Effect of workup strategy on the cost-effectiveness of fecal occult blood screening for colorectal cancer

Physicians respond to a positive fecal occult blood test with a variety of workup strategies. To study the effect of the choice of strategy on the net costs and health benefits of colorectal cancer screening using this test, we used a decision analysis model to compare seven strategies that physicians might choose to examine a positive "screenee." Strategies using rigid or flexible sigmoidoscopy alone are not only insensitive, but also have high cost-effectiveness ratios. The strategy of air contrast barium enema alone had the lowest cost-effectiveness ratio. Rigid sigmoidoscopy combined with barium enema had a lower cost-effectiveness ratio than primary colonoscopy, but the strategy of primary colonoscopy could have an equal or better ratio depending on assumptions about test costs and the benefit of removing benign polyps. The primary colonoscopy strategy is both more effective and less costly than the combination of flexible sigmoidoscopy and barium enema. The optimal strategy will vary with local factors, and with the perspective of the decision-maker.     

Case-control study of screening colonoscopy in relatives of patients with colorectal cancer

OBJECTIVES: The efficacy of colonoscopic screening and polypectomy for the prevention of colorectal cancer (CRC) is well accepted but has never been documented in a prospective, controlled study. Screening by sigmoidoscopy has been found to reduce mortality from cancer of the rectum and distal colon. Case-control studies provide an alternative method for determining the efficacy of screening methods. METHODS: Between 1998 and 2000, a total of 40 subjects were found to have CRC (study group) and 160 had a normal colon (control group) among asymptomatic individuals participating in a screening colonoscopy program for a high-risk population of first-degree relatives of CRC patients. We compared these groups for screening by fecal occult blood testing, flexible sigmoidoscopy, barium enema, and colonoscopy in the 10-yr period before the index colonoscopy. RESULTS: Screening colonoscopy was performed in only 2.5% of the case subjects and 48.7% of controls (p < 0.0001), and all screening procedures in 12.5% and 73.7%, respectively (p < 0.0001). A statistically significant difference was also found for screening with fecal occult blood test, but not for flexible sigmoidoscopy or barium enema. Significant adenomatous polyps >1 cm in diameter were detected and removed in 19% of the control group within 10 yr of the index colonoscopy. Six (15%) of the patients in the study group died of CRC. CONCLUSIONS: Screening by colonoscopy can prevent progression to CRC from adenomatous polyps and may reduce the mortality associated with this devastating disease.     

Flexible sigmoidoscopy plus air contrast barium enema versus colonoscopy for suspected lower gastrointestinal bleeding

A randomized, controlled trial was performed to compare the diagnostic yields and cost-effectiveness of two strategies for the evaluation of nonemergent lower gastrointestinal bleeding. Three hundred eighty patients aged greater than or equal to 40 yr were randomized to undergo initial flexible sigmoidoscopy plus air contrast barium enema or colonoscopy; 332 completed the initial studies. Initial colonoscopy detected more cases of polyps less than 9 mm in size, adenomas, and arteriovenous malformations but fewer cases of diverticulosis. No significant difference was found between strategies in the number of patients detected with cancers or polyps greater than or equal to 9 mm in size. In both strategies, cancers were more common in subjects aged greater than or equal to 55 yr (8% overall) than in those aged less than 55 yr (1%). Among patients aged less than 55 yr with suspected lower gastrointestinal bleeding, initial flexible sigmoidoscopy plus air contrast barium enema is a more cost-effective strategy for the detection of colonic neoplasms than initial colonoscopy. However, initial colonoscopy is more cost effective for those aged greater than or equal to 55 yr.     

The use of screening colonoscopy for patients cared for by the Department of Veterans Affairs

BACKGROUND: Medicare data indicate an increase in colorectal cancer (CRC) screening using colonoscopy and a decline in fecal occult blood testing, flexible sigmoidoscopy, and double-contrast barium enema. Because of differences in the delivery of health care, this trend in use of colonoscopy in fee-for-service settings might not be paralleled in the Department of Veterans Affairs (VA). METHODS: National inpatient and outpatient VA databases were searched for codes indicative of colonoscopy, flexible sigmoidoscopy, fecal occult blood testing, and double-contrast barium enema during fiscal years 1998 to 2003 among VA users aged 49 to 75 years. RESULTS: The frequency of tests for CRC screening increased from 432,778 in 1998 to 1,179,764 in 2003. Of those who were screened, only the proportion of subjects screened with fecal occult blood testing increased from 81.7% to 90.4%, while screening colonoscopy declined from 5.7% to 4.7%; flexible sigmoidoscopy declined from 8.3% to 3.6%; and double-contrast barium enema declined from 4.1% to 1.3%. The total use of screening colonoscopy procedures increased from 24,955 in 1998 to 55,199 in 2003, but the proportion of colonoscopy procedures performed for CRC screening purposes increased only slightly from 34.3% to 38.4%. In regression models adjusting for age, race, and sex, there was no consistent secular trend in the likelihood of undergoing screening colonoscopy for patients cared for in the VA health care system. CONCLUSIONS: Colorectal cancer screening has dramatically increased in the VA, but unlike in other practice settings, fecal occult blood testing is the dominant mode of screening. Although screening colonoscopy more than doubled in frequency, it constitutes a small proportion of the total CRC screening procedures used in the VA health care setting.     

Fecal occult blood and flexible sigmoidoscopy screening for colorectal cancer: modeling the impact on colonoscopy requirements and cancer detection rates

AiM: The aim of this study was to estimate the colonoscopy requirements and the likely impact of fecal occult blood and flexible sigmoidoscopy screening on the detection of colorectal cancer by using previously published data. METHODS: Fecal occult blood and flexible sigmoidoscopy screening programs were applied to the 2.04 million subjects aged 50-65 years, at a participation rate of 40%. The following strategies were evaluated: Fecal occult blood testing with colonoscopy follow up of all positive tests; flexible sigmoidoscopy with colonoscopy follow up of all adenomatous polyps; and flexible sigmoidoscopy with colonoscopy follow up of all adenomatous polyps > 10 mm in size. RESULTS: The fecal occult blood program detected 5.6% of all colorectal cancer cases at a rate of 2,914 colonoscopies/percentage of detection of colorectal cancer. The flexible sigmoidoscopy program detected 14% of all colorectal cancer cases at a rate of 8,160 colonoscopies/percentage of detection of colorectal cancer. The flexible sigmoidoscopy program with follow up of adenomatous polyps > 10 mm in size detected 13% of all colorectal cancer cases at a rate of 1,230 colonoscopies/percentage of detection of colorectal cancer. CONCLUSIONS: Flexible sigmoidoscopy screening followed by colonoscopic follow up of adenomatous polyps > 10 mm in size is the most efficient screening strategy in terms of colonoscopies generated and cases of colorectal cancer detected.     

The Quebec Association of Gastroenterology position paper on colorectal cancer screening - 2003.

Colorectal cancer is a leading cause of death and the third most common cancer in Canada. Evidence suggests that screening can reduce mortality rates and the cost effectiveness of a program compares favourably with initiatives for breast and cervical cancer. The objectives of the Association des gastro-entérologues du Québec Task Force were to determine the need for a policy on screening for colorectal cancer in Quebec, to evaluate the testing methods available and to propose one or more of these alternatives as part of a formal screening program, if indicated. Fecal occult blood testing (FOBT), endoscopy (including sigmoidoscopy and colonoscopy), barium enema and virtual colonoscopy were considered. Although most clinical efficacy data are available for FOBT and sigmoidoscopy, there are limitations to programs based on these strategies. FOBT has a high false positive rate and a low detection yield, and even a combination of these strategies will miss 24% of cancers. Colonoscopy is the best strategy to both detect and remove polyps and to diagnose colorectal cancer, with double contrast barium enema also being a sensitive detection method. The Task Force recommended the establishment, in Quebec, of a screening program with five- to 10-yearly double contrast barium enema or 10-yearly colonoscopy for individuals aged 50 years or older at low risk. The program should include outcome monitoring, public and professional education to increase awareness and promote compliance, and central coordination with other provincial programs. The program should be evaluated; specific billing codes for screening for colorectal cancer would help facilitate this. Formal feasibility, effectiveness and cost-effectiveness studies in Quebec are now warranted.     

Flexible sigmoidoscopy may be ineffective for secondary prevention of colorectal cancer in asymptomatic,average-risk men

Asymptomatic men (N=114) 50 years of age or older had screening for colorectal neoplasia with flexible sigmoidoscopy followed by colonoscopy regardless of the sigmoidoscopic result. Our study objective was to determine the prevalence of patients having isolated adenomatous polyps in a proximal colonic segment in the absence of a distal index neoplasm within reach of the sigmoidoscope. Through the combined use of sigmoidoscopy and colonoscopy, adenomatous polyps were detected in 47 of 114 individuals (41%). A total of 88 adenomas was found. Seventeen patients had isolated neoplasms in proximal colonic segments in the absence of distal adenomas. These patients represented 15% of screened subjects (17 of 114) and 20% of individuals who lacked adenomas on sigmoidoscopy (17 of 84). The majority of proximal neoplasms were small (<1.0 cm), tubular adenomas. Flexible sigmoidoscopy may be ineffective for screening asymptomatic men for neoplasia. However, it remains to be determined if a 20% miss rate (for those with a normal sigmoidoscopic examination) is significant and whether small proximal adenomas are worth finding.     

Significance of distal polyps detected with flexible sigmoidoscopy in asymptomatic patients.

BACKGROUND--Colorectal cancer is a frequent cause of death from cancer. To reduce the mortality associated with this disease, regular flexible sigmoidoscopy is recommended. However, the significance of diminutive polyps (adenomatous or hyperplastic) detected during flexible sigmoidoscopy remains controversial, as does the appropriate endoscope length (35 vs 60 cm) for colorectal cancer screening. METHODS--One hundred one consecutive patients with no history of colonic disease, gastrointestinal tract symptoms, or positive results of fecal occult blood testing underwent flexible sigmoidoscopy as part of a colorectal cancer screening program. All patients with distal polyps detected during flexible sigmoidoscopy underwent colonoscopy. RESULTS--More than 25% of these asymptomatic, predominantly male subjects had colonic neoplasms or polyps detected. Fifty percent more lesions could be detected with a 60-cm sigmoidoscope than with a 35-cm sigmoidoscope, and detection of any distal polyp, whether adenomatous or hyperplastic, was associated with at least one proximal colon adenoma in 20% of patients. "Extended flexible sigmoidoscopy" for colorectal cancer screening was well tolerated by patients, as evidenced by insertion to the hepatic flexure in 25% of patients, and provided significantly more information than could be obtained with a 35-cm sigmoidoscope. CONCLUSIONS--Colorectal cancer screening should be performed with a 60-cm flexible sigmoidoscope, and distal colonic polyps or neoplasms will be detected in 25% of asymptomatic patients.     

Distal colonic neoplasms predict proximal neoplasia in average-risk, asymptomatic subjects

Flexible sigmoidoscopy has been recommended as a screening method to reduce the incidence of colorectal cancer in asymptomatic, average-risk subjects through the early detection and removal of polyps. However, the association between distal and proximal colonic neoplasia and, hence, the requirement for colonoscopic follow up of screen-detected distal neoplasms is unclear. Our aims were: (i) to evaluate the risk of having proximal neoplasms in those with distal colonic neoplasms; and (ii) to determine whether the risk was dependent on the number, size, histology or morphology of the distal lesions. We prospectively evaluated asymptomatic subjects in a flexible sigmoidoscopy based screening programme. Those with rectosigmoid neoplasia underwent colonoscopy. The number, size, histology and morphology of the polyps were recorded. Advanced lesions were defined as adenomas > 1 cm or with a villous component or severe dysplasia, carcinoma in situ or cancer. Adenomatous polyps were found in 17% (135) of screening flexible sigmoidoscopies. At colonoscopy, up to 30% of subjects with distal colonic neoplasms had synchronous proximal lesions at colonoscopy and up to 20% had advanced proximal lesions. The risk of proximal colonic neoplasia was increased in those with distal sessile colonic neoplasms but appeared independent of distal lesion size, number or morphology. In conclusion, distal colonic neoplasia predicts proximal neoplasia in up to 30% of subjects and these were advanced lesions in up to 20%. We recommend that all subjects with biopsy proven distal colonic neoplasia undergo colonoscopy.     

Cost-effectiveness of colonoscopy in screening for colorectal cancer

BACKGROUND: Fecal occult blood testing, flexible sigmoidoscopy, and colonoscopy are used to screen patients for colorectal cancer. OBJECTIVE: To compare the cost-effectiveness of fecal occult blood testing, flexible sigmoidoscopy, and colonoscopy. DESIGN: The cost-effectiveness of the three screening strategies was compared by using computer models of a Markov process. In the model, a hypothetical population of 100 000 persons 50 years of age undergoes annual fecal occult blood testing, sigmoidoscopy every 5 years, or colonoscopy every 10 years. Positive results on fecal occult blood testing or adenomatous polyps found during sigmoidoscopy are worked up by using colonoscopy. After polypectomy, colonoscopy is repeated every 3 years until no polyps are found. DATA SOURCES: Transition rates were estimated from U.S. vital statistics and cancer statistics and from published data on the sensitivity, specificity, and efficacy of various screening techniques. Costs of screening and cancer care were estimated from Medicare reimbursement data. TARGET POPULATION: Persons 50 years of age in the general population. TIME HORIZON: The study population was followed annually until death. PERSPECTIVE: Third-party payer. OUTCOME MEASURE: Incremental cost-effectiveness ratio. RESULTS OF BASE-CASE ANALYSIS: Compared with colonoscopy, annual screening with fecal occult blood testing costs less but saves fewer life-years. A screening strategy based on flexible sigmoidoscopy every 5 or 10 years is less cost-effective than the other two screening methods. RESULTS OF SENSITIVITY ANALYSIS: Screening with fecal occult blood testing is more sensitive to changes in compliance rates, and it becomes easily dominated by colonoscopy under most conditions assuming less than perfect compliance. Other assumptions about the sensitivity and specificity of fecal occult blood testing, screening frequency, efficacy of colonoscopy in preventing cancer, and polyp incidence have a lesser influence on the differences in cost-effectiveness between colonoscopy and fecal occult blood testing. CONCLUSIONS: Colonoscopy represents a cost-effective means of screening for colorectal cancer because it reduces mortality at relatively low incremental costs. Low compliance rates render colonoscopy every 10 years the most cost-effective primary screening strategy for colorectal cancer.     

Flexible fiberoptic sigmoidoscopy and double-contrast barium-enema examination in the identification of adenomas and carcinoma of the colon

To assess the accuracy of the flexible fiberoptic sigmoidoscope, 227 consecutive patients (mean age 61.8±13 years) requiring investigation of colonic symptoms were evaluated using rigid and flexible sigmoidoscopy (PAF and KDV) and double-contrast barium enema (SSA). Patients with equivocal findings or adenomatous polyps underwent colonoscopy (TWB). Thirty-four patients had carcinoma and 50 patients had one or more adenomatous polyps (>5mm). The neoplastic yield from rigid sigmoidoscopy was 12 per cent, flexible fiberoptic sigmoidoscopy 90 per cent, and double-contrast barium enema only 76 per cent. Barium enema failed to identify eight carcinomas and 13 adenomatous polyps; seven of the eight carcinomas were polypoid Dukes' Stage A lesions, and associated diverticular disease was present in 62.5 per cent of cases. Flexible fiberoptic sigmoidoscopy failed to identify seven carcinomas and one adenomatous polyp. Five of the carcinomas were beyond range of the instrument; in one patient, a stricture was seen that was caused by the carcinoma; and in the seventh patient, the examination was terminated because of angulation spasm. Double-contrast barium enema is inaccurate in detecting lesions in the sigmoid colon, with flexible sigmoidoscopy being superior.     

A population-based, community estimate of total colon examination: the impact on compliance with screening for colorectal cancer

OBJECTIVE: Colorectal cancer screening is underutilized. Total colon examination (TCE), such as with colonoscopy, can have a significant effect on the measured compliance with screening, as colonoscopy may be able to be performed as infrequently as once every 10 yr. In a population-based survey we determined the prevalence and validated the self-reporting of TCE and assessed its impact on compliance with screening. METHODS: We interviewed an age- and sex-stratified random sample of 50- to 79-yr-old residents in two communities in southwestern Pennsylvania. Subjects reported ever having had and duration since last use of fecal occult blood testing (FOBT), flexible sigmoidoscopy (FS), rigid proctoscopy, barium enema, and colonoscopy. Self-reports of colorectal testing were validated via retrieval of procedure reports. RESULTS: Out of 1223 individuals sampled, 496 completed a telephone interview (40.6% overall and 58.3% of eligible contacts). In those without personal or family histories of colorectal cancer or personal histories of polyps (n = 377), 50%, 19.6%, 39.8%, and 17.5% reported ever having had FOBT, FS, barium enema, and colonoscopy, respectively. Thirty-one percent reported having FOBT within the previous year or FS within the previous 5 yr. Including TCE within the previous 5 yr increased the measured compliance to 39.7%. Compliance was significantly greater among subjects with family histories of colorectal cancer (62.9% vs 39.7%, odds ratio = 2.6, 95% CI = 1.3-5.2). Self-reports of recent colonoscopy were verified in 29 of 35 instances (83%). CONCLUSION: The prevalence of TCE in this population was significant, and including TCE substantially increased measured compliance with colorectal cancer screening. Self-reported use of colonoscopy was validated as accurate.     

Comparison of flexible sigmoidoscopy with other diagnostic techniques in the diagnosis of rectocolon neoplasia

Flexible sigmoidoscopy was compared to rigid sigmoidoscopy in the detection of colorectal neoplasia in a select group of patients. A distance of 30 cm or greater was obtained by flexible sigmoidoscopy in 94% of patients and a distance of 50 cm or greater in 46% of patients. A significant number of cancers and adenomas detected by flexible sigmoidoscopy were not detected by rigid sigmoidoscopy. Flexible sigmoidoscopy was tolerated better than rigid sigmoidoscopy but required twice the time. Flexible sigmoidoscopy could be combined with air-contrast barium enema the same day with the one preparation and did not interfere with the x-ray examination. All cancers and a significant number of adenomas detected subsequently on colonoscopy were detected by the combination of flexible sigmoidoscopy and air-contrast barium enema. Although the combination of flexible sigmoidoscopy and air-contrast barium enema is not adequate for thorough diagnostic evaluation of patients with a positive screening test, it may be of value in other select clinical situations. Flexible sigmoidoscopy has the potential for higher yield and better patient tolerance as compared to rigid sigmoidoscopy. This warrants further evaluation.This study presented in part at the 1977 Annual Meeting of the American Society for Gastrointestinal Endoscopy, May 1977, Toronto.This work supported in part by Public Health Service Research Grant CA-15429 from the National Cancer Institute through the National Large Bowel Cancer Project.     

Which colon cancer screening test? A comparison of costs, effectiveness, and compliance.

PURPOSE: Recent media reports have advocated the use of colonoscopy for colorectal cancer screening. However, colonoscopy is expensive compared with other screening modalities, such as fecal occult blood testing and flexible sigmoidoscopy. We sought to determine the cost effectiveness of different screening strategies for colorectal cancer at levels of compliance likely to be achieved in clinical practice. METHODS: A Markov decision model was used to examine screening strategies, including fecal occult blood testing alone, fecal occult blood testing combined with flexible sigmoidoscopy, flexible sigmoidoscopy alone, and colonoscopy. The timing and frequency of screening was varied to assess optimal screening intervals. Sensitivity analyses were conducted to assess the factors that have the greatest effect on the cost effectiveness of screening. RESULTS: All strategies are cost effective versus no screening, at less than $20,000 per life-year saved. Direct comparison suggests that the most effective strategies are twice-lifetime colonoscopy and flexible sigmoidoscopy combined with fecal occult blood testing. Assuming perfect compliance, flexible sigmoidoscopy combined with fecal occult blood testing is slightly more effective than twice-lifetime colonoscopy (at ages 50 and 60 years) but is substantially more expensive, with an incremental cost effectiveness of $390,000 per additional life-year saved. However, compliance with primary screening tests and colonoscopic follow-up for polyps affect screening decisions. Colonoscopy at ages 50 and 60 years is the preferred test regardless of compliance with the primary screening test. However, if follow-up colonoscopy for polyps is less than 75%, then even once-lifetime colonoscopy is preferred over most combinations of flexible sigmoidoscopy and fecal occult blood testing. Costs of colonoscopy and proportion of cancer arising from polyps also affect cost effectiveness. CONCLUSIONS: Colonoscopic screening for colorectal cancer appears preferable to current screening recommendations. Screening recommendations should be tailored to the compliance levels achievable in different practice settings.     

Prospective comparison of double contrast barium enema plus flexible sigmoidoscopy v colonoscopy in rectal bleeding: barium enema v colonoscopy in rectal bleeding.

Rectal bleeding often heralds serious colonic disease. The literature suggests that colonoscopy is superior to barium enema plus sigmoidoscopy, although no good comparative studies exist. Seventy one patients with overt rectal bleeding had prospectively flexible sigmoidoscopy, double contrast barium enema and colonoscopy completed independently. Against the gold standard, the sensitivity and specificity of colonoscopy were 0.69 and 0.78 respectively for a spectrum of colonic lesions, while for combined flexible sigmoidoscopy and double contrast barium enema these values were 0.80 and 0.56, respectively. When assessing adenoma or carcinoma, colonoscopy was more sensitive at 0.82 v 0.73, while flexible sigmoidoscopy plus double contrast barium enema was superior for detecting diverticular disease. The positive predictive value for colonoscopy was 0.87 against 0.81 for flexible sigmoidoscopy and double contrast barium enema. This study confirms that colonoscopy should be a first line investigation in subjects likely to require biopsy or therapeutic intervention.     

Geographic variation among Medicare beneficiaries in the use of colorectal carcinoma screening procedures

OBJECTIVES: To study geographic variation in the use of recommended screening procedures for colorectal carcinoma. METHODS: All Medicare claims for fecal occult blood testing (FOBT), flexible sigmoidoscopy, colonoscopy, barium enema and two reference procedures, upper endoscopy, and upper gastrointestinal series in patients > or = 65 yr were obtained from the 1997-1999 physician-supplier and outpatient files. State-level procedure rates and the change in rates from 1997 to 1999 were calculated. RESULTS: The median annual rates were as follows: FOBT, 14.54%; flexible sigmoidoscopy, 3.03%; colonoscopy, 6.22%; barium enema, 2.21%; upper gastrointestinal endoscopy, 4.88%; and upper gastrointestinal series, 2.78%. Whereas there was at least a 50% difference between the 25th and 75th percentiles for state rates of FOBT and sigmoidoscopy, the variation in other procedures was more modest. State-level rates of colonoscopy and upper gastrointestinal endoscopy were highly correlated (r = 0.79; p < 0.0001), as were the rates of barium enema and upper gastrointestinal series (r = 0.68; p < 0.0001). Universal increases in colonoscopy use (median +25.0%) and decreases in barium enema use (median -20.9%) from 1997 to 1999 were observed among individual states. CONCLUSIONS: There is variation at the state level in the use of some, but not all colorectal procedures, as well as fairly consistent temporal trends. The etiology of the differences is not clear, but the correlation in the rates of selected procedures suggests the presence of local practice patterns.     

Barium enema versus colonoscopy for patients with polyps found during flexible sigmoidoscopy

This prospective study compares the accuracy of barium enema examination performed by experienced radiologists to colonoscopy performed by experienced gastroenterologists blinded to the radiographic findings to detect proximal, synchronous lesions in patients with polyps detected during fiberoptic sigmoidoscopy. Three thousand six patients were examined, of whom 147 (5%) had polyps larger than 0.5 cm in diameter. Of 114 patients who completed the protocol, 46 patients (40%) had synchronous, proximal colonic lesions. There were no radiographic false positives, but the single-contrast barium enema missed polyps in 13 while detecting polyps in 2 patients (sensitivity = 13%). The double-contrast barium enema missed proximal polyps in 23 patients while detecting them in 8 (sensitivity = 26%). We conclude that patients with neoplastic polyps found during fiberoptic sigmoidoscopy should have colonoscopy without barium enema. If the entire colon cannot be examined at colonoscopy, we advise double-contrast barium enema.     

Yield of advanced adenoma and cancer based on polyp size detected at screening flexible sigmoidoscopy

BACKGROUND & AIMS: Observational screening of the colon with subsequent referral for colonoscopy raises questions about the threshold of polyp size that necessitates referral. To examine the yield at colonoscopy when a given size lesion is observed, we assessed the yield of advanced adenoma and cancer at colonoscopy based on the size of the abnormality detected at flexible sigmoidoscopy (FSG). METHODS: We used data from the Prostate, Lung, Colorectal, and Ovarian Cancer Screening Trial, a randomized, controlled, community-based study of FSG. RESULTS: Subsequent colonoscopy was performed on 10,850 subjects (60.4% male; mean age, 62.9 years) with a polyp visualized on screening FSG. For women with a polyp 0.5-0.9 cm on FSG (n = 1426), the yield in the distal colon on colonoscopy was 0.6% for cancer (number needed to screen [NNS] = 166) and 14.5% for advanced adenoma (NNS = 7). In men (n = 2183), the yield was 0.7% (NNS = 142) for cancer and 15.9% (NNS = 6) for advanced adenoma. Among persons with polyps 0.5-0.9 cm identified on FSG, 5.5% (198/3609) had distal advanced adenomas that measured <1.0 cm but had villous histology or high-grade dysplasia, and 9.9% (357/3609) had adenomas > or =1 cm. CONCLUSIONS: The yield for a distal advanced adenomatous lesion when a polyp 0.5-0.9 cm is observed at FSG is substantial and is due to the presence of advanced histology in polyps <1 cm and to detection of polyps that measure > or =1.0 cm on colonoscopy. Establishing thresholds for observation versus evaluation will require careful assessment of the overall yield.     

Racial differences in use of colonoscopy,sigmoidoscopy, and barium enema in Medicare beneficiaries

Colorectal cancer is often diagnosed at a later stage in blacks. We wanted to know if racial differences existed in the use of tests for detection of colorectal cancer. A 5% random sample was obtained of all Medicare beneficiaries with Part B coverage, aged 65 years and older and classified as white or black race. The numbers of colonoscopies, flexible sigmoidoscopies, and barium enemas were determined from the Physician/Supplier file. Blacks were 18% less likely to receive colonoscopy and 39% less likely to receive flexible sigmoidoscopy after controlling for age, sex, income, and access to care in a multivariable logistic regression model. Barium enema was not significantly different between the races. Black men had 25% lower use of colonoscopy and 50% decreased use of flexible sigmoidoscopy. Blacks receive less colonoscopy and flexible sigmoidoscopy than whites. Black men are particularly vulnerable to the under-use of these tests.