Engaging lower screening groups: a field experiment to evaluate the impact of a multiwave national campaign on participation in the National Bowel Cancer Screening Program.

Objectives: This field study evaluated a multiwave media campaign that aired in 2019 to promote participation in the Australian National Bowel Cancer Screening Program (NBCSP), which provides free biennial mailed-out immunochemical faecal occult blood test (iFOBT) kits to Australians aged 50-74 years.

Design: Adjusted negative binomial regression models determined rate ratios of iFOBT kits returned during and following three campaign waves compared with 2018 (baseline). Interaction terms determined whether effects differed by gender×age group, socioeconomic status (SES) and previous participation.

Setting: Australia.

Participants: All Australians eligible for the NBCSP (men and women aged 50-74 years) who returned an iFOBT kit between 1 January 2018 and 30 October 2019.

Interventions: A multiwave national integrated media campaign to promote participation in the NBCSP.

Main Outcome Measures: iFOBT kit return rate and number of iFOBT kits returned during and immediately following campaign activity overall and within historically lower screening groups (men, 50-59 years old; lower SES; never participants).

Results: The rate of iFOBT kits returned increased significantly during all three campaign waves, with evidence of carry-over effects of the second wave coinciding with a general practitioner mail-out strategy (all p<0.001). At each wave, effects were observed among men and women in the younger (50-59 years old) age group, but were less consistent for the older age group. Each SES group and both never and previous participants had increased return rates at each wave, but increases were stronger among mid-higher SES and those who had never participated. An estimated 93 075 extra iFOBT kits were returned due to the campaign.

Conclusions: The campaign increased participation, especially among those who were younger and never previously screened-key groups to recruit given reparticipation rates of over 80%. Ongoing investment in national integrated media campaigns of sufficient duration and intensity can increase bowel cancer screening and ultimately save lives.