Number of subjects followed up (FU) at each follow up round until 30 November 1996
| High risk | Low risk | ||||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| (1) 1 yearly FS | (2) 2 yearly FS | (3) 2 yearly colon | (4) 2 yearly FS | (5) 5 yearly FS | (6) 5 yearly colon | ||||||||||||
| Follow up visit2-1 | n avail2-2 | n (%) FU2-3 | n avail2-2 | n (%) FU2-3 | n avail2-2 | n (%) FU2-3 | n avail2-2 | n (%) FU2-3 | n avail2-2 | n (%) FU2-3 | n avail2-2 | n (%) FU2-3 | |||||
| 1 | 114 | 103 (90) | 93 | 81 (87) | 73 | 63 (86) | 147 | 126 (86) | 101 | 75 (74) | 73 | 48 (66) | |||||
| 2 | 95 | 86 (91) | 58 | 49 (85) | 44 | 38 (86) | 88 | 76 (86) | 25 | 19 (76) | 16 | 12 (75) | |||||
| 3 | 76 | 66 (87) | 36 | 34 (94) | 24 | 22 (92) | 55 | 43 (78) | 6 | 6 (100) | 3 | 2 (67) | |||||
| 4 | 56 | 51 (91) | 19 | 18 (95) | 14 | 11 (79) | 23 | 17 (74) | 3 | 3 (100) | 0 | — | |||||
| 5 | 38 | 34 (90) | 6 | 4 (67) | 6 | 3 (50) | 9 | 9 (100) | 1 | 1 (100) | 0 | — | |||||
| 6 | 29 | 25 (86) | 2 | 2 (100) | 2 | 1 (50) | 5 | 5 (100) | 0 | — | 0 | — | |||||
| Lost to follow up3 | n (%) | n (%) | n (%) | n (%) | n (%) | n (%) | |||||||||||
| After 2 years | 20 (19) | 12 (13) | 10 (14) | 21 (14) | — | — | |||||||||||
| After 5 years | 39 (53) | 22 (35)2-150 | 17 (36) | 39 (40) | 26 (26)2-160 | 25 (34)2-150 | |||||||||||
↵2-1 Number of subjects available for follow up. Subjects not available for follow up are those who died before there next follow up visit was due, who were aged over 75 when their next follow up visit was due, or whose next follow up visit was due after 30 November 1996.
↵2-2 Number and percentage of those available for follow up that were successfully followed up.
↵2-3 Denominator for percentage calculation only includes subjects who were available for follow up.
↵2-150 p<0.05,
↵2-160 p<0.01 compared with group 1.
FS, flexible sigmoidoscopy; colon, colonoscopy.