Endoscopic vs Histological Look at Polyps During Colonoscopy
Endoscopic vs Histological Look at Polyps During Colonoscopy
Table 1 shows details of patients, colonoscopy procedures and polyps detected. In the following, the results for both groups are mostly presented combined.
The caecum was reached in almost all cases (residual faeces or technical problems prevented full inspection of the caecum in three cases). No complications were encountered. A total of 11 carcinomas were found, but these were not counted in the calculation of adenoma rate.
In total, 724 out of 729 polyps detected were available for analysis; in the remaining five cases, no histological data wren gained or documented. A total of 681 of these polyps were either adenomas or hyperplastic polyps, but in six cases, in vivo assessment by examiners was missing. Thus, 675 polyps were left for final data analysis, of which 461 were adenomas (including six sessile serrated adenomas) and 214 hyperplastic polyps. Polyp size was <1 cm for 86.9% of adenomas and 99.5% for hyperplastic polyps. Larger-size polyps (>1 cm) were all adenomas except for one. Polyp location was right or left sided for 38.1% and 61.9% of adenomas and 28.5% and 71.5% of hyperplastic polyps, respectively.
The accuracy results with respect to polyp characteristics are shown in Table 2. Overall accuracy was 76.6%; sensitivity (78.1%) and specificity (73.4%) were also only moderate. Intraclass correlation was 0.30 (p<0.001), indicating that the diagnostic quality was more similar in polyps from the same patient than in polyps from different patients. In other words, the diagnostic quality was determined in 30% of cases by the individual patient and in 70% of cases by the individual polyp. The corresponding log-linear model (figure 1) analysing different factors with regards to patients, polyps, examiner and instrument characteristics demonstrates that accuracy did not depend on age, gender, polyp location or examiners' adenoma detection rate. However, longer withdrawal times had a significant influence on accuracy (p=0.02). In polyps 6–10 mm in size, accuracy was significantly higher than for smaller size polyps (1–5 mm) for adenomatous polyps, not for hyperplastic polyps; the same was true for flat adenomas (not hyperplastic polyps). Accuracy over the study period did not differ significantly between the first half and the second half of cases included by all participating physicians (77.9% vs 74.9%).
(Enlarge Image)
Figure 1.
In vivo diagnosis of adenomas (n=461) versus hyperplastic polyps (n=214): forest plot of factors potentially influencing the diagnostic accuracy, resulting from a generalised logistic mixed model; OR. LCL, lower confidence limit; UCL, upper confidence limit.
Of the included patients, 530 were randomly assigned to the conventional (Classic Line) group and 539 to the new technology (Hi Line with I-Scan, called I-Scan) group. Adenoma detection rate (rate of patients with at least one adenoma) was not significantly different between these two groups; in addition, the differential diagnostic ability was not different. In detail, sensitivity was higher for Hi Line and specificity higher for Classic Line. Detailed results are shown in table 3. Also, the log-linear model (see figure 1) showed a significant superiority of the newer type instruments (iScan) in the correct diagnosis of adenomas, but not of hyperplastic polyps. Since there was no difference between the groups, the results are mostly presented in combination.
The results for appropriate follow-up recommendations based on polyp in vivo assessment in patients with polyps up to 10 mm in size are shown in Table 4. Of 409 patients with colon polyps in the study, 347 were selected as suitable for this analysis; exclusion of the remaining 62 was due to larger polyp size (n=44), missing histological data or missing in vivo assessment (n=18). Incorrect follow-up allocation was found in 30.5% of all patients; no significant differences were found between patient groups with polyps 1–5 mm or 6–10 mm.
Table 5 shows the results of the five examiners for sensitivity and specificity on the basis of images selected as suitable by each of them, the rate of which was highly variable. The results are again shown for both types of instruments in combination. Since accuracy values for each examiner were only calculated on the basis of the set of polyps they had individually selected as suitable, a direct comparison of the observed values would be substantially biased as they related to individually selected images. We therefore used a statistical model that adjusted for covariates and polyp/image selection. In a multivariate analysis (figure 2), overall accuracy increased with polyp size (p<0.001) and the number of images available (p=0.004). In general, agreement between physicians was low: κ values were 0.45 for all five examiners, 0.55 for the three endoscopists in private practice and 0.53 for the two hospital endoscopists. However, university endoscopists were significantly more accurate in correctly diagnosing adenomas, but significantly inferior in correctly diagnosing hyperplastic polyps (figure 2). Examples of endoscopic polyp images are shown in figure 3.
(Enlarge Image)
Figure 2.
Post hoc analysis using photographs of 198 polyps (see text): forest plot of factors potentially influencing the diagnostic accuracy, resulting from a generalised logistic mixed model; OR. LCL, lower confidence limit; UCL, upper confidence limit.
(Enlarge Image)
Figure 3.
Endoscopic images of a 5 mm colon low-grade adenoma without (A) and with (B) iScan function, and of a 3 mm colonic hyperplastic polyp without (C) and with (D) iScan function.
Results
Patients and Polyps
Table 1 shows details of patients, colonoscopy procedures and polyps detected. In the following, the results for both groups are mostly presented combined.
The caecum was reached in almost all cases (residual faeces or technical problems prevented full inspection of the caecum in three cases). No complications were encountered. A total of 11 carcinomas were found, but these were not counted in the calculation of adenoma rate.
In total, 724 out of 729 polyps detected were available for analysis; in the remaining five cases, no histological data wren gained or documented. A total of 681 of these polyps were either adenomas or hyperplastic polyps, but in six cases, in vivo assessment by examiners was missing. Thus, 675 polyps were left for final data analysis, of which 461 were adenomas (including six sessile serrated adenomas) and 214 hyperplastic polyps. Polyp size was <1 cm for 86.9% of adenomas and 99.5% for hyperplastic polyps. Larger-size polyps (>1 cm) were all adenomas except for one. Polyp location was right or left sided for 38.1% and 61.9% of adenomas and 28.5% and 71.5% of hyperplastic polyps, respectively.
In Vivo Polyp Differential Diagnosis
The accuracy results with respect to polyp characteristics are shown in Table 2. Overall accuracy was 76.6%; sensitivity (78.1%) and specificity (73.4%) were also only moderate. Intraclass correlation was 0.30 (p<0.001), indicating that the diagnostic quality was more similar in polyps from the same patient than in polyps from different patients. In other words, the diagnostic quality was determined in 30% of cases by the individual patient and in 70% of cases by the individual polyp. The corresponding log-linear model (figure 1) analysing different factors with regards to patients, polyps, examiner and instrument characteristics demonstrates that accuracy did not depend on age, gender, polyp location or examiners' adenoma detection rate. However, longer withdrawal times had a significant influence on accuracy (p=0.02). In polyps 6–10 mm in size, accuracy was significantly higher than for smaller size polyps (1–5 mm) for adenomatous polyps, not for hyperplastic polyps; the same was true for flat adenomas (not hyperplastic polyps). Accuracy over the study period did not differ significantly between the first half and the second half of cases included by all participating physicians (77.9% vs 74.9%).
(Enlarge Image)
Figure 1.
In vivo diagnosis of adenomas (n=461) versus hyperplastic polyps (n=214): forest plot of factors potentially influencing the diagnostic accuracy, resulting from a generalised logistic mixed model; OR. LCL, lower confidence limit; UCL, upper confidence limit.
Differences Between Endoscopes
Of the included patients, 530 were randomly assigned to the conventional (Classic Line) group and 539 to the new technology (Hi Line with I-Scan, called I-Scan) group. Adenoma detection rate (rate of patients with at least one adenoma) was not significantly different between these two groups; in addition, the differential diagnostic ability was not different. In detail, sensitivity was higher for Hi Line and specificity higher for Classic Line. Detailed results are shown in table 3. Also, the log-linear model (see figure 1) showed a significant superiority of the newer type instruments (iScan) in the correct diagnosis of adenomas, but not of hyperplastic polyps. Since there was no difference between the groups, the results are mostly presented in combination.
Accuracy of Follow-up Recommendations
The results for appropriate follow-up recommendations based on polyp in vivo assessment in patients with polyps up to 10 mm in size are shown in Table 4. Of 409 patients with colon polyps in the study, 347 were selected as suitable for this analysis; exclusion of the remaining 62 was due to larger polyp size (n=44), missing histological data or missing in vivo assessment (n=18). Incorrect follow-up allocation was found in 30.5% of all patients; no significant differences were found between patient groups with polyps 1–5 mm or 6–10 mm.
Post Hoc Polyp Image Analysis
Table 5 shows the results of the five examiners for sensitivity and specificity on the basis of images selected as suitable by each of them, the rate of which was highly variable. The results are again shown for both types of instruments in combination. Since accuracy values for each examiner were only calculated on the basis of the set of polyps they had individually selected as suitable, a direct comparison of the observed values would be substantially biased as they related to individually selected images. We therefore used a statistical model that adjusted for covariates and polyp/image selection. In a multivariate analysis (figure 2), overall accuracy increased with polyp size (p<0.001) and the number of images available (p=0.004). In general, agreement between physicians was low: κ values were 0.45 for all five examiners, 0.55 for the three endoscopists in private practice and 0.53 for the two hospital endoscopists. However, university endoscopists were significantly more accurate in correctly diagnosing adenomas, but significantly inferior in correctly diagnosing hyperplastic polyps (figure 2). Examples of endoscopic polyp images are shown in figure 3.
(Enlarge Image)
Figure 2.
Post hoc analysis using photographs of 198 polyps (see text): forest plot of factors potentially influencing the diagnostic accuracy, resulting from a generalised logistic mixed model; OR. LCL, lower confidence limit; UCL, upper confidence limit.
(Enlarge Image)
Figure 3.
Endoscopic images of a 5 mm colon low-grade adenoma without (A) and with (B) iScan function, and of a 3 mm colonic hyperplastic polyp without (C) and with (D) iScan function.