Colorectal cancer is the second major cause of cancer-related death in the United States. The long time involved in progression of mucosal dysplasia from a small polyp to an invasive cancer and the ability to image the colon mucosa are features that make early detection and prevention of colorectal cancer by colonoscopy possible. Although colonoscopy has contributed to a marked decline in the number of colorectal cancer-related deaths, the protective effect of colonoscopy, when used in routine clinical practice, has not lived up to the expectations raised by carefully controlled prospective research studies. Therefore new systems that assess quality of colonoscopy are needed.
Introduction: prevention of colorectal cancer by colonoscopy
Colorectal cancer is the second major cause of cancer-related death in the United States. The long time involved in progression of mucosal dysplasia from a small polyp to an invasive cancer, the mucosal shedding of molecules and cells into stool during this process, and the ability to image the colon mucosa using direct inspection or x-ray techniques are features that make early detection and prevention of colorectal cancer possible. Various screening tests, such as digital rectal examination, fecal occult blood testing, double-contrast barium enema, and colonoscopy, have increasingly contributed to the detection of polyps and early cancers. Among these tests, colonoscopy is the most accepted screening method for the detection of colorectal cancer or its precursor lesions and is the only colorectal cancer screening and surveillance technology that allows for diagnostic and therapeutic operations in one procedure. Colonoscopy has contributed to a marked decline in the number of colorectal cancer-related deaths.
The problem with colonoscopy: not all colorectal cancers are prevented
Recent data suggest, however, that there is a significant miss rate for detection of even large polyps and cancers. Examples include a double-procedure study from the author’s institution where colonoscopy failed to detect 4 out of 5 individual colorectal cancers detected by CT colography, a double-cohort study where colonoscopy detected fewer colorectal cancers than CT colography, a population-based case control study in Canada where colonoscopy did not prevent death from right-sided colorectal cancer, and a screening study from Germany where the repeat colonoscopy findings were similar to the case-control study findings in Canada. The conclusion from these and other studies (for a comprehensive summary, see Hewett and colleagues ) is that the protective effect of colonoscopy, when used in routine clinical practice, has not lived up to the expectations raised by carefully controlled prospective research studies. Furthermore, the protective effect seems minor or absent for right-sided cancers and at best approximately 70% for left-sided cancers.
The problem with colonoscopy: not all colorectal cancers are prevented
Recent data suggest, however, that there is a significant miss rate for detection of even large polyps and cancers. Examples include a double-procedure study from the author’s institution where colonoscopy failed to detect 4 out of 5 individual colorectal cancers detected by CT colography, a double-cohort study where colonoscopy detected fewer colorectal cancers than CT colography, a population-based case control study in Canada where colonoscopy did not prevent death from right-sided colorectal cancer, and a screening study from Germany where the repeat colonoscopy findings were similar to the case-control study findings in Canada. The conclusion from these and other studies (for a comprehensive summary, see Hewett and colleagues ) is that the protective effect of colonoscopy, when used in routine clinical practice, has not lived up to the expectations raised by carefully controlled prospective research studies. Furthermore, the protective effect seems minor or absent for right-sided cancers and at best approximately 70% for left-sided cancers.
Assumptions: factors that may explain failures of colonoscopy
Several factors may contribute to the miss rate. In general, these factors can be divided into those related to the patient, the equipment used, and the endoscopist performing the procedure. A cooperative patient, either due to voluntary control of the patient or due to a moderate amount of sedatives and analgesics, is a requirement for a successful endoscopic examination. Similarly, a colonic anatomy allowing passage of the colonoscope to the cecum is assumed—this is the case in nearly all patients. The patient-related factors that may lower miss rates consist mainly of two important actions: first, discontinuation of any nutrients other than clear liquids for a defined time before the procedure (most often 1–2 days), and, second, strict adherence to a bowel cleansing program 1 to 2 days before the procedure. The desired end result is a colon free of any solid food with either no liquid content or small amounts of highly diluted stool and gastrointestinal juices that are easily aspirated. Although no truly objective measurements for judging colonic preparation exist, a semiquantitive subjective scoring system is used by most endoscopists. The equipment-related protective factors are variable and less dominant than in the past, given the overall quality of the currently available commercial endoscopes. Nevertheless, there are real differences between endoscopes of different manufacturers that can affect the protective effect of colonoscopy. The endoscopist-related protective factors consist mainly of skill set, the inspection time, and the effort exerted to inspect as much of the visible mucosa as possible. At present, skill set is defined as having completed a minimal number of procedures during a formal fellowship; a subset of these procedures should include certain endoscopic diagnostic and therapeutic instrumentations. Formal testing of the acquired skill set does not take place. There is debate about what constitutes optimal inspection time; however, the American Society for Gastroentintestinal Endoscopy (ASGE) and American College of Gastroenterology (ACG) in a consensus document in 2006 suggest that independent of patient, equipment, and endoscopist, at least 6 to 10 minutes should be spent during the withdrawal phase on careful inspection of all visible colon mucosa. The third endoscopist-related factor is the effort to inspect as much of the visible mucosa as possible. Effort is different from skill set. Meticulous effort means that by using all options available, such as torque, lateral (left/right) and vertical (up/down) tip deflexion, aspiration, washing of mucosa, retroflexion, and repeatedly moving through tight angulations, the endoscopist tries to inspect the entire colon mucosa. Current equipment allows inspection of most (>90%–95%) of the colon mucosa (the visible mucosa) during a routine screening colonoscopy in a normal 50-year-old patient if all these techniques are used as required during the procedure. A complete inspection (100% of colon mucosa) is unusual with current endoscopic equipment; inspection of less than 90% to 95% in a well-cleansed colon of a normal 50-year-old patient should lead to questioning the skill set or the level of effort of the endoscopist.
Defining quality of colonoscopy
Metrics that are Being Collected
For each colonoscopic procedure, some data are collected. At the most basic form, data collection consists of a handwritten or dictated free text report with or without a few images in the form of separate photographs. To get paid, a set of billing codes is available, frequently in a separate practice management system. In cases when specimens are obtained, another piece of paper, such as a letter from a pathology laboratory, may hold the final histologic diagnosis. Additional data, in particular data related to quality of the procedure, may not be collected. Meaningful data extraction to examine quality is not possible because this would be prohibitively expensive and provide little or no useful information.
In the most detailed and comprehensive form, detailed electronic data are available with structured information about the indication for the colonoscopy, preprocedure education and instructions, adherence to the bowel preparation regimen, the procedure with all its details, digital images of key anatomic locations and findings, any complications related to the procedure, recovery and discharge, any histologic findings from specimens removed, and suggested follow-up. At present, sophisticated systems allowing all of this are mostly available in large gastroenterology group practices and academic centers. Sometimes practice-, research-, and quality-related data are collected in separate electronic applications; sometimes—and ideally—all these data types are collected in a single application that serves all needs and prevents redundant data collection activity. In reality, in 2010 most endoscopists, whether or not solo practitioners, in a small single specialty group, or in a large multispecialty center, have implemented data collection methods somewhere between basic paper-based and highly comprehensive, digital formats.
Given these descriptions of the wide variety of data collection methods coupled with (1) an absence of any central (ie, federal, state, societal, or insurance) requirements regarding which data should be collected, (2) the voluntary nature of establishing some kind of prospective data collection, (3) the lack of a minimum set of universally agreed-on data types worthy to be collected, (4) the lack of a financial incentive to collect data that would prove quality, and (5) the possible legal ramifications of collecting data that can possibly incriminate the physicians performing the procedures, it is not surprising that most if not all data that currently are collected regarding colonoscopy are simple, limited in quantity, easy to obtain, inexpensive to collect, and not reflecting what actually happened during the procedure.
In 2006, the ASGE and ACG published a consensus report in which these organizations listed a set of minimal criteria related to quality as recommendations. Of these recommendations the following four intraprocedure recommendations are not related to pre-existing disease conditions and best define skill set and effort of the endoscopist during colonoscopy:
- 1.
Cecal intubation rates: visualization of the cecum by notation of landmarks and photo documentation of landmarks should be documented in every procedure.
- 2.
Detection of adenomas in asymptomatic individuals (screening): adenomas should be detected in at least 25% of men and at least 15% women more than 50 years old.
- 3.
Withdrawal times: mean withdrawal time should be at least 6 minutes in colonoscopies with normal results performed in patients with intact colons.
- 4.
Mucosally based pedunculated polyps and sessile polyps less than 2 cm in size should not be sent for surgical resection without an attempt at endoscopic resection or documentation of endoscopic inaccessibility.
The problem with these four recommendations is that they do not reflect the eventual result of colonoscopy—the final state of colon preparation after removal of remaining fecal material, the amount of mucosa inspected, and the completeness of removal of all lesions. If cecal intubation is documented by a good-quality image, then there is solid evidence of the fact that the entire colon was traversed; if an image is not available, the opinion of the endoscopist can be relied on. Finding one or more polyps is not a guarantee that other polyps are not missed. Similarly, spending 6 minutes during withdrawal is not a guarantee that all mucosa was cleaned as needed and inspected. Finally, an attempt at polypectomy of a lesion less than 2 cm is not the same as being able to remove a polyp less than 2 cm without remaining polypoid tissue in (nearly) all cases.
In summary, current intraprocedural quality measures are subjective and do not reflect the effort of the endoscopist to clean, inspect all mucosa, and remove all abnormalities (ie, they do not reflect true quality of colonoscopy). In addition, these limited data provide a false sense of measuring or providing quality and allow easy manipulation (eg, remove one polyp and delay endoscope removal until a withdrawal time of 6 minutes is reached) of data toward an apparently favorable outcome.
Metrics that Should be Collected
Only two things matter when it comes to colonoscopy and colorectal cancer: Was colorectal cancer prevented in the patients who underwent colonoscopy (less morbidity)? and Did the patient live longer due to the intervention (less mortality)? If cancer is prevented but patients do not experience a better quality or longer life, screening is not indicated. Assuming that prevention of colorectal cancer does lead to longer, good quality of life, in my opinion, there are two choices to evaluate colonoscopy ( Fig. 1 ). First, when, where, and how colonoscopy fails to prevent colorectal cancer can be measured by calculating the frequency of colorectal cancer despite colonoscopy (CCdC) or the interval colorectal cancer rate. This is not a trivial task—it requires long-term follow-up of a large study population and requires detailed data about the condition of the patient and specimens removed from the patient. Second, whether or not a high-quality colonoscopy was performed can be measured based on evaluation of the entire colonoscopy instead of a limited data set, as is currently the case.
Assessing whether or not colonoscopy prevents colorectal cancer
At the Mayo Clinic, the author and colleagues have created a large database spanning from 1992 to 2009. This database contains all endoscopy, diagnosis, and pathology information about all patients seen at the institution. As data are currently under review, the results are not disclosed in this article. Several important conclusions, however, are drawn based on the results.
- 1.
First, CCdC is not a random event. Among many factors and features examined, the endoscopist doing the procedure is of key importance because some seem more often involved in CCdC cases than others.
- 2.
Second, most cases of CCdC seem to be truly missed tumors not rapidly growing de novo tumors.
- 3.
Third, these tumors seem to have similar features than tumors that are not missed, suggesting once more that they are truly missed and not rapidly growing de novo tumors.
- 4.
Fourth, withdrawal time duration was not related to number of CCdC, neither was polyp detection rate.
- 5.
Finally, the protective effect for some endoscopists against CCdC extends beyond 3 years and may even extend beyond 5 years, the longest period the author and colleagues have studied thus far.
These preliminary data, from the largest and most detailed study done so far, clearly point to the endoscopist as the key factor determining whether or not a patient develops colorectal cancer in the first 3 to 5 years after a colonoscopy.
Assessing whether or not colonoscopies are of high quality
Measuring failure of prevention of colorectal cancer as the ultimate outcome provides objective, meaningful data but takes many years of careful observation and detailed clinical data acquisition. In addition, patients who underwent a suboptimal colonoscopy may develop and die from colorectal cancer during the observation period, thus not benefiting at all from the quality-control efforts. To address this issue related to colonoscopy, the author and colleagues developed a second approach that uses the entire procedure to determine quality. Instead of taking a few convenient, easily measurable, multiple, procedure-based features, such as cecal intubation rate, adenoma detection rate, and average withdrawal time, the author and colleagues proposed obtaining detailed quality-related information from every colonoscopy representing the entire procedure. Instead of providing an average, subjective, surrogate rating of quality for an endoscopist, which is meaningless for an individual patient, the author and colleagues proposed providing an objective, detailed report of an individual procedure reflecting the actual quality provided to an individual patient.
How is achieving an objective, detailed report for every individual patient proposed? The solution is algorithm-based, automated analysis of the video stream representing the entire procedure. The author and colleagues realize that other important quality features cannot be derived from the video stream, such as preoperative instructions, the amount of discomfort of a patient during the procedure, reasons for not removing polyps, and any follow-up instructions. All of these features are important but become irrelevant in the presence of a poor-quality colonoscopy.
For colonoscopy, one needs to measure from insertion until removal of the endoscope whether or not the endoscopist instituted all efforts reasonably possible to CLEAR the colon of all lesions during the procedure. CLEAR is an acronym that reflects the three important aspects of colonoscopy, which the author and colleagues think define quality:
- 1.
C lean—the patient should adhere to the colon preparation instructions and the endoscopist should remove remaining fecal material. The end result at the time of withdrawal should be a good or excellent prepared colon as defined in the ASGE and ACG guidelines.
- 2.
L ook E verywhere—the endoscopist has to actively look behind every fold (working the folds) and move or remove remaining stool to achieve as close to 100% inspection of the colon mucosa.
- 3.
A bnormality R emoval—the endoscopist has to remove polyps by biopsy forceps, snare polypectomy, or other modalities; lesions left behind may develop into a malignant lesion before a next screening or surveillance procedure is performed.
For each of these three key aspects of colonoscopy, one or more metrics need to be developed to provide a meaningful quality report that truly reflects how well the colonic preparation was after removal of remaining fecal material, how much of the colonic mucosa was well seen, and how completely any premalignant lesions were removed.
Endoscopic Multimedia Information System
During the past 7 years, the author and colleagues have developed an automated, innovative system that uses computer-based algorithms to analyze the image stream generated during colonoscopy for specific metrics. This system is named the Endoscopic Multimedia Information System (EMIS). EMIS at present does not interfere with actual colonoscopy because the same image stream analyzed by computer is also displayed on a monitor, allowing a colonoscopist to view the colonic mucosa and perform diagnostic and therapeutic procedures as indicated. The ultimate goal of EMIS, however, is completely automated real-time (ie, during a procedure) analysis of colonoscopy with feedback to the endoscopist to confirm that specific quality milestones have been achieved or to drive endoscopist behavior toward achieving these milestones in case this seems not to happen. EMIS consists of several components, each critical for pursuing the ultimate goal.
EM-Capture
The first component of EMIS is EM-Capture, a set of fully automated, real-time endoscopy video stream capture and file-generation algorithms. The algorithms determine whether or not the image frames are derived from an endoscope with its tip containing the video camera inside the patient. The algorithms use a combination of frame-derived color, movement, and shape aspects in real time to determine absence or presence of an inside-the-patient state. Since May 2007, the author and colleagues have gradually expanded the number of endoscopy rooms equipped with this software from 2 to 13 with outstanding results: under specific conditions, the algorithms remove nearly 100% of all leading outside-the-patient frames and no trailing outside-the-patient frames as programmed. Recording stops after a few continuous minutes of outside-the-patient recording to allow for removal of polyps that are too big to pass via the working channel, change in endoscope, lens cleaning, and so forth. Initially, the author and colleagues recorded a few minutes of the video stream after the endoscope had been removed from the patient to verify that the entire colonocopy procedure has been captured; currently, the author and colleagues record all inside-the-patient images until the time point that the endoscope passes through the anus while verifying that no repeat insertion of the endoscope occurs over the next minutes. In addition, the author and colleagues have verified the number of procedures recorded by the system over a 4-day time span with the number of procedures performed according to endoscopy practice data: comparison showed that the automated, inside-the-patient technology captures every procedure. Comparison showed also that endoscopy practice data—despite best attempts—contained at predictable regularity errors, such as incorrect room assignment and incorrect start and end times of the procedure.
EM-Capture runs on a robotic workstation; this system has no keyboard, mouse, or monitor and is managed remotely by another set of algorithms running on a central server, EM-Central (discussed later). The workstation consists of inexpensive common off-the-shelf hardware: a Core 2 Duo CPU, 4 to 8 GB RAM, two 250-GB or larger hard drives, and a video capture card for total costs, including installation of less than $1500 per endoscopy room. Three cables connect it to (1) 110 V, (2) the image processor of the endoscope, and (3) the intranet. The EM-Capture algorithms run as a component of the operating system; therefore, anyone logging on or off remotely does not interrupt image capture or video file generation. Video file size is variable depending on the length of the procedure. At present, MPEG-2 video files are generated consisting of 30 720 × 480 pixel color images per second, which results in approximately 1 GB of hard drive space per 20 minutes. Video file capture in high definition format requires substantially more hard drive space per video file.
To summarize, EM-Capture automatically detects when an endoscope enters a patient and provides a collection of video files that represent all endoscopies performed in the rooms where EM-Capture is installed. With EM-Capture, there is a record of every endoscopy from start to finish.
EM-Central
The second component of EMIS is EM-Central, a set of control and scheduling algorithms that reside on a central server. As with EM-Capture on the robotic workstations, EM-Central operates autonomously: it gathers information about the state of the workstations, schedules specific tasks at specific times, and sends e-mails to the programming staff if any of the operating conditions from any of the workstations or the server itself are out of predefined bounds. The EM-Central server also functions as a Web server allowing review of the state of EMIS and access to the various functions of EM-Central via an Internet browser. Currently EM-Central has five main functions:
- 1.
A summary of all captured video files is available under the tab, “Captured Videos.” Files can be listed in tabular format or in graphic outline per room and per time period. For instance, a complete overview of a single day, week, month, or year is available per room or for the entire unit ( Fig. 2 ).
Related posts:
Reducing Infection Risk in Colonoscopy
Sedation Issues in Quality Colonoscopy
Complications of Colonoscopy: Magnitude and Management
Colonoscopy Reports and Current State of Performance Measures
The Use of Databases and Registries to Enhance Colonoscopy Quality
Defining an Episode of Care for Colonoscopy: Work of the High Value Health Care Project Characterizing Episodes and Costs of Care
Stay updated, free articles. Join our Telegram channel
Full access? Get Clinical Tree
