Independent and combined effects of methamphetamine use disorders and APOEε4 allele on cognitive performance and brain morphometry

AIMS

Prior studies showed that methamphetamine (METH) users had greater than normal age-related brain atrophy; whether having the apolipoprotein E (APOE)-ε4 allele may be a contributory factor has not been evaluated. We aimed to determine the independent and combined effects of chronic heavy METH use and having at least one copy of the APOE-ε4 allele (APOE-ε4+) on brain morphometry and cognition, especially in relation to aging.

METHODS

We compared brain morphometry and cognitive performance in 77 individuals with chronic heavy METH use (26 APOE-ε4+, 51 APOE-ε4-) and 226 Non-METH users (66 APOE-ε4+, 160 APOE-ε4-), using a 2 × 2 design (two-way analysis of co-variance). Vertex-wise cortical volumes, thickness and seven subcortical volumes, were automatically measured using FreeSurfer. Linear regression between regional brain measures, and cognitive scores that showed group differences were evaluated. Group differences in age-related decline in brain and cognitive measures were also explored.

RESULTS

Regardless of APOE-ε4 genotype, METH users had lower Motor Z-scores (P = 0.005), thinner right lateral-orbitofrontal cortices (P < 0.001), smaller left pars-triangularis gyrus volumes (P = 0.004), but larger pallida, hippocampi and amygdalae (P = 0.004-0.006) than nonusers. Across groups, APOE-ε4+ METH users had the smallest volumes of superior frontal cortical gyri bilaterally, and of the smallest volume in left rostral-middle frontal gyri (all P-values <0.001). Smaller right superior-frontal gyrus predicted poorer motor function only in APOE-ε4+ participants (interaction-P < 0.001). Cortical volumes and thickness declined with age similarly across all participants; however, APOE-ε4-carriers showed thinner right inferior parietal cortices than noncarriers at younger age (interaction-P < 0.001).

CONCLUSIONS

Chronic heavy use and having at least one copy of the APOE-ε4 allele may have synergistic effects on brain atrophy, particularly in frontal cortices, which may contribute to their poorer cognitive function. However, the enlarged subcortical volumes in METH users replicated prior studies, and are likely due to METH-mediated neuroinflammation.

Brain Microstructure and Impulsivity Differ between Current and Past Methamphetamine Users

Methamphetamine (Meth) use disorder continues to be highly prevalent worldwide. Meth users have higher impulsivity and brain abnormalities that may be different between current and past Meth users. The current study assessed impulsivity and depressive symptoms in 94 participants (27 current Meth users, 32 past Meth users and 35 non-drug user controls). Additionally, brain microstructure was assessed using diffusion tensor imaging (DTI); fractional anisotropy (FA) and mean diffusivity (MD) were assessed in the striatum, and FA, MD, radial and axial diffusivity were quantified in five white matter structures using DtiStudio.Across the three subject groups, current users had the highest self-reported impulsivity scores, while both Meth user groups had larger striatal structures than the controls. Past Meth users had the highest FA and lowest MD in the striatum, which is likely due to greater magnetic susceptibility from higher iron content and greater dendritic spine density. In white matter tracts, current Meth users had higher AD than past users, indicating greater water diffusion along the axons, and suggesting inflammation with axonal swelling. In contrast, past users had the lowest AD, indicating more restricted diffusion, which might have resulted from reactive gliosis. Although current Meth users had greater impulsivity than past users, the brain microstructural abnormalities showed differences that may reflect different stages of neuroinflammation or iron-induced neurodegeneration. Combining current and past Meth users may lead to greater variability in studies of Meth users. Longitudinal studies are needed to further evaluate the relationship between recency of Meth use and brain microstructure.

Altered brain activation during visuomotor integration in chronic active cannabis users: relationship to cortisol levels

Cannabis is the most abused illegal substance in the United States. Alterations in brain function and motor behavior have been reported in chronic cannabis users, but the results have been variable. The current study aimed to determine whether chronic active cannabis use in humans may alter psychomotor function, brain activation, and hypothalamic-pituitary-axis (HPA) function in men and women. Thirty cannabis users (16 men, 14 women, 18-45 years old) and 30 nondrug user controls (16 men, 14 women, 19-44 years old) were evaluated with neuropsychological tests designed to assess motor behavior and with fMRI using a 3 Tesla scanner during a visually paced finger-sequencing task, cued by a flashing checkerboard (at 2 or 4 Hz). Salivary cortisol was measured to assess HPA function. Male, but not female, cannabis users had significantly slower performance on psychomotor speed tests. As a group, cannabis users had greater activation in BA 6 than controls, while controls had greater activation in the visual area BA 17 than cannabis users. Cannabis users also had higher salivary cortisol levels than controls (p = 0.002). Chronic active cannabis use is associated with slower and less efficient psychomotor function, especially in male users, as indicated by a shift from regions involved with automated visually guided responses to more executive or attentional control areas. The greater but altered brain activities may be mediated by the higher cortisol levels in the cannabis users, which in turn may lead to less efficient visual-motor function.

Impact of apolipoprotein E ε4 and HIV on cognition and brain atrophy: antagonistic pleiotropy and premature brain aging

OBJECTIVE

The apolipoprotein E (APOE) ε4 allele may accelerate the progression of HIV disease, and increase the risk for developing HIV-associated neurocognitive disorder (HAND). Whether APOEε4 allele(s) and age may influence brain atrophy in HIV patients is unknown and was evaluated.

METHODS

Automated morphometry on magnetic resonance images, using FreeSurfer analyses, neuropsychological testing and APOE genotyping were performed in 139 subjects [70 seronegative controls (SN); 69 clinically-stable HIV subjects].

RESULTS

Compared to SN, HIV subjects had smaller volumes throughout the brain regardless of their HAND status. Compared to APOEε4- subjects, SN controls with APOEε4 had better memory and larger global brain volumes (cerebral white matter and cortex) while HIV subjects with the APOEε4 allele(s) had poorer cognition (verbal fluency, learning, executive function and memory) and smaller cerebral and cerebellar white matter and subcortical structures. Further stratification of age showed that younger (<50 years) APOEε4+SN subjects had larger putamen and cerebral white matter, while younger APOEε4+HIV subjects had poorer performance on verbal fluency and smaller brain volumes [3-way (HIV-status×APOEε4×Age) interaction-p-values=0.005 to 0.03].

INTERPRETATION

These findings suggest that APOEε4 allele(s) may show antagonistic pleiotropy on cognition and brain atrophy in SN controls, but may lead to premature aging with neurodegeneration in younger HIV patients prior to the development of HAND. Potential mechanisms for such interactions may include stronger neuro-inflammation or greater amyloid deposition in younger HIV subjects with APOEε4 allele(s). Early screening for the APOEε4 allele and brain atrophy with morphometry may guide neuroprotective intervention of cognitively normal HIV subjects prior to the development of HAND. Longitudinal follow-up studies and larger sample sizes are needed to validate these cross-sectional results.

Methamphetamine users show greater than normal age-related cortical gray matter loss

BACKGROUND

Methamphetamine (Meth) abuse continues to be a major illicit drug of abuse. Neuroimaging findings suggest that Meth is neurotoxic and may alter various brain structures, but the effect of Meth on the aging brain has not been studied.

AIM

The aim was to determine regional volumes of cortical gray matter in the brains of adult Meth users versus healthy control subjects, and their interaction with age and Meth-usage variables.

DESIGN

Cross-sectional study

SETTING

Magnetic resonance imaging (MRI) Research Center located in a university-affiliated hospital.

PARTICIPANTS

Thirty-four Meth-dependent subjects (21 men and 13 women; ages 33.1 ± 8.9 years), diagnosed according to DSM-IV criteria, and 31 healthy non-Meth user comparison subjects (23 men and 8 women ages 35.7 ± 8.4 years).

MEASUREMENT

Regional gray matter volumes were segmented automatically in all subjects and evaluated in relation to age, using high-resolution MRIs at 3.0 Tesla.

FINDINGS

After adjustment for the effects of cranium size, the Meth users showed enhanced cortical gray matter volume loss with age in the frontal (analysis of covariance interaction P = 0.02), occipital (interaction P = 0.01), temporal (interaction P < 0.001) and the insular lobes (interaction P = 0.01) compared to controls, independently of Meth-usage patterns. Additionally, Meth users showed smaller gray matter volumes than control subjects in several subregions (dorsolateral prefrontal: P = 0.02; orbitofrontal: P = 0.03; prefrontal: P = 0.047; superior temporal: P = 0.04).

CONCLUSIONS

Methamphetamine users appear to show increased cortical gray matter loss with age which raises the possibility of accelerated decline in mental functioning.

Lower brain glutamate is associated with cognitive deficits in HIV patients: a new mechanism for HIV-associated neurocognitive disorder

PURPOSE

To determine whether subjects with human immunodeficiency virus (HIV)-associated neurocognitive disorder (HAND) show altered concentrations of brain glutamate (GLU), and whether lower GLU levels correlate with cognitive deficits.

MATERIALS AND METHODS

GLU concentrations were measured in the basal ganglia, frontal gray and white matter, and parietal gray matter of 45 HIV-positive and 46 age-and-education-matched HIV-negative subjects using echo-time averaged proton magnetic resonance spectroscopy ((1)H MRS).

RESULTS

Compared to controls, HIV subjects with cognitive deficits had lower GLU in the parietal gray matter, while those without cognitive deficits tended to show higher basal ganglia GLU. Lower parietal and frontal gray matter GLU were associated with a greater number of nucleoside reverse transcriptase inhibitors, and were predictive of poorer cognitive performance. Correlations between GLU and cognitive performance, but not the other findings, remained significant after correction for multiple comparisons.

CONCLUSION

Parietal gray matter GLU is lower in HIV subjects with cognitive deficits. This reduction might result from reduced astrocytic reuptake of GLU, secondary excitotoxicity, and mitochondrial toxicity from antiretroviral treatments. The glutamatergic system may play an important role in the pathophysiology of HAND, and brain GLU on (1)H MRS may provide an early surrogate marker for monitoring disease severity and treatment effects.

Declined neural efficiency in cognitively stable human immunodeficiency virus patients

OBJECTIVE

To determine whether brain activation changes in clinically and neurocognitively normal human immunodeficiency virus (HIV)-infected and in HIV-seronegative control (SN) participants over a 1-year period.

METHODS

Functional magnetic resonance imaging (fMRI) was performed in 32 SN and 31 HIV patients (all with stable combination antiretroviral treatment) at baseline and after 1 year. Each participant performed a set of visual attention tasks with increasing attentional load (from tracking two, three, or four balls). All HIV and SN participants had normal neuropsychological function at both examinations.

RESULTS

Over 1 year, HIV patients showed no change in their neurocognitive status or in task performance during fMRI. However, HIV patients showed significant 1-year increases in fMRI signals in the prefrontal and posterior parietal cortices for the more difficult tasks, whereas SN control participants showed only decreases in brain activation in these regions. This resulted in significant interactions between HIV status and time of study in left insula, left parietal, left temporal, and several frontal regions (left and right middle frontal gyrus, and anterior cingulate).

INTERPRETATION

Because fMRI task performance remained unchanged in both groups, the HIV patients appeared to maintain performance by increasing usage of the attention network, whereas the control participants reduced usage of the attention network after 1 year. These findings suggest improved efficiency or a practice effect in the SN participants but declined efficiency of the neural substrate in HIV patients, possibly because of ongoing brain injury associated with the HIV infection, despite their apparent stable clinical course.

Association between psychiatric symptoms and craving in methamphetamine users

This study examined the differences in psychiatric symptoms between adult methamphetamine users (n = 46) and control subjects (n = 31), the relationship between psychiatric symptoms and the intensity of methamphetamine craving, and whether psychiatric symptoms were correlated to methamphetamine drug-usage variables (ie, length of abstinence, frequency, duration, and lifetime grams). We found that depressive symptoms on the Center for Epidemiology Studies-Depression (CES-D) and many other psychiatric symptoms on the Symptom Checklist-90 (SCL-90) significantly correlated with craving methamphetamine on the visual analog scale (VAS) for craving. Methamphetamine users had significantly more depressive symptoms (on CES-D) and psychotic symptoms (on SCL-90) compared to controls. There were no significant correlations between psychiatric symptoms and methamphetamine-usage variables. This study provides the first evidence to suggest that depressive symptoms (on CES-D) and psychiatric symptoms (on SCL-90) are strongly associated with the intensity of craving (on VAS) for the drug in methamphetamine users. However, the methamphetamine usage variables had no relationship with psychiatric symptoms. Therefore, methamphetamine users, regardless of their usage patterns, may benefit from treatment of their psychiatric symptoms in order to minimize craving and subsequent relapse to drug use.

Antiretroviral treatment is associated with increased attentional load-dependent brain activation in HIV patients

OBJECTIVE

The purpose of this paper was to determine whether antiretroviral medications, especially the nucleoside analogue reverse transcriptase inhibitors, lead to altered brain activation due to their potential neurotoxic effects in patients with human immunodeficiency virus (HIV) infection.

METHODS

Forty-two right-handed men were enrolled in three groups: seronegative controls (SN, n = 18), HIV subjects treated with antiretroviral medications (HIV+ARV, n = 12), or not treated with antiretroviral medications (HIV+NARV, n = 12). Each subject performed a set of visual attention tasks with increasing difficulty or load (tracking two, three or four balls) during functional magnetic resonance imaging.

RESULTS

HIV subjects, both groups combined, showed greater load-dependent increases in brain activation in the right frontal regions compared to SN (p-corrected = 0.006). HIV+ARV additionally showed greater load-dependent increases in activation compared to SN in bilateral superior frontal regions (p-corrected = 0.032) and a lower percent accuracy on the performance of the most difficult task (tracking four balls). Region of interest analyses further demonstrated that SN showed load-dependent decreases (with repeated trials despite increasing difficulty), while HIV subjects showed load-dependent increases in activation with the more difficult tasks, especially those on ARVs.

INTERPRETATION

These findings suggest that chronic ARV treatments may lead to greater requirement of the attentional network reserve and hence less efficient usage of the network and less practice effects in these HIV patients. As the brain has a limited reserve capacity, exhausting the reserve capacity in HIV+ARV would lead to declined performance with more difficult tasks that require more attention.

Age-related cancer detection rate and costs for one cancer detected in one screening by immunochemical fecal occult blood test

PURPOSE

This study was performed to assess, from the aspects of screening efficiency and cost-effectiveness, the optimal lower limit of age in immunochemical occult blood screening for colorectal cancer.

METHODS

Seven thousand four hundred asymptomatic individuals were the subjects of this study. They gave samples for an immunochemical fecal occult blood test (OC-Hemodia), and colonoscopy was performed during a medical checkup. They were divided into three groups according to their ages: younger (40-49), middle (50-59), and older (60+) groups. The detection rate for colorectal cancer and the average costs to detect one patient with colorectal cancer were evaluated among the three groups.

RESULTS

The detection rate for colorectal cancer and the average costs to detect one cancer patient were calculated as 0.3 percent and $6024 for the younger group, 1.6 percent and $1425 for the middle group, and 1.7 percent and $1410 for the older group, respectively. The cancer detection rate was significantly different between the younger and middle groups (P < 0.05) and between the younger and older groups (P < 0.05).

CONCLUSIONS

This analysis suggests that the subjects aged less than 50 have some disadvantage when carrying out the immunochemical fecal occult blood test, OC-Hemodia for colorectal cancer screening, from the aspects of screening efficiency and cost-effectiveness.

Comparisons of cancer detection rate and costs of one cancer detected among different age-cohorts in immunochemical occult blood screening

PURPOSE

This study was carried out to compare the detection rate for colorectal cancer and the average costs to detect one patient with colorectal cancer among three different age-cohorts in immunochemical occult blood screening by OC-Hemodia.

METHODS

In a population-screening program, 17,432 subjects received an immunochemical fecal occult blood test. In a medical checkup for colorectal cancer 7,232 subjects received colonoscopy. They were divided into three groups according to their ages: younger (4,049 years); middle (50-59); and older (60+) groups. The detection rate for colorectal cancer and the average costs to detect one patient with colorectal cancer were evaluated among the three groups.

RESULTS

In the screening program-based study, the cancer detection rate and the average costs for one colorectal cancer detected were calculated as 0.09% and $13,352, 0.28% and $4,555, 0.29% and $4,461 for the younger, middle, and older groups, respectively. In addition, in the medical checkup-based study, the detection rate and the average costs were calculated as 0.3% and $6,851, 1.5% and $1,517, 1.7% and $1,391 for the younger, middle, and older groups, respectively. In these two studies, the cancer detection rates were significantly different between the younger and middle groups (P < 0.05), and between the younger and older groups (P < 0.05).

CONCLUSIONS

These findings indicate that the subjects aged under 50 have some disadvantage when carrying out the immunochemical fecal occult blood test--OC-Hemodia for colorectal cancer screening--from the viewpoint of screening efficiency as well as cost-effectiveness.

Does stool collection method affect outcomes in immunochemical fecal occult blood testing?

PURPOSE

This paper compares the positive predictive value of an immunochemical fecal occult blood test for colorectal neoplasms between the stool specimens obtained during the digital rectal examination and those obtained during the routine screening.

METHODS

In a medical check-up, 1,688 subjects received both an immunochemical fecal occult blood test and a colonoscopy. Fecal occult blood was tested by two methods: digital rectal examination and routine screening. The positivity rate of an immunochemical fecal occult blood test and the positive predictive value for colorectal cancer and large adenomatous polyp were determined by these two methods.

RESULTS

The positivity rate and the positive predictive value were 5.4 percent and 19.8 percent (4.4 percent for cancer and 15.4 percent for adenomatous polyp) in the digital rectal examination method and 3.5 percent and 27.1 percent (6.8 percent for cancer and 20.3 percent for adenomatous polyp) in the routine screening method, respectively. These figures indicate a significant difference in the positivity rate (P < 0.01) and the positive predictive value (P < 0.05) between these two methods.

CONCLUSIONS

These findings indicate that the stool obtained by routine screening has a better positive predictive value than stool collected during the digital rectal examination.

H(2)O(2) produced by viridans group streptococci may contribute to inhibition of methicillin-resistant Staphylococcus aureus colonization of oral cavities in newborns

In an accompanying report, we showed that viridans group streptococci may prevent methicillin-resistant Staphylococcus aureus (MRSA) colonization of the oral cavities of newborns. In the present study, we investigated the mechanism of prevention in vitro. Most viridans group streptococci had bacteriocin-like activity and killed MRSA, Burkholderia cepacia, Enterobacter aerogenes, and Pseudomonas aeruginosa; however, Escherichia coli, Enterobacter cloacae, and Candida albicans were resistant. The activity was induced only by H(2)O(2)-secreting strains and was inhibited by horseradish peroxidase or catalase in a dose-dependent manner. The mean concentration of H(2)O(2) produced by 18 strains of viridans group streptococci (1 x 10(8) cfu in 200 microL of culture medium+/-standard deviation was 1.24+/-0.60 mmol. Viridans group streptococci inhibited MRSA growth in saliva as well as in culture media. These results indicate that H(2)O(2) produced by viridans group streptococci may inhibit MRSA colonization of oral cavities in newborns.

Inhibition of methicillin-resistant Staphylococcus aureus colonization of oral cavities in newborns by viridans group streptococci

We investigated the role of viridans group streptococci in the prevention of colonization with methicillin-resistant Staphylococcus aureus (MRSA) in neonatal intensive care units. During a 26-month period at a children's hospital, 207 (49.9%) of 415 newborns were colonized with MRSA by the time of discharge. Two groups of newborns with matching durations of hospitalization were compared with regard to the prevalence of future colonization with MRSA: group 1 (103 patients) did not acquire colonization with viridans group streptococci and group 2 (63 patients) did acquire colonization with viridans group streptococci at birth or by 1 to 2 weeks (age, < or =11 days). The rate of colonization among patients in group 2 (9.5%) was significantly lower than that among patients in group 1 (44.7%; P<.001). No significant difference in patient characteristics (e.g., birth weight, diseases) was observed. These results indicate that viridans group streptococci, as bacteria that formerly occupied the oral cavities in newborns, may inhibit later colonization with MRSA.

Characteristics of colorectal cancer that produce positive immunochemical occult blood test results on stool obtained by digital rectal examination

OBJECTIVE

To clarify the clinicopathological features of colorectal cancer that show positive results on an immunochemical fecal occult blood test of stool obtained by digital rectal examination.

METHODS

In a cross-sectional study, 9952 subjects received both an immunochemical fecal occult blood test of stool obtained by digital rectal examination and colonoscopy annually over a nine-year period of medical checkups; 64 patients with colorectal cancer were identified. The study subjects comprised 39 patients with colorectal cancer who had positive results (positive group) and 25 patients with colorectal cancer who had negative results (negative group) on an immunochemical fecal occult blood test of stool obtained by digital rectal examination. The positive and negative groups were compared in terms of their individual factors, such as site, size, Dukes classification and histological type of the cancer lesions.

RESULTS

The prevalence of rectal cancers was higher in the positive group than in the negative group (P<0.05), but there were no differences between the two groups with respect to any other factors.

CONCLUSIONS

These findings indicate that stool obtained during the digital rectal examination is unsuitable for detecting fecal occult blood, especially for the detection of proximal colon neoplasms.

Evaluation of the optimum cut-off point in immunochemical occult blood testing in screening for colorectal cancer

This study was carried out to assess, from the aspects of cost-effectiveness and diagnostic validity, the optimum cut-off point for immunochemical occult blood testing using a 2-day method as a means of screening for colorectal cancer. Four thousand, two hundred and sixty asymptomatic individuals were subjects of this study. They gave samples for an immunochemical fecal occult blood test, and colonoscopy was carried out during a medical check-up. For evaluation of the optimum cut-off point, three cut-off levels of fecal haemoglobin, 50, 150 and 300 ng/ml, were used. A total of 27 patients with colorectal cancer were diagnosed. The average costs to detect one patient with colorectal cancer and the sensitivity and specificity of these three cut-off points of fecal haemoglobin were evaluated. The average costs for the detection of one cancer case were calculated as $2870.45 for cut-off level of 50 ng/ml, $2492.98 for that of 150 ng/ml and $3329.09 for that of 300 ng/ml, respectively. The sensitivity and specificity were calculated as 89 and 94% for the 50 ng/ml cut-off level, 81% and 96% for the 150 ng/ml cut-off level and 56 and 97% for the 300 ng/ml cut-off level, respectively, indicating a significant difference in the sensitivity between the 50 and 300 ng/ml levels (P<0.05), as well as between the 150 and 300 ng/ml levels (P<0.05), and a significant difference in the specificity between the 50 and 300 ng/ml levels (P<0.05). However, no significant difference was observed in the specificity between the 50 and 150 ng/ml levels. The findings show that 150 ng/ml of fecal haemoglobin is the optimal cut-off point when carrying out the OC-Hemodia test as a means of screening for colorectal cancer.

Evaluation of the optimum cut-off point in immunochemical occult blood testing in screening for colorectal cancer

This study was carried out to assess, from the aspects of cost-effectiveness and diagnostic validity, the optimum cut-off point for immunochemical occult blood testing using a 2-day method as a means of screening for colorectal cancer. Four thousand, two hundred and sixty asymptomatic individuals were subjects of this study. They gave samples for an immunochemical fecal occult blood test, and colonoscopy was carried out during a medical check-up. For evaluation of the optimum cut-off point, three cut-off levels of fecal haemoglobin, 50, 150 and 300 ng/ml, were used. A total of 27 patients with colorectal cancer were diagnosed. The average costs to detect one patient with colorectal cancer and the sensitivity and specificity of these three cut-off points of fecal haemoglobin were evaluated. The average costs for the detection of one cancer case were calculated as $2870.45 for cut-off level of 50 ng/ml, $2492.98 for that of 150 ng/ml and $3329.09 for that of 300 ng/ml, respectively. The sensitivity and specificity were calculated as 89 and 94% for the 50 ng/ml cut-off level, 81% and 96% for the 150 ng/ml cut-off level and 56 and 97% for the 300 ng/ml cut-off level, respectively, indicating a significant difference in the sensitivity between the 50 and 300 ng/ml levels (P<0.05), as well as between the 150 and 300 ng/ml levels (P<0.05), and a significant difference in the specificity between the 50 and 300 ng/ml levels (P<0.05). However, no significant difference was observed in the specificity between the 50 and 150 ng/ml levels. The findings show that 150 ng/ml of fecal haemoglobin is the optimal cut-off point when carrying out the OC-Hemodia test as a means of screening for colorectal cancer.

Digital rectal examination sampling of stool is less predictive of significant colorectal pathology than stool passed spontaneously

OBJECTIVES

To compare the positivity rate and the positive predictive value of an immunochemical faecal occult blood test (FOBT) carried out by using stool samples obtained during a routine screening method and those obtained during digital rectal examination.

DESIGN

Screening programme-based, cross-sectional study.

METHODS

In a screening programme-based, cross-sectional study, 1,044 subjects who received both an immunochemical FOBT and colonoscopy were divided into two groups according to stool collection techniques--the routine screening method and the digital rectal examination method. The positivity rate of the immunochemical FOBT, as well as the positive predictive value for colorectal cancer and large adenomatous polyp, were determined in the two groups.

RESULTS

The positivity rate and positive predictive value were 3.8% and 60.0% (10.0% for cancer and 50.0% for adenomatous polyp) in the routine screening group, and 9.4% and 26.5% (4.1% for cancer and 22.4% for adenomatous polyp) in the digital rectal examination group, respectively, indicating a significant difference in the positivity rate (P < 0.01) as well as the positive predictive value (P< 0.05) between the two groups.

CONCLUSIONS

These results show that digital rectal examination sampling of stool is less predictive of significant colorectal pathology than stool passed spontaneously, and therefore the latter is the preferred method for stool sampling.

Colorectal cancer in iron deficiency anemia with a positive result on immunochemical fecal occult blood

We examined the relationships between iron deficiency anemia, immunochemical fecal occult blood test results, and colorectal cancer. Samples were collected from 17,664 asymptomatic individuals for an immunochemical occult blood test, and colonoscopy was carried out during medical check-up. The positivity rate on the occult blood test and detection rate for colorectal cancer were compared in those with and those without iron deficiency anemia. In addition, the detection rate for colorectal cancer was determined in four groups stratified by occult blood test results and the presence of iron deficiency anemia. The occult blood test was positive in 18.4% of those with and in 3.8% of those without iron deficiency anemia (P < 0.001), and colorectal cancer was detected in 2.7% of those with and in 0.4% of those without iron deficiency anemia (P < 0.05). The highest rate of colorectal cancer was found in subjects with both iron deficiency anemia and positive occult blood test result. These findings indicate positive associations between iron deficiency anemia and immunochemical occult blood test results, and between iron deficiency anemia and colorectal cancer. Colonoscopy is thus necessary particularly in cases of positive immunochemical occult blood test result and iron deficiency anemia.

Immunochemical fecal occult blood test is inadequate for screening test of stomach cancer

The present study was carried out to investigate the diagnostic accuracy of the immunochemical fecal occult blood test in the screening for stomach cancer. In the hospital-based case-control study, the test was positive in 6 (14.3%) subjects with stomach cancer, in 32 (76.2%) subjects with colorectal cancer, and in 10 (7.9%) healthy subjects, respectively, showing a significant difference in detection rate between the subjects with stomach cancer and colorectal cancer (p < 0.01). In the population-based cross-sectional study, detection rate for stomach cancer was 0.13% and 0.15% for negative and positive groups decided by immunochemical fecal occult blood test, indicating no significant difference. These results reveal that the immunochemical fecal occult blood test is inadequate as the screening test for stomach cancer and suggest that examination of the upper digestive tract is unnecessary in cases where the result of fecal occult blood test is positive with no sign of colorectal diseases.

Relative risk of dietary components and colorectal cancer

OBJECTIVES

To investigate the relative risk factor of dietary components for colorectal cancer in a Chinese rural area through a hospital-based study.

DESIGN AND SETTING

Colorectal cancer patients diagnosed at a county cancer center, Hebei Province, China, and out-patients with similar age, sex and resident place were selected for cases and controls, respectively. All subjects were given to interview about their food intake using a foods frequency questionnaire. The intake of different dietary components and life style were compared between cases and controls.

MAIN RESULTS

There were 45 colorectal cancer patients and 45 outpatients being the cases and controls in the hospital-based study. In comparison of dietary components between cases and controls, milks, vegetables, fruits and teas had protective effect, and odds ratios were 0.21 (95% CI 0.07-0.60), 0.13 (95% CI 0.03-0.49), 0.27 (95% CI 0.11-0.68) and 0.39 (95% CI 0.16-0.98), respectively. Meats and saturated fats had an increased risk for colorectal cancer, and odds ratios were 5. 13 (95% CI 1.54-17.00) and 3.61 (95% CI 1.17-11.11), respectively.

CONCLUSIONS

These findings indicate that there is a similar trend of dietary factors and risk of colorectal cancer in rural areas in comparison with westem dietary pattern, and suggest that the special attention should be paid to dietary habit for prevention and control of colorectal cancer in Chinese rural area.

Relationships between a sign of rectal bleeding and the results of an immunochemical occult blood test, and colorectal cancer

A cross-sectional study based on medical check-up was carried out to investigate the association between signs of rectal bleeding and colorectal cancer, and the results of an immunochemical faecal occult blood test. The 9625 patients received both an immunochemical faecal occult blood test using a two-consecutive-day method and colonoscopy. They were then divided into two groups, according to the results of a self-completed questionnaire on the signs of rectal bleeding. The positivity rate of the immunochemical faecal occult blood test as well as the positive predictive value for colorectal cancer were determined in these two groups. The faecal occult blood test was positive in 9.3% of patients with rectal bleeding and in 4.4% of patients without rectal bleeding, and the positive predictive value for colorectal cancer was 0.79 and 0.27 in patients with and without rectal bleeding, respectively. This indicates a significant difference in the positivity rate (P < 0.001) as well as the positive predictive value (P < 0.05) between these two groups. The results suggest that there are positive associations between the signs of rectal bleeding and the results of immunochemical faecal occult blood test, and between the patients presenting with rectal bleeding and colorectal cancer.

Family history of colorectal adenomatous polyps as a risk factor for colorectal cancer

The aim of this study was to evaluate the risk of common colorectal cancer among first-degree relatives of patients with colorectal adenomatous polyps. In a population screening programme, 59406 subjects underwent an immunochemical faecal occult blood test. In a medical check-up-based cross-sectional study, 6139 subjects had a colonoscopic examination. They were divided into two groups, according to the results of a questionnaire on family history of colorectal adenomatous polyps, and the detection rates for colorectal cancer were compared in the groups positive or negative for a family history of colorectal adenomatous polyps. In the screening programme-based cross-sectional study, the detection rate for colorectal cancer was 0.57% (95% confidence interval (CI): 0.38-0.76) and 0.15% (95% CI: 0.12-0.18) in subjects with and without a family history of colorectal adenomatous polyps, respectively, showing a significant difference in the detection rate for colorectal cancer between the two groups (P<0.05). In the medical check-up-based cross-sectional study, the detection rate for colorectal cancer was 2.31% (95% CI: 1.15-3.47) and 0.53% (95% CI: 0. 34-0.72) in subjects with and without a family history of colorectal adenomatous polyps, respectively, indicating a significant difference between the two groups (P<0.05). These findings indicate that first-degree relatives of patients with colorectal adenomatous polyps have an elevated risk for common colorectal cancer, and that people with a family history of colorectal adenomatous polyps should be considered as a priority group for colorectal cancer screening.

Association of diverticulosis coli and vascular ectasias and the results of fecal occult blood test

BACKGROUND/AIMS

This study was conducted to clarify the diagnostic value of an immunochemical fecal occult blood test for diverticulosis coli and vascular ectasias of the colon, and to assess the association of these diseases to the results of fecal occult blood test.

METHODOLOGY

An immunochemical fecal occult blood test over 2 consecutive days was carried out on 72 patients with diverticulosis coli, on 36 patients with vascular ectasias of the colon, on 36 patients with colon cancer, and on 144 healthy subjects.

RESULTS

The test was positive in 13.8% patients with diverticulosis coli, in 11.1% patients with vascular ectasias, in 83.3% patients with colon cancer, and in 6.2% healthy subjects, respectively, showing a significant difference in the detection rate between colonic diverticulosis and colon cancer, between vascular ectasias and colon cancer (P < 0.001). However, there was no significant difference in the detection rate between diverticulosis coli and healthy subjects, and between vascular ectasias and healthy subjects. In addition, there was no significant association between the degrees of diverticulosis coli and vascular ectasias to the results of immunochemical fecal occult blood test.

CONCLUSIONS

These findings indicate that the immunochemical fecal occult blood is unsuitable for the diagnosis of the patients with colonic diverticulosis and patients with vascular ectasias, and these disorders have little influence on the results of fecal occult blood test.

Cost-effectiveness analysis of immunochemical occult blood screening for colorectal cancer among three fecal sampling methods

BACKGROUND/AIMS

To evaluate the optimal sampling times of stool in immunochemical occult blood screening from the viewpoint of the cost-effectiveness.

METHODOLOGY

A colorectal cancer screening was conducted in 5 municipalities (Matsumoto, Hata, Yamagata, Asahi, Sakai), Nagano prefecture, Japan in 1996. Each participant received a fecal occult blood test with 3 consecutive days. For the economic assessment of testing methods, the results of the 1st day, those of the 1st and 2nd days and those of the 3 consecutive days were used for a single-day method, a 2-day method, and a 3-day method. The average costs per detection of one cancer patient and diagnostic validity were evaluated among 3 months.

RESULTS

The average costs for one cancer case detected were calculated to be $5924 for a single-day method, $6014 for a 2-day method, and $7123 for a 3-day method, respectively. The sensitivity and specificity were calculated to be 58% and 96% for a single-day method, 89% and 95% for a 2-day method, and 100% and 94% for a 3-day method, respectively, indicating a significant difference in the sensitivity between a single-day method and a 2-day as well as a 3-day method (P < 0.05), and in the specificity among 3 testing methods (P < 0.001).

CONCLUSIONS

The present analysis suggests that a 2-day collection method is recommended in the immunochemical occult blood screening from the viewpoint of the cost-effectiveness as well as the diagnostic accuracy.

Characteristics and survival rate of elderly patients with colorectal cancer detected by immunochemical occult blood screening

BACKGROUND/AIMS

A comparative study was carried out to clarify the clinicopathological features and survival rate of elderly patients with colorectal cancer diagnosed by immunochemical fecal occult blood screening.

METHODOLOGY

The study subjects included 208 patients with colorectal cancer, who were divided into 2 groups based on their ages: 52 patients aged 75 years and over (older group) and 156 patients aged 50-74 years (younger group). The 2 groups were compared in terms of their individual factors, including site, size, Dukes' classification, histo-pathological type of their cancer lesions and 5-year survival rate.

RESULTS

There was a significant difference in prevalence of tumor sites between the older and younger groups (P < 0.05). Particularly, the frequency of right colon cancers was higher in the older group (34.6%) than in the younger group (20.5%), but there were no differences found in any other factors such as size, Dukes' classification, and histopathological type. Survival rate was almost the same between the 2 groups.

CONCLUSIONS

These results suggest that elderly patients are susceptible to right colon cancer but there is no difference in the clinicopathological characteristics and 5-year survival rate between older and younger patients with colorectal cancer detected by immunochemical fecal occult blood test. The older as well as younger people should be encouraged to attend the screening program for colorectal cancer by immunochemical fecal occult blood test.

A comparative study of immunochemical fecal tests for detection of colorectal adenomatous polyps

BACKGROUND/AIMS

This study was conducted to assess the diagnostic validity of new different immunochemical fecal occult blood tests for colorectal adenomatous polyps, including reversed passive hemagglutination test (Immudia-HemSp), combination monoclonal antibody guaiac test (Monohaem), latex agglutination inhibition test (Iatro Hemcheck), and latex agglutination tests (LA Hemochaser, OC-Hemodia).

METHODOLOGY

Two hundred and fifty patients with colorectal adenomatous polyps 1.0 cm or larger in diameter and the same number of healthy controls served as subjects for the study. Each subject received a set of 5 immunochemical tests within 3 consecutive days, and sensitivities and specificities of these tests were evaluated.

RESULTS

Mean sensitivity and specificity in a set of 5 immunochemical tests were 47.6% and 95.8%, respectively. Sensitivities and specificities of 5 different immunochemical tests were calculated as 47.6% and 96.8% for Immudia-Hem Sp, 46.8% and 95.2% for Monohem, 46.4% and 95.2% for Iatro Hemchek, 48.0% and 96.4% for LA Hemochaser, and 49.2% and 95.6% for OC-Hemodia, respectively, showing no significant difference in sensitivity and specificity among the 5 tests.

CONCLUSIONS

These findings suggest that there is no difference in the degree of accuracy for colorectal adenomatous polyps among several types of immunochemical fecal occult blood test.

A cost-effective analysis of the optimum number of stool specimens collected for immunochemical occult blood screening for colorectal cancer

This study was carried out to assess, from the viewpoint of cost-effectiveness, the optimum number of faecal specimens to collect for use in immunochemical occult blood testing as a means of screening for colorectal cancer. 3300 asymptomatic individuals were subjects of this study. They gave samples for an immunochemical faecal occult blood test, monohaem and colonoscopy was carried out during a medical check-up. For evaluation of the optimum number of sampling specimens, the results of the first day of sampling, those of the first and second days, and those of samples taken for 3 consecutive days were considered as the single-day method, the 2-day method and the 3-day method respectively. The average cost to detect 1 patient with colorectal cancer, the detection rate and the false-positive rate of these three faecal sample collection methods were evaluated. The average costs for one cancer case detected were calculated as $3,630.68 for the single-day method, $3,350.65 for the 2-day method and $4,136.36 for the 3-day method, respectively. The detection rate and the false-positive rate were calculated as 47 and 3.5% for the single-day method, 82 and 4.7% for the 2-day method and 88 and 5.3% for the 3-day method, respectively. This detection rate was significantly different between the single- and the 2-day methods, as well as between the single- and the 3-day methods (P<0. 05). No significant differences in the false-positive rate amongst the three testing methods were observed. This analysis suggests that a 2-day faecal collection method is recommended for immunochemical occult blood screening by Monohaem from the aspects of cost-effectiveness and diagnostic accuracy.

Bacterial interference among nasal inhabitants: eradication of Staphylococcus aureus from nasal cavities by artificial implantation of Corynebacterium sp

To evaluate the role of normal flora in the nares in preventing Staphylococcus aureus colonization, we conducted a replacement study in vivo. Staphylococcus epidermidis (rate of colonization: 100%), various species of corynebacteria (52.5%) and S. aureus (25.%) were the major bacterial inhabitants in the nares of 156 healthy volunteers. The low incidence of S. aureus colonization in the carriers with corynebacteria (8.5%), compared to non-carriers (44. 5%) indicated the possibility of competition for survival between S. aureus and corynebacteria. To confirm this hypothesis, we artificially implanted a strain of Corynebacterium sp (API Coryne bioprofile; 5100304), denoted as Co304 into the nares of 17 S. aureus carriers. S. aureus was completely eradicated in 71% of carriers by up to 15 inoculations of Co304. However, similar doses of 0.9% NaCl or S. epidermidis into the nares of 10 volunteers did not eradicate S. aureus. No bacteriocin-like activity against S. aureus was detectable, even after mitomycin C stimulation of Co304. Thus Co304 interfered with S. aureus by a different mechanism to a bacteriocin-like activity.

Comparison of predictive value for colorectal cancer in subjects with and without rectal bleeding

BACKGROUND/AIMS

To clarify the association between a sign of rectal bleeding and colorectal cancer, and to reveal the relationship of rectal bleeding to the results of an immunochemical fecal occult blood test.

METHODOLOGY

In a population-based cross sectional study, 30,138 subjects who received immunochemical fecal occult blood screening with a 2-day method were divided into two groups, according to the results of a questionnaire on a sign of rectal bleeding, and the positivity rate of an immunochemical occult blood test as well as the predictive value for colorectal cancer were compared in the two groups.

RESULTS

The fecal occult blood test was positive in 8.8% of subjects with rectal bleeding and in 6.0% of subjects without rectal bleeding, and the predictive value was 6.4% and 3.3% in subjects with and without rectal bleeding, respectively, showing a significant difference in the positivity rate (p<0.001) as well as the predictive value (p<0.05) between these two groups.

CONCLUSIONS

These findings indicate that there are positive relations between the subjects with rectal bleeding presentation and colorectal cancer, and a sign of rectal bleeding and the results of an immunochemical fecal occult blood test.

Colonoscopic evaluation of immunochemical fecal occult blood test for detection of colorectal neoplasia

BACKGROUND/AIMS

This study was carried out to assess the validity of three testing methods of immunochemical occult blood according to the number of collection times as a means for colorectal cancer screening.

METHODOLOGY

Four thousand six hundred and eleven asymptomatic individuals, who received both an immunochemical occult blood test with a three-day method and colonoscopy during a medical checkup, served as subjects for this study. For evaluation of the desirable number of sampling times, we used the results of the first day for the 1-day method, the results of the first and second days for the 2-day method, and the results of three-consecutive days for the 3-day method. Sensitivities and specificities of these three testing methods were evaluated.

RESULTS

Sensitivities and specificities for colorectal cancer were calculated to be 56% and 97% for the 1-day method, 83% and 96% for the 2-day method, and 89% and 94% for the 3-day method, respectively, showing a significant difference in sensitivity between the 1-day and the 2-day methods, as well as the 3-day method (p < 0.01), and in specificity between the 1-day as well as the 2-day and 3-day methods (p < 0.05).

CONCLUSIONS

These findings indicate that the immunochemical fecal occult blood test is useful for the diagnosis of colorectal cancer, and that 2-day testing is recommended as a means of screening for colorectal cancer.

Levodopa effective parkinsonism associated with aqueductal stenosis: a case report and review of the literature

A case of aqueductal stenosis (AS) associated with marked parkinsonism is described. A ventriculoperitoneal (V-P) shunt was performed in an 18-year-old female because of hydrocephalus associated with non-neoplastic aqueductal stenosis. The patient developed acute parkinsonism with Parinaud's sign after the shunt revision. She had a marked response to levodopa and the parkinsonism improved. Subsequently, levodopa therapy was gradually discontinued without any manifestation of parkinsonism. The pathophysiology of this type of parkinsonism probably involved presynaptic dopaminergic dysfunction. However, the etiology of this complication has not been confirmed.

Sensitivity and specificity of several immunochemical tests for colorectal cancer

BACKGROUND/AIM

The purpose of this study was to evaluate the diagnostic accuracy of new different immunochemical fecal occult blood tests for colorectal cancer, including Iatro Hemcheck, Immudia-Hem Sp, LA Hemochaser, Monohaem and OC-Hemodia.

METHODOLOGY

Ninety-six patients with colorectal cancer and the same number of healthy controls served as subjects for the study. In this study, each subject received a set of five immunochemical tests over three consecutive days; and sensitivities and specificity of these tests were evaluated.

RESULTS

Mean sensitivity and specificity in a set of five immunochemical tests were 91.0% and 95.2%, respectively. Sensitivities and specificity of five different immunochemical tests were calculated as 92.7% and 92.7% for Iatro-Hemcheck, 90.6% and 96.9% for Immudia-Hem Sp, 88.5% and 96.9% for LA Hemochaser, 91.7% and 95.8% for Monohaem, and 91.7% and 93.8% for OC-Hemodia, respectively, showing no significant difference in sensitivity and specificity among five tests.

CONCLUSIONS

These results suggest that immunochemical tests for fecal occult blood tests has high diagnostic validity for colorectal cancer. In addition, there is no significant difference in the degree of accuracy among the several types of immunochemical tests.

Reasons for non-compliance in colorectal cancer screening with fecal occult blood test

OBJECTIVES

To identify the reasons for non-compliance with fecal occultblood test in the screening programme for colorectal cancer.

DESIGN AND SETTING

The people who had never participated in the screening programme for colorectal cancer served as the subjects of this study. A structured questionnaire which included the reasons for rejection was sent to each of non-compliers. They were requested to choose two major reasons which were described in a best way that why they did not participate in the programme. The frequency of the stated reasons were analysed from the viewpoint of both sex and age effects.

MAIN RESULTS

A total of 439 people was identified as non-compliers, and 356 (81.1%) people completed the questionnaire. No significant difference was noted in response to the questionnaire between male and female as well as aged 40-59 and those 60-79. The most commonest reason was felt well (47.8%) in male, fear or shyness of further examination (40.2%) in female, and also felt well (48.5%) in aged 40-59, fear or shyness of further examination (40.1%) in aged 60-79. Significant differences were observed in the frequencies of felt well (p<0.01), fear or shyness of further examination (p<0. 01), busy for work (p<0.01) and fear of cancer (p<0.01) between male and female, and also felt well (p<0.01), fear or shyness of further examination (p<0.01), busy for work (p<0.01) and coexistent disease (p<0.01) between aged 40-59 and those 60-79.

CONCLUSIONS

These results suggest that public education about the concept of asymptomatic illness, the benefits of early detection, the safety and painless colonoscopy, and the effective treatment should be emphasised to increase compliance with screening for fecal occult blood.

Screen compliance rates in 14-years annual screening program for colorectal cancer with immunochemical fecal occult blood test-- identification of higher priority subjects in health education

OBJECTIVES

The present study was carried out to assess compliance rates with annual colorectal cancer screening for fecal occult blood, and to identify the subjects with higher priority in health education to increase screen compliance.

DESIGN AND SETTING

A screening program for colorectal cancer was conducted between 1982 and 1995 in a Japanese villlage. Screen compliance rates in this program were summarised related to sex distribution as well as 10-year age cohorts.

MAIN RESULTS

Screen compliance declined slowly during 14 years time period, and averaged 55.4%. Mean screen compliance was significantly higher in women (56.8%) than in men (53. 8%), and also in aged 50-79 (63.5%) than in aged 50 or less (43.8%), and those 80 and older(12.3%). Subjects who experienced a negative result on colonoscopic examination had significantly lower compliance with screening.

CONCLUSIONS

These findings indicate that the youngest as well as oldest subjects, and the subjects with negative results of fecal occult blood test should be given higher priority in health education to improve screen compliance.

Immunologic detection of fecal occult blood from upper digestive tract diseases

BACKGROUND/AIMS

This study was conducted to evaluate the accuracy of the immunochemical occult blood test for upper digestive tract diseases.

METHODOLOGY

The test was performed on 226 subjects, including 124 upper digestive tract diseases (12 ulcerative esophagitis cases, 10 esophageal cancer cases, 33 gastric ulcer cases, 33 gastric cancer cases, and 36 duodenal ulcer cases), 34 colorectal cancer cases, and 68 healthy subjects, after which, the accuracy of this test was evaluated.

RESULTS

The test was positive 23 in upper digestive tract diseases (2 in ulcerative esophagitis, 2 in esophageal cancer, 5 in gastric ulcer, 8 in gastric cancer, 6 in duodenal ulcer), 31 in colorectal cancer, and 3 in healthy subjects, respectively. Thus, the sensitivity was 19% for upper digestive tract diseases (16.7% for ulcerative esophagitis, 20% for esophageal cancer, 15% for gastric ulcer, 24% for gastric cancer, 20% for duodenal ulcer) and 91% for colorectal cancer, and the specificity was 96%. Significant difference was noted in the sensitivity between upper digestive tract diseases and colorectal cancers (p0.001), whereas there was no difference among 5 upper digestive tract diseases.

CONCLUSIONS

These results indicate that the immunochemical occult blood is inadequate as means for detection of upper digestive tract diseases, and that an examination of upper digestive tract is unnecessary in cases where the immunochemical occult blood test is positive, but there is no evidence of diseases in colon and rectum.

Colorectal adenomatous polyps detected by immunochemical occult blood screening

BACKGROUND/AIMS

This study aimed to evaluate the validity of immuno-chemical occult blood screening for colorectal adenomas and to clarify the characteristics of this disease which are detected.

METHODOLOGY

We studied 140 colorectal adenomas and 140 healthy controls in a hospital based case control study, in which three-day testing was conducted to assess the accuracy of the immuno-chemical occult blood screening test (total 280 patients). A further 80 colorectal adenomas 1 cm or larger, which were detected by a screening program, were compared with matched cases detected by the outpatient clinics (total 160 patients). A comparison of characteristics including tumor location, shape and histology was made between the two groups.

RESULTS

Sensitivity and specificity were calculated to be 46% (61% for tumors larger than 1 cm, 30% for those less than 1 cm), and 96% respectively, showing a significant difference in sensitivity between large and small adenomas (p < 0.01). The proportion of rectal adenomas was significantly higher in the outpatient clinics (41%) than in the screening program (21%) (p < 0.05), whereas no differences were noted in the other measures.

CONCLUSIONS

These results suggest that immuno-chemical occult blood is inadequate as a screening test for detecting small adenomas, as t can not differentiate between the detection of rectal adenomas from large adenomatous polyps.

Clinico-pathological features of colorectal adenomatous polyps with negative results on immunochemical fecal occult blood test

BACKGROUND

This study was carried out to clarify the clinico-pathological features of colorectal adenomatous polyps showing negative results on an immunochemical fecal occult blood test.

METHODS

Four hundred sixty patients with colorectal adenoma 1.0 cm or larger in diameter served as subjects of this study. They were divided into two groups based on the results of an immunochemical fecal occult blood test with a 3-day method: two hundred twenty four patients with positive results (positive group) and two hundred thirty six patients with negative results (negative group). The above two groups were compared in terms of their individual factors such as lesion site, lesion size, lesion shape, and histological type.

RESULTS

In negative group, the frequencies of rectal adenomatous polyps (p<0.01) and colorectal adenomatous polyps 1.0-1.5 cm in size (p<0.001) were higher, and also pedunculated type (p<0.05) were lower than in positive group, but there was no difference in histological type between the two groups.

CONCLUSIONS

These findings suggest that immunochemical fecal occult blood testing is relatively inferior for the detection of colorectal adenomatous polyps in rectum, smaller size, and non-pedunculated type.

Detection rate of immunochemical fecal occult blood test for colorectal adenomatous polyps with severe dysplasia

This study was conducted to assess the accuracy of an immunochemical occult blood test for detecting colorectal adenomas with severe dysplasia, and to determine the relationship between the grading of adenomatous dysplasia and the results of this test. Sixteen colorectal adenomas under 1 cm with severe dysplasia, 65 adenomas under 1 cm with mild-to-moderate dysplasia, 65 adenomas 1 cm or larger with mild-to-moderate dysplasia, 65 colorectal cancers and 130 healthy controls were investigated. Each subject was tested with an immunochemical fecal occult blood test on 3 consecutive days, and the accuracy of the test was evaluated. The detection rate of this test was 13% for severe dysplasia under 1 cm, 45% for severe dysplasia 1 cm or more, 17% for mild-to-moderate dysplasia under 1 cm, 40% for mild-to-moderate dysplasia 1 cm or more, and 89% for colorectal cancers, and the false positive rate was 5%, showing a significant difference in the detection rate between severe dysplasias 1 cm or more and those under 1 cm (P < 0.05) as well as significant difference between severe dysplasias 1 cm or more and mild-to-moderate dysplasia under 1 cm (P < 0.01), and between cancers and adenomas (P < 0.001), whereas there was no significant difference between the detection rates for severe dysplasia 1 cm or more and mild-to-moderate dysplasia 1 cm or more. These results indicate that there is no association between the detection rate of this immunochemical occult blood test for adenomas and the grade of adenomatous dysplasia.

Relationship between fecal sampling times and sensitivity and specificity of immunochemical fecal occult blood tests for colorectal cancer: a comparative study

PURPOSE

The present study was conducted to assess the accuracy of three testing methods using an immunochemical fecal occult blood test based on the number of samples as the optimum means for screening of colorectal cancer.

METHOD

One hundred eighty-four patients with colorectal cancer and 368 healthy controls served as the subjects for this study. Each subject was tested by an immunochemical fecal occult blood test for three consecutive days. For evaluation of the most desirable number of sampling times, we used the results of the first day for the one-day method, results of the first and second days for the two-day method, and results of three consecutive days for the three-day method. Sensitivities and specificities of the three testing methods were evaluated.

RESULTS

Sensitivities of an immunochemical fecal occult blood test were calculated as 67.9 percent for the one-day method, 88 percent for the two-day method, and 90.8 percent for the three-day method; specificity was as follows: 97.5 percent for the one-day method, 95.6 percent for the two-day method, and 92.1 percent for the three-day method. A significant difference in sensitivity was shown between the one-day and two-day and the one-day and three-day methods (P < 0.01); also, a significant difference in specificity was shown between one-day and three-day and two-day and three-day methods (P <0.05).

CONCLUSIONS

These results indicate that the two-day method is recommended for immunochemical fecal occult blood testing as a means of screening for colorectal cancer.

Immunochemical fecal occult blood test is not suitable for diagnosis of hemorrhoids

PURPOSE

This study was conducted to clarify the diagnostic value of an immunochemical fecal occult blood test for hemorrhoids.

PATIENTS AND METHODS

In a case-control study, an immunochemical fecal occult blood test with a 2-day method was carried out on 82 subjects with hemorrhoids, on 82 subjects with colorectal cancer, and on 82 healthy subjects. In a population-based cross-sectional study, 29,714 subjects who received an immunochemical occult blood screening with a 2-day method were divided into two groups, according to the results of a questionnaire on hemorrhoids, and the positivity rate of an immunochemical test as well as the predictive value for colorectal cancer were compared in the two groups. Moreover, both an immunochemical occult blood test with a 2-day method and colonoscopy were conducted at the same time on asymptomatic subjects during a medical checkup.

RESULTS

In the case-control study, the test was positive in 13.4% subjects with hemorrhoids, in 84.1% subjects with colorectal cancer, and in 4.9% healthy subjects, respectively, showing a significant difference in the detection rate between the two diseases (P < 0.001). In the population screening program, the test was positive in 6.9% subjects with hemorrhoids and in 6.5% subjects without hemorrhoids, and the predictive value was 3.2% in subjects with and without hemorrhoids, respectively, indicating no significant difference in the positivity rate as well as the predictive value between the two groups. Among 232 subjects in a medical checkup, 28 patients with hemorrhoids and 21 patients with colorectal polyp 1 cm or larger were diagnosed by colonoscopy, and the occult blood test was positive in 16.7% patients with hemorrhoids and in 52.4% patients with colorectal polyp, respectively. There was a significant difference in the sensitivity between the two disease groups (P < 0.05).

CONCLUSIONS

These findings indicate that the immunochemical fecal occult blood is unsuitable for the diagnosis of the patients with hemorrhoids and an examination of the colorectum is necessary in cases where the occult blood test is positive but there is a sign of hemorrhoids.

Diagnostic value of immunochemical fecal occult blood test for small colorectal neoplasms

This study was designed to assess the diagnostic value of an immunochemical fecal occult blood test for small colorectal adenomas. In a screening program based comparative study, 60 colorectal adenomas under 1 cm (small polyp group), 60 colorectal adenomas 1 cm or larger (large polyp group) and 60 colorectal cancers (cancer group) detected by occult blood screening, and 120 healthy controls (control group), served as subjects. Moreover, 50 small adenomas, 50 large adenomas and 50 cancers detected in out-patient clinics, and 100 controls, served as subjects of a hospital based comparative study. Each of these subjects was tested by an immunochemical occult blood with 3 consecutive days, after removal of these colorectal neoplasms in a screening program based study and before as well as after removal in a hospital based study, and the positivity rate of this test was evaluated among these four groups in the two comparative studies. The positivity rate in a screening program based study was 23% for small polyp group, 8% for large polyp group, 5% for cancer group and 6% for control group, respectively. Significant difference was noted between small polyp and cancer as well as control groups (p <0.01), and between small polyp and large polyp groups (p <0.05). In a hospital based study, however, there was no significant difference in the positivity rate among four groups. These results suggest that high proportion of small polyps detected by fecal occult blood test screening may not be associated with bleeding from adenomas but probably from another gastrointestinal pathology.