Table 1.
The five rounds of the ARISTOTLE programme: duration, number of participants and demographics.
| Round A | Round B | Round C | Round D | Round E | |
|---|---|---|---|---|---|
| Time period of recruitment | 20 August 2012–29 October 2012 | 4 December 2012–1 March 2013 | 19 March 2013–7 June 2013 | 17 June 2013–11 September 2013 | 19 September 2013–16 December 2013 |
| Duration of recruitment (weeks) | 10.0 | 12.4 | 11.4 | 12.3 | 12.6 |
| Maximum number of recruitment waves achieved | 9a | 23 | 19 | 18 | 20 |
| Number of seeds | 11 | 6 | 5 | 7 | 6 |
| Number of participants | |||||
| All participants | 1415 | 1444 | 1434 | 1413 | 1407 |
| First-time participants, n (%) | 1415 (100.0) | 766 (53.1) | 458 (31.9) | 370 (26.2) | 311 (22.1) |
| Repeat participants, n (%) | 0 (0.0) | 678 (46.9) | 976 (68.1) | 1043 (73.8) | 1096 (77.9) |
| Age, mean (SD) | |||||
| All participants | 35.5 (7.8) | 35.9 (8.2) | 36.2 (8.1) | 36.3 (8.0) | 36.3 (7.9) |
| First-time participants | 35.5 (7.8) | 36.0 (8.8) | 36.3 (8.8) | 36.1 (8.7) | 35.5 (8.2) |
| Repeat participants | – | 35.7 (7.5) | 36.2 (7.8) | 36.5 (7.7) | 36.6 (7.8) |
| Male, n (%) | |||||
| All participants | 1206 (85.2) | 1198 (83.0) | 1185 (82.6) | 1153 (81.6) | 1153 (82.0) |
| First-time participants | 1206 (85.2) | 631 (82.4) | 392 (85.6) | 316 (85.4) | 261 (83.9) |
| Repeat participants | – | 567 (83.6) | 793 (81.3) | 837 (80.3) | 892 (81.4) |
a
In round A, a 10-digit number was allowed for in the coupons where the first one or two digits identified the seed and the remaining digits identified the waves. Thus, up to nine waves were allowed for in the recruitment. Since round B, this limit in the coupon numbering was removed. SD = standard deviation.