Table 2.
Characteristics of articles reporting adherence to aspirin for cancer prevention (n = 29).
| Study and location | Design and quality | Population | Dose/timing | n⁎ | Age, years | Adherence measure | Day-to-day adherence definition | Persistence adherence definition | Follow-up time | Day-to-day adherence | Persistence adherence | Associations with adherence/ persistence |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
|
Barnes et al., 1999 US |
Non- randomised MMAT score: 4 |
Adenomatous polyps | 81 mg/daily | 10 | Mean (range) 53.6 (47–64) | Pill count | % who took medication | – | 3 months | 100.0% | – | None reported |
|
Baron et al., 2003 US and Canada |
RCT MMAT score: 3 |
Colorectal adenomas | 81 mg/daily or 325 mg/daily | 1121 | Mean (SD): 57.3 (9.9) - 57.7 (9.1) | Self-report | % who took 6–7 tablets/week | % who took ≥50% tablets in final year of trial | Approx. 3 years | 81 mg aspirin: 89.8% 325 mg aspirin: 88.0% Placebo: 87.1% |
Year 1: 97.8% Year 3: 93.6% |
None reported |
|
Benamouzig et al., 2001 France |
RCT MMAT score: 1 |
Colorectal adenomatous polyps | 300 mg/daily or 160 mg/daily | 274 | Mean (SD) 57.7 (9.4) | Pill count | % of pills taken | – | 16 months | 84.1% | – | No association with risk (ND)+ No association with gender (ND)+ |
|
Benamouzig et al., 2003 France |
RCT MMAT score: 1 |
272 | Mean % of pills taken | – | Approx. 1 year | Aspirin: 87.0% Placebo: 88.0% |
– | No association with risk (ND)+ No association with gender (ND)+ |
||||
|
Benamouzig et al., 2012 France |
RCT MMAT score: 2 |
Mean % of pills taken | – | Approx. 4 years | 88.0% | – | Adherence similar between aspirin 160 mg/day vs. aspirin 300 mg/day vs. placebo (ND)+ | |||||
|
Burn et al., 2008 International |
RCT MMAT score: 2 |
LS | 300 mg/twice daily plus resistant starch | 937 | Mean (range): 45 (25–79) | Pill count | % who took the tablets ≥80.0% of the time | – | Approx. 2 years | 81.0% | – | None reported |
|
Burn et al., 2013 International |
RCT MMAT score: 3 |
% who took 1400 (300 mg) pills ≥2 years | Mean duration of treatment | Aspirin: 30.0% Placebo: 29.1% |
Mean: 25.2 months | None reported | ||||||
|
Burney et al., 1996 US |
Non-randomised MMAT score: 2 |
Healthy adults | Up to 640 mg/daily | 64 | Not reported | Self-report and MEMS | % who took ≥80.0% of the pills | – | 14 days | Self-report: 73.0% MEMS: 44.0% Self-report and MEMS: 35.0% |
– | Self-report vs. MEMS (p = 0.002) No association with gender (p = 0.95, p = 0.78) |
|
Cook et al., 2013 US |
RCT MMAT score: 3 |
Healthy female healthcare providers | 100 mg/alternate day Plus vitamin E |
39,876 | Mean: 55 | Self-report | Active trial: % took ≥2/3 of aspirin Post-trial: % took aspirin ≥3 days per month |
Median duration of treatment | Active trial: 8 years Post-trial: 15 years |
Active trial: Aspirin (64.0%) Placebo (65.0%) Post-trial: Aspirin (46.0%) placebo (43.0%) |
Median: 9 years | None reported |
|
Duggan et al., 2014 US |
RCT MMAT score: 2 |
Post-menopausal women | 325 mg/daily | 144 | Mean (SD): 59.4 (5.4) | Pill count | % of pills taken | – | 6 months | Aspirin (87.0%) placebo (87.0%) | – | None reported |
|
Falk et al., 2012 US, Canada, Puerto Rico |
RCT MMAT score: 2 |
Barrett's Oesophagus | 81 mg/daily or 325 mg/daily Plus esomeprazole |
122 | Mean (SD): 59.7 (11.2) | Not reported | Median number of tablets taken Percentage of adherence (median) |
– | 28 days | 27–28 tablets for aspirin and placebo (median) 100.0% (median) |
– | None reported |
|
Frommel et al., 1997 US |
Non-randomised MMAT score: 3 |
CRC | 325 mg/daily then 325 mg/twice daily | 17 | Mean (SD): 65.6 (13.6) | Bleeding time | – | Increase in bleeding time at 120 days | 120 days | – | 94.1% | None reported |
|
Garland et al., 2019 US |
RCT MMAT score: 2 |
High risk of lung cancer | Intermittent: 81 mg/daily one week/placebo one week Continuous: 81 mg/daily |
54 | Mean (SD): 52 (8) | Pill count | Mean % of pills taken | % who completed the intervention | 12 weeks | 98.0% | 83.3% | None reported |
|
Hull et al., 2018 UK |
RCT MMAT score: 4 |
Colorectal adenomas | 300 mg/daily and/or eicosapentaenoic acid | 709 | Mean: 65 | Self-report | Mean % of pills taken | – | 1 year | Aspirin: 97.0% Placebo: 97.0% |
– | None reported |
|
Ishikawa et al., 2013 Japan |
RCT MMAT score: 3 |
FAP | 100 mg/daily | 34 | Mean (SD): 36.7 (13.9) – 39.7 (12.8) |
Self-report | Not reported | – | 10 months | Aspirin: 83.3% Placebo: 88.4% |
– | None reported |
|
Jankowski et al., 2018 UK and Canada |
RCT MMAT score: 2 |
Barrett's oesophagus | 300 mg/daily (UK) or 325 mg/daily (Canada) Plus esomeprazole |
2557 | Mean: 58–59 | Not reported | – | % still taking aspirin at 10 years Median duration of treatment |
Approx. 10 years | – | >25% still taking aspirin at 10 years Median: 8.9 years |
None reported |
|
Joharatnam-Hogan et al., 2019 UK |
RCT MMAT score: 3 |
Gastro-oesophageal, CRC, breast, prostate cancer | 100 mg/daily or 300 mg/daily | 2719 | Median: 52–71 | Self-report | % who took 6–7 tablets/week | – | 8 weeks | 95.0% | – | None reported |
|
Krishnan et al., 2001 US |
Non-randomised MMAT score: 4 |
High vs. normal risk for CRC | 81 mg/daily | 92 | Mean (SD): 36.5 (14.8) – 55.2 (13.9) | Self-report and pill counts | % who took ≥80.0% of the pills | – | 28 days | 100.0% | – | None reported |
|
Liesenfeld et al., 2016 US |
RCT MMAT score: 2 |
Healthy men and women | 325 mg/daily | 40 | Mean (SD): 31 (6.2) | Salicylic acid metabolites | – | % with salicylic acid metabolites detected at study end | 60 days | – | 92.5% | None reported |
|
Lipton et al., 1982 US |
RCT MMAT score: 1 |
Dukes B2 and CRC/rectal cancer | 600 mg/twice daily | 66 | Not described | Blood salicylate levels | – | % who had a salicylate level of ≥4 mg/dl at study end | Not described | – | 83.3% | None reported |
|
Logan et al., 2008 UK |
RCT MMAT score: 3 |
Colorectal adenomas | 300 mg/daily or 300 mg plus folate/daily | 939 | Mean (range): 57.8 (27.6–74.6) | Self-report and pill count | % who took ≥95.0% of the pills | % who completed trial medication | Approx. 3 years | Aspirin: 75.4% Placebo: 76.4% |
66.8% | None reported |
|
Pommergaard et al., 2016 International |
RCT MMAT score: 3 |
Colorectal adenomas | 37.5 mg aspirin with calcium carbonate/twice daily Plus calcitriol |
1107 | Median (SD): 59 (8.1) – 60 (8.3) | Pill count | Median % of pills taken | % who completed 3 years of treatment | 3 years | Aspirin: 99.0% Placebo: 99.0% |
38.6% | None reported |
|
Roop et al., 2013 US |
RCT MMAT score: 2 |
Metastatic breast cancer | 325 mg/daily plus clopidogrel | 48 | Mean: 50.7–58.4 | Platelet-function tests | – | Inhibition of platelet-function | 4 weeks | – | p < 0.001 | None reported |
|
Roy et al., 2017 US |
RCT MMAT score: 3 |
Colonoscopy For adenoma or CRC resected |
325 mg/daily | 79 | Mean (SD): 54 (11) – 57 (9) | Clinical assessment and pill counts | % who took ≥80.0% of the pills | – | 3-months | Aspirin: 100.0% Placebo: 100.0% |
– | None reported |
|
Ruffin et al., 1997 US |
Non-randomised MMAT score: 3 |
Healthy participants | 40.5 mg, 81 mg, 162 mg, 324 mg, or 648 mg/daily | 66 | Mean (range) 27.8 (19–56) | Self-report and MEMS | % who took an extra dose on day 15 | % who completed the protocol | 14 days | 40.5 mg = 20.0% 81 mg = 10.0% 162 mg = 20.0% 324 mg = 10.0% |
98.5% | None reported |
|
Sample et al., 2002a US |
RCT MMAT score: 1 |
Colorectal adenomas | 81 mg/daily or 325 mg/daily or 650 mg/daily | 60 | Mean: 58.2 | Self-report, pill count; plasma salicylate levels | % of pills taken | % whose plasma salicylate levels significantly exceeded baseline | 4 weeks | 99.0% | 93.0% (81 mg); 100.0% (325 mg); 79.0% (650 mg) |
None reported |
|
Sample et al., 2002b US |
RCT MMAT score: 1 |
43 | 40–50 (10.5%); 51–60 (36.8%); 61–70 (52.6%) |
Self-report | – | % taking aspirin regularly at mean 17.3 months | – | – | 41.9% | None reported | ||
|
Sandler et al., 2003 US |
RCT MMAT score: 3 |
CRC | 325 mg/daily | 635 | ≤39 (1%); 40–49 (14%); 50–59 (24%); 60–69 (33%); ≥70 (28%) |
Self-report | % taking 7 pills per week | Median duration of treatment | Not reported | – | Median: 30.9 months | None reported |
|
Sinicrope et al., 2019 US |
RCT MMAT score: 2 |
Advanced adenomas or cancer | 325 mg/daily plus Difluoromethylornithine | 104 | Mean (SD): 62.6 (9.09) | Pill count | % who took ≥80.0% of the pills | – | 1 year | 98.1% | – | None reported |
Key: RCT = Randomised Control Trial; n⁎ = number of participants enrolled at the beginning of the study; ND = no data presented; +significance testing not reported; MEMS = Medication Event Monitoring System; FAP = Familial Adenomatous Polyposis; LS = Lynch Syndrome; CRC = Colorectal Cancer.