Colonoscopy and flexible sigmoidoscopy practice patterns in Ontario: a population-based study

Duration of risk reduction in colorectal cancer incidence and mortality after a complete colonoscopy in Ontario, Canada: a population-based cohort study

BACKGROUND

Colorectal cancer guidelines recommend screening colonoscopy every 10 years after a negative procedure. If risk reduction extends past 10 years, the recommended interval could be extended, reducing the burden on the individual and health-care system. We aimed to estimate the duration that patients remain at reduced risk of colorectal cancer incidence and mortality after a complete colonoscopy.

METHODS

We did a population-based cohort study of individuals aged 50-65 years between Jan 1, 1994, to Dec 31, 2017. We excluded individuals with previous exposure to colonoscopy or colorectal surgery, those previously diagnosed with colorectal cancer, or a history of hereditary or other bowel disorders. We followed up participants until Dec 31, 2018, and identified all colonoscopies performed in this time period. We used a 9-level time-varying measure of exposure, capturing time since last complete colonoscopy (no complete colonoscopy, ≤5 years, >5-10 years, >10-15 years, and >15 years) and whether an intervention was performed (biopsy or polypectomy). A Cox proportional hazards regression model adjusting for age, sex, comorbidity, residential income quintile, and immigration status was used to estimate the association between exposure to a complete colonoscopy and colorectal cancer incidence and mortality.

FINDINGS

5 298 033 individuals (2 609 060 [49·2%] female and 2 688 973 [50·8%] male; no data on ethnicity were available) were included in the cohort, with a median follow-up of 12·56 years (IQR 6·26-20·13). 90 532 (1·7%) individuals were diagnosed with colorectal cancer and 44 088 (0·8%) died from colorectal cancer. Compared with those who did not have a colonoscopy, the risk of colorectal cancer in those who had a complete negative colonoscopy was reduced at all timepoints, including when the procedure occurred more than 15 years earlier (hazard ratio [HR] 0·62 [95% CI 0·51-0·77] for female individuals and 0·57 [0·46-0·70] for male individuals. A similar finding was observed for colorectal cancer mortality, with lower risk at all timepoints, including when the procedure occurred more than 15 years earlier (HR 0·64 [95% CI 0·49-0·83] for female participants and 0·65 [0·50-0·83] for male participants). Those who had a colonoscopy with intervention had a significantly lower colorectal cancer incidence than those who did not undergo colonoscopy if the procedure occurred within 10 years for females (HR 0·70 [95% CI 0·63-0·77]) and up to 15 years for males (0·62 [(0·53-0·72]).

INTERPRETATION

Compared with those who do not receive colonoscopy, individuals who have a negative colonoscopy result remain at lower risk for colorectal cancer incidence and mortality more than 15 years after the procedure. The current recommendation of repeat screening at 10 years in these individuals should be reassessed.

FUNDING

Canadian Institutes of Health Research.

Geographic variation in the provider of screening colonoscopy in Canada: a population-based cohort study

BACKGROUND

Screening colonoscopy for the detection of colorectal carcinoma is provided by several specialties. Few studies have assessed geographic variation in the delivery of this care. Our objective was to investigate how geographic and socioeconomic factors affect who provides screening colonoscopy in Canada.

METHODS

This was a population-based cohort of all screening colonoscopy procedures performed at publicly funded Canadian health care facilities (excluding those in Quebec) between April 2008 and March 2015. The main outcome of interest was the proportion of colonoscopy procedures performed by surgeons versus gastroenterologists at the neighbourhood level. Predictors of interest included socioeconomic and geographic variables. We used spatial analysis to evaluate significant clustering of practitioner services and multinomial logistic regression to model predictors.

RESULTS

We identified 658 113 screening colonoscopy procedures performed by 1886 providers (1169 surgeons and 717 gastroenterologists) over the study period, of which 353 165 (53.7%) were performed by surgeons. A total of 24.2% of neighbourhoods were located within clusters predominantly served by gastroenterologists, and 19.5% were within surgeon clusters; the remainder were in mixed clusters. Rural neighbourhoods had a significantly increased relative risk of being within a surgeon cluster (relative risk [RR] 5.38, 95% confidence interval [CI] 3.48-8.01) compared to mixed clusters and nearly 100 times higher relative risk of being in a surgeon cluster compared to gastroenterologist clusters (RR 98.95, 95% CI 15.3-427.2). Neighbourhoods with the highest socioeconomic status were 1.74 (95% CI 1.14-2.56) times likelier to be in gastroenterologist clusters than in mixed clusters.

INTERPRETATION

Surgeons provide a large proportion of colonoscopy procedures in Canada and are essential for access to care, particularly in rural regions. Most Canadians are served relatively equally by surgeons and gastroenterologists. This emphasizes the importance of both specialties to the delivery of colonoscopy care across the country.

Understanding the Effects of Competition for Constrained Colonoscopy Services with the Introduction of Population-level Colorectal Cancer Screening

BACKGROUND

Median wait times for gastroenterology services in Canada exceed consensus-recommended targets and have worsened substantially over the past decade. Meanwhile, efforts to control colorectal cancer have shifted their focus to screening asymptomatic, average-risk individuals. Along with increasing prevalence of colorectal cancer due to an aging population, screening programs are expected to add substantially to the existing burden on colonoscopy services, and create competition for limited services among individuals of varying risk. Failure to understand the effects of operational programmatic screening decisions may cause unintended harm to both screening participants and higher-risk patients, make inefficient use of limited health care resources, and ultimately hinder a program's success.

METHODS

We present a new simulation model (Simulation of Cancer Outcomes for Planning Exercises, or SCOPE) for colorectal cancer screening which, unlike many other colorectal cancer screening models, reflects the effects of competition for limited colonoscopy services between patient groups and can be used to guide planning to ensure adequate resource allocation. We include verification and validation results for the SCOPE model.

RESULTS

A discrete event simulation model was developed based on an epidemiological representation of colorectal cancer in a sample population. Colonoscopy service and screening modules were added to allow observation of screening scenarios and resource considerations. The model reproduces population-based data on prevalence of colorectal cancer by stage, and mortality by cause of death, age, and sex, and attendant demand and wait times for colonoscopy services.

CONCLUSIONS

The study model differs from existing screening models in that it explicitly considers the colonoscopy resource implications of screening activities and the impact of constrained resources on screening effectiveness.

Endoscopy training in Canadian general surgery residency programs

Currently, general surgeons provide about 50% of endoscopy services across Canada and an even greater proportion outside large urban centres. It is essential that endoscopy remain a core component of general surgery practice and a core competency of general surgery residency training. The Canadian Association of General Surgeons Residents Committee supports the position that quality endoscopy training for all Canadian general surgery residents is in the best interest of the Canadian public. However, the means by which quality endoscopy training is achieved has not been defined at a national level. Endoscopy training in Canadian general surgery residency programs requires standardization across the country and improved measurement to ensure that competency and basic credentialing requirements are met.

Hyponatremia and sodium picosulfate bowel preparations in older adults

OBJECTIVES

Bowel preparations are commonly prescribed drugs. Case reports and our clinical experience suggest that sodium picosulfate bowel preparations can precipitate severe hyponatremia in some older adults. At present, this risk is poorly quantified. We investigated the association between sodium picosulfate use and the risk of hyponatremia in older adults.

METHODS

We conducted a population-based retrospective cohort study using six linked administrative databases in Ontario, Canada. All Ontario residents over the age of 65 years who filled an outpatient bowel preparation prescription before colonoscopy were eligible. We enrolled new users of either sodium picosulfate (n=99,237) or polyethylene glycol (n=48,595). The primary outcome was hospitalization with hyponatremia within 30 days of the bowel preparation assessed by database codes. The secondary outcomes were hospitalization with urgent head computed tomography (CT) (a proxy for acute central nervous system disturbance) and all-cause mortality.

RESULTS

The baseline characteristics of the two groups, including patient demographics, comorbid conditions, and concomitant medications, were nearly identical. Compared with polyethylene glycol, sodium picosulfate was associated with a higher risk of hospitalization with hyponatremia (absolute risk increase: 0.05%, 95% confidence interval (CI): 0.04-0.06%, relative risk (RR): 2.4, 95% CI: 1.5-3.9), but not hospitalization with urgent CT head (RR: 1.1, 95% CI: 0.7-1.4) or mortality (RR: 0.9, 95% CI: 0.7-1.3).

CONCLUSIONS

Sodium picosulfate bowel preparations lead to more hyponatremia than polyethylene glycol. There was no evidence of increased risk of acute neurologic symptoms or mortality. The absolute increase in risk of hospitalization with hyponatremia remains low but may be avoidable through appropriate fluid intake or preferential use of polyethylene glycol in some older adults.

Potentially inappropriate screening colonoscopy in Medicare patients: variation by physician and geographic region

IMPORTANCE

Inappropriate use of colonoscopy involves unnecessary risk for older patients and consumes resources that could be used more effectively.

OBJECTIVES

To determine the frequency of potentially inappropriate colonoscopy in Medicare beneficiaries in Texas and to examine variation among physicians and across geographic regions.

DESIGN, SETTING, AND PARTICIPANTS

This retrospective cohort study used 100% Medicare claims data for Texas and a 5% sample from the United States from 2000 through 2009. We identified Medicare beneficiaries aged 70 years or older who underwent a colonoscopy from October 1, 2008, through September 30, 2009.

MAIN OUTCOME MEASURES

Colonoscopies were classified as screening in the absence of a diagnosis suggesting an indication for the procedure. Screening colonoscopy was considered potentially inappropriate on the basis of patient age or occurrence too soon after colonoscopy with negative findings. The percentage of patients undergoing potentially inappropriate screening colonoscopy was estimated for each colonoscopist and hospital service area.

RESULTS

A large percentage of colonoscopies performed in older adults were potentially inappropriate: 23.4% for the overall Texas cohort and 9.9%, 38.8%, and 24.9%, respectively, in patients aged 70 to 75, 76 to 85, or 86 years or older. There was considerable variation across the 797 colonoscopists in the percentages of colonoscopies performed that were potentially inappropriate. In a multilevel model including patient sex, race or ethnicity, number of comorbid conditions, educational level, and urban or rural residence, 73 colonoscopists had percentages significantly above the mean (23.9%), ranging from 28.7% to 45.5%, and 119 had percentages significantly below the mean (23.9%), ranging from 6.7% to 18.6%. The colonoscopists with percentages significantly above the mean were more likely to be surgeons, graduates of US medical schools, medical school graduates before 1990, and higher-volume colonoscopists than those with percentages significantly below the mean. Colonoscopist rankings were fairly stable over time (2006-2007 vs 2008-2009). There was also geographic variation across Texas and the United States, with percentages ranging from 13.3% to 34.9% in Texas and from 19.5% to 30.5% across the United States.

CONCLUSIONS AND RELEVANCE

Many colonoscopies performed in older adults may be inappropriate. The likelihood of undergoing potentially inappropriate colonoscopy depends in part on where patients live and what physician they see.

Serious events in older Ontario residents receiving bowel preparations for outpatient colonoscopy with various comorbidity profiles: a descriptive, population-based study

BACKGROUND

Polyethylene glycol-based bowel preparations (PEGBPs) and sodium picosulfate (NaPS) are commonly used for bowel cleansing before colonoscopy. Little is known about adverse events associated with these preparations, particularly in older patients or patients with medical comorbidities.

OBJECTIVE

To characterize the incidence of serious events following outpatient colonoscopy in patients using PEGBPs or NaPS.

METHODS

The present population-based retrospective cohort study examined data from Ontario health care databases between April 1, 2005 and December 31, 2007, including patients >=66 years of age who received either PEGBP or NaPS for an outpatient colonoscopy. Patients with cardiac or renal disease, long-term care residents or patients receiving concurrent diuretic therapy were identified as high risk for adverse events. The primary outcome was a serious event (SE) defined as a composite of nonelective hospitalization, emergency department visit or death within seven days of the colonoscopy.

RESULTS

Of the 50,660 outpatients >=66 years of age who underwent a colonoscopy, SEs were observed in 675 (2.4%) and 543 (2.4%) patients in the PEGBP and NaPS groups, respectively. Among high-risk patients (n=30,168), SEs occurred in 481 (2.8%) and 367 (2.8%) of patients receiving PEGBP and NaPS, respectively.

CONCLUSIONS

The SE rate within seven days of outpatient colonoscopy was 24 per 1000 procedures, and among high-risk patients was 28 per 1000 procedures. The rates were similar for PEGBP and NaPS. Clinicians should be aware of the risks associated with colonoscopy in older patients with comorbidities.

The use of registered nurses to perform flexible sigmoidoscopy procedures in ontario: a cost minimization analysis

RATIONALE

Rates of colorectal cancer (CRC) are on the rise in Canada. Flexible sigmoidoscopy (FS) is an initial screening test for CRC primarily used in adults aged 50 years and older at average risk for the disease. Physicians and registered nurses have been shown to have the same effectiveness in performing a FS procedure. This paper presents an analysis of the use of registered nurses (RN) compared to physicians in Ontario to assess costs to the healthcare system.

OBJECTIVES

To evaluate whether FS performed by RNs is a less costly alternative to increase access to CRC screening capacity in Ontario.

METHODOLOGY

A cost minimization analysis was conducted from a health system perspective.

DISCUSSION

RN-performed FS is a viable alternative for increasing CRC screening capacity in Ontario. Remuneration schedules for on-call physicians must be taken into consideration if policies are developed for the implementation of RN screening procedures.

RESULTS

The findings suggest that the use of RNs may be cost saving compared to physician-performed FS procedures, depending on physician remuneration.

Social disparities in the use of colonoscopy by primary care physicians in Ontario

Background

It is unclear if all persons in Ontario have equal access to colonoscopy. This research was designed to describe long-term trends in the use of colonoscopy by primary care physicians (PCPs) in Ontario, and to determine whether PCP characteristics influence the use of colonoscopy.

Methods

We conducted a population-based retrospective study of PCPs in Ontario between the years 1996-2005. Using administrative data we identified a screen-eligible group of patients aged 50-74 years in Ontario. These patients were linked to the PCP who provided the most continuous care to them during each year. We determined the use of any colonoscopy among these patients. We calculated the rate of colonoscopy for each PCP as the number of patients undergoing colonoscopies per 100 screen eligible patients. Negative binomial regression was used to identify factors associated with the rate of colonoscopy, using generalized estimating equations to account for clustering of patients within PCPs.

Results

Between 7,955 and 8,419 PCPs in Ontario per year (median age 43 years) had at least 10 eligible patients in their practices. The use of colonoscopy by PCPs increased sharply in Ontario during the study period, from a median rate of 1.51 [inter quartile range (IQR) 0.57-2.62] per 100 screen eligible patients in 1996 to 4.71 (IQR 2.70-7.53) in 2005. There was substantial variation between PCPs in their use of colonoscopy. PCPs who were Canadian medical graduates and with more years of experience were more likely to use colonoscopy after adjusting for their patient characteristics. PCPs were more likely to use colonoscopy if their patient populations were predominantly women, older, had more illnesses, and if their patients resided in less marginalized neighborhoods (lower unemployment, fewer immigrants, higher income, higher education, and higher English/French fluency).

Conclusions

There is substantial variation in the use of colonoscopy by PCPs, and this variation has increased as the overall use of colonoscopy increased over time. PCPs whose patients were more marginalized were less likely to use colonoscopy, suggesting that there are inequities in access.

Accuracy of administrative claims data for polypectomy

BACKGROUND

The frequency of polypectomy is an important indicator of quality assurance for population-based colorectal cancer screening programs. Although administrative databases of physician claims provide population-level data on the performance of polypectomy, the accuracy of the procedure codes has not been examined. We determined the level of agreement between physician claims for polypectomy and documentation of the procedure in endoscopy reports.

METHODS

We conducted a retrospective cohort study involving patients aged 50-80 years who underwent colonoscopy at seven study sites in Montréal, Que., between January and March 2007. We obtained data on physician claims for polypectomy from the Régie de l'Assurance Maladie du Québec (RAMQ) database. We evaluated the accuracy of the RAMQ data against information in the endoscopy reports.

RESULTS

We collected data on 689 patients who underwent colonoscopy during the study period. The sensitivity of physician claims for polypectomy in the administrative database was 84.7% (95% confidence interval [CI] 78.6%-89.4%), the specificity was 99.0% (95% CI 97.5%-99.6%), concordance was 95.1% (95% CI 93.1%-96.5%), and the kappa value was 0.87 (95% CI 0.83-0.91).

INTERPRETATION

Despite providing a reasonably accurate estimate of the frequency of polypectomy, physician claims underestimated the number of procedures performed by more than 15%. Such differences could affect conclusions regarding quality assurance if used to evaluate population-based screening programs for colorectal cancer. Even when a high level of accuracy is anticipated, validating physician claims data from administrative databases is recommended.

Association between colonoscopy rates and colorectal cancer mortality

OBJECTIVES

Although colonoscopy use has increased in the United States and Canada since the early 1990s, it is unclear whether this has been associated with benefit at the population level. Our objective was to evaluate the association between regional colonoscopy rates and death from colorectal cancer (CRC).

METHODS

We conducted a natural experiment involving a 14-year follow-up of a cohort of all men and women 50-90 years of age living in Ontario on 1 January 1993 exposed to different intensities of colonoscopy use. Each member of the study cohort was assigned to a region each year, on the basis of his/her residence. Each individual was followed up through 31 December 2006; age- and sex-standardized CRC incidence rates were calculated and all CRC deaths were identified. Each year, for each region, the rate of colonoscopies performed on persons 50-90 years of age, per 1,000 population 50-90 years of age, living in the region, was calculated. Multivariable cox proportional hazards models were used to evaluate the association between colonoscopy rate and death from CRC, adjusting for age, sex, comorbidity, income, and location of residence (urban/rural).

RESULTS

The study cohort comprised 2,412,077 persons 50-90 years of age. The mean age was 64 years, and 53.7% were women. Colonoscopy rates increased in all regions during 1993-2006. The increased rate of complete colonoscopy was inversely associated with death from CRC. For every 1% increase in complete colonoscopy rate, the hazard of death decreased by 3%.

CONCLUSIONS

Increased colonoscopy use was associated with mortality reduction from CRC at the population level.

Participation in colorectal cancer screening with FOBT and colonoscopy: an Italian, multicentre, randomized population study

BACKGROUND

Data on the adherence rate to screening colonoscopy (OC) in the average-risk general population are limited and variable. Aim of this study was to compare the uptake of OC screening with that of fecal occult blood (FOBT).

METHODS

A nationwide, population-based, multicentre, randomized trial comparing attendance to OC with that to FOBT was performed. Sixty-four general practitioners (GPs), overall including in their lists 9889 average-risk subjects aged 55-64 years, were randomized between OC and FOBT screening programs. Eligible subjects were mailed a personal invitation letter co-signed by their GP and the coordinator of the area-reference GI centre. Attendance rate and detection rate for advanced neoplasia (colorectal cancer, adenoma >10mm or with villous histology or high-grade dysplasia) for each arm of the study were assessed.

RESULTS

The overall attendance rate was 18.7% (1563/8378 eligible subjects). It was markedly lower in the OC than in the FOBT strategy (10% vs. 27.1%; OR 0.28, 95% CI: 0.25-0.32; P<0.0001). In particular, participation in OC screening arm was extremely low in South Italy (2.8%), whilst it was higher in North-Central Italy (12.4%; P<0.0001). Compliance to colonoscopy in those with a positive FOBT was only 58%. Advanced neoplasia was detected in 28 (6.8%) patients in the OC arm and in 6 (18%) in those with a positive FOBT submitted to OC.

CONCLUSIONS

The results of our study underline the difficulties and barriers to implement a OC population screening in Italy, at least through primary care. Although attendance to FOBT was higher, it was disappointingly less than 30%. Significant actions to improve awareness amongst GPs and the population are a high priority.

Hypokalemia following polyethylene glycol-based bowel preparation for colonoscopy in older hospitalized patients with significant comorbidities

BACKGROUND

Polyethylene glycol-based bowel preparations (PEGBPs) are widely perceived as safe and effective alternatives to oral sodium phosphate for bowel cleansing prior to colonoscopy. Most studies supporting this belief involve young patients with few comorbidities.

OBJECTIVE

To characterize the incidence of electrolyte disturbances following PEGBPs administered prior to colonoscopy among elderly inpatients and hypothesize that PEGBP would be associated with hypokalemia in this setting.

METHODS

This retrospective chart review, conducted at 3 tertiary care teaching hospitals in Toronto, Canada, from 2005 to 2007, included 96 consecutive patients aged 65 or older who were admitted to the hospital and given PEGBP prior to their first inpatient colonoscopy. Patients were excluded if they received additional cathartics, underwent colonoscopy while admitted to a critical care unit, or were admitted for a complication arising from an outpatient colonoscopy. The primary outcome was hypokalemia (serum potassium < or =3.2 mEq/L) within 48 hours of PEGBP.

RESULTS

Of 96 patients, 73 had serum electrolytes measured at baseline and within 48 hours following PEGBP administration. Hypokalemia was identified in 4 patients (5.5%) prior to PEGBP and in 15 patients (20.5%) after PEGBP (p < 0.001). The incidence of significant hypokalemia, defined as serum potassium < or =3.0 mEq/L, in this group was 9.6% (p = 0.008). We found consistent results among patients with and without concomitant diuretic treatment.

CONCLUSIONS

Among older patients, administration of PEGBP is commonly complicated by the development of hypokalemia, which is occasionally severe. Monitoring of electrolytes may be necessary following colonoscopy, particularly in patients with cardiac or renal disease.

Population-based prevalence estimates of history of colonoscopy or sigmoidoscopy: review and analysis of recent trends

BACKGROUND

Lower GI endoscopy, such as colonoscopy or sigmoidoscopy, is thought to have a substantial impact on colorectal cancer incidence and mortality through detection and removal of precancerous lesions and early cancers. We aimed to review prevalence estimates of history of colonoscopy or sigmoidoscopy in the general population and to analyze recent trends.

METHODS

A systematic review of the medical literature, including MEDLINE (1966 to August 2008) and EMBASE (1980 to August 2008), was undertaken, supplemented by searches of the European Health Interview & Health Examination Surveys database and bibliographies. Detailed age-specific and sex-specific prevalence estimates from the United States were obtained from the Behavioral Risk Factor Surveillance System surveys 2002, 2004, and 2006.

RESULTS

The search yielded 55 studies that met our inclusion criteria. The majority of the reports (43) originated from the United States. Other countries of origin included Australia (2), Austria (2), Canada (5), France (1), Germany (1), and Greece (1). Estimates from the United States were generally increasing over time up to 56% (2006) for lifetime use of colonoscopy or sigmoidoscopy in people aged 50 years and older. Analysis of national survey data showed higher prevalences among men aged 55 years and older than for women of the same age. Prevalences were highest for people aged 70 to 79 years.

CONCLUSION

Data from outside the United States were extremely limited. Prevalence estimates from the United States indicate that a considerable and increasing proportion of the population at risk has had at least 1 colonoscopy or sigmoidoscopy in their lives, although differences between age and sex groups persist. Prevalences of previous colonoscopy or sigmoidoscopy need to be taken into account in the interpretation of time trends in, and variation across, populations of colorectal cancer incidence and mortality.

Who provides gastrointestinal endoscopy in Canada?

PURPOSE

To determine who provides gastrointestinal endoscopy in Canada and to understand provincial and regional differences in endoscopy providers.

METHODS

Aggregate physician sociodemographic and activity data for 2002 were obtained from the Canadian Institute of Health Information's National Physician Database. Physicians were classified as gastroenterologists, general surgeons and others.

RESULTS

In 2002, 1444 physicians, including 735 surgeons, 551 gastroenterologists and 158 others, performed at least 100 colonoscopies or 100 gastroscopies. Gastroenterologists performed 53% of all colonoscopies and 59% of all gastroscopies. Gastroenterologists were the primary providers of colonoscopies in large urban areas, whereas surgeons were the primary providers in smaller urban and rural areas. An average of 317 colonoscopies were performed by surgeons, 516 by gastroenterologists and 203 by other physicians. The proportion of surgeon colonoscopists in each province ranged from 47% to 71%.

CONCLUSIONS

Surgeons and gastroenterologists are the major providers of gastrointestinal endoscopy in Canada, but the distribution of these providers among provinces and urban and rural areas varies. Although surgeon endoscopists are more numerous, on average, they perform fewer procedures annually than internists.