A total of 64,554 participants completed the baseline questionnaires and underwent baseline FSG. The mean age of the participants was 63 years, 51.1% were male, the mean BMI was 27.3 kg/m2 and 10.6% had a first-degree relative with CRC. A total of 57,470 (89%) participants had adequate FSG examination while 7,084 (11%) participants had inadequate FSG at baseline. Of 49,359 participants included in this study who were expected for repeat FSG screening 3–5 years later, 39,385 (79.8%) returned for their procedures. When compared to those with adequate baseline FSG who were expected for repeat screening, participants with inadequate FSG at baseline were less likely to return for repeat screening overall (65.3% versus 81.6%; P value <0.001). When analyzed by the expected time to return for repeat FSG, of participants expected for a FSG in year 3, 80.8% returned (82.4% with adequate and 67.7% with inadequate baseline FSG). Of participants expected for a repeat FSG at year 5, 79.4% returned (81.3% with adequate and 64.3% with inadequate baseline FSG).
A total of 5,021 (12.7%) participants had inadequate FSG at repeat screening 3–5 years after the baseline examination. displays reasons for inadequate FSG at baseline and at repeat FSG 3–5 years later. The depth of insertion was not recorded for 21 (0.3%) and 6 (0.1%) participants at baseline and repeat FSG, respectively. At baseline, of 6,496 participants with less than 50 cm depth of insertion, 4,889 (75.3%) reported patient discomfort. Of the 567 participants with adequate depth of insertion, 500 (88.2%) were due to poor bowel preparation. Of the 5,015 participants with inadequate FSG at repeat screening with known depth of insertion of the sigmoidoscope, 4,509 (89.9%) had less than 50 cm depth of insertion and participant discomfort was associated with 3,275 (72.6%) inadequate procedures. The mean length of insertion of sigmoidoscope for participants with less than 50cm of insertion was 34.9 cm at baseline and 35.4 cm at repeat FSG. Suboptimal bowel preparation was documented for 1,759 (35.0%) inadequate FSG at repeat examination, of whom 469 (26.7%) had adequate depth of insertion.
Reasons for inadequate flexible sigmoidoscopy (FSG) screening by depth of insertion a
When compared to those with adequate FSG at baseline, participants with an inadequate examination were older (mean age 63.6 versus 63.0 years; P value <0.001) and had lower mean BMI (26.7 versus 27.4 kg/m2; P value <0.001). However, there was no difference in the proportion of participants with a first degree relative with a history of CRC (10.7% versus 10.6%; P value = 0.935). We found a similar pattern among participants who underwent repeat FSG 3–5 years after the baseline examination (data not shown).
In our fully adjusted model for baseline FSG, advancing age in 5-year increment from age 60 was associated with significantly increased odds of inadequate FSG with odds ratios (OR) ranging from 1.08 to 1.51 (). Female sex and history of smoking particularly current smoking were also associated with inadequate FSG. Advanced education, overweight (BMI 25– 29 kg/m2) and obesity (BMI > 30 kg/m2) were associated with reduced odds. At repeat FSG 3–5 years later, a similar pattern was observed except that cigarette smoking was not significantly associated with increased odds of inadequate FSG (). However, the strongest predictor of inadequate FSG at repeat screening was inadequate baseline FSG (OR = 6.24; 95% CI: 5.77 – 6.75). An astonishing 44% of those with inadequate FSG at baseline had inadequate FSG at repeat examination 3–5 years later.
Risk factors for inadequate baseline flexible sigmoidoscopy a
Risk factors for inadequate repeat flexible sigmoidoscopy a