Antidepressants and gastrointestinal symptoms in the general Dutch adult population.

BACKGROUND: Gastrointestinal symptoms are frequently reported adverse effects of antidepressants, but antidepressants are also a treatment modality in functional gastrointestinal disorders. We aimed to assess the association between antidepressant use and gastrointestinal symptoms in the general adult population. METHODS: We assessed gastrointestinal symptoms, medication use, and comorbidity through structured questionnaires in randomly selected individuals. We compared presence of gastrointestinal symptoms in respondents who reported antidepressant use with those who did not. We used multivariable regression analysis to verify the association between antidepressant use and gastrointestinal symptoms. RESULTS: In total, 16,758 questionnaires were returned and eligible for analysis. Antidepressant use was reported by 701 respondents (4.2%). Gastrointestinal symptoms were more frequently reported by antidepressant users compared with nonusers (40% vs 25%, P < 0.01). This apparent association between antidepressant use and gastrointestinal symptoms did not remain after adjusting for demographic factors, comorbidity, and use of other medications (adjusted odds ratio, 0.94; 95% confidence interval, 0.74-1.18). CONCLUSIONS: In our cross-sectional population-based study, we did not find an association between antidepressant use and gastrointestinal symptoms.

Gastrointestinal symptoms are still prevalent and negatively impact health-related quality of life: a large cross-sectional population based study in The Netherlands.

BACKGROUND: Over the last decades important risk factors for gastrointestinal symptoms have shifted, which may have changed its population prevalence. The aim of this study was to assess the current prevalence of gastrointestinal symptoms, appraise associated factors and assess health-related quality of life in the general population. METHODS: A total of 51,869 questionnaires were sent to a representative sample of the Dutch adult general population in December 2008. Demographic characteristics, gastrointestinal symptoms, health-related quality of life, medication use and co-morbidity were reported. We used multivariable logistic regression analysis to determine factors associated with gastrointestinal symptoms. RESULTS: A total of 18,317 questionnaires were returned, and 16,758 were eligible for analysis. Prevalence of gastrointestinal symptoms was 26%. Most frequent symptoms were bloating (63%), borborygmi (60%) and flatulence (71%). Female gender (adjusted OR (aOR) 1.59, 95% CI 1.43-1.77), asthma/COPD (aOR 1.47, 95% CI 1.21-1.79), use of paracetamol (aOR 1.33, 95% CI 1.20-1.47), antidepressants (aOR 1.56, 95% CI 1.22-2.00) and acid-suppressive medication were independently associated with presence of gastrointestinal symptoms. Age over 65 years (aOR 0.75, 95% CI 0.65-0.87), and use of statins (aOR 0.75, 95% CI 0.61-0.93) were associated with a lower prevalence of gastrointestinal symptoms. Respondents with gastrointestinal symptoms had a lower mean health-related quality of life of 0.81 (SD = 0.21) compared to 0.92 (SD = 0.14) for persons without gastrointestinal symptoms (P<0.01). CONCLUSIONS: Prevalence of gastrointestinal symptoms in the Dutch community is high and associated with decreased health-related quality of life.

[Colorectal cancer screening in the Netherlands: which faecal occult blood test?]. / Bevolkingsonderzoek naar dikkedarmkanker: welke ontlastingstest?

The Dutch Ministry of Health has instructed the National Institute for Public Health and the Environment (RIVM) to prepare a national screening programme for colorectal cancer. The RIVM put the immunochemical faecal occult blood test (iFOBT) for the programme out to public tender, after which a panel of experts recommended the FOB Gold test. This is surprising since previous studies favoured the OC Sensor test and the FOB Gold test has never been used in the Netherlands. Before starting the national programme in September 2013, the RIVM wants to ascertain which FOB Gold test cut-off value is comparable with the 75 ng/ml of the OC Sensor test recommended by the Health Council of the Netherlands. This cut-off level is crucial for capacity planning of colonoscopies. We advocate starting the national screening programme with the OC Sensor test and subsequent careful comparison with the FOB Gold test during the screening programme.

Similar fecal immunochemical test results in screening and referral colorectal cancer.

AIM: To improve the interpretation of fecal immunochemical test (FIT) results in colorectal cancer (CRC) cases from screening and referral cohorts. METHODS: In this comparative observational study, two prospective cohorts of CRC cases were compared. The first cohort was obtained from 10 322 average risk subjects invited for CRC screening with FIT, of which, only subjects with a positive FIT were referred for colonoscopy. The second cohort was obtained from 3637 subjects scheduled for elective colonoscopy with a positive FIT result. The same FIT and positivity threshold (OC sensor; ≥ 50 ng/mL) was used in both cohorts. Colonoscopy was performed in all referral subjects and in FIT positive screening subjects. All CRC cases were selected from both cohorts. Outcome measurements were mean FIT results and FIT scores per tissue tumor stage (T stage). RESULTS: One hundred and eighteen patients with CRC were included in the present study: 28 cases obtained from the screening cohort (64% male; mean age 65 years, SD 6.5) and 90 cases obtained from the referral cohort (58% male; mean age 69 years, SD 9.8). The mean FIT results found were higher in the referral cohort (829 ± 302 ng/mL vs 613 ± 368 ng/mL, P = 0.02). Tissue tumor stage (T stage) distribution was different between both populations [screening population: 13 (46%) T1, eight (29%) T2, six (21%) T3, one (4%) T4 carcinoma; referral population: 12 (13%) T1, 22 (24%) T2, 52 (58%) T3, four (4%) T4 carcinoma], and higher T stage was significantly associated with higher FIT results (P < 0.001). Per tumor stage, no significant difference in mean FIT results was observed (screening vs referral: T1 498 ± 382 ng/mL vs 725 ± 374 ng/mL, P = 0.22; T2 787 ± 303 ng/mL vs 794 ± 341 ng/mL, P = 0.79; T3 563 ± 368 ng/mL vs 870 ± 258 ng/mL, P = 0.13; T4 not available). After correction for T stage in logistic regression analysis, no significant differences in mean FIT results were observed between both types of cohorts (P = 0.10). CONCLUSION: Differences in T stage distribution largely explain differences in FIT results between screening and referral cohorts. Therefore, FIT results should be reported according to T stage.

Psychosocial complaints are associated with venous access-device related complications in patients on home parenteral nutrition.

BACKGROUND: Complications related to venous access devices (VADs) remain the major drawback of home parenteral nutrition (HPN) support. In addition to technical issues, patients also experience psychosocial problems. The aim of this study is to present an overview of VAD-related complications in patients on long-term HPN and to assess whether these adversities are related to experienced psychosocial problems and quality of life (QOL). METHODS: Information on VAD-related complications was collected from the medical charts of 110 adult HPN patients who were followed by the 2 major referral centers in the Netherlands. In addition, a survey was conducted in this group to characterize psychosocial problems and assess their association with technique-related complications; 75 patients (68%) responded. RESULTS: At the time of survey, the majority of patients (76%) had developed 1 or more episodes of catheter-related sepsis at some point during their HPN treatment. The overall incidence of VAD-related blood stream infections (BSIs) was 3 per 1,000 venous access days. The incidence of VAD occlusions was 0.8 per 1,000 venous access days. During the observation period, there was a highly significant association between the incidence of VAD-related complications and the occurrence of psychosocial complaints (eg, depression, fatigue, social impairment, and decreased QOL). CONCLUSIONS: Psychosocial complaints are associated with previously experienced VAD-related complications in patients on HPN therapy. Although only an association, and not a causal relationship is demonstrated by these findings, our results underscore the need for preventive and therapeutic measures regarding both types of problems in these patients.

Cost-effectiveness analysis of a quantitative immunochemical test for colorectal cancer screening.

BACKGROUND & AIMS: Two European randomized trials (N = 30,000) compared guaiac fecal occult blood testing with quantitative fecal immunochemical testing (FIT) and showed better attendance rates and test characteristics for FIT. We aimed to identify the most cost-effective FIT cutoff level for referral to colonoscopy based on data from these trials and allowing for differences in screening ages. METHODS: We used the validated MIcrosimulation SCreening ANalysis (MISCAN)-Colon microsimulation model to estimate costs and effects of different screening strategies for FIT cutoff levels of 50, 75, 100, 150, and 200 ng/mL hemoglobin. For each cutoff level, screening strategies were assessed with various age ranges and screening intervals. We assumed sufficient colonoscopy capacity for all strategies. RESULTS: At all cost levels, FIT screening was most effective with the 50 ng/mL cutoff level. The incremental cost-effectiveness ratio of biennial screening between ages 55 and 75 years using FIT at 50 ng/mL, for example, was 3900 euro per life year gained. Annual screening had an incremental cost-effectiveness ratio of 14,900 euro per life year gained, in combination with a wider age range (between ages 45 and 80 years). In the sensitivity analysis, 50 ng/mL remained the preferred cutoff level. CONCLUSIONS: FIT screening is more cost-effective at a cutoff level of 50 ng/mL than at higher cutoff levels. This supports the recommendation to use FIT at a cutoff level of 50 ng/mL, which is considerably lower than the values used in current practice.

Colorectal cancer screening comparing no screening, immunochemical and guaiac fecal occult blood tests: a cost-effectiveness analysis.

Comparability of cost-effectiveness of colorectal cancer (CRC) screening strategies is limited if heterogeneous study data are combined. We analyzed prospective empirical data from a randomized-controlled trial to compare cost-effectiveness of screening with either one round of immunochemical fecal occult blood testing (I-FOBT; OC-Sensor®), one round of guaiac FOBT (G-FOBT; Hemoccult-II®) or no screening in Dutch aged 50 to 75 years, completed with cancer registry and literature data, from a third-party payer perspective in a Markov model with first- and second-order Monte Carlo simulation. Costs were measured in Euros (€), effects in life-years gained, and both were discounted with 3%. Uncertainty surrounding important parameters was analyzed. I-FOBT dominated the alternatives: after one round of I-FOBT screening, a hypothetical person would on average gain 0.003 life-years and save the health care system €27 compared with G-FOBT and 0.003 life years and €72 compared with no screening. Overall, in 4,460,265 Dutch aged 50-75 years, after one round I-FOBT screening, 13,400 life-years and €320 million would have been saved compared with no screening. I-FOBT also dominated in sensitivity analyses, varying uncertainty surrounding important effect and cost parameters. CRC screening with I-FOBT dominated G-FOBT and no screening with or without accounting for uncertainty.

[Endoscopic removal of large colonic lipomas]. / Endoscopische verwijdering van grote dikkedarmlipomen.

Lipomas are benign tumours that are sometimes found in the colon, where they may cause symptoms through constriction and blood loss. Until recently, surgical removal of large lipomas was the therapy of choice, because of the danger of bleeding and perforation during endoscopy. The endoloop (PolyLoop, Olympus Medical Systems Corp., Tokyo, Japan), by use of which the base of the lipoma is constricted by a nylon loop, has changed this approach. We describe the successful removal of a large lipoma located in the ascending colon in 2 patients who were referred shortly after one another to the endoscopy department of our hospital. This endoscopic technique should be considered for removal of large pedunculated polyps in the intestine.

Comparison of guaiac and immunological fecal occult blood tests in colorectal cancer screening: the patient perspective.

OBJECTIVE: Colorectal cancer (CRC) screening programs can decide upon the type of fecal occult blood test (FOBT): the guaiac FOBT (g-FOBT) or the immunological FOBT (i-FOBT). The effectiveness of any screening program depends not only on the diagnostic performance of the screening test but also on the compliance and general acceptance of the test by the public. Any decision on the type of FOBT for CRC screening should also take acceptation and perception into account. The aim of the present study was to study differences in patient perception between i-FOBT and g-FOBT and differences in perception and participation rates among relevant subgroups in a population based study. MATERIAL AND METHODS: Differences in patient perception of i-FOBT and g-FOBT and differences in perception and participation rates among relevant subgroups were investigated (n = 20,623) by sending a short questionnaire to all invited to the first Dutch CRC screening trial. RESULTS: i-FOBT was perceived significantly more favorable than g-FOBT. About 1275 (32%) participants reported the g-FOBT not easy to use, not easy to perform, disgusting or shameful compared to 742 (16%) for the i-FOBT (p < 0.001). The participation rate was significantly higher in those who received i-FOBT compared to the g-FOBT group: 6159 of 10,322 (60%) versus 4839 of 10,301 (47%) (p < 0.001). CONCLUSIONS: These findings support the selection of i-FOBT as the more appropriate test for population screening programs.

Identification of NSAID users at risk for gastrointestinal complications: a systematic review of current guidelines and consensus agreements.

NSAIDs are among the most often used drugs worldwide. Numerous NSAID users are at risk for developing gastrointestinal complications. The purpose of this review was to identify and stratify risk factors for gastrointestinal complications in NSAID users documented in guidelines and consensus agreements, and to collect recommendations regarding over-the-counter (OTC) NSAID use. To facilitate this, a PubMed search from 1 January 1999 until 1 March 2009 was performed, resulting in the inclusion of nine English-language guidelines in our analysis. Risk factors were defined as 'definite' if mentioned in all guidelines; otherwise they were defined as 'controversial' risk factors. 'Definite' risk factors were a history of (complicated) peptic ulcer disease, older age (cut-off range 60-75 years), concomitant anticoagulant or corticosteroid use and multiple NSAID use, including low-dose aspirin (acetylsalicylic acid). 'Controversial' risk factors were high-dose NSAID use, concomitant clopidogrel or selective serotonin reuptake inhibitor use, a history of gastrointestinal symptoms, rheumatoid arthritis disability and cardiovascular disease. Infection with Helicobacter pylori was identified as an additive risk factor. Risk factors in OTC NSAID users were difficult to identify in the current literature. Risk factors were not all uniformly present in analysed guidelines and consensus agreements. We identified a history of (complicated) peptic ulcer disease, older age, concomitant anticoagulant or corticosteroid use and multiple NSAID use, including low-dose aspirin, as definite gastrointestinal risk factors in NSAID users.

Diagnostic efficacy of the secretin stimulation test for the Zollinger-Ellison syndrome: an intra-individual comparison using different dosages in patients and controls.

BACKGROUND/AIMS: The secretin stimulation test is the principal diagnostic tool to identify Zollinger-Ellison syndrome (ZES). We investigated, by intra-individual comparison, which dose of secretin results in the highest diagnostic efficacy to identify the ZES. METHODS: Fifty-seven paired secretin stimulation tests, using both 0.26 microg/kg and 0.78 microg/kg secretin, performed in 13 ZES patients and 12 controls, were analyzed and the findings confirmed in a validation cohort. RESULTS: A gastrin increase of >100 ng/l was found to be the most sensitive and specific criterion for a positive test. Higher gastrin increases after 0.78 microg/kg compared to 0.26 microg/kg secretin contributed to a slightly more sensitive (82.9 vs. 80.5%) but less specific (68.8 vs. 81.3%) test. A validation cohort, with 98 tests using 0.26 microg/kg secretin in 21 ZES patients and 39 controls, provided similar results. In ZES patients with normal fasting serum gastrin levels (<100 ng/l), there was no diagnostic benefit from the use of a higher secretin dose. CONCLUSIONS: The 0.26 microg/kg secretin stimulation test has the best diagnostic efficacy for the ZES. and IAP.

Mutational analysis of the gene encoding the zymogen granule membrane glycoprotein 2 (GP2) in patients with chronic pancreatitis.

OBJECTIVES: Premature activation of pancreatic digestive enzymes is considered as a major factor in the pathogenesis of pancreatitis. Genetic alterations of different pancreatic zymogens or their inhibitors have been associated with chronic pancreatitis (CP). METHODS: We sequenced all 12 GP2 exons in 380 German CP patients and in 182 German control subjects. In addition, we analyzed exon 3 of GP2 in 803 further CP patients and 1780 controls originating from Germany, the Netherlands, and India by targeted DNA sequencing. RESULTS: We detected 12 nonsynonymous and 6 synonymous exonic variants. All nonsynonymous changes with exception of c.220C>T (p.R74X) and c.502_503delG (p.G168fsX174) in exon 3 and c.541C>T (p.R181X) in exon 4 were missense mutations and predominantly located in exon 3. All nonsynonymous variants were found in single cases only, with exception of 2 alterations, c.355A>G (p.M119V) and c.409G>A (p. A137T), both located in exon 3. To elucidate the role of these 2 exon 3 variants, we investigated additional patients and controls. The frequency of these variants was similar between patients and controls regardless of ethnic background or cause of CP. CONCLUSIONS: Our data suggest that GP2 alterations do not alter the risk for the development of CP.

Polymorphisms in gene encoding TRPV1-receptor involved in pain perception are unrelated to chronic pancreatitis.

BACKGROUND: The major clinical feature in chronic pancreatitis is pain, but the genetic basis of pancreatic pain in chronic pancreatitis is poorly understood. The transient receptor potential vanilloid receptor 1 (TRPV1) gene has been associated with pain perception, and genetic variations in TRPV1 may modify the presence and phenotype of chronic pancreatitis. The aim of our study was to investigate the genetic variation of TRPV1 in Dutch patients with chronic pancreatitis and healthy controls. METHODS: We genotyped 4 SNPs (rs222749, rs222747, rs224534 and rs8065080) in 228 chronic pancreatitis-patients and 207 healthy controls by PCR, followed by restriction-fragment-length-polymorphism analysis and DNA sequencing. We generated 27 diplotypes and compared prevalence between patients and controls. RESULTS: There was no significant difference in allele frequency of the 4 TRPV1 gene SNPs in patients with chronic pancreatitis and healthy controls. Distribution of diplotypes was not statistically significantly different between patients and controls. CONCLUSION: TRPV1 diplotypes are not associated with chronic pancreatitis.

Genetic polymorphisms in UDP-glucuronosyltransferase 1A6 are not associated with NSAIDs-related peptic ulcer haemorrhage.

UDP-glucuronosyltransferase 1A6 (UGT1A6) is involved in metabolizing non-steroidal anti-inflammatory drugs (NSAIDs). Genotype variation in UGT1A6 may influence the metabolism of NSAIDs and we studied whether this might modulate the gastrointestinal toxicity of NSAIDs. UGT1A6 genotypes of 114 patients with peptic ulcer haemorrhage were compared with those of two subsets of controls: 158 cardiology patients using similar amounts of NSAIDs and 140 healthy controls, hardly using NSAIDs. Risk factors for peptic ulcer bleeding were male gender (Odds ratio (OR) 2.66, 95% confidence interval (CI) 1.7-4.2), age above 60 years (OR 2.15, 95% CI 1.4-3.4) and use of NSAIDs/aspirin (OR 4.50, 95% CI 2.8-7.3). UGT1A6 genotype frequencies did not differ between patients with peptic ulcer and the two control groups (p=0.76). We conclude that polymorphic UGT1A6 is not implicated in the pathogenesis of NSAIDs-related peptic ulcer disease.

[Dutch patients with hereditary pancreatitis; high mutation frequency, relatively little pain]. / Nederlandse patiënten met erfelijke pancreatitis. Hoge PRSS1-mutatiefrequentie, relatief weinig pijn.

OBJECTIVE: To assess genetic, clinical and morphological characteristics of hereditary pancreatitis, a rare type of chronic pancreatitis with an early onset of symptoms, which is, among others, caused by mutations in the PRSS1 gene. DESIGN: Observational cohort study. METHOD: The study population consisted of 496 patients (27,375 person-years) who were referred to Radboud University Nijmegen Medical Centre for molecular diagnosis of hereditary pancreatitis during period 2000 to 2007. 61 patients with a positive family history of hereditary pancreatitis were selected. Analysis for PRSS1 gene mutations was performed by complete sequence analysis of the exons. All patients received a structured questionnaire. RESULTS: From 25 families 61 patients were included (2,047 person-years). PRSS1 mutations were detected in 52 patients (85.2%): p.R122H (67.2%), p.N29I (14.8%), p.E79K (1.6%), p.N29T (1.6%). In the 40 patients whose clinical data were known the median age at diagnosis was 10.5 years (range: 0-42 years). Pain was reported in 28 (70% of 40 patients in whom all information was complete). 27 patients (67.5%) were admitted to the hospital once or more due to the attacks of pancreatitis. Exocrine and endocrine dysfunction was seen in 6 patients (15%). 24 patients (60%) had undergone a surgical intervention, 10 of whom had undergone a pancreaticojejunostomy. A family history of pancreatic carcinoma was found in 5 patients (12.5%). CONCLUSION: The percentage of PRSS1 mutation was high (85.2%) among this Dutch population that was selected on basis of a positive family history of hereditary pancreatitis. Most patients had no chronic pain.

[Colorectal cancer screening: immunological test for faecal occult blood preferred]. / Bevolkingsonderzoek naar dikkedarmkanker. Bij voorkeur met een immunologische test op fecaal occult bloed.

In 2003, the European Commission advised the Member States to start colorectal cancer screening. More than 12 million Europeans have been tested to date, not only by means of faecal occult blood testing but often also by opportunistic endoscopy. Nearly all of the screening programmes concerned were opportunistic in nature. The Dutch government is currently considering the implementation of an organised screening programme for the detection of colorectal cancer. The question no longer seems to be whether a screening programme should be started but rather which screening test should be used. We argue that an immunological faecal occult blood test is to be preferred over other screening tests, such as endoscopy.

Cyclooxygenase-2 polymorphisms and the risk of esophageal adeno- or squamous cell carcinoma.

AIM: To determine whether -1195 A-->G and/or -765 G-->C polymorphisms in Cyclooxygenase-2 (COX-2) may have a risk modifying effect on the development of esophageal carcinoma in a Dutch Caucasian population. METHODS: Two study groups were recruited, 252 patients with esophageal carcinoma and 240 healthy controls, matched for race, age, gender and recruiting area. DNA was isolated from whole blood and used for genotyping. PCR products were digested with restriction enzymes and products were analyzed by agarose gel electrophoresis. Odds ratios (OR) and 95% confidence intervals (CI) were estimated. RESULTS: The distribution of the -1195 A-->G polymorphism was significantly different in esophageal cancer patients compared to controls. The -1195 GG genotype resulted in a higher risk of developing esophageal adenocarcinoma (OR = 3.85, 95% CI: 1.45-10.3) compared with the -1195 AA genotype as a reference. The -765 G-->C genotype distribution was not different between the two groups. The GG/GG haplotype was present more often in esophageal adenocarcinoma patients than in controls (OR = 3.45, 95% CI: 1.24-9.58; with AG/AG as a reference). The same trends were observed in patients with squamous cell carcinomas, however, the results did not reach statistical significance. CONCLUSION: Presence of the COX-2 -1195 GG genotype and of the GG/GG haplotype may result in a higher risk of developing esophageal carcinoma.

Arteriovenous fistulae as an alternative to central venous catheters for delivery of long-term home parenteral nutrition.

BACKGROUND & AIMS: The success of home parenteral nutrition (HPN) programs is compromised by complications of central venous catheters (CVCs), such as occlusions and bloodstream infections. We performed a retrospective analysis of complication rates of arteriovenous fistulae versus CVCs in patients on long-term HPN. METHODS: Data were collected from 127 consecutive patients who received HPN between January 2000 and October 2006, comprising 344 access years of CVCs and 194 access years of arteriovenous fistulae. We evaluated access-related bloodstream infection and occlusion incidence rates (number of complications per access year) using Poisson-normal regression analysis. Complication incidence rate ratios were calculated by dividing complication incidence rates of CVCs by those of arteriovenous fistulae, adjusting for HPN frequency, medication use, infusion fluid composition, and underlying diseases. RESULTS: Bloodstream infection incidence rates were 0.03/year for arteriovenous fistulae, 1.37/year for long-term CVCs (Port-a-Caths and tunneled catheters), and 3.12/year for short-term CVCs (nontunneled catheters). Occlusion incidence rates were 0.60/year for arteriovenous fistulae, 0.35/year for long-term CVCs, and 0.93/year for shortterm CVCs. Adjusted incidence rate ratios of long-term CVCs over arteriovenous fistulae were 47 (95% confidence interval, 19-117) for bloodstream infections and 0.53 (95% confidence interval, 0.31-0.89) for occlusions. CONCLUSIONS: The occlusion incidence rate was higher for arteriovenous fistulae than for certain types of CVCs. The incidence rate of the most serious access-related complication (bloodstream infections) was much lower for arteriovenous fistulae than for all types of CVCs. Thus, arteriovenous fistulae are safe and valuable alternatives to CVCs for patients requiring long-term HPN.

False negative fecal occult blood tests due to delayed sample return in colorectal cancer screening.

Delayed return of immunochemical fecal occult blood test (iFOBT) samples to a laboratory might cause false negatives because of hemoglobin degradation. Quantitative iFOBT's became increasingly more accepted in colorectal cancer screening. Therefore, we studied the effects of delay between sampling and laboratory delivery on iFOBT performance. IFOBT positivity (>or=50 ng/ml hemoglobin) in colorectal cancer screening participants without delay between sampling and laboratory delivery (<5 days), was compared with positivity in participants with >or=5 and >or=7 days delay. Additionally, positive tests were stored at room temperature and retested 5 times within 10-14 days. The sampling date was reported by 61% (n = 3,767) of the participants: in 19% delay was >or=5 days and in 5% >or=7 days. Compared with no-delay, the adenoma detection rate was already significantly decreased after >or=5 days delay (OR 0.6; 95%CI 0.4-0.9). We retested iFOBT samples of 170 positives of which 139 (82%) had a colonoscopy: 45 (32%) had advanced adenomas (not colorectal cancer) and 8 (6%) had colorectal cancer. Mean daily fecal hemoglobin decrease was 29 ng/ml (S.D. 38 and median 11 ng/ml). In patients with advanced adenomas, hemoglobin in the sample was <50 ng/ml in 5 (11%) 2-3 days after the initial test and in 16 (36%) after 10-14 days. Seven days after the initial test, 2 (25%) colorectal cancer patients became false negative. Both had stage I colorectal cancer and initial values below 100 ng/ml, where the average for stage I is 532 ng/ml. Delay in sample return increased false negative immunochemical FOBT's. Mainly precursor lesions, but also colorectal cancer, will be missed due to delayed sample return.