Timing of surveillance colonoscopy relative to recommended intervals according to guideline in effect (by period) and adenoma patient group, Kaplan-Meier analysis
| Period of index colonoscopy | Recommended interval (year) | Too early (%) | Appropriate* (%) | Delayed or no surveillance (%) | No surveillance† (%) |
|---|---|---|---|---|---|
| June 1998–2001 | |||||
| 1 adenoma (n=1676) | 2–3 | 24 | 24 | 53 | 35 |
| 2 adenomas (n=397) | 1 | 4 | 23 | 73 | 32 |
| 3+ adenomas (n=230) | 1 | 6 | 30 | 63 | 22 |
| Overall (n=2303) | 19 | 24 | 57 | 33 | |
| In 2002 | |||||
| 1 adenoma (n=417) | 6 | 47 | 9 | 44 | 40 |
| 2 adenomas (n=160) | 6 | 57 | 11 | 33 | 33 |
| 3+ adenomas (n=117) | 3 | 39 | 18 | 43 | 33 |
| Overall (n=694) | 48 | 11 | 41 | 37 | |
| Overall, all patients (n=2997) | 25 | 21 | 53 | 34 | |
Due to rounding row percentages may not add up to 100%.
*Appropriate interval, before 2002: 1-year plus or minus 3 months, 2–3 years plus or minus 6 months; and in 2002: 3- or 6-years plus or minus 6 months.
†by the end of the study (1 December 2008) or within 90 months, whichever came first.