Interpretations of 'appropriate' minority inclusion in clinical research

The range of possible interpretations of the phrase "appropriate representation" has left investigators struggling with the practical application of the National Institutes of Health guidelines on the inclusion of minorities in research. At least three goals might be reached by including minorities in clinical research: to test specific hypotheses about differences by race and ethnicity; to generate hypotheses about possible differences by race and ethnicity; and to ensure the just distribution of the benefits and burdens of participation in research, regardless of whether there are expected differences in outcome by race or ethnicity. In this paper, we describe possible interpretations of "appropriate representation," as well as provide a general approach that investigators might use to address this issue. To expand scientific knowledge about the health of minority populations, investigators should be expected to state which goal they have selected and why that goal is appropriate as compared with other possible goals.

Using risk for advanced proximal colonic neoplasia to tailor endoscopic screening for colorectal cancer

BACKGROUND

Colonoscopic screening for colorectal cancer has been suggested because sigmoidoscopy misses nearly half of persons with advanced proximal neoplasia.

OBJECTIVE

To create a clinical index to stratify risk for advanced proximal neoplasia and to identify a subgroup with very low risk in which screening sigmoidoscopy alone might suffice.

DESIGN

Cross-sectional study.

SETTING

A company-based program of screening colonoscopy for colorectal cancer.

PATIENTS

Consecutive persons 50 years of age or older undergoing first-time screening colonoscopy between September 1995 and June 2001.

MEASUREMENTS

A clinical index with 3 variables was created from information on the first 1994 persons. Points were assigned to categories of age, sex, and distal findings. Risk for advanced proximal neoplasia (defined as an adenoma 1 cm or larger or one with villous histology, severe dysplasia, or cancer) was measured for each score. The index was tested on the next 1031 persons from the same screening program.

RESULTS

Of 1994 persons, 67 (3.4%) had advanced proximal neoplasia. A low-risk subgroup comprising 37% of the cohort had scores of 0 or 1 and a risk of 0.68% (95% CI, 0.22% to 1.57%). Among the validation group of 1031 persons, risk for advanced proximal neoplasia in the low-risk subgroup (comprising 47% of the cohort) was 0.4% (upper confidence limit of 1.49%). Application of this index detected 92% of persons with advanced proximal neoplasms and, if applied following screening sigmoidoscopy, could reduce the need for colonoscopy by 40%. The marginal benefit of colonoscopy among low-risk persons was small: To detect 7 additional persons with advanced proximal neoplasia, 1217 additional colonoscopies would be required.

CONCLUSIONS

This clinical index stratifies the risk for advanced proximal neoplasia and identifies a subgroup at very low risk. If it is validated in other cohorts or groups, the index could be used to tailor endoscopic screening for colorectal cancer.

Accuracy of self-reports of fecal occult blood tests and test results among individuals in the carpentry trade

BACKGROUND

Inaccuracy in self-reports of colorectal cancer (CRC) screening procedures (e.g., over- or underreporting) may interfere with individuals adhering to appropriate screening intervals, and can blur the true effects of physician recommendations to screen and the effects of interventions designed to promote screening. We assessed accuracy of self-report of having a fecal occult blood test (FOBT) within a 1-year window based on receipt of FOBT kits among individuals aged 50 and older in the carpentry trade (N = 658) who were off-schedule for having had a FOBT.

METHOD

Indices of evaluating accuracy of self-reports (concordance, specificity, false-positive and false-negative rates) were calculated relative to receipt of a mailed FOBT. Among those who mailed a completed FOBT, we assessed accuracy of reporting the test result.

RESULTS

Participants underestimated having performed a FOBT (false-negative rate of 44%). Accuracy was unrelated to perceptions of getting or worrying about CRC or family history. Self-reports of having a negative FOBT result more consistently matched the laboratory result (specificity 98%) than having a positive test result (sensitivity 63%).

CONCLUSIONS

Contrary to other findings, participants under- rather than over reported FOBT screening. Results suggest greater efforts are needed to enhance accurate recall of FOBT screening.

International variation in screening mammography interpretations in community-based programs

BACKGROUND

Variations in mammography interpretations may have important clinical and economic implications. To evaluate international variability in mammography interpretation, we analyzed published reports from community-based screening programs from around the world.

METHODS

A total of 32 publications were identified in MEDLINE that fit the study inclusion criteria. Data abstracted from the publications included features of the population screened, examination technique, and clinical outcomes, including the percentage of mammograms judged to be abnormal, positive predictive value of an abnormal mammogram (PPV(A)), positive predictive value of a biopsy performed (PPV(B)), and percentages of breast cancer patients with ductal carcinoma in situ (DCIS) and minimal disease (DCIS and/or tumor size < or =10 mm). North American screening programs were compared with those from other countries using meta-regression analysis. All statistical tests were two-sided.

RESULTS

Wide ranges were noted for the percentage of mammograms judged to be abnormal (1.2%-15.0%), for PPV(A) (3.4%-48.7%), for PPV(B) (5.0%-85.2%), for percentage diagnosed with DCIS (4.3%-68.1%), and for percentage diagnosed with minimal disease (14.0%-80.6%). The percentage of mammograms judged to be abnormal were 2-4 percentage points higher in North American screening programs than they were in programs from other countries, after adjusting for covariates such as percentage of women who were less than 50 years of age and calendar year in which the mammogram was performed. The percentage of mammograms judged to be abnormal had a negative association with PPV(A) and PPV(B) (both P<.001) and a positive association with the frequency of DCIS cases diagnosed (P =.008) and the number of DCIS cases diagnosed per 1000 screens (P =.024); no consistent relationship was observed with the proportion of breast cancer diagnoses reported as having minimal disease or the number of minimal disease cases diagnosed per 1000 screens.

CONCLUSION

North American screening programs appear to interpret a higher percentage of mammograms as abnormal than programs from other countries without evident benefit in the yield of cancers detected per 1000 screens, although an increase in DCIS detection was noted.

Screening colonoscopy in balance. Issues of implementation

Although colonoscopy is currently considered an option for colon cancer screening, its choice as a preferred screening test is not supported by data, recommendations, or cost-effectiveness analysis. The use of colonoscopy in postpolypectomy surveillance constitutes a huge potential effort that should be appropriately anticipated and managed. Noninvasive methods for colon cancer screening may reduce the need for colonoscopy in the future.

Why is prostate cancer screening so common when the evidence is so uncertain? A system without negative feedback

The degree of enthusiasm for prostate cancer screening seems high given the limited evidence of benefit and the well-documented harms of treatment that include impotence and incontinence. The purpose of this review is to understand the reasons for enthusiasm and positive reinforcement perceived in clinical decisions about whether to screen, whether to choose aggressive therapy for cancer, and in how to view adverse effects following therapy. We discuss a case of a man who must decide whether to undergo prostate-specific antigen screening and treatment to illustrate the kinds of reinforcement that may occur for each decision.Strong positive reinforcement for each decision would make screening and aggressive therapy appear to be successful and the correct decision even if prostate cancer screening and therapy were not beneficial. A physician is positively reinforced for recommending screening, regardless of the test result, because a negative result makes a patient grateful for reassurance and a positive result makes a patient grateful for early detection. A patient who is impotent and incontinent after a decision for curative treatment may attribute his survival to surgery and be grateful for having his cancer cured. Individual experience provides almost no negative feedback that early detection and aggressive treatment may not work. Although reinforcement operates similarly in other medical decisions, the example of prostate cancer provides insight into the strength of the forces at work because the personal harms, which are relatively common and dramatic, are readily discounted or explained away. Even if prostate cancer screening is eventually demonstrated to provide benefit for asymptomatic persons, it is important to appreciate the strength of forces that may act independently of benefit and reinforce decision makers' choices to be aggressive about screening and treatment. Interventions should be considered to temper possible overenthusiasm for screening and treatment.

Challenges and opportunities in evaluating diagnostic tests

The field of clinical research conducted to evaluate diagnostic tests has evolved substantially over the last 25 years. This article discusses three current challenges and opportunities in conducting such research: the limitations of the "traditional focus" of clinical epidemiology in evaluating tests; how different decision makers use data produced by clinical epidemiology research, and what those uses mean for future research; and special challenges and opportunities in evaluating molecular-based tests.

Results of screening colonoscopy among persons 40 to 49 years of age

BACKGROUND

The prevalence of colorectal lesions in persons 40 to 49 years of age, as identified on colonoscopy, has not been determined.

METHODS

We reviewed the procedure and pathology reports for 906 consecutive persons 40 to 49 years of age who voluntarily participated in an employer-based screening-colonoscopy program. The histologic features of lesions that were identified and removed on endoscopy were categorized according to those of the most advanced lesion removed proximally (up to the junction of the splenic flexure and the descending colon) and the most advanced lesion removed distally. An advanced lesion was defined as an adenoma at least 1 cm in diameter, a polyp with villous histologic features or severe dysplasia, or a cancer.

RESULTS

Among those who underwent colonoscopic screening, 78.9 percent had no detected lesions, 10.0 percent had hyperplastic polyps, 8.7 percent had tubular adenomas, and 3.5 percent had advanced neoplasms, none of which were cancerous (95 percent confidence interval for cancer, 0 to 0.4 percent). Eighteen of 33 advanced neoplasms (55 percent) were located distally and were potentially within reach of a sigmoidoscope. If these results are applicable to the general population, at least 250 persons, and perhaps 1000 or more, would need to be screened to detect one cancer in this age group.

CONCLUSIONS

Colonoscopic detection of colorectal cancer is uncommon in asymptomatic persons 40 to 49 years of age. The noncancerous lesions are equally distributed proximally and distally. The low yield of screening colonoscopy in this age group is consistent with current recommendations about the age at which to begin screening in persons at average risk.

Gastroesophageal reflux, Barrett esophagus, and esophageal cancer: clinical applications

Gastroesophageal reflux disease (GERD), a condition commonly encountered in the primary care setting, is a risk factor for adenocarcinoma of the esophagus. Despite the ubiquity of the complaint, considerable uncertainty exists with respect to several basic questions, including when to perform endoscopy in patients with chronic reflux symptoms and how to address the cancer risk associated with GERD. These clinical vignettes illustrate common clinical questions encountered in caring for patients with GERD, especially as they relate to the issue of cancer risk. Applying data reviewed in the companion article, we propose practical answers to common clinical situations regarding care of patients with reflux. We also present an algorithm for treatment of patients with chronic GERD symptoms.

Gastroesophageal reflux, barrett esophagus, and esophageal cancer: scientific review

CONTEXT

Gastroesophageal reflux disease (GERD) is a risk factor for adenocarcinoma of the esophagus, a rare cancer whose incidence is increasing. Adenocarcinoma may develop from Barrett esophagus, a metaplastic change of the esophageal epithelium from squamous to intestinalized columnar mucosa, which is associated with chronic reflux. Some have recommended that patients with chronic reflux symptoms undergo upper endoscopy to assess for Barrett esophagus and to screen for cancer.

OBJECTIVES

To review the evidence linking GERD and Barrett esophagus to esophageal adenocarcinoma and to examine the utility of upper endoscopy as a screening tool in adenocarcinoma of the esophagus among individuals with GERD.

DATA SOURCES

A MEDLINE search was performed to identify all pertinent English-language reports about GERD, adenocarcinoma, and Barrett esophagus from 1968 through 2001. Reports were of randomized controlled clinical trials if available, case-control data if trials were unavailable, and cohort studies if case-control data were unavailable. Pertinent bibliographies were also reviewed to find reports not otherwise identified.

STUDY SELECTION AND DATA EXTRACTION

Studies were selected by using the search terms gastroesophageal reflux, adenocarcinoma, and Barrett's esophagus, with subheadings for classification, complications, drug therapy, economics, epidemiology, mortality, surgery, and prevention and control. Clinical guidelines for the care of subjects with GERD and Barrett esophagus were retrieved and abstracted.

DATA SYNTHESIS

Cohort studies demonstrate that symptoms of GERD occur monthly in almost 50% of US adults and weekly in almost 20%. Three large case-control studies demonstrate a positive association between reflux symptoms and risk of adenocarcinoma of the esophagus, with more prolonged and severe symptoms accentuating this risk. However, because of the low incidence of adenocarcinoma of the esophagus and the ubiquity of reflux symptoms, the risk of cancer in any given individual with reflux symptoms is low. No randomized trial data are available to demonstrate either decreased cancer incidence or increased life expectancy in subjects with GERD who undergo screening endoscopy.

CONCLUSIONS

Strong evidence supports the association of GERD and adenocarcinoma of the esophagus; however, the risk of cancer in any given individual with GERD is low. Barrett esophagus appears to be a common precursor lesion to this cancer. Given the low absolute risk of cancer in those with GERD and the lack of demonstrated efficacy of endoscopic screening, insufficient evidence exists to endorse routine endoscopic screening of patients with chronic GERD symptoms.

Achieving quality in flexible sigmoidoscopy screening for colorectal cancer

BACKGROUND

Sigmoidoscopy screening, which can dramatically reduce colorectal cancer mortality, is supported increasingly by physicians and payers, and is likely to be performed more frequently in the future. As more physicians and nonphysician medical personnel learn how to perform this procedure, and with attention to quality standards, the overall impact of sigmoidoscopy screening may improve. This review describes elements that characterize high-quality examinations and identifies resources for in-depth information on performing flexible sigmoidoscopy.

METHODS

The domains of quality were identified from textbooks, articles, and the professional opinions of gastroenterologists and primary care physicians. Information was obtained from MEDLINE, bibliographies in recent articles, medical professional organizations, equipment manufacturers' representatives, and focus groups of primary care physicians.

RESULTS

Nine domains of quality are identified and discussed: training, logistical start-up, patient interaction, bowel preparation, examination technique, lesion recognition, complications, reporting, and processing (equipment cleaning and disinfection).

CONCLUSIONS

Persons learning how to perform and to implement flexible sigmoidoscopy may use this information to help ensure the quality of screening examinations.

Effectiveness and economic impact of screening for colorectal cancer by mass fecal occult blood testing

OBJECTIVES

Fecal occult blood testing has been shown to reduce mortality from colorectal cancer in large randomized, controlled trials conducted in the United States, Denmark, and the United Kingdom, and mathematical simulation modeling found it to be cost-effective relative to other health care services. Before making a concerted effort to implement mass fecal occult blood testing based on this evidence alone, however, we considered it prudent to critically re-evaluate the effectiveness and economic impact of screening in the US population as a whole.

METHODS

To assess the effectiveness of screening, we projected published outcomes from each of the three large randomized controlled trials of fecal occult blood testing to the US population, as if each clinical trial had been done in the population as a whole. We then determined the resource costs of detection and treatment that would be associated with the outcomes predicted from each trial.

RESULTS

More than 1 million colorectal cancers could be expected to arise over 10 yr in the cohort of US residents eligible to enter a screening program in 1997, and trial outcomes indicate that > or = 60% of these cancers would be fatal. If the 60-67% compliance rate of the population-based randomized controlled trials were achieved, a fecal occult blood testing program would detect 30% of known colorectal cancers and save 100,000 lives over 10 yr. Screening would incur total costs of $3-4 billion over 10 yr, or $2,500 per life-year saved.

CONCLUSIONS

Mass fecal occult blood testing is cost-effective, and, although not inexpensive, many would consider the total cost acceptable. Even with a concerted effort to achieve compliance, however, the effectiveness of fecal occult blood testing would be limited to saving the lives of < or = 15% of those who otherwise would die from their cancer in the first 10 yr after beginning mass screening. The limitations of fecal occult blood testing suggest the need to further evaluate the role of endoscopy in screening, and to develop more effective, noninvasive screening tools.