Poster Presentation Clinical Oncology Society of Australia Annual Scientific Meeting 2022

Should I take aspirin? (SITA): An RCT of a decision aid to support informed choices about taking aspirin to prevent cancer and other chronic disease: trial results (#219)

Shakira R Milton 1 2 , Jennifer McIntosh 2 3 , Finlay Macrae 2 4 , Patty Chondros 2 , Lucy Boyd 3 , Rushani Wijesuriya 5 , Sibel Saya 2 , Napin Karnchanachari 1 2 , Kitty Novy 2 , Natalie Taylor 6 , Mark Jenkins 3 , Fiona Walter 7 , Lyndal Trevena 8 , Javiera Martinez Gutierrez 1 2 , Kate Broun 9 , Sarah McGill 10 , Sara Whitburn 11 , George Fishman 12 , Julie Marker 12 , Max Shub 12 , Jon Emery 1 2
  1. Centre for Cancer Research, University of Melbourne, Melbourne, Victoria, Australlia
  2. Department of General Practice, University of Melbourne, Melbourne, Victoria, Australia
  3. Melbourne School of Population and Global Health, University of Melbourne, Melbourne, Victoria, Australia
  4. Colorectal Medicine and Genetics, The Royal Melbourne Hospital, Melbourne, Victoria , Australia
  5. Murdoch Childrens Research Institute, Melbourne, Victoria, Australia
  6. School of Population Health, University of New South Wales, Sydney, New South Wales, Australia
  7. Wolfson Institute of Population Health, Queen Mary London Univerisity, London, United Kingdom
  8. Primary Health Care, School of Public Health, University of Sydney, Sydney, NSW, Australia
  9. Early Detection and Immunisation, Prevention Department, Cancer Council Victoria, Melbourne, Victoria, Australia
  10. Cancer Institute of New South Wales, Sydney, New South Wales, Australia
  11. Belmore Road Medical Centre, Melbourne, Victoria, Australia
  12. PC4 Joint Community Advisory Group, University of Melbourne, Melbourne, Victoria, Australia

Background

Australian guidelines recommend that all people aged 50-70 years old consider taking aspirin for 2.5 to 5 years to reduce their risk of colorectal cancer (CRC).(1) This trial, SITA, is a randomised controlled trial with general practice patients that aims to test the efficacy of a health consultation and use of a sex-specific decision aid, to present the benefits and harms of taking low dose aspirin, on two co-primary outcomes including informed decision-making at one-month and uptake of aspirin at six-months.

Methods
Patients who weren’t currently taking aspirin were invited to participate in the trial. Participants were talked through either a decision aid or the control brochure before their GP appointments. We used multiple imputation to handle the missing trial data for the co-primary outcomes and present the complete case analysis as a sensitivity analysis.

Results
261 participants (87% of eligible patients) were randomised (129 intervention, 132 control). Baseline characteristics were balanced between the control and intervention groups. For informed choice at one-month the odds were 2.42 (0.92 to 6.36) p = 0.040. There was a 10.9% absolute increase in informed choice at 1 month in the intervention group for the complete case analysis [OR 2.76 (1.03 to 7.42) p = 0.021], (113 intervention, 118 control). The odds were 0.72 (0.29 to 1.77) p = 0.408, for aspirin uptake at six-months. A -4.1% difference between the groups for the complete case analysis [OR 0.71 (0.29 to 1.77) p = 0.417], (intervention 118, control 116).

Conclusion

A decision aid, presenting the aspirin guidelines increased informed choice but there was no difference in aspirin uptake between the intervention and control groups. As participants in both study groups were taking aspirin over time, there was contamination as this was an individually randomised trial and the control group was an active control.