title: Adherence to colorectal cancer screening: four rounds of faecal immunochemical test-based screening.
abstract: The effectiveness of faecal immunochemical test (FIT)-based screening programs is highly dependent on consistent participation over multiple rounds. We evaluated adherence to FIT screening over four rounds and aimed to identify determinants of participation behaviour.
  
  
  
  A total of 23 339 randomly selected asymptomatic persons aged 50-74 years were invited for biennial FIT-based colorectal cancer screening between 2006 and 2014. All were invited for every consecutive round, except for those who had moved out of the area, passed the upper age limit, or had tested positive in a previous screening round. A reminder letter was sent to non-responders. We calculated participation rates per round, response rates to a reminder letter, and differences in participation between subgroups defined by age, sex, and socioeconomic status (SES).
  
  
  
  Over the four rounds, participation rates increased significantly, from 60% (95% CI 60-61), 60% (95% CI 59-60), 62% (95% CI 61-63) to 63% (95% CI 62-64; P for trend<0.001) with significantly higher participation rates in women in all rounds (P<0.001). Of the 17 312 invitees eligible for at least two rounds of FIT screening, 12 455 (72%) participated at least once, whereas 4857 (28%) never participated; 8271 (48%) attended all rounds when eligible. Consistent participation was associated with older age, female sex, and higher SES. Offering a reminder letter after the initial invite in the first round increased uptake with 12%; in subsequent screening rounds this resulted in an additional uptake of up to 10%.
  
  
  
  In four rounds of a pilot biennial FIT-screening program, we observed a consistently high and increasing participation rate, whereas sending reminders remain effective. The substantial proportion of inconsistent participants suggests the existence of incidental barriers to participation, which, if possible, should be identified and removed.
authors.affiliation: Department of Gastroenterology and Hepatology, Academic Medical Centre, University of Amsterdam, Meibergdreef 9, Amsterdam 1105 AZ, The Netherlands.
authors.forename: Manon
authors.initials: M
authors.lastname: van der Vlugt
authors.affiliation: Department of Gastroenterology and Hepatology, Erasmus University Medical Centre, Gravendijkwal 230, Rotterdam 3015 CE, The Netherlands.
authors.forename: Esmée J
authors.initials: EJ
authors.lastname: Grobbee
authors.affiliation: Department of Clinical Epidemiology, Biostatistics and Bioinformatics, Academic Medical Center, University of Amsterdam, Meibergdreef 9, Amsterdam 1105 AZ, The Netherlands.
authors.forename: Patrick Mm
authors.initials: PM
authors.lastname: Bossuyt
authors.affiliation: Regional Organization for Population Screening Mid-West Netherlands, Hoogoorddreef 54 E, Amsterdam 1101 BE, The Netherlands.
authors.forename: Evelien
authors.initials: E
authors.lastname: Bongers
authors.affiliation: Regional Organization for Population Screening South-West Netherlands, Maasstadweg 124, Rotterdam 3079 DZ, The Netherlands.
authors.forename: Wolfert
authors.initials: W
authors.lastname: Spijker
authors.affiliation: Department of Gastroenterology and Hepatology, Erasmus University Medical Centre, Gravendijkwal 230, Rotterdam 3015 CE, The Netherlands.
authors.forename: Ernst J
authors.initials: EJ
authors.lastname: Kuipers
authors.affiliation: Department of Public Health, Erasmus University Medical Centre, Gravendijkwal 230, Rotterdam 3015 CE, The Netherlands.
authors.forename: Iris
authors.initials: I
authors.lastname: Lansdorp-Vogelaar
authors.affiliation: Department of Public Health, Academic Medical Center, University of Amsterdam, 's-Gravendijkwal 230, Amsterdam 3015 CE, The Netherlands.
authors.forename: Marie-Louise
authors.initials: ML
authors.lastname: Essink-Bot
authors.affiliation: Department of Gastroenterology and Hepatology, Erasmus University Medical Centre, Gravendijkwal 230, Rotterdam 3015 CE, The Netherlands.
authors.forename: Manon C W
authors.initials: MC
authors.lastname: Spaander
authors.affiliation: Department of Gastroenterology and Hepatology, Academic Medical Centre, University of Amsterdam, Meibergdreef 9, Amsterdam 1105 AZ, The Netherlands.
authors.forename: Evelien
authors.initials: E
authors.lastname: Dekker
mesh_terms: D000368:Aged; D015179:Colorectal Neoplasms / Q000175:diagnosis* / Q000453:epidemiology / Q000378:metabolism; D055088:Early Detection of Cancer / Q000379:methods / Q000706:statistics & numerical data*; D005243:Feces / Q000737:chemistry*; D005260:Female; D006801:Humans; D007150:Immunohistochemistry / Q000706:statistics & numerical data; D008297:Male; D008403:Mass Screening / Q000379:methods / Q000706:statistics & numerical data; D008875:Middle Aged; D009426:Netherlands / Q000453:epidemiology; D009780:Occult Blood; D010349:Patient Compliance / Q000706:statistics & numerical data*; D010358:Patient Participation; D012042:Registries