Effects of pre-notification, invitation length, questionnaire length and reminder on participation rate: a quasi-randomised controlled trial

Abstract

BackgroundImproving participation rates in epidemiologic studies using questionnaires and biological sampling is important for the generalizability of the outcome. The aim of this study was to examine the effects of pre-notification, invitation length, questionnaire length, and reminder on participation rate and to investigate whether some factors contributed to participants doing both the questionnaire and blood sampling as oppose to only one part.MethodsOur study was embedded within the pilot testing of a large population-based study about prostate cancer screening. Our study sample consisted of 28.134 men between 50 and 69 years of age and living in the region of Stockholm (Sweden) invited to respond to a web-based questionnaire and to provide blood for prostate cancer testing. The men were randomly allocated according to birth of date to receive either: (a) a pre-notification postcard or not; (b) a shorter or a longer invitation letter; (c) a shorter or a longer web-based questionnaire, and (d) a reminder or not. The effects of the survey design factors were tested using chi-square.ResultsThe use of a pre-notification (p < 0.0001), a longer questionnaire (p = 0.004) and the use of a reminder (p = 0.02) were associated with an increase in overall participation, i.e. responding to the questionnaire or providing blood for PCT or performing both components.ConclusionsThe results of this pilot study justified the use of a pre-notification and a reminder in the following large population based study since the benefits of increased participation traded off against the greater costs incurred. Furthermore, we were able to use the longer version of the questionnaire, which allowed us to collect more information without risking a lower response rate.Electronic supplementary materialThe online version of this article (10.1186/s12874-017-0467-5) contains supplementary material, which is available to authorized users.

Patients’ reasoning regarding the decision to participate in clinical cancer trials: an interview study

“…In some cases, the referring physician had taken up the issue of clinical trials before the patient arrived at the oncology department; this may have contributed to a faster decision-making process there, as the patient had time to consider the question beforehand. Furthermore, epidemiological studies have shown that pre-notification significantly increased participation in clinical trials [ 24 ]. This is in line with other research [ 25 ] and points to the importance of regarding informed consent not as a single event but rather as a multistage process.…”

Predictors of participation in risk-based prostate cancer screening

“…In case of the latter option, there is room for improvement to increase interest in PCS and thus enhance the participation rates. Another study embedded within STHLM3 [ 25 ] showed how the use of a pre-notification postcard i.e. an introductory postcard sent a couple weeks prior to the invitation itself to STHLM3, increased participation rates.…”

A cross-sectional survey examining motivation and beliefs to participating in a web-based prospective cohort study on nutrition and health among individuals with a low socioeconomic status

“…Studies have often reported an inverse association between the length of the questionnaires and response rate [48,[53][54][55]. Inversely, results from another study showed that longer questionnaires were associated with higher participation rates, which could possibly be explained by the fact that a greater involvement in the study seemed to increase interest in research participation [56]. Participation in epidemiological studies has decreased in the past decades [46], emphasizing the importance of identifying underlying factors, including questionnaire length.…”