Keywords Endoscopy Lower GI Tract - Polyps / adenomas / ... - Colorectal cancer - CRC screening
- Quality and logistical aspects - Sedation and monitoring - Quality management
Introduction
Colorectal cancer (CRC) was diagnosed in 1.9 million people worldwide in 2022, making
it the third most common cancer. Norway has the second highest incidence of CRC in
the world after Denmark, with an estimated age-standardized incidence rate of 45.3
per 100,000 population [1 ]. Studies have shown that an increased adenoma detection rate (ADR) reduces risk
of post-colonoscopy CRC [2 ]
[3 ].
In 2017, the European Society of Gastrointestinal Endoscopy (ESGE) published performance
measures for lower gastrointestinal endoscopy as a quality improvement initiative
[4 ]. In Norway, the performance measures are registered in Gastronet [5 ], the national quality registry for colonoscopy. Gastronet uses PDR-5 (the proportion
of at least one polyp ≥ 5 mm in size per colonoscopy) as a surrogate marker for ADR.
High-quality colonoscopies are a prerequisite for preventing CRC.
Numerous factors can influence colonoscopy performance [4 ]
[6 ]
[7 ]
[8 ]. When seeking to improve colonoscopy quality, the focus has been mainly on factors
related to the endoscopist and bowel preparation. However, unmodifiable patient factors
such
as age, sex, and indication for colonoscopy, the case-mix, may vary between institutions
and
explain performance differences [9 ]
[10 ]
[11 ]
[12 ].
Regarding earlier studies on case-mix factors and quality indicators, Corley et al.
demonstrated that older and male patients have more adenomas [13 ]. Boroff et al. showed that the indication colitis had relatively low ADR [7 ]. Several studies showed that endoscopies performed as surveillance after polypectomy
or CRC treatment had high ADR [6 ]
[7 ]
[8 ]. Seip et al. [14 ] and Holme et al. [15 ] showed that pain was associated with female sex and age < 40 years. Harris et al.
showed considerable variations in colonoscopy performance between centers. Controlling
for case-mix did not significantly modify these variations, indicating that center
and procedure characteristics play a role [16 ].
In a real-life patient mix, including inflammatory bowel disease (IBD), variances
in pretest probability for presence of polyps created by differences in population
case-mix may influence PDR-5. Furthermore, case-mix factors may also impact the other
colonoscopy quality parameters cecal intubation rate (CIR) and severe pain. In this
study, based on endoscopist and patient-reported data in Gastronet, we aimed to: 1)
describe differences in patient characteristics and indications for colonoscopy among
four colonoscopy centers covering a population of approximately 400,000; and 2) identify
how differences in case-mix influence colonoscopy performance on a center level.
Patients and methods
Study design and subjects
We performed a cross-sectional study of data collected in Gastronet from January 1,
2020 to December 31, 2021 about patients who underwent colonoscopy at a university
clinic (Center 1), two local hospitals (Centers 2 and 4), and a high-volume outpatient
endoscopy practice (Center 3). The Western Norway Regional Health Authority finances
all centers and has public health responsibility for a population of approximately
400,000. The university clinic is a public, academic hospital with a substantial cohort
of IBD patients. The two local hospitals are smaller public hospitals with fewer IBD
patients. The three hospitals have endoscopy trainees, whereas the outpatient endoscopy
center only has experienced endoscopists. The outpatient endoscopy center is private
and has a public revenue agreement. It has few IBD patients. Two hospitals are CRC
screening centers, but the national screening program did not start during the study
period. The few cases classified as “screening” refer to surveillance colonoscopies
in families with CRC or “wild screening.”
Gastronet receives a report from the endoscopist and the patient. Colonoscopies for
which only the patient questionnaire was received and not the endoscopist questionnaire
were excluded. Colonoscopies with inadequate or missing demographic data were also
excluded. In patients with more than one colonoscopy performed during the study period,
we only included the first colonoscopy ([Fig. 1 ]).
Fig. 1 Patient inclusion.
Data collection from Gastronet
Gastronet data are acquired from a structured endoscopy report filled in by the endoscopist
and a patient-reported outcome measures (PROM) questionnaire completed by the patient
after the examination.
We extracted the following variables from Gastronet: demographic data (age, sex),
indication for colonoscopy, use of sedation/analgesia, Boston Bowel Preparation Scale
(BBPS), CIR (unadjusted), PDR-5, withdrawal time, and patient-reported pain (no, some,
moderate, or severe). Colonoscopy indications registered in Gastronet are several:
symptoms, post-polypectomy surveillance, post-CRC surveillance, family history of
CRC, screening, IBD, diverticulitis, appendicitis, or other. Due to few examinations
for some of the indications, we combined them into the following categories: Symptoms,
surveillance (post-polypectomy/-CRC), IBD, CRC family/screening and other (diverticulitis,
appendicitis, and other).
Recommended standards of performance measures in Gastronet are based on diagnostic
and surveillance indications and include PDR-5 ≥25% in patients ≥50 years, CIR ≥90%,
and severe pain ≤15%. Colonoscopies are performed without or with moderate sedation/analgesia,
commonly midazolam and/or alfentanil administered intravenously [17 ]. Doses of midazolam doses are typically 1 to 2 mg and of alfentanil are 0.25 to
0.50 mg. Self-reported data by the endoscopists include indication for colonoscopy,
use of sedation/analgesia with doses, bowel preparation (BBPS) [18 ]), CIR (unadjusted for poor bowel preparation or not passable strictures), PDR-5,
and withdrawal time (WT). In Gastronet the registered WT is the time spent inspecting
the mucosa during withdrawal of the colonoscope from the cecum to the anal canal,
rounded to the nearest whole minute, also including polypectomies and/or biopsies
if performed. Gastronet uses PDR-5 as a surrogate marker for ADR [5 ]
[19 ]. The endoscopist estimates polyp size using a biopsy forceps or polypectomy snare
as a reference. PDR-5 is readily available, not dependent on histology and encompasses
both adenomas and serrated polyps.
In Norway, all clinical activity is reported to the Norwegian Patient Register (NPR).
Completeness of NPR is considered to be 100% because non-reported procedures are unpaid.
NPR is used to estimate coverage of reporting to Gastronet. Completeness in this study
was defined as the proportion of NPR-registered outpatient colonoscopies reported
to Gastronet in 2020 and 2021.
Ethical considerations
Gastronet uses an anonymous registration number linked to the patient, endoscopist,
and center. Information in Gastronet is collected according to The Norwegian Directorate
of Health’s exemption from the duty of confidentiality. The Norwegian Data Protection
Authority licenses the register. The concession does not require patient consent for
registration, but patients have the right to opt out of registration and are informed
how to do this in writing [20 ]. The Regional Committee for Medical and Health Research Ethics (REC) of Western
Norway approved the study (REC-identification number 275068).
Statistical analyses
Continuous variables were presented as medians with interquartile ranges (IQRs). Categorical
variables were presented as frequencies and percentages with 95% confidence interval
(CI) using the Wald method. Pearson’s chi-squared test was used to test differences
for categorical variables. Student’s t -test was used to evaluate continuous variables. Univariable and multivariable logistic
regression analyses were performed to estimate the effect of the case-mix factors
and center on the three performance measures. We reported odds ratio (OR) and 95%
CI. We performed a sensitivity analysis in which we also included BBPS and sedation
in the multivariable models. Withdrawal time was left out of the multivariable regression
analyses because of a large amount of excluded data, because we only included colonoscopies
without biopsies or interventions. Withdrawal time is essential for visualizing as
much mucosa as possible; however, total withdrawal time may not reflect mucosa visualization
when polypectomies or multiple biopsies are performed. Statistical significance was
defined as P <0.05 using two-sided tests. Data were analyzed using IBM SPSS Statistics Version
29 (IBM, Armonk, New York, United States).
Results
Inclusion
A total of 15,990 colonoscopies were reported to Gastronet during the study period
and 1225 examinations were excluded ([Fig. 1 ]). A total of 14,765 colonoscopies/patients were included and 7873 patient questionnaires
(53.3%) were returned.
Coverage of Gastronet
In 2020 and 2021, coverage of colonoscopies reported to Gastronet increased from 71.1%
to 79% in Center 1 but decreased in all the other clinics from 69.5% to 62.3% in Center
2, 93.9% to 82.9% in Center 3, and 93.8% to 92.7% in Center 4. The proportion of returned
patient questionnaires was 47.3% (935/1978) for Center 1, 56.8% (676/1190) for Center
2, 52.7% (5481/10410) for Center 3, and 65.8% (781/1187) for Center 4.
Case-mix
[Table 1 ] shows case-mix characteristics of each center. There was significant sex difference;
54% were women (P = 0.002). Median age of the total study population was 60 years (IQR 46–71). There
were age differences between the center populations; Center 4 had the highest age
at median 65 years (IQR 53–73) and Center 1 the lowest at median 55 years (IQR 38–68),
P < 0.001. Indication frequency varied significantly among centers, P < 0.001, e.g. IBD was the indication for colonoscopy in 31.2% of the patients at
Center 1 and 1.3% at Center 3.
Table 1 Patient and center characteristics (case-mix per center).
Total N (%)
Center 1 N (%)
Center 2 N (%)
Center 3 N (%)
Center 4 N (%)
P value
CRC, colorectal cancer; IBD, inflammatory bowel disease; IQR, interquartile range.
Center 1: University clinic. Centers 2 and 4: Local hospitals. Center 3: Outpatient
endoscopy practice.
Patients
14765 (100)
1978 (100)
1190 (100)
10410 (100)
1187 (100)
Sex
0.002
6797 (46.0)
936 (47.3)
594 (49.9)
4693 (45.1)
574 (48.4)
7968 (54.0)
1042 (52.7)
596 (50.1)
5717 (54.9)
613 (51.6)
Age, years
< 0.001
2518 (17.1)
542 (27.4)
230 (19.3)
1615 (15.5)
131 (11.0)
2003 (13.6)
289 (14.6)
155 (13.0)
1445 (13.9)
114 (9.6)
2745 (18.6)
336 (17.0)
187 (15.7)
2017 (19.4)
205 (17.3)
3343 (22.6)
370 (18.7)
235 (19.7)
2448 (23.5)
295 (24.9)
3147 (21.3)
344 (17.4)
277 (23.3)
2206 (21.2)
320 (27.0)
1004 (6.8)
97 (4.9)
106 (8.9)
679 (6.5)
122 (10.3)
60 (46–71)
55 (38–68)
61 (44–72)
60 (47–71)
65 (53–73)
Indications
<0.001
8860 (60.4)
804 (41.3)
707 (60.3)
6608 (63.6)
741 (63.4)
1879 (12.8)
226 (11.6)
205 (17.5)
1267 (12.2)
181 (15.5)
1343 (9.2)
161 (8.3)
47 (4.0)
1070 (10.3)
65 (5.6)
941 (6.4)
607 (31.2)
129 (11.0)
135 (1.3)
70 (6.0)
1649 (11.2)
149 (7.7)
84 (7.2)
1305 (12.6)
111 (9.5)
93
31
18
25
19
Performance measures
PDR-5 per indication varied substantially, as illustrated in [Fig. 2 ]. The highest PDR-5 was found in surveillance colonoscopies in patients aged ≥ 50
years at 45.1% and the lowest in IBD patients at 19.1% (P < 0.001).
Fig. 2 PDR-5 per indication (% with 95 % confidence interval), all centers.
[Table 2 ] shows differences in performance measures among the centers. Severe pain was reported
in < 15% of examinations at all centers, but with significant center differences (P = 0.042) ([Table 2 ] and [Fig. 3 ]). Sedation/analgesia was administered more frequently to women than to men (P < 0.001). Regardless of this, in all centers, women reported significantly more pain
than men (P < 0.001) ([Fig. 4 ]). Withdrawal time (without biopsies or intervention) was significantly different
among the centers, with Center 1 having the longest of 10 minutes (IQR 7–12) and Center
2 the shortest of 7 minutes (IQR 5–10) (P < 0.001).
Table 2 Performance measures per center.
Total N (% [95%CI])
Center 1 N (% [95%CI])
Center 2 N (% [95%CI])
Center 3 N (% [95%CI])
Center 4 N (% [95%CI])
P value
BBPS, Boston Bowel Preparation Scale; CIR, cecal intubation rate; IQR, interquartile
range; PDR-5, proportion of at least one polyp ≥ 5 mm in size per colonoscopy.
Center 1: University clinic. Centers 2 and 4: Local hospitals. Center 3: Outpatient
endoscopy practice.
*Without biopsies/therapy.
PDR-5
3988 (27.0 [26.3–27.7])
479 (24.2 [22.3–26.1])
268 (22.5 [20.1–24.9])
2933 (28.2 [27.3–29.0])
308 (25.9 [23.5–28.4])
< 0.001
PDR-5 ≥ 50 years
3316 (32.4 [31.5–33.3])
370 (32.3 [29.6–35.0])
216 (26.8 [23.8–29.9])
2458 (33.4 [32.4–34.5])
272 (28.9 [26.0–31.8])
< 0.001
CIR
< 0.001
14278 (97.6 [97.4–97.8])
1856 (96.5 [95.6–97.3])
1116 (95.2 [94.0–96.4])
10228 (98.6 [98.4–98.8])
1078 (93.0 [91.5–94.5])
349 (2.4 [2.1–2.4])
68 (3.5 [2.7–4.4])
56 (4.8 [3.6–6.0])
144 (1.4 [1.2–1.6])
81 (7.0 [5.5–8.5])
Missing
138
54
18
38
28
BBPS
< 0.001
13514 (96.0 [95.7–96.3])
1717 (92.9 [91.7–94.0])
1039 (94.9 [93.6–96.2])
9750 (97.0 [96.6–97.3])
1008 (93.2 [91.7–94.7])
566 (4.0 [3.7–4.3])
132 (7.1 [6.0–8.3])
56 (5.1 [3.8–6.4])
304 (3.0 [2.7–3.4])
74 (6.8 [5.3–8.3])
685
129
95
356
105
Pain, severe
0.042
713 (9.2 [8.5–9.8])
90 (9.7 [7.8–11.7])
78 (11.7 [9.2–14.1])
467 (8.6 [7.9–9.4])
78 (10.1 [8.0–12.3])
7072 (90.8 [90.2–91.5])
834 (90.3 [88.3–92.2])
591 (88.3 [85.9–90.8])
4955 (91.4 [90.6–92.1])
692 (89.9 [87.7–92.0])
6980
1054
521
4988
417
Sedation/analgesia
< 0.001
5360 (36.8 [36.1–37.6)])
1286 (69.0 [66.9–71.1])
581 (50.7 [47.8–53.5])
2664 (25.7 [24.8–26.5])
829 (71.5 [68.9–74.1])
9190 (63.2 [62.4–63.9])
579 (31.0 [28.9–33.1])
566 (49.3 [46.5–52.2])
7714 (74.3 [73.5–75.2])
331 (28.5 [25.9–31.1])
215
113
43
32
27
Withdrawal time*
< 0.001
4093 (75.2 [74.1–76.4])
317 (87.1 [83.6–90.5])
267 (63.0 [58.4–67.6])
3126 (74.9 [73.6–76.2])
383 (79.8 [76.2–83.4])
1347 (24.8 [23.6–25.9])
47 (12.9 [9.5–16.4])
157 (37.0 [32.4–41.6])
1046 (25.1 [23.8–26.4])
97 (20.2 [16.6–23.8])
9325
1614
766
6238
707
8 (6–10)
10 (7–12)
7 (5–10)
8 (5–11)
8 (6–10)
Fig. 3 Performance measures per center (%) with 95% confidence interval. Significant differences
between centres: †p <0.001. ‡p=0.042.
Fig. 4 Severe pain and sedation/analgesia. % with 95 % confidence interval. Women report
more severe pain (13.1%) than men (4.6%) (p<0.001). More women (48.3%) than men (22.8%)
receive sedation/analgesia (p<0.001).
Case-mix influence on performance measures
[Table 3 ] displays univariable and multivariable regression analyses of the performance measures
PDR-5, CIR, and severe pain related to the case-mix (sex, age, indication) and center.
Table 3 Univariable and multivariable analyses of case-mix and performance measures.
PDR-5
CIR
Severe pain
Variable
Categories
N N (% [95% CI])
P value
OR (95 % CI)
N N (% [95% CI])
P value
OR (95 % CI)
N N (% [95% CI])
P value
OR (95 % CI)
CI, confidence interval; CIR, cecal intubation rate; CRC, colorectal cancer; IBD,
inflammatory bowel disease; OR, odds ratio PDR-5, proportion of at least one polyp
≥ 5 mm in size per colonoscopy.
Bold font identifies significant results.
Center 1: University clinic. Centers 2 and 4: Local hospitals. Center 3: Outpatient
endoscopy practice.
P values derive from Pearson’s chi-squared test (univariable analysis). ORs were calculated
through a binary logistic regression (multivariable analysis).
Sex
Women
1959 (24.6 [23.6–25.5])
< 0.001
Reference
7694 (97.4 [97.1–97.8])
0.140
Reference
549 (13.1 [12.1–14.1])
< 0.001
Reference
Men
2029 (29.9 [28.8–30.9])
1.27 (1.18–1.37)
6584 (97.8 [97.5–98.2])
1.21 (0.97–1.51)
164 (4.6 [3.9–5.2])
0.33 (0.27–0.39)
Age, years
< 40
280 (11.1 [9.9–12.3])
< 0.001
Reference
2465 (98.9 [98.5–99.3])
< 0.001
Reference
71 (11.4 [8.9–13.9])
0.290
Reference
40–49
392 (19.6 [17.8–21.3])
1.85 (1.57–2.19)
1969 (98.9 [98.4–99.4])
0.87 (0.49–1.54)
58 (8.2 [6.2–10.3])
0.71 (0.49–1.03)
50–59
627 (22.8 [21.3–24.4])
2.25 (1.93–2.63)
2670 (98.1 [97.5–98.6])
0.48 (0.30–0.77)
134 (9.5 [8.0–11.1])
0.87 (0.63–1.19)
60–69
1198 (35.8 [34.2–37.4])
3.96 (3.42–4.58)
3241 (97.5 [97.0–98.1])
0.37 (0.24–0.59)
184 (8.5 [7.3–9.7])
0.80 (0.59–1.08)
70–79
1136 (36.1 [34.4–37.8])
4.03 (3.47–4.67)
2988 (96.2 [95.5–96.8])
0.26 (0.17–0.40)
210 (9.4 [8.2–10.6])
0.87 (0.65–1.17)
≥ 80
355 (35.4 [32.4–38.3])
4.01 (3.34–4.82)
945 (95.4 [94.0–96.7])
0.23 (0.14–0.38)
56 (8.6 [6.4–10.7])
0.75 (0.51–1.10)
Indications
Symptoms
2206 (24.9 [24.0–25.8])
< 0.001
Reference
8573 (97.5 [97.1–97.8])
< 0.001
Reference
447 (10.1 [9.2–11.0])
< 0.001
Reference
Surveillance (polyp, CRC)
843 (44.9 [42.6–47.1])
1.88 (1.69–2.09)
1834 (98.1 [97.5–98.7])
1.90 (1.31–2.74)
73 (6.1 [4.7–7.4])
0.66 (0.51–0.86)
CRC family/screening
377 (28.1 [25.7–30.5])
1.12 (0.98–1.28)
1320 (99.0 [98.5–99.6])
2.27 (1.29–4.02)
53 (6.9 [5.1–8.7])
0.69 (0.51–0.93)
IBD
137 (14.6 [12.3–16.8])
0.64 (0.52–0.78)
903 (98.0 [97.2–98.9])
1.74 (1.04–2.92)
25 (5.9 [3.6–8.1])
0.52 (0.33–0.81)
Other
404 (24.5 [22.4–26.6])
0.79 (0.70–0.89)
1578 (96.9 [96.1–97.8])
0.88 (0.64–1.20)
112 (12.3 [10.2–14.4])
1.34 (1.07–1.68)
Missing
21 (22.6 [14.1–31.1])
0.89 (0.54–1.46)
70 (88.6 [81.6–95.6])
0.34 (0.16–0.71)
3 (5.7 [0–11.9])
0.52 (0.16–1.71)
Center
Center 1
479 (24.2 [22.3–26.1])
< 0.001
1.02 (0.90–1.15)
1856 (96.5 [95.6–97.3])
< 0.001
0.30 (0.22–0.41)
90 (9.7 [7.8–11.7])
0.040
1.36 (1.05–1.76)
Center 2
268 (22.5 [20.1–24.9])
0.72 (0.62–0.83)
1116 (95.2 [94.0–96.4])
0.27 (0.20–0.37)
78 (11.7 [9.2–14.1])
1.57 (1.21–2.04)
Center 3
2933 (28.2 [27.3–29.0])
Reference
10228 (98.6 [98.4–98.8])
Reference
467 (8.6 [7.9–9.4])
Reference
Center 4
308 (25.9 [23.5–28.4])
0.79 (0.69–0.91)
1078 (93.0 [91.5–94.5])
0.21 (0.16–0.28)
78 (10.1 [8.0–12.3])
1.26 (0.98–1.64)
PDR-5 increased with male sex (OR 1.27, 95 % CI 1.18–1.37) and higher age. PDR-5 was
significantly influenced by indication, i.e. surveillance (OR 1.88, 95% CI 1.69–2.09)
and IBD (OR 0.64, 95% CI 0.52–0.78). Center influenced PDR-5, with Center 2 (OR 0.72,
95% CI 0.62–0.83) and Center 4 (OR 0.79, 95% CI 0.69–0.91) having significantly lower
PDR-5.
CIR was reduced by increasing age. CIR was significantly influenced by indication,
i.e. surveillance (OR 1.90, 95% CI 1.31–2.74) and IBD (OR 1.74, 95% CI 1.04–2.92).
CIR was not affected by sex (OR 1.21, 95% CI 0.97–1.51).
Severe pain was less frequent in men (OR 0.33, 95% CI 0.27–0.39). Indication significantly
influenced pain, i.e. surveillance (OR 0.66, 95% CI 0.51–0.86) and IBD (OR 0.52, 95%
CI 0.33–0.81). Severe pain was not affected by age. There was a significant difference
in severe pain when comparing the age groups over and under 40 years with univariable
analysis. In the group aged < 40 years, 71 of 622 patients (11.4%, 95% CI 8.9–13.9)
reported severe pain, whereas 642 of 7163 patients aged ≥ 40 years (9.0%, 95% CI 8.3–9.6)
reported severe pain (P = 0.042). When performing multivariable regression analysis with the case-mix factors,
age < 40 years was not significant for severe pain (OR 1.22, 95% CI 0.93–1.60).
When we adjusted P values for BBPS and sedation, as shown in [Table 4 ], there were no substantial effects on the results. Differences among centers remained
when the same analyses were performed with stratification for each indication.
Table 4 Univariable and multivariable analyses of performance measures after inclusion of
BBPS and sedation/analgesia.
PDR-5
CIR
Severe pain
Variable
Categories
N (% [95% CI])
P value
OR (95 % CI)
N (% [95% CI])
P value
OR (95 % CI)
N (% [95% CI])
P value
OR (95 % CI)
BBPS, Boston Bowel Preparation Scale; CI, confidence interval; CIR, cecal intubation
rate; CRC, colorectal cancer; IBD, inflammatory bowel disease; OR, odds ratio; PDR-5,
proportion of at least one polyp ≥ 5 mm in size per colonoscopy.
Bold font identifies significant results.
Center 1: University clinic. Centers 2 and 4: Local hospitals. Center 3: Outpatient
endoscopy practice.
P values derive from Pearson’s chi-squared test (univariable analysis).
ORs were calculated through a binary logistic regression (multivariable analysis).
Sex
Women
1959 (24.6 [23.6–25.5])
< 0.001
Reference
7694 (97.4 [97.1–97.8])
0.140
Reference
549 (13.1 [12.1–14.1])
< 0.001
Reference
Men
2029 (29.9 [28.8–30.9])
1.30 (1.20–1.40)
6584 (97.8 [97.5–98.2])
1.12 (0.85–1.48)
164 (4.6 [3.9–5.2])
0.46 (0.38–0.56)
Age, years
< 40
280 (11.1 [9.9–12.3])
< 0.001
Reference
2465 (98.9 [98.5–99.3])
< 0.001
Reference
71 (11.4 [8.9–13.9])
0.290
Reference
40–49
392 (19.6 [17.8–21.3])
1.86 (1.56–2.20)
1969 (98.9 [98.4–99.4])
0.88 (0.46–1.68)
58 (8.2 [6.2–10.3])
0.71 (0.49–1.03)
50–59
627 (22.8 [21.3–24.4])
2.27 (1.94–2.65)
2670 (98.1 [97.5–98.6])
0.49 (0.28–0.84)
134 (9.5 [8.0–11.1])
0.87 (0.63–1.20)
60–69
1198 (35.8 [34.2–37.4])
3.99 (3.45–4.62)
3241 (97.5 [97.0–98.1])
0.46 (0.28–0.77)
184 (8.5 [7.3–9.7])
0.78 (0.57–1.06)
70–79
1136 (36.1 [34.4–37.8])
4.08 (3.52–4.73)
2988 (96.2 [95.5–96.8])
0.30 (0.18–0.49)
210 (9.4 [8.2–10.6])
0.85 (0.63–1.15)
≥80
355 (35.4 [32.4–38.3])
4.10 (3.41–4.92)
945 (95.4 [94.0–96.7])
0.37 (0.21–0.66)
56 (8.6 [6.4–10.7])
0.74 (0.50–1.09)
Indications
Symptoms
2206 (24.9 [24.0–25.8])
< 0.001
Reference
8573 (97.5 [97.1–97.8])
< 0.001
Reference
447 (10.1 [9.2–11.0])
< 0.001
Reference
Surveillance (polyp, CRC)
843 (44.9 [42.6–47.1])
1.90 (1.71–2.12)
1834 (98.1 [97.5–98.7])
4.49 (2.95–6.86)
73 (6.1 [4.7–7.4])
0.65 (0.50–0.85)
CRC family/screening
377 (28.1 [25.7–30.5])
1.12 (0.98–1.28)
1320 (99.0 [98.5–99.6])
1.74 (0.91–3.30)
53 (6.9 [5.1–8.7])
0.77 (0.57–1.05)
IBD
137 (14.6 [12.3–16.8])
0.64 (0.52–0.78)
903 (98.0 [97.2–98.9])
1.87 (1.03–3.42)
25 (5.9 [3.6–8.1])
0.51 (0.33-–0.80)
Other
404 (24.5 [22.4–26.6])
0.79 (0.70–0.89)
1578 (96.9 [96.1–97.8])
1.06 (0.72–1.56)
112 (12.3 [10.2–14.4])
1.28 (1.01–1.61)
Missing
21 (22.6 [14.1–31.1])
0.93 (0.56–1.53)
70 (88.6 [81.6–95.6])
0.59 (0.22–1.56)
3 (5.7 [0–11.9])
0.56 (0.17–1.84)
Center
Center 1
479 (24.2 [22.3–26.1])
< 0.001
1.00 (0.88–1.14)
1856 (96.5 [95.6–97.3])
< 0.001
0.54 (0.36–0.79)
90 (9.7 [7.8–11.7])
0.040
0.82 (0.63–1.07)
Center 2
268 (22.5 [20.1–24.9])
0.72 (0.62–0.83)
1116 (95.2 [94.0–96.4])
0.40 (0.27–0.60)
78 (11.7 [9.2–14.1])
1.16 (0.89–1.53)
Center 3
2933 (28.2 [27.3–29.0])
Reference
10228 (98.6 [98.4–98.8])
Reference
467 (8.6 [7.9–9.4])
Reference
Center 4
308 (25.9 [23.5–28.4])
0.78 (0.67–0.90)
1078 (93.0 [91.5–94.5])
0.33 (0.22–0.48)
78 (10.1 [8.0–12.3])
0.71 (0.54–0.93)
BBPS
≥ 6
3637 (26.9 [26.2–27.7])
0.200
Reference
13337 (99.5 [99.4–99.6])
< 0.001
Reference
636 (8.9 [8.3–9.6])
0.009
Reference
< 6
171 (30.2 [26.4–34.0])
0.99 (0.82–1.20)
519 (92.5 [90.3–94.7])
0.07 (0.05–0.11)
28 (9.6 [6.2–12.9])
1.17 (0.77–1.76)
Sedation/analgesia
Yes
1350 (25.2 [24.0–26.3])
< 0.001
1.07 (0.98–1.17)
5093 (96.3 [95.8–96.8])
< 0.001
0.67 (0.50–0.90)
452 (17.1 [15.6–18.5])
< 0.001
3.36 (2.81–4.02)
No
2585 (28.1 [27.2–29.0])
Reference
8992 (98.4 [98.2–98.7])
Reference
257 (5.1 [4.5–5.7])
Reference
Discussion
We evaluated 14,765 first colonoscopies from western Norway registered in Gastronet
over 2 years. There were significant effects from the examined case-mix factors (age,
sex, and indication) on the colonoscopy performance measures PDR-5, CIR, and pain.
First, we demonstrated that all factors strongly influence PDR-5. Consistent with
previous findings [13 ], we found that older patients and men had higher PDR-5. We found that IBD had the
lowest PDR-5 and surveillance the highest. These results align with earlier studies
[7 ]
[19 ]
[21 ]
[22 ]. Overall, previous studies have found that ADR in primary screening was comparable
to ADR in clinical colonoscopies. A consistent finding in these studies was that the
indication surveillance after polypectomy had a high ADR. The indication IBD had a
relatively low PDR-5 in our material, even in the age group ≥ 50 years. This is surprising
because we have learned that IBD increases risk of colorectal cancer [23 ]. A recent study from Sweden concluded that there was an increased risk of neoplastic
colorectal polyps in IBD patients [24 ]. The low PDR-5 in IBD patients in our data may be due to several colonoscopies from
an early age and surveillance. Also, carcinogenesis in IBD might not follow the traditional
adenoma-carcinoma sequence. There may be non-mass-forming dysplasia in IBD, which
can be challenging to detect [23 ].
CIR was influenced by age and indication. Younger patients had significantly higher
CIR, as shown by Nass et al. [9 ]. CIR was not associated with sex in our data; this differs from the study by Nass
et al., which showed that male sex was associated with higher CIR. Good-quality BBPS
was significantly associated with high CIR. This concurs with earlier studies, e.g.
Hoff et al. [25 ]. Sedation was associated with higher CIR, which indicates more successful intubation
when pain is relieved.
Among indications, surveillance and IBD had higher CIR and less pain. This may be
due to repeated colonoscopies and adequate sedation related to previous colonoscopy
experiences.
Pain is the only parameter reported by patients in this study. Even though it is an
important performance measure, pain is rarely reported in larger colonoscopy studies.
To the best of our knowledge, our study is one of the few that have examined patient-reported
pain in addition to the performance measures polyp detection and cecal intubation.
Sex and indication, but not age, were associated with pain. Age < 40 years was a significant
factor for severe pain in the univariable analysis, but this association was no longer
significant in the multivariable analysis. This differs from the studies by Seip et
al. [14 ] and Holme et al. [15 ]. Pain was highly associated with increased sedation/analgesia. This may indicate
that when sedation/analgesia is provided, its dosage and timing is inadequate. It
may also indicate that other factors besides sedation are essential to reduce pain,
e.g. colonoscopy technique.
There were significant differences among the centers in case-mix and performance measures.
The difference in withdrawal time between the centers is especially interesting. Center
1 had a longer withdrawal time than the other centers, at 10 minutes, and this may
contribute to the relatively high PDR-5 at Center 1, even though they had a large
cohort of IBD patients. Center 2 had a relatively low withdrawal time of 7 minutes,
which can lead to a lower PDR-5. A limitation is that we only included withdrawal
time in colonoscopies during which no interventions or biopsies were performed. This
reflects visualization time more adequately than when time is used on procedures,
leaving out 63.2% of the colonoscopies. However, 24.8% of the included colonoscopies
had withdrawal time < 6 minutes. ESGE performance measures for lower gastrointestinal
endoscopy recommend a minimum withdrawal time of 6 minutes and a target of 10 minutes
[4 ]. All centers met the minimum performance standards for PDR-5, CIR, and severe pain.
They also performed well on bowel cleansing, with > 90% adequate BBPS. However, there
are apparent differences in the performance measures among the centers, which may
depend on the individual endoscopist.
A strength of our study is the large number of colonoscopies and inclusion of different
clinical indications, which reflect everyday practice. The different types of centers
represent the spectrum of outpatient colonoscopy services. Gastronet is widely used
in Norway and encompasses a solid database with many parameters.
Retrospective evaluation of data on a center level with few centers may limit general
conclusions about center differences. Individual endoscopist factors such as experience,
volume, and training may explain some of the center differences. Individual endoscopist
data were not available in this study. Gastronet data rely on self-reporting by individual
endoscopists, and missing reports may introduce selection bias. Coverage of Gastronet
for colonoscopy in the four studied centers was 62% to 94% in 2020 and 2021. Because
these data are used to evaluate colonoscopy performance, low coverage represents an
important limitation to quality registers. Self-reported data may be incomplete or
biased when the same data are used publicly to study the endoscopy centers [26 ]. Endoscopists may also be prone to the Hawthorne effect, i.e. attempt to change
or improve their behavior when being evaluated or studied [27 ]. A limitation regarding patient experience and pain is a relatively low patient
response, varying from 47.3% to 65.8%.
A future aspect of evaluation of colonoscopy quality is a more objective standardization
of performance indicators. To adjust the performance measures for case-mix, various
methods have been suggested, e.g. the ADR-ESS (ADR Extended to all Screening/ Surveillance)
Score by Ladabaum et al. [10 ] and the observed/expected ratio (O/E ratio) by Nass et al. [9 ]. This may be considered in quality registries like Gastronet.
In the future, artificial intelligence (AI) may also aid in standardizing performance
measures and reporting. Endoscopic imaging is well suited for evaluation by AI, not
only as a polyp detection and characterization tool but also as a quality-of-endoscopy
tool. AI can evaluate bowel preparation, completeness of colonoscopy, and withdrawal
time, parameters that are subjectively reported by endoscopists today. This may influence
the performance measure thresholds and warrants future studies.
Conclusions
This study found that case-mix (age, sex, and indication) significantly influences
the colonoscopy performance measures PDR-5, CIR, and severe pain on a center level.
This may affect institutional and individual colonoscopy quality parameters, which
is vital for the individual track record of endoscopists. Although we showed center
differences in performance, other factors, such as individual endoscopist skills,
probably influence performance measures. The effect of using case-mix-adjusted quality
parameters for evaluation of colonoscopy performance warrants further prospective
follow-up studies.
Bibliographical Record
