participation rates of childhood cancer survivors to self-administered questionnaires: a systematic review

This review aimed to assess participation rates of childhood cancer survivors (CCS) invited to fill out a health-related questionnaire. Additionally, effects of study and CCS characteristics on participation rates were examined. PubMed, Web of Science, Ovid (EMBASE) and CINAHL databases were searched. Publications included were questionnaire-based studies among CCS diagnosed with cancer before the age of 21, alive at least 5 years past diagnosis and aged 16 years or older at the time of study. Thirty-five studies were included; the median participation rate was 65%. Sixteen studies reported information about CCS actively declining participation (median rate 5%). Five study characteristics seemed to influence participation rates: the use of reminders and incentives, the option to answer a shortened questionnaire, the recruitment of participants through their general practitioner and a pre-notification before sending out the questionnaire. Furthermore, CCS characteristics related to improved participation were female gender, Caucasian ethnicity and a higher educational level. The results of this study will help to improve the (methodological) quality of future questionnaire-based studies among CCS, thereby increasing our knowledge about late effects among this group of survivors.