Effect of Colonoscopy Screening on Risks of Colorectal Cancer and Related Death.

BACKGROUND: Although colonoscopy is widely used as a screening test to detect colorectal cancer, its effect on the risks of colorectal cancer and related death is unclear. METHODS: We performed a pragmatic, randomized trial involving presumptively healthy men and women 55 to 64 years of age drawn from population registries in Poland, Norway, Sweden, and the Netherlands between 2009 and 2014. The participants were randomly assigned in a 1:2 ratio either to receive an invitation to undergo a single screening colonoscopy (the invited group) or to receive no invitation or screening (the usual-care group). The primary end points were the risks of colorectal cancer and related death, and the secondary end point was death from any cause. RESULTS: Follow-up data were available for 84,585 participants in Poland, Norway, and Sweden - 28,220 in the invited group, 11,843 of whom (42.0%) underwent screening, and 56,365 in the usual-care group. A total of 15 participants had major bleeding after polyp removal. No perforations or screening-related deaths occurred within 30 days after colonoscopy. During a median follow-up of 10 years, 259 cases of colorectal cancer were diagnosed in the invited group as compared with 622 cases in the usual-care group. In intention-to-screen analyses, the risk of colorectal cancer at 10 years was 0.98% in the invited group and 1.20% in the usual-care group, a risk reduction of 18% (risk ratio, 0.82; 95% confidence interval [CI], 0.70 to 0.93). The risk of death from colorectal cancer was 0.28% in the invited group and 0.31% in the usual-care group (risk ratio, 0.90; 95% CI, 0.64 to 1.16). The number needed to invite to undergo screening to prevent one case of colorectal cancer was 455 (95% CI, 270 to 1429). The risk of death from any cause was 11.03% in the invited group and 11.04% in the usual-care group (risk ratio, 0.99; 95% CI, 0.96 to 1.04). CONCLUSIONS: In this randomized trial, the risk of colorectal cancer at 10 years was lower among participants who were invited to undergo screening colonoscopy than among those who were assigned to no screening. (Funded by the Research Council of Norway and others; NordICC ClinicalTrials.gov number, NCT00883792.).

A Comparison of Risk Classification Systems of Colorectal Adenomas: A Case-Cohort Study.

BACKGROUND & AIMS: Because post-polypectomy surveillance uses a growing proportion of colonoscopy capacity, more targeted surveillance is warranted. We therefore compared surveillance burden and cancer detection using 3 different adenoma classification systems. METHODS: In a case-cohort study among individuals who had adenomas removed between 1993 and 2007, we included 675 individuals with colorectal cancer (cases) diagnosed a median of 5.6 years after adenoma removal and 906 randomly selected individuals (subcohort). We compared colorectal cancer incidence among high- and low-risk individuals defined according to the traditional (high-risk: diameter ≥10 mm, high-grade dysplasia, villous growth pattern, or 3 or more adenomas), European Society of Gastrointestinal Endoscopy (ESGE) 2020 (high-risk: diameter ≥10 mm, high-grade dysplasia, or 5 or more adenomas), and novel (high-risk: diameter ≥20 mm or high-grade dysplasia) classification systems. For the different classification systems, we calculated the number of individuals recommended frequent surveillance colonoscopy and estimated number of delayed cancer diagnoses. RESULTS: Four hundred and thirty individuals with adenomas (52.7%) were high risk based on the traditional classification, 369 (45.2%) were high risk based on the ESGE 2020 classification, and 220 (27.0%) were high risk based on the novel classification. Using the traditional, ESGE 2020, and novel classifications, the colorectal cancer incidences per 100,000 person-years were 479, 552, and 690 among high-risk individuals, and 123, 124, and 179 among low-risk individuals, respectively. Compared with the traditional classification, the number of individuals who needed frequent surveillance was reduced by 13.9% and 44.2%, respectively, and 1 (3.4%) and 7 (24.1%) cancer diagnoses were delayed using the ESGE 2020 and novel classifications. CONCLUSIONS: Using the ESGE 2020 and novel risk classifications will substantially reduce resources needed for colonoscopy surveillance after adenoma removal.

Rates of repeated colonoscopies to clean the colon from low-risk and high-risk adenomas: results from the EPoS trials.

OBJECTIVE: High-quality colonoscopy (adequate bowel preparation, whole-colon visualisation and removal of all neoplastic polyps) is a prerequisite to start polyp surveillance, and is ideally achieved in one colonoscopy. In a large multinational polyp surveillance trial, we aimed to investigate clinical practice variation in number of colonoscopies needed to enrol patients with low-risk and high-risk adenomas in polyp surveillance. DESIGN: We retrieved data of all patients with low-risk adenomas (one or two tubular adenomas <10 mm with low-grade dysplasia) and high-risk adenomas (3-10 adenomas, ≥1 adenoma ≥10 mm, high-grade dysplasia or villous components) in the European Polyp Surveillance trials fulfilling certain logistic and methodologic criteria. We analysed variations in number of colonoscopies needed to achieve high-quality colonoscopy and enter polyp surveillance by endoscopy centre, and by endoscopists who enrolled ≥30 patients. RESULTS: The study comprised 15 581 patients from 38 endoscopy centres in five European countries; 6794 patients had low-risk and 8787 had high-risk adenomas. 961 patients (6.2%, 95% CI 5.8% to 6.6%) underwent two or more colonoscopies before surveillance began; 101 (1.5%, 95% CI 1.2% to 1.8%) in the low-risk group and 860 (9.8%, 95% CI 9.2% to 10.4%) in the high-risk group. Main reasons were poor bowel preparation (21.3%) or incomplete colonoscopy/polypectomy (14.4%) or planned second procedure (27.8%). Need of repeat colonoscopy varied between study centres ranging from 0% to 11.8% in low-risk adenoma patients and from 0% to 63.9% in high-risk adenoma patients. On the second colonoscopy, the two most common reasons for a repeat (third) colonoscopy were piecemeal resection (26.5%) and unspecified reason (23.9%). CONCLUSION: There is considerable practice variation in the number of colonoscopies performed to achieve complete polyp removal, indicating need for targeted quality improvement to reduce patient burden. TRIAL REGISTRATION NUMBER: NCT02319928.

Impact of time between faecal immunochemical tests in colorectal cancer screening on screening results: A natural experiment.

Repeated rounds of faecal immunochemical testing (FIT) for occult blood is a common method for screening for colorectal cancer (CRC). However, the time interval between FIT rounds is not thoroughly investigated. In a CRC screening trial in South-Eastern Norway, individuals were invited for biennial FIT between 2012 and 2019. The positivity threshold was >15 mcg haemoglobin/g faeces (mcg/g). Due to organizational challenges, the interval between screening rounds randomly varied between 1.5 and 3.5 years, forming a natural experiment. We investigated the detection rate of CRC and advanced neoplasia (AN: CRC or advanced adenoma) at the subsequent round (FIT2 ), according to the faecal haemoglobin concentration (f-Hb) at the initial screening round (FIT1 ), and time between the two screening rounds. 18 522 individuals with negative FIT1 who attended FIT2 were included in this study. 245 AN were detected at FIT2 , of which 34 were CRC. The CRC detection rate at FIT2 for participants with FIT1  = 0 mcg/g was 0.09% while it was 0.28% for participant with 0 > FIT1 ≤ 15 mcg/g; odds ratio (OR) 3.22, 95% CI 1.49-6.95. For each 3 months' increment between FITs, the OR for detecting CRC was 1.33 (95% CI 0.98-1.79), while the OR was 1.13 (1.02-1.26) for AN. Individuals with FIT1 -value of 0 mcg/g, had a lower AN detection rate compared with participants with 0 > FIT1 ≤ 15 mcg/g, irrespective of time between tests. Although CRC and AN detection rates increase with increasing time interval between FITs, individuals with undetectable f-Hb at first screen have substantially lower risk of CRC at the next screening round compared with individuals with detectable f-Hb.

Impact of Artificial Intelligence on Colonoscopy Surveillance After Polyp Removal: A Pooled Analysis of Randomized Trials.

BACKGROUND AND AIMS: Artificial intelligence (AI) tools aimed at improving polyp detection have been shown to increase the adenoma detection rate during colonoscopy. However, it is unknown how increased polyp detection rates by AI affect the burden of patient surveillance after polyp removal. METHODS: We conducted a pooled analysis of 9 randomized controlled trials (5 in China, 2 in Italy, 1 in Japan, and 1 in the United States) comparing colonoscopy with or without AI detection aids. The primary outcome was the proportion of patients recommended to undergo intensive surveillance (ie, 3-year interval). We analyzed intervals for AI and non-AI colonoscopies for the U.S. and European recommendations separately. We estimated proportions by calculating relative risks using the Mantel-Haenszel method. RESULTS: A total of 5796 patients (51% male, mean 53 years of age) were included; 2894 underwent AI-assisted colonoscopy and 2902 non-AI colonoscopy. When following U.S. guidelines, the proportion of patients recommended intensive surveillance increased from 8.4% (95% CI, 7.4%-9.5%) in the non-AI group to 11.3% (95% CI, 10.2%-12.6%) in the AI group (absolute difference, 2.9% [95% CI, 1.4%-4.4%]; risk ratio, 1.35 [95% CI, 1.16-1.57]). When following European guidelines, it increased from 6.1% (95% CI, 5.3%-7.0%) to 7.4% (95% CI, 6.5%-8.4%) (absolute difference, 1.3% [95% CI, 0.01%-2.6%]; risk ratio, 1.22 [95% CI, 1.01-1.47]). CONCLUSIONS: The use of AI during colonoscopy increased the proportion of patients requiring intensive colonoscopy surveillance by approximately 35% in the United States and 20% in Europe (absolute increases of 2.9% and 1.3%, respectively). While this may contribute to improved cancer prevention, it significantly adds patient burden and healthcare costs.

A pilot study of implementation of endoscopic sleeve gastroplasty (ESG) in Norway.

BACKGROUND AND AIM: Bariatric surgery is the most effective treatment for obesity but is invasive and associated with serious complications. Endoscopic sleeve gastroplasty (ESG) is a less invasive weight loss procedure to reduce the stomach volume by full-thickness sutures. ESG has been adopted in many countries, but implementation at Scandinavian centres has not yet been documented. We performed a clinical pilot trial at a Norwegian centre with the primary objective to assess the feasibility of the ESG procedure. PATIENTS AND METHODS: We included the first 10 patients treated with ESG at a Norwegian centre in a single-arm pilot study. The eligibility criteria were either a body mass index (BMI) of 40-49.9 kg/m2, BMI 35-39.9 kg/m2 and at least one obesity-related comorbidity, or BMI 30-34.9 kg/m2 and type 2 diabetes. Patient follow-up resembled the scheme used for bariatric surgery at the center, including dietary plans and outpatient visits. RESULTS: All procedures were technically successful except for one patient who had adhesions between the stomach and anterior abdominal wall, related to a prior hernia repair, resulting in less-than-intended stomach volume reduction. Mean total body weight loss (TBWL) after 26 and 52 weeks was 12.2% (95% CI 8.1-16.2) and 9.1% (95% CI 3.3 - 15.0). One patient experienced a minor suture-induced diaphragmatic injury, which was successfully managed conservatively. CONCLUSIONS: This first Scandinavian clinical trial of ESG, documenting the implementation of the procedure at a Norwegian center, demonstrated acceptable feasibility and safety, with large variations in individual weight loss during the 52-week follow-up period.

Speedometer for withdrawal time monitoring during colonoscopy: a clinical implementation trial.

OBJECTIVES: Meticulous inspection of the mucosa during colonoscopy, represents a lengthier withdrawal time, but has been shown to increase adenoma detection rate (ADR). We investigated if artificial intelligence-aided speed monitoring can improve suboptimal withdrawal time. METHODS: We evaluated the implementation of a computer-aided speed monitoring device during colonoscopy at a large academic endoscopy center. After informed consent, patients ≥18 years undergoing colonoscopy between 5 March and 29 April 2021 were examined without the use of the speedometer, and with the speedometer between 29 April and 30 June 2021. All colonoscopies were recorded, and withdrawal time was assessed based on the recordings in a blinded fashion. We compared mean withdrawal time, percentage of withdrawal time ≥6 min, and ADR with and without the speedometer. RESULTS: One hundred sixty-six patients in each group were eligible for analyses. Mean withdrawal time was 9 min and 6.6 s (95% CI: 8 min and 34.8 s to 9 min and 39 s) without the use of the speedometer, and 9 min and 9 s (95% CI: 8 min and 45 s to 9 min and 33.6 s) with the speedometer; difference 2.3 s (95% CI: -42.3-37.7, p = 0.91). The ADRs were 45.2% (95% CI: 37.6-52.8) without the speedometer as compared to 45.8% (95% CI: 38.2-53.4) with the speedometer (p = 0.91). The proportion of colonoscopies with withdrawal time ≥6 min without the speedometer was 85.5% (95% CI: 80.2-90.9) versus 86.7% (95% CI: 81.6-91.9) with the speedometer (p = 0.75). CONCLUSIONS: Use of speed monitoring during withdrawal did not increase withdrawal time or ADR in colonoscopy. CLINICALTRIALS.GOV IDENTIFIER: NCT04710251.

15-Year Benefits of Sigmoidoscopy Screening on Colorectal Cancer Incidence and Mortality : A Pooled Analysis of Randomized Trials.

BACKGROUND: The effectiveness of screening for colorectal cancer (CRC) by sex and age in randomized trials is uncertain. OBJECTIVE: To evaluate the 15-year effect of sigmoidoscopy screening on CRC incidence and mortality. DESIGN: Pooled analysis of 4 large-scale randomized trials of sigmoidoscopy screening. SETTING: Norway, the United States, the United Kingdom, and Italy. PARTICIPANTS: Women and men aged 55 to 64 years at enrollment. INTERVENTION: Sigmoidoscopy screening. MEASUREMENTS: Primary end points were cumulative incidence rate ratio (IRR) and mortality rate ratio (MRR) and rate differences after 15 years of follow-up comparing screening versus usual care in intention-to-treat analyses. Stratified analyses were done by sex, cancer site, and age at screening. RESULTS: Analyses comprised 274 952 persons (50.7% women), 137 493 in the screening and 137 459 in the usual care group. Screening attendance was 58% to 84%. After 15 years, the rate difference for CRC incidence was 0.51 cases (95% CI, 0.40 to 0.63 cases) per 100 persons and the IRR was 0.79 (CI, 0.75 to 0.83). The rate difference for CRC mortality was 0.13 deaths (CI, 0.07 to 0.19 deaths) per 100 persons, and the MRR was 0.80 (CI, 0.72 to 0.88). Women had less benefit from screening than men for CRC incidence (IRR for women, 0.84 [CI, 0.77 to 0.91]; IRR for men, 0.75 [CI, 0.70 to 0.81]; P = 0.032 for difference) and mortality (MRR for women, 0.91 [CI, 0.77 to 1.17]; MRR for men, 0.73 [CI, 0.64 to 0.83]; P = 0.025 for difference). There was no statistically significant difference in screening effect between persons aged 55 to 59 years and those aged 60 to 64 years. LIMITATION: Data from the U.K. trial were less granular because of privacy regulations. CONCLUSION: This pooled analysis of all large randomized trials of sigmoidoscopy screening demonstrates a significant and sustained effect of sigmoidoscopy on CRC incidence and mortality for 15 years. PRIMARY FUNDING SOURCE: Health Fund of South-East Norway.

Colonoscopist Performance and Colorectal Cancer Risk After Adenoma Removal to Stratify Surveillance: Two Nationwide Observational Studies.

BACKGROUND AND AIMS: Colonoscopy surveillance after adenoma removal is an increasing burden in many countries. Surveillance recommendations consider characteristics of removed adenomas, but not colonoscopist performance. We investigated the impact of colonoscopist performance on colorectal cancer risk after adenoma removal. METHODS: We compared colorectal cancer risk after removal of high-risk adenomas, low-risk adenomas, and after negative colonoscopy for all colonoscopies performed by colonoscopists with low vs high performance quality (adenoma detection rate <20% vs ≥20%) in the Polish screening program between 2000 and 2011, with follow-up until 2017. Findings were validated in the Austrian colonoscopy screening program. RESULTS: A total of 173,288 Polish colonoscopies were included in the study. Of 262 colonoscopists, 160 (61.1%) were low performers, and 102 (38.9%) were high performers; 11.1% of individuals had low-risk and 6.6% had high-risk adenomas removed at screening; 82.2% had no adenomas. During 10 years of follow-up, 443 colorectal cancers were diagnosed. For low-risk adenoma individuals, colorectal cancer incidence was 0.55% (95% confidence interval [CI] 0.40-0.75) with low-performing colonoscopists vs 0.22% (95% CI 0.14-0.34) with high-performing colonoscopists (hazard ratio [HR] 2.35; 95% CI 1.31-4.21; P = .004). For individuals with high-risk adenomas, colorectal cancer incidence was 1.14% (95% CI 0.87-1.48) with low-performing colonoscopists vs 0.43% (95% CI 0.27-0.69) with high-performing colonoscopists (HR 2.69; 95% CI 1.62-4.47; P < .001). After negative colonoscopy, colorectal cancer incidence was 0.30% (95% CI 0.27-0.34) for individuals examined by low-performing colonoscopists, vs 0.15% (95% CI 0.11-0.20) for high-performing (HR 2.10; 95% CI 1.52-2.91; P < .001). The observed trends were reproduced in the Austrian validation cohort. CONCLUSIONS: Our results suggest that endoscopist performance may be an important contributor in addition to polyp characteristics in determining colorectal cancer risk after colonoscopy screening.

Complete polyp resection with cold snare versus hot snare polypectomy for polyps of 4-9 mm: a randomized controlled trial.

BACKGROUND: Endoscopic screening with polypectomy reduces the incidence of colorectal cancer (CRC). Incomplete polyp removal may attenuate the effect of screening. This randomized trial compared cold snare polypectomy (CSP) with hot snare polypectomy (HSP) in terms of complete polyp resection. METHODS: We included patients ≥ 40 years of age at eight hospitals in four countries who had at least one non-pedunculated polyp of 4-9 mm detected at colonoscopy. Patients were randomized 1:1 to CSP or HSP. Biopsies from the resection margins were obtained systematically after polypectomy in both groups. We hypothesized that CSP would be non-inferior to HSP, with a non-inferiority margin of 5 %. Logistic regression models were fitted to identify the factors explaining incomplete resection. RESULTS: 425 patients, with 601 polyps, randomized to either CSP or HSP were included in the analysis. Of 318 polyps removed by CSP and 283 polyps removed by HSP, 34 (10.7 %) and 21 (7.4 %) were incompletely resected, respectively, with an adjusted risk difference of 3.2 % (95 %CI -1.4 % to 7.8 %). There was no difference between the groups in terms of post-polypectomy bleeding, perforation, or abdominal pain. Independent risk factors for incomplete removal were serrated histology (odds ratio [OR] 3.96; 95 %CI 1.63 to 9.66) and hyperplastic histology (OR 2.52; 95 %CI 1.30 to 4.86) in adjusted analyses. CONCLUSION: In this randomized trial, non-inferiority for CSP could not be demonstrated. Polyps with serrated histology are more prone to incomplete resection compared with adenomas. CSP can be used safely for small polyps in routine colonoscopy practice.

A progressive three-state model to estimate time to cancer: a likelihood-based approach.

BACKGROUND: To optimize colorectal cancer (CRC) screening and surveillance, information regarding the time-dependent risk of advanced adenomas (AA) to develop into CRC is crucial. However, since AA are removed after diagnosis, the time from AA to CRC cannot be observed in an ethically acceptable manner. We propose a statistical method to indirectly infer this time in a progressive three-state disease model using surveillance data. METHODS: Sixteen models were specified, with and without covariates. Parameters of the parametric time-to-event distributions from the adenoma-free state (AF) to AA and from AA to CRC were estimated simultaneously, by maximizing the likelihood function. Model performance was assessed via simulation. The methodology was applied to a random sample of 878 individuals from a Norwegian adenoma cohort. RESULTS: Estimates of the parameters of the time distributions are consistent and the 95% confidence intervals (CIs) have good coverage. For the Norwegian sample (AF: 78%, AA: 20%, CRC: 2%), a Weibull model for both transition times was selected as the final model based on information criteria. The mean time among those who have made the transition to CRC since AA onset within 50 years was estimated to be 4.80 years (95% CI: 0; 7.61). The 5-year and 10-year cumulative incidence of CRC from AA was 13.8% (95% CI: 7.8%;23.8%) and 15.4% (95% CI: 8.2%;34.0%), respectively. CONCLUSIONS: The time-dependent risk from AA to CRC is crucial to explain differences in the outcomes of microsimulation models used for the optimization of CRC prevention. Our method allows for improving models by the inclusion of data-driven time distributions.

A novel intragastric balloon for treatment of obesity and type 2 diabetes. A two-center pilot trial.

BACKGROUND AND AIMS: Obesity with type-2 diabetes is a global challenge. Lifestyle interventions have limited effect for most patients. Bariatric surgery is highly effective, but resource-demanding, invasive and associated with serious complications. Recently, a new intragastric balloon was introduced, not requiring endoscopy for placement or removal (Elipse™, Allurion Inc., Natick, MA). The balloon is swallowed in a capsule and filled with water once in the stomach. The balloon self-deflates after 4 months and is naturally excreted. The present trial investigated balloon feasibility, safety and efficacy in patients with obesity and type-2 diabetes. PATIENTS AND METHODS: We treated 19 patients, with type-2 diabetes and body mass index (BMI) of 30.0-39.9 kg/m2 at two Norwegian centers with the Elipse balloon. Patient follow-up during balloon treatment mimicked real-world clinical practice, including dietary plan and outpatient visits. The primary efficacy endpoints were total body weight loss (TBWL) and HbA1c at weeks 16 and 52. RESULTS: All patients underwent balloon insertion uneventfully as out-patients. Mean TBWL and HbA1c reduction after 16 and 52 weeks of balloon insertion was 3.9% (95%CI 2.1-5.7) and 0.8% (95%CI 1.9-3.5); and 7 (95%CI 4-10), and 1 (95%CI -6 to 9) mmol/mol, respectively. Adverse events occurred in two patients (10.5%): one developed gastric outlet obstruction, managed by endoscopic balloon removal; the other excessive vomiting and dehydration, managed conservatively. CONCLUSIONS: This first Scandinavian real-world clinical trial with a new minimally invasive intragastric balloon system demonstrated good feasibility, but did not confirm expected efficacy for weight loss and diabetes control.

Impact of artificial intelligence on colorectal polyp detection for early-career endoscopists: an international comparative study.

BACKGROUND: Artificial intelligence (AI) for polyp detection is being introduced to colonoscopy, but there is uncertainty how this affects endoscopists' ability to detect polyps and neoplasms. We performed a video-based study to address whether AI improved the endoscopists' performance to detect polyps. METHODS: We established a dataset of 200 colonoscopy videos (length 5 s; 100 without polyps and 100 with one polyp). About 33 early-career endoscopists (50-400 colonoscopies performed) from 10 European countries classified each video as either 'polyp present' or 'polyp not present'. The video assessment was performed twice with a four-week interval. The first assessment was performed without any AI tool, whereas the second was performed with an AI tool for polyp detection. The primary endpoint was early-career endoscopists' sensitivity to detect polyps. Gold standard for presence and histology of polyps were confirmed by two expert endoscopists and pathologists, respectively. McNemar's test was used for statistical significance. RESULTS: There were 86 neoplastic and 14 non-neoplastic polyps (mean size 5.6 mm) in the 100 videos with polyps. Early-career endoscopists' sensitivity to detect polyps increased from 86.3% (95% confidence interval [CI]: 85.1-87.5%) to 91.7% (95%CI: 90.7-92.6%) with the AI aid (p < .0001). Their sensitivity to detect neoplastic polyps increased from 85.4% (95% CI: 84.0-86.7%) to 92.1% (95%CI: 91.1-93.1%) with the AI aid (p < .0001). CONCLUSION: The polyp detection AI tool helped early-career endoscopists to increase their sensitivity to identify all polyps and neoplastic polyps during colonoscopy.

Emergency hospital admissions, prognosis, and population mortality in Norway during the first wave of the Covid-19 epidemic.

BACKGROUND: During the first wave of the Covid-19 epidemic, a national lockdown was established in Norway, and inhabitants were asked to contact healthcare only if absolutely necessary. We investigated hospital admissions and mortality due to non-Covid-19 disease during the lockdown compared to previous years. METHODS: We compared the number of emergency admissions and in-hospital fatality for diagnoses probably unaffected (acute myocardial infarction, acute abdominal conditions, cerebrovascular diseases) and affected by the lockdown (infections, injuries) in the South-Eastern Health Region of Norway during weeks 12-22, 2020, compared to the mean of the same period in the years 2017-2019. We also compared population mortality March-May 2020, to the mean of the same period in years 2017-2019. RESULTS: A total of 280,043 emergency admissions were observed; 20,911 admissions probably unaffected, and 30,905 admissions probably affected by the lockdown. Admissions due to diagnoses probably unaffected was reduced by 12% (95% confidence interval (CI) 9-15%), compared to 2017-2019. Admissions for diagnoses probably affected was reduced by 30% (95% CI 28-32%). There was a 34% reduction in in-hospital fatality due to acute myocardial infarction (95% CI 4-56%), 19% due to infections (95% CI 1-33%), and no change for the other diagnoses, compared to 2017-2019. The risk of in-hospital mortality to total mortality was lower for acute myocardial infarction (relative risk 0.85, 95% CI 0.73-0.99) and injuries (relative risk 0.83, 95% CI 0.70-0.98). CONCLUSIONS: Even though fewer patients were admitted to hospital, there was no increase in in-hospital fatality or population mortality, indicating that those who were most in need still received adequate care.

Mortality in Norway and Sweden during the COVID-19 pandemic.

Background: Norway and Sweden are similar countries in terms of socioeconomics and health care. Norway implemented extensive COVID-19 measures, such as school closures and lockdowns, whereas Sweden did not. Aims: To compare mortality in Norway and Sweden, two similar countries with very different mitigation measures against COVID-19. Methods: Using real-world data from national registries, we compared all-cause and COVID-19-related mortality rates with 95% confidence intervals (CI) per 100,000 person-weeks and mortality rate ratios (MRR) comparing the five preceding years (2015-2019) with the pandemic year (2020) in Norway and Sweden. Results: In Norway, all-cause mortality was stable from 2015 to 2019 (mortality rate 14.6-15.1 per 100,000 person-weeks; mean mortality rate 14.9) and was lower in 2020 than from 2015 to 2019 (mortality rate 14.4; MRR 0.97; 95% CI 0.96-0.98). In Sweden, all-cause mortality was stable from 2015 to 2018 (mortality rate 17.0-17.8; mean mortality rate 17.1) and similar to that in 2020 (mortality rate 17.6), but lower in 2019 (mortality rate 16.2). Compared with the years 2015-2019, all-cause mortality in the pandemic year was 3% higher due to the lower rate in 2019 (MRR 1.03; 95% CI 1.02-1.04). Excess mortality was confined to people aged ⩾70 years in Sweden compared with previous years. The COVID-19-associated mortality rates per 100,000 person-weeks during the first wave of the pandemic were 0.3 in Norway and 2.9 in Sweden. Conclusions: All-cause mortality in 2020 decreased in Norway and increased in Sweden compared with previous years. The observed excess deaths in Sweden during the pandemic may, in part, be explained by mortality displacement due to the low all-cause mortality in the previous year.

Reply to: Letter to the Editor regarding "Covid-19 transmission in fitness centers in Norway-a randomized trial".

In this correspondence we respond to critique of our randomized trial of Covid-19 transmission in fitness centers. The trial was performed in Norway during May and June 2020.

Colorectal Cancer Incidence and Mortality After Removal of Adenomas During Screening Colonoscopies.

BACKGROUND & AIMS: Recommendation of surveillance colonoscopy should be based on risk of colorectal cancer and death after adenoma removal. We aimed to develop a risk classification system based on colorectal cancer incidence and mortality following adenoma removal. METHODS: We performed a multicenter population-based cohort study of 236,089 individuals (median patient age, 56 years; 37.8% male) undergoing screening colonoscopies with adequate bowel cleansing and cecum intubation at 132 centers in the Polish National Colorectal Cancer Screening Program, from 2000 through 2011. Subjects were followed for a median 7.1 years and information was collected on colorectal cancer development and death. We used recursive partitioning and multivariable Cox models to identify associations between colorectal cancer risk and patient and adenoma characteristics (diameter, growth pattern, grade of dysplasia, and number of adenomas). We developed a risk classification system based on standardized incidence ratios, using data from the Polish population for comparison. The primary endpoints were colorectal cancer incidence and colorectal cancer death. RESULTS: We identified 130 colorectal cancers in individuals who had adenomas removed at screening (46.5 per 100,000 person-years) vs 309 in individuals without adenomas (22.2 per 100,000 person-years). Compared with individuals without adenomas, adenomas ≥20 mm in diameter and high-grade dysplasia were associated with increased risk of colorectal cancer (adjusted hazard ratios 9.25; 95% confidence interval [CI] 6.39-13.39, and 3.58; 95% CI 1.96-6.54, respectively). Compared with the general population, colorectal cancer risk was higher or comparable only for individuals with adenomas ≥20 mm in diameter (standardized incidence ratio [SIR] 2.07; 95% CI 1.40-2.93) or with high-grade dysplasia (SIR 0.79; 95% CI 0.39-1.41), whereas for individuals with other adenoma characteristics the risk was lower (SIR 0.35; 95% CI 0.28-0.44). We developed a high-risk classification based on adenoma size ≥20 mm or high-grade dysplasia (instead of the current high-risk classification cutoff of ≥3 adenomas or any adenoma with villous growth pattern, high-grade dysplasia, or ≥10 mm in diameter). Our classification system would reduce the number of individuals classified as high-risk and requiring intensive surveillance from 15,242 (36.5%) to 3980 (9.5%), without increasing risk of colorectal cancer in patients with adenomas (risk difference per 100,000 person-years, 5.6; 95% CI -10.7 to 22.0). CONCLUSIONS: Using data from the Polish National Colorectal Cancer Screening Program, we developed a risk classification system that would reduce the number of individuals classified as high risk and require intensive surveillance more than 3-fold, without increasing risk of colorectal cancer in patients with adenomas. This system could optimize the use of surveillance colonoscopy.

Artificial intelligence for polyp detection during colonoscopy: a systematic review and meta-analysis.

BACKGROUND: Artificial intelligence (AI)-based polyp detection systems are used during colonoscopy with the aim of increasing lesion detection and improving colonoscopy quality. PATIENTS AND METHODS: We performed a systematic review and meta-analysis of prospective trials to determine the value of AI-based polyp detection systems for detection of polyps and colorectal cancer. We performed systematic searches in MEDLINE, EMBASE, and Cochrane CENTRAL. Independent reviewers screened studies and assessed eligibility, certainty of evidence, and risk of bias. We compared colonoscopy with and without AI by calculating relative and absolute risks and mean differences for detection of polyps, adenomas, and colorectal cancer. RESULTS: Five randomized trials were eligible for analysis. Colonoscopy with AI increased adenoma detection rates (ADRs) and polyp detection rates (PDRs) compared to colonoscopy without AI (values given with 95 %CI). ADR with AI was 29.6 % (22.2 % - 37.0 %) versus 19.3 % (12.7 % - 25.9 %) without AI; relative risk (RR] 1.52 (1.31 - 1.77), with high certainty. PDR was 45.4 % (41.1 % - 49.8 %) with AI versus 30.6 % (26.5 % - 34.6 %) without AI; RR 1.48 (1.37 - 1.60), with high certainty. There was no difference in detection of advanced adenomas (mean advanced adenomas per colonoscopy 0.03 for each group, high certainty). Mean adenomas detected per colonoscopy was higher for small adenomas (≤ 5 mm) for AI versus non-AI (mean difference 0.15 [0.12 - 0.18]), but not for larger adenomas (> 5 - ≤ 10 mm, mean difference 0.03 [0.01 - 0.05]; > 10 mm, mean difference 0.01 [0.00 - 0.02]; high certainty). Data on cancer are unavailable. CONCLUSIONS: AI-based polyp detection systems during colonoscopy increase detection of small nonadvanced adenomas and polyps, but not of advanced adenomas.

Incomplete endoscopic resection of colorectal polyps: a prospective quality assurance study.

BACKGROUND: Endoscopic screening with polypectomy has been shown to reduce colorectal cancer incidence in randomized trials. Incomplete polyp removal and subsequent development of post-colonoscopy cancers may attenuate the effect of screening. This study aimed to quantify the extent of incomplete polyp removal. METHODS: We included patients aged 50-75 years with nonpedunculated polyps ≥ 5 mm removed during colonoscopy at four hospitals in Norway. To evaluate completeness of polyp removal, biopsies from the resection margins were obtained after polypectomy. Logistic regression models were fitted to identify factors explaining incomplete resection. RESULTS: 246 patients with 339 polyps underwent polypectomy between January 2015 and June 2017. A total of 12 polyps were excluded due to biopsy electrocautery damage, and 327 polyps in 246 patients (mean age 67 years [range 42-83]; 52 % male) were included in the analysis. Overall, 54 polyps (15.9 %) in 54 patients were incompletely resected. Histological diagnosis of the polyp (sessile serrated lesions vs. adenoma, odds ratio [OR] 10.9, 95 % confidence interval [CI] 3.9-30.1) and polyp location (proximal vs. distal colon, OR 2.8, 95 %CI 1.0-7.7) were independent risk factors for incomplete removal of polyps 5-19 mm. Board-certified endoscopists were not associated with lower rates of incomplete resection compared with trainees (14.0 % vs. 14.2 %), OR 1.0 (95 %CI 0.5-2.1). CONCLUSION: Incomplete polyp resection was frequent after polypectomy in routine clinical practice. Serrated histology and proximal location were independent risk factors for incomplete resection. The performance of board-certified gastroenterologists was not superior to that of trainees.