Compliance with fecal occult blood testing: the role of restrictive diets

Colorectal Cancer Screening by Fecal Occult Blood Testing: Results of a Population-Based Experience

Aims and background

The study evaluated the results of an experimental screening protocol for colorectal cancer by fecal occult blood testing in a municipality of the Province of Florence.

Methods

A total of 15,235 subjects aged 50–70 years were invited to perform a 1-day immunochemical fecal occult blood testing without any dietary restrictions. All eligible subjects were sent a personal invitation letter, followed by a postal reminder to non-responders. Subjects with a negative stool test were advised to repeat screening after 2 years. Subjects with a positive screening test were invited to undergo full colonoscopy or a combination of left colonoscopy and a double contrast barium enema.

Results

A total of 6,418 subjects performed the screening test, with an overall compliance of 42.1%. A total of 268 compilers had positive test results. The positivity rate was 4.2%. Detection rate for cancer and for adenomas was 5.1‰ and 11.6‰, respectively. The positive predictive value was 14.3% for cancer and 32.5% for adenoma. A higher compliance was recorded in subjects born in the province of Florence or living in the centre of the town, in married subjects, and in women. The best results in compliance were associated with the direct distribution of fecal occult blood testing kits by general practitioners to their outpatients.

Conclusions

The study provides useful information about the efficiency and feasibility of a screening program for colorectal cancer using fecal occult blood testing. Compliance results confirm the importance of GP involvement in oncological screening.

A Randomised Trial of the Impact of New Faecal Haemoglobin Test Technologies on Population Participation in Screening for Colorectal Cancer

OBJECTIVES

To investigate the effect on participation in colorectal cancer screening of testing for blood products in faeces using technologies that remove dietary restrictions (i.e. immunochemical tests) and simplify faecal sampling (i.e. tests that use brush sampling).

METHODS

SETTING

Urban residents (n=1818) of Adelaide, Australia, aged between 50 and 69 years, randomly selected from the electoral roll.

DESIGN

Three randomised cohorts of 606 invitees were offered a screening test by mail in 2001. The Hemoccult SENSA and FlexSure OBT cohorts were instructed to sample three stools using a spatula while the InSureTM cohort sampled two stools using a brush. The Hemoccult SENSA cohort was asked to restrict certain (high-peroxidase) foods and drugs.

MAIN OUTCOME MEASURES

Participation (i.e. return of completed sample kits within 12 weeks) and generalised linear modelling (GLM) of relationships between participation, test technologies and demographic variables.

RESULTS

Participation was 23.4%, 30.5% and 39.6% for the Hemoccult, FlexSure and InSure cohorts, respectively (chi(2)=37.1, p<0.00001). GLM demonstrated that participation was increased by 28% by removal of restrictions (p=0.01) and by 30% by simplification of sampling (p=0.001); both together increased participation by 66% (p<0.001). The differences in participation between tests occurred in the first three weeks. Socio-economic status, gender or age did not significantly influence technology-based improvements in participation.

CONCLUSIONS

The brush-sampling faecal immunochemical test for haemoglobin (InSure) achieves the best participation rates by simplifying sampling and removing the need for restrictions of diet and drugs. Because participation in screening is vital to detection, this new technology should contribute to better detection of neoplasia at the population level.

Prescreening Evaluation of a Brush-Based Faecal Immunochemical Test for Haemoglobin

OBJECTIVES

To undertake a prescreening evaluation of a new brush-based faecal immunochemical test for haemoglobin, relative to a traditional spatula-sampling immunochemical test.

METHODS

SETTING

Patients aged between 24 and 90 years, scheduled to undergo diagnostic colonoscopy in two major urban hospitals, for a range of clinical indications.

DESIGN

Patients sampled three stools using a spatula for the reference FlexSure OBT test and two stools using a brush for the InSure test; order of sampling was randomised. Faecal haemoglobin was quantified by a modified InSure in a subset of patients to determine whether brush-sampling allowed discrimination between groups.

MAIN OUTCOME MEASURES

Sensitivity for cancer or adenoma; false-positive rate in normals. Faecal haemoglobin levels. Preference for sampling method.

RESULTS

InSure and FlexSure OBT did not differ in their sensitivities for cancer (27/36, 75% vs 29/36, 80.5%, respectively), adenomas >or= 10 mm (12/29, 41.4% vs 13/29, 44.8%) or adenomas <10 mm (each 8/56, 14.3%). Likewise, false-positive rates in normals were similar: 4/179 (2.2%) and 5/179 (2.8%) respectively (specificities of 97.8% and 97.2%, respectively). Levels of faecal haemoglobin were highest in those with cancers; those with adenomas had intermediate levels which were also significantly higher than those in normals. The brush sampling method was preferred by 38/46 (82.6%), while 4/46 (8.7%) preferred the spatula (p<0.00001).

CONCLUSIONS

InSure is as sensitive and specific as FlexSure OBT for faecal haemoglobin. The novel stool-sampling method of InSure allows discrimination between normals and classes of neoplasia, and is highly preferred. The brush-sampling faecal immunochemical test InSure should now be evaluated in a screening population.

Implementation intentions and colorectal screening: a randomized trial in safety-net clinics

CONTEXT

Low-income and racial/ethnic minority populations experience disproportionate colorectal cancer (CRC) burden and poorer survival. Novel behavioral strategies are needed to improve screening rates in these groups.

BACKGROUND

The study aimed to test a theoretically based "implementation intentions" intervention for improving CRC screening among unscreened adults in urban safety-net clinics.

DESIGN

Randomized controlled trial.

SETTING/PARTICIPANTS

Adults (N=470) aged ≥50 years, due for CRC screening, from urban safety-net clinics were recruited.

INTERVENTION

The intervention (conducted in 2009-2011) was delivered via touchscreen computers that tailored informational messages to decisional stage and screening barriers. The computer then randomized participants to generic health information on diet and exercise (Comparison group) or "implementation intentions" questions and planning (Experimental group) specific to the CRC screening test chosen (fecal immunochemical test or colonoscopy).

MAIN OUTCOME MEASURES

The primary study outcome was completion of CRC screening at 26 weeks based on test reports (analysis conducted in 2012-2013).

RESULTS

The study population had a mean age of 57 years and was 42% non-Hispanic African American, 28% non-Hispanic white, and 27% Hispanic. Those receiving the implementation intentions-based intervention had higher odds (AOR=1.83, 95% CI=1.23, 2.73) of completing CRC screening than the Comparison group. Those with higher self-efficacy for screening (AOR=1.57, 95% CI=1.03, 2.39), history of asthma (AOR=2.20, 95% CI=1.26, 3.84), no history of diabetes (AOR=1.86, 95% CI=1.21, 2.86), and reporting they had never heard that "cutting on cancer" makes it spread (AOR=1.78, 95% CI=1.16, 2.72) were more likely to complete CRC screening.

CONCLUSIONS

The results of this study suggest that programs incorporating an implementation intentions approach can contribute to successful completion of CRC screening even among very low-income and diverse primary care populations. Future initiatives to reduce CRC incidence and mortality disparities may be able to employ implementation intentions in large-scale efforts to encourage screening and prevention behaviors.

Comparison of fecal occult blood tests for colorectal cancer screening in an Alaska Native population with high prevalence of Helicobacter pylori infection, 2008-2012

Introduction

Alaska Native colorectal cancer (CRC) incidence and mortality rates are the highest of any ethnic/racial group in the United States. CRC screening using guaiac-based fecal occult blood tests (gFOBT) are not recommended for Alaska Native people because of false-positive results associated with a high prevalence of Helicobacter pylori-associated hemorrhagic gastritis. This study evaluated whether the newer immunochemical FOBT (iFOBT) resulted in a lower false-positive rate and higher specificity for detecting advanced colorectal neoplasia than gFOBT in a population with elevated prevalence of H. pylori infection.

Methods

We used a population-based sample of 304 asymptomatic Alaska Native adults aged 40 years or older undergoing screening or surveillance colonoscopy (April 2008–January 2012).

Results

Specificity differed significantly (P < .001) between gFOBT (76%; 95% CI, 71%–81%) and iFOBT (92%; 95% CI, 89%–96%). Among H. pylori-positive participants (54%), specificity of iFOBT was even higher (93% vs 69%). Overall, sensitivity did not differ significantly (P = .73) between gFOBT (29%) and iFOBT (36%). Positive predictive value was 11% for gFOBT and 32% for iFOBT.

Conclusion

The iFOBT had a significantly higher specificity than gFOBT, especially in participants with current H. pylori infection. The iFOBT represents a potential strategy for expanding CRC screening among Alaska Native and other populations with elevated prevalence of H. pylori, especially where access to screening endoscopy is limited.

Dietary interventions for fecal occult blood test screening: systematic review of the literature

OBJECTIVE

To determine whether dietary restrictions enhance the specificity of guaiac-based fecal occult blood tests (FOBTs) when screening for colorectal cancer.

DATA SOURCES

PubMed-MEDLINE, the Cumulative Index to Nursing and Allied Health Literature, and Cochrane databases were searched.

STUDY SELECTION

English-language case series, cohort studies, randomized controlled trials (RCTs), and meta-analyses were selected. Studies that did not include dietary manipulation or the use of guaiac-based FOBTs available in North America were excluded.

SYNTHESIS

Ten case series, 5 cohort studies, 4 RCTs, and 1 meta-analysis were critically appraised. All studies used Hemoccult, Hemoccult II, or Hemoccult SENSA tests. Data from case series involving challenge diets showed no increase in positive FOBT results from high-peroxidase vegetables, but results varied with red-meat challenges depending on the amount of meat consumed and the test used. Case series, cohort studies, and RCTs comparing FOBT results during restricted versus unrestricted diets consistently showed no differences in positive FOBT results.

CONCLUSION

Most of the evidence evaluating the effect of dietary restrictions on FOBT results is dated and of suboptimal quality. However, 4 RCTs and a meta-analysis of these data do not support dietary restrictions when screening for colorectal cancer. Because patient adherence can be an issue with FOBTs, and dietary restrictions can affect adherence in some populations, it is reasonable to abandon these recommendations without fear of substantially affecting specificity.

Effect of dietary restriction on participation in faecal occult blood test screening for colorectal cancer

OBJECTIVES

To determine if participation in colorectal cancer screening using faecal occult blood testing (FOBT) is affected by a restrictive diet and if it is associated with certain demographic variables.

PARTICIPANTS AND SETTING

1,203 residents of South Australia aged 50-69 years, with no "currently active bowel disease", randomly selected from a database of people willing to be contacted about unspecified health issues.

DESIGN

Randomised controlled trial: participants were offered screening by immunochemical FOBT by mail in 1998. Half were randomly allocated to a group instructed to follow a low-peroxidase diet, as required for guaiac FOBT, while the other group was not so restricted.

MAIN OUTCOME MEASURES

Effect of diet restriction on participation (return of correctly completed FOBT sample cards within 15 weeks); time taken to return cards; relationships between participation and demographic variables.

RESULTS

Participation rates were 65.9% (no-diet group) and 53.3% (diet group) (difference, 12.6%; 95% CI, 7.1%-18.1%). In the first week, rates of return as a proportion of all tests returned were 13.1% (no-diet) and 1.6% (diet) (difference, 11.5%; 95% CI, 8.6%-14.4%), increasing to 54.3% and 44.5%, respectively, after five weeks (difference, 9.8%; 95% CI, 4.2%-15.4%). Participation was significantly associated with older age (odds ratio, 1.40; 95% CI, 1.10-1.78), but not sex, Index of Social Disadvantage or rural versus urban address.

CONCLUSIONS

Dietary restrictions create a barrier to FOBT-based screening for colorectal cancer. The use of immunochemical rather than guaiac FOBT removes this barrier.

Participation in colorectal cancer screening: a review

The purpose of this review is to evaluate the published literature on adherence to colorectal cancer (CRC) screening with fecal occult blood testing (FOBT) and sigmoidoscopy. Specifically, the review addresses the following: 1) prevalence of FOBT and sigmoidoscopy; 2) interventions to increase adherence to FOBT and sigmoidoscopy; 3) correlates or predictors of adherence to FOBT and sigmoidoscopy; and 4) reasons for nonadherence. Other objectives are to put the literature on CRC screening adherence in the context of recently reported findings from experimental interventions to change prevention and early detection behaviors and to suggest directions for future research on CRC screening adherence. CRC screening offers the potential both for primary and for secondary prevention. Data from the 1992 National Health Interview Survey show that 26% of the population more than 49 years of age report FOBT within the past 3 years and 33% report ever having had sigmoidoscopy. The Year 2000 goals set forth in Healthy People 2000 are for 50% of the population more than 49 years of age to report FOBT within the past 2 years and for 40% to report that they ever had sigmoidoscopy. Thus, systematic efforts to increase CRC screening are warranted. To date, attempts to promote CRC screening have used both a public health model that targets entire communities, e.g., mass media campaigns, and a medical model that targets individuals, e.g., general practice patients. Most of these efforts, however, did not include systematic evaluation of strategies to increase adherence. The data on FOBT show that the median adherence rate to programmatic offers of FOBT is between 40% and 50%, depending on the type of population offered the test, e.g., patients or employees. Approximately, 50% of those initially offered testing in unselected populations will respond to minimal prompts or interventions. A salient issue for FOBT, however, is whether or not the behavior can be sustained over time. Fewer studies examined adherence to sigmoidoscopy. Adherence was highest in relatives of CRC cases and in employer-sponsored programs offered to workers at increased risk of CRC. At present, we know very little about the determinants of CRC screening behaviors, particularly as they relate to rescreening.