Advancing healthcare through laboratory on a chip technology:Transforming microorganism identification and diagnostics

In a recent case report in the World Journal of Clinical Cases,emphasized the crucial role of rapidly and accurately identifying pathogens to optimize patient treatment outcomes.Laboratory-on-a-chip(LOC)technology has emerged as a transformative tool in health care,offering rapid,sensitive,and specific identification of microorganisms.This editorial provides a comprehensive overview of LOC technology,highlighting its principles,advantages,applications,challenges,and future directions.Success studies from the field have demonstrated the practical benefits of LOC devices in clinical diagnostics,epidemiology,and food safety.Comparative studies have underscored the superiority of LOC technology over traditional methods,showcasing improvements in speed,accuracy,and portability.The future integration of LOC with biosensors,artificial intelligence,and data analytics promises further innovation and expansion.This call to action emphasizes the importance of continued research,investment,and adoption to realize the full potential of LOC technology in improving healthcare outcomes worldwide.

Evaluation of urea breath test as a diagnostic tool for Helicobacter pylori infection in adult dyspeptic patients

In this editorial,we discuss the article in the World Journal of Gastroenterology.The article conducts a meta-analysis of the diagnostic accuracy of the urea breath test(UBT),a non-invasive method for detecting Helicobacter pylori(H.pylori)infection in humans.It is based on radionuclide-labeled urea.Various methods,both invasive and non-invasive,are available for diagnosing H.pylori infection,inclu-ding endoscopy with biopsy,serology for immunoglobulin titers,stool antigen analysis,and UBT.Several guidelines recommend UBTs as the primary choice for diagnosing H.pylori infection and for reexamining after eradication therapy.It is used to be the first choice non-invasive test due to their high accuracy,specificity,rapid results,and simplicity.Moreover,its performance remains unaffected by the distribution of H.pylori in the stomach,allowing a high flow of patients to be tested.Despite its widespread use,the performance characteristics of UBT have been inconsistently described and remain incompletely defined.There are two UBTs available with Food and Drug Administration approval:The 13C and 14C tests.Both tests are affordable and can provide real-time results.Physicians may prefer the 13C test because it is non-radioactive,compared to 14C which uses a radioactive isotope,especially in young children and pregnant women.Although there was heterogeneity among the studies regarding the diagnostic accuracy of both UBTs,13C-UBT consistently outperforms the 14C-UBT.This makes the 13C-UBT the preferred diagnostic approach.Furthermore,the provided findings of the meta-analysis emphasize the significance of precise considerations when choosing urea dosage,assessment timing,and measurement techniques for both the 13C-UBT and 14C-UBT,to enhance diagnostic precision.

Urea breath test for Helicobacter pylori infection in adult dyspeptic patients: A meta-analysis of diagnostic test accuracy

BACKGROUND Helicobacter pylori(H.pylori)infection has been well-established as a significant risk factor for several gastrointestinal disorders.The urea breath test(UBT)has emerged as a leading non-invasive method for detecting H.pylori.Despite numerous studies confirming its substantial accuracy,the reliability of UBT results is often compromised by inherent limitations.These findings underscore the need for a rigorous statistical synthesis to clarify and reconcile the diagnostic accuracy of the UBT for the diagnosis of H.pylori infection.AIM To determine and compare the diagnostic accuracy of 13C-UBT and 14C-UBT for H.pylori infection in adult patients with dyspepsia.METHODS We conducted an independent search of the PubMed/MEDLINE,EMBASE,and Cochrane Central databases until April 2022.Our search included diagnostic accuracy studies that evaluated at least one of the index tests(^(13)C-UBT or ^(14)C-UBT)against a reference standard.We used the QUADAS-2 tool to assess the methodo-logical quality of the studies.We utilized the bivariate random-effects model to calculate sensitivity,specificity,positive and negative test likelihood ratios(LR+and LR-),as well as the diagnostic odds ratio(DOR),and their 95%confidence intervals.We conducted subgroup analyses based on urea dosing,time after urea administration,and assessment technique.To investigate a possible threshold effect,we conducted Spearman correlation analysis,and we generated summary receiver operating characteristic(SROC)curves to assess heterogeneity.Finally,we visually inspected a funnel plot and used Egger’s test to evaluate publication bias.endorsing both as reliable diagnostic tools in clinical practice.CONCLUSION In summary,our study has demonstrated that ^(13)C-UBT has been found to outperform the ^(14)C-UBT,making it the preferred diagnostic approach.Additionally,our results emphasize the significance of carefully considering urea dosage,assessment timing,and measurement techniques for both tests to enhance diagnostic precision.Nevertheless,it is crucial for researchers and clinicians to evaluate the strengths and limitations of our findings before implementing them in practice.

Evaluation of a Rapid Diagnostic Test, Boson Biotech SARS CoV-2 Ag, for the Detection of SARS-CoV-2 in Gabon

1) Background: Rapid and acurate diagnostic testing for case identification, quarantine, and contact tracing is essential for managing the COVID 19 pandemic. Rapid antigen detection tests are available, however, it is important to evaluate their performances before use. We tested a rapid antigen detection of SARS-CoV-2, based on the immunochromatography (Boson Biotech SARS-CoV-2 Ag Test (Xiamen Boson Biotech Co., Ltd., China)) and the results were compared with the real time reverse transcriptase-Polymerase chain reaction (RT-PCR) (Gold standard) results;2) Methods: From November 2021 to December 2021, samples were collected from symptomatic patients and asymptomatic individuals referred for testing in a hospital during the second pandemic wave in Gabon. All these participants attending “CTA Angondjé”, a field hospital set up as part of the management of COVID-19 in Gabon. Two nasopharyngeal swabs were collected in all the patients, one for Ag test and the other for RT-PCR;3) Results: A total of 300 samples were collected from 189 symptomatic and 111 asymptomatic individuals. The sensitivity and specificity of the antigen test were 82.5% [95%CI 73.8 - 89.3] and 97.9 % [95%CI 92.2 - 98.2] respectively, and the diagnostic accuracy was 84.4% (95% CI: 79.8 - 88.3%). The antigen test was more likely to be positive for samples with RT-PCR Ct values ≤ 32, with a sensitivity of 89.8%;4) Conclusions: The Boson Biotech SARS-CoV-2 Ag Test has good sensitivity and can detect SARS-CoV-2 infection, especially among symptomatic individuals with low viral load. This test could be incorporated into efficient testing algorithms as an alternative to PCR to decrease diagnostic delays and curb viral transmission.

New fecal test for non-invasive Helicobacter pylori detection:A diagnostic accuracy study

AIM To assess the diagnostic accuracy of a new fecal test for detecting Helicobacter pylori(H. pylori), using ^(13)Curea breath test as the reference standard, and explore bacterial antibiotic resistance. METHODS We conducted a prospective two-center diagnostic test accuracy study. We enrolled consecutive people≥ 18 years without previous diagnosis of H. pylori infection, referred for dyspepsia between February and October 2017. At enrollment, all participants underwent 13 C-urea breath test. Participants aged over 50 years were scheduled to undergo upper endoscopy with histology. Participants collected stool samples 1-3 d after enrollment for a new fecal investigation(THD fecal test). The detection of bacterial 23 S rRNA subunit gene indicated H. pylori infection. We also used the index diagnostic test to examine mutations conferring resistance to clarithromycin and levofloxacin. Independent investigators analyzed index test and reference test standard results blinded to the other test findings. We estimated sensitivity, specificity, positive(PPV) and negative(NPV) predictive value, diagnostic accuracy, positive and negative likelihood ratio(LR), together with 95% confidence intervals(CI).RESULTS We enrolled 294 consecutive participants(age: Median 37.0 years, IQR: 29.0-46.0 years; men: 39.8%). Ninetyfive(32.3%) participants had a positive ^(13)C-urea breath test. Twenty-three(7.8%) participants underwent upper endoscopy with histology, with a full concordance between ^(13)C-urea breath test and histology in detecting H. pylori infection. Four(1.4%) out of the 294 participants withdrew from the study after the enrollment visit and did not undergo THD fecal testing. In the 290 participants who completed the study, the THD fecal test sensitivity was 90.2%(CI: 84.2%-96.3%), specificity 98.5%(CI:96.8%-100%), PPV 96.5%(CI: 92.6%-100%), NPV 95.6%(CI: 92.8%-98.4%), accuracy 95.9%(CI: 93.6%-98.2%), positive LR 59.5(CI: 19.3-183.4), negative LR 0.10(CI: 0.05-0.18). Out of 83 infected participants identified with the THD fecal test, 34(41.0%) had bacterial genotypic changes consistent with antibiotic-resistant H. pylori infection. Of these, 27(32.5%) had bacterial strains resistant to clarithromycin, 3(3.6%) to levofloxacin, and 4(4.8%) to both antibiotics. CONCLUSION The THD fecal test has high performance for the non-invasive diagnosis of H. pylori infection while additionally enabling the assessment of bacterial antibiotic resistances.

A comparative laboratory diagnosis of malaria:microscopy versus rapid diagnostic test kits

Objective:To compare the two methods of rapid diagnostic tests(RDTs)and microscopy in the diagnosis of malaria.Methods:RDTs and microscopy were carried out to diagnose malaria. Percentage malaria parasitaemia was calculated on thin films and all non-acute cases of plasmodiasis with less than 0.001%malaria parasitaemia were regarded as negative.Results were simply presented as percentage positive of the total number of patients under study.The results of RDTs were compared to those of microscopy while those of RDTs based on antigen were compared to those of RDTs based on antibody.Patients' follow-up was made for all cases.Results: All the 200 patients under present study tested positive to RDTs based on malaria antibodies(serum)method(100%).128 out of 200 tested positive to RDTs based on malaria antigen(whole blood)method(64%),while 118 out of 200 patients under present study tested positive to visual microscopy of Lieshman and diluted Giemsa(59%).All patients that tested positive to microscopy also tested positive to RDTs based on antigen.All patients on the second day of follow-up were non-febrile and had antimalaria drugs.Conclusions;We conclude based on the present study that the RDTs based on malaria antigen(whole blood)method is as specific as the traditional microscopy and even appears more sensitive than microscopy.The RDTs based on antibody(serum)method is unspecific thus it should not be encouraged.It is most likely that Africa being an endemic region,formation of certain levels of malaria antibody may not be uncommon.The present study also supports the opinion that a good number of febrile cases is not due to malaria. We support WHO's report on cost effectiveness of RDTs but,recommend that only the antigen based method should possibly,be adopted in Africa and other malaria endemic regions of the world.

Hypertrophic cardiomyopathy: Can the noninvasive diagnostic testing identify high risk patients?

Hypertrophic cardiomyopathy(HCM) is the most common cause of sudden cardiac death(SCD) in the young, particularly among athletes. Identifying high risk individuals is very important for SCD prevention. The purpose of this review is to stress that noninvasive diagnostic testing is important for risk assessment. Extreme left ventricular hypertrophy and documented ventricular tachycardia and fibrillation increase the risk of SCD. Fragmented QRS and T wave inversion in multiple leads are more common in high risk patients. Cardiac magnetic resonance imaging provides complete visualization of the left ventricular chamber, allowing precise localization of the distribution of hypertrophy and measurement of wall thickness and cardiac mass. Moreover, with late gadolinium enhancement, patchy myocardial fibrosis within the area of hypertrophy can be detected, which is also helpful in risk stratification. Genetic testing is encouraged in all cases, especially in those with a family history of HCM and SCD.

Comparison of a rapid diagnostic test and microimmunofluorescence assay for detecting antibody to Orientia tsutsugamushi in scrub typhus patients in China

Objective:To evaluate the detection of IgM and IgG antibodies to Orientia tsutsugamushi(O. tsutsugamushi) by rapid diagnostic test(RDT) and microimmunofluorescence assay(ml FA). Methods:RDT using a mixture of recombinant 56-kDa proteins of O.tsutsugamushi and mIFA assay were performed on 20 patients from Fujian and 13 patients from Yunnan Province,and 82 sera samples from healthy farmers in Anhui Province and Beijing City in 2009.Comparison of the RDT and mIFA assay was performed by using X test and the P level of 【0.05 was considered to be significance.Results:Among these 82 normal sera samples,the specificity of RDT was 100%for both IgM and IgG tests.In 33 samples from patients with scrub typhus,5 cases were positively detected earlier by RDT than by mIFA in IgM test,and 2 cases were positive in IgG test.Sensitivities of RDT were 93.9%and 90.9%for IgM and IgG,respectively.The sensitivity of combination lest of IgM and IgG was 100%.Geometric mean titer diluted sera from confirmed cases by IFA and RDT assay were 1:37 vs.1:113(P【0.001) in IgM test and 1:99 vs.1:279 (P【0.05) in IgG test.Conclusions:RDT is more sensitivite than mIFA in the early diagnosis of scrub typhus and it is particularly applicable in rural areas.

Diagnostic and economic value of carcinoembryonic antigen,carbohydrate antigen 19-9,and carbohydrate antigen 72-4 in gastrointestinal cancers

BACKGROUND The diagnostic and economic value of carcinoembryonic antigen(CEA),carbohydrate antigen 19-9(CA19-9)and CA72-4 for gastrointestinal malignant tumors lacked evaluation in a larger scale.AIM To reassess the diagnostic and economic value of the three tumor biomarkers.METHODS A retrospective analysis of all 32857 subjects who underwent CEA,CA19-9,CA72-4,gastroscopy and colonoscopy from October 2006 to May 2018 was conducted.Then,we assessed the discrimination and clinical usefulness.Total cost,cost per capita and cost-effectiveness ratios were used to evaluate the economic value of two schemes(gastrointestinal endoscopy for all people without blood tests vs both gastroscopy and colonoscopy when blood tests were positive).RESULTS The analysis of 32857 subjects showed that CEA was a qualified biomarker for colorectal cancer(CRC),while the diagnostic efficiencies of CA72-4 were catastrophic for all gastrointestinal cancers(GICs).Regarding early diagnosis,only CEA could be used for early CRC.The combination of biomarkers didn’t greatly increase the area under the curve.The economic indicators of CEA were superior to those of CA19-9,CA72-4 and any combination.At the threshold of 1.8μg/L to 10.4μg/L,all four indicators of CEA were lower than those in the scheme that conducted gastrointestinal endoscopy only.Subgroup analysis implied that the health checkup of CEA for people above 65 years old was economically valuable.CONCLUSION CEA had qualified diagnostic value for CRC and superior economic value for GICs,especially for elderly health checkup subjects.CA72-4 was not suitable as a diagnostic biomarker.

Update on diagnostic value of breath test in gastrointestinal and liver diseases

In the field of gastroenterology,breath tests(BTs) are used intermittently as diagnostic tools that allow indirect,non-invasive and relatively less cumbersome evaluation of several disorders by simply quantifying the appearance in exhaled breath of a metabolite of a specific substrate administered.The aim of this review is to have an insight into the principles,methods of analysis and performance parameters of various hydrogen,methane and carbon BTs which are available for diagnosing gastrointestinal disorders such as Helicobacter pylori infection,small intestinal bacterial overgrowth,and carbohydrate malabsorption.Evaluation of gastric emptying is routinely performed by scintigraphy which is however,difficult to perform and not suitable for children and pregnant women,this review has abridged the 13C-octanoic acid test in comparison to scintigraphy and has emphasized on its working protocol and challenges.A new development such as electronic nose test is also highlighted.Moreover we have also explored the limitations and constraints restraining the wide use of these BT.We conclude that breath testing has an enormous potential to be used as a diagnostic modality.In addition it offers distinct advantages over the traditional invasive methods commonly employed.

Early diagnostic strategies for colorectal cancer

At present,cancer is still an important factor threatening human health.Colorectal cancer(CRC)is one of the top three most common cancers worldwide and one of the deadliest malignancies in humans.The latest data showed that CRC incidence and mortality rank third and second,respectively,among global malignancies.Early and accurate diagnosis is crucial to reduce the morbidity,mortality and improve survival of patients with CRC,but the current early diagnostic methods have limitations.The effectiveness and compliance of diagnostic methods have a certain impact on whether people choose screening.In this editorial,we explore strategies for the early diagnosis of CRC,including stool-based,blood-based,direct visualization,and imaging examinations.

Accuracy Evaluation of A Diagnostic Test by Detecting Outliers and Influential Observations

Logit regression analysis is widely applied in scientific studies and laboratory experiments, where skewed observations on a data set are often encountered. A number of problems with this method, for example, oudiers and influential observations, can cause overdispersion when a model is fitted. In this study a systematic statistical approach, including the plotting of several indices is used to diagnose the lack-of-fit of a logistic regression model. The outliers and influential observations on data from laboratory experiments are then detected. Specifically we take account of the interaction of an internal sohtary wave （ISW） with an obstacle, i.e., an underwater ridge, and also analyze the effects of the ridge height, the lower layer water depth, and the potential energy on the amplitude-based transmission rate of the ISW. As concluded, the goodness-of-fit of the revised logit regression model is better than that of the model without this approach.

Diagnostic tests for hepatitis C: Recent trends in electrochemical immunosensor and genosensor analysis

Hepatitis C is a liver disease that is transmitted through contact with the blood of an infected person. An estimated 150 million individuals worldwide have been chronically infected with the hepatitis C virus(HCV). Hepatitis C shows significant genetic variation in the global population, due to the high rate of viral RNA mutation. There are six variants of the virus(HCV genotypes 1, 2, 3, 4, 5, and 6), with 15 recorded subtypes that vary in prevalence across different regions of the world. A variety of devices are used to diagnose hepatitis C, including HCV antibody test, HCV viral load test, HCV genotype test and liver biopsy. Rapid, inexpensive, sensitive, and robust analytical devices are therefore essential for effective diagnosis and monitoring of disease treatment. This review provides an overview of current electrochemical immunosensor and genosensortechnologies employed in HCV detection.There are a limited number of publications showing electrochemical biosensors being used for the detection of HCV.Due to their simplicity,specificity,and reliability,electrochemical biosensor devices have potential clinical applications in several viral infections.

Information content method for evaluating diagnostic tests and its comparison of power with other methods

This paper derives the variance of the information content and develops its statistical inference method. We describe the relations between information content and sensitivity, specificity, efficiency, prevalence rate. If sensitivity, specificity and efficiency are fixed, the closer to 0. 5 the prevalence rate is, the more the information content. If prevalence rate and efficiency are fixed, the closer to each other the sensitivity and specificity are, the more the information content. We compare the power of information content method, efficiecy test, Youden's index test and kappa coefficient method. The information content method has higher power than the other methods in most conditions. It is especially sensitive to the difference between two sensitivities. It comes to conclusion that the information content method has more virtues than the other methods mentioned in this paper.

Fecal microbial biomarkers combined with multi-target stool DNA test improve diagnostic accuracy for colorectal cancer

BACKGROUND Colorectal cancer(CRC)is a major global health burden.The current diagnostic tests have shortcomings of being invasive and low accuracy.AIM To explore the combination of intestinal microbiome composition and multi-target stool DNA(MT-sDNA)test in the diagnosis of CRC.METHODS We assessed the performance of the MT-sDNA test based on a hospital clinical trial.The intestinal microbiota was tested using 16S rRNA gene sequencing.This case-control study enrolled 54 CRC patients and 51 healthy controls.We identified biomarkers of bacterial structure,analyzed the relationship between different tumor markers and the relative abundance of related flora components,and distinguished CRC patients from healthy subjects by the linear discriminant analysis effect size,redundancy analysis,and random forest analysis.RESULTS MT-sDNA was associated with Bacteroides.MT-sDNA and carcinoembryonic antigen(CEA)were positively correlated with the existence of Parabacteroides,and alpha-fetoprotein(AFP)was positively associated with Faecalibacterium and Megamonas.In the random forest model,the existence of Streptococcus,Escherichia,Chitinophaga,Parasutterella,Lachnospira,and Romboutsia can distinguish CRC from health controls.The diagnostic accuracy of MT-sDNA combined with the six genera and CEA in the diagnosis of CRC was 97.1%,with a sensitivity and specificity of 98.1%and 92.3%,respectively.CONCLUSION There is a positive correlation of MT-sDNA,CEA,and AFP with intestinal microbiome.Eight biomarkers including six genera of gut microbiota,MT-sDNA,and CEA showed a prominent sensitivity and specificity for CRC prediction,which could be used as a non-invasive method for improving the diagnostic accuracy for this malignancy.

Comparison of Microscopic Determination and Rapid Diagnostic Tests (RDTs) in the Detection of Plasmodium Infection

Malaria infection is the most common diagnosis made in Africa. Efficient diagnosis of malaria parasite is very vital for treatment of malaria infection. The efficacy of rapid diagnostic tests (RDTs) in comparison to microscopy, the gold standard, in the diagnosis of malaria in Nigeria has not been fully ascertained. This study compared the sensitivity, specificity and predictive values of RDTs available in Nigeria market with microscopy. Two RDT kits were used and their results were compared with the gold standard, microscopy using thick and thin blood films (TBF and tBF). TBF had sensitivity of 85%, specificity of 30%, positive predictive value (PPV) of 55.2%, and negative predictive value (NPV) of 66.6%;tBF had sensitivity of 80%, specificity of 35%, positive predictive value (PPV) of 55.2%, and negative predictive value (NPV) of 63.6%. Among the RDTs, Care Start HRP2 kit had sensitivity of 65%, specificity of 50%, positive predictive value (PPV) of 56.5%, and negative predictive value (NPV) of 59% while SD Bioline kit had sensitivity of 55%, specificity of 65%, PPV of 61%, and NPV of 59%. It can thus be inferred that rapid diagnostic test kits are not as sensitive as microscopy in diagnosis of malaria parasite, but they are more accurate and are thus suitable alternatives to microscopy.

Relation of predictive value to sensitivity and specificity of a diagnostic test

This paper discusses how the positive and negative predictive values vary withcontrary variations of sensitivity and specificity at a certain disease prevalence.Let thesensitiviy be Se and the specificity be Sp at the initial cutoff point,correspondingly Se’and Sp’ at a new cutoff point:A=Se’/Se:B-(1-Sp’)/(1-Sp):C=Sp’/Sp;D=(I-Se’)/(I-Se).Moving the cutoff point from the initial point to the new point,if the contrary variationsof the sensitivity and specificity satisfy the inequality A】B,then the positive predictivevalue increases,otherwise it decreases or remains unchanged.If the variations satisfy theinequality C】D,then the negative prcdictive value increases,otherwise it decreasses or re-mains unchanged.

Evaluation of Three Rapid Diagnostic Test Kits in the Diagnosis of <i>Plasmodium</i>Species Infections among Primary School Children in Baringo County, Kenya

Background: Due to the difficulty in implementing microscopy-based definitive diagnosis of malaria especially in resource-poor areas, rapid diagnostic test (RDT) kits as alternatives have been developed by different companies. Kits from different companies may differ in sensitivity and specificity. It is therefore imperative to conduct field evaluation of kits from different manufacturers before they are recommended for widespread use in diagnosis of malaria. The present study sought to evaluate the performance of malaria RDT kits from two manufacturers against microscopy in detection of Plasmodium spp. infections among primary school children in Baringo County, Kenya. Methods: Two cross-sectional comparative surveys to assess three RDT kits (CareStart HRP-2, SD Bioline Ag-Pf and SD Bioline Ag-Pf/Pan) were conducted on 561 pupils from three primary schools within the Kerio Valley of Baringo County, Kenya. Results: A total of 561 blood samples were tested for Plasmodium spp. within a period of four months. SD Bioline Ag-Pf/ Pan RDT kit had a higher sensitivity (90%) compared to that of CareStart HRP-2 (70%) but this was not statistically significant (McNemar’s χ2 = 0.5, df = 1, p = 0.4795). The sensitivity of SD Bioline Ag-Pf was the same as that of Care Start HRP-2 (82.4%). The number of positive samples by microscopy was relatively lower than those detected by RDT kits. Two cases of non-P. falciparum infections were detected by RDT kits during the second survey. Conclusion: The results of the present study suggest that the performance of the three kits in the diagnosis of P. falciparum infections was better than microscopy. The sensitivity of SD Bioline Ag-Pf/Pan was slightly greater than that of Care Start HRP-2, although not statistically different.

Secondary analysis of malaria rapid diagnostic tests from rounds 5–8 of WHO product testing with a focus on false-negative results

Despite the widespread use of malaria rapid diagnostic test(RDT)in clinical practice,there are a lot of challenges.We conducted a secondary analysis of 129 malaria RDT data from rounds 5–8 of the World Health Organization(WHO)product testing summary and discuss the causes of false-negative(FN)results with a focus on low parasite density,improper RDT storage,operation and interpretation,and Plasmodium falciparum with a pfhrp2/3 gene deletion.The results demonstrated that the malaria RDTs currently commercially available might cause FN results in practice.

Patterns and Trends in Diagnostic Tests Used for Detection of Colorectal Cancer after Screening with the Immunochemical Fecal Occult Blood Test in Japan

According to the guidelines by the Japanese government, optical colonoscopy is the most strongly recommended diagnostic test after screening with the immunochemical fecal occult blood test (iFOBT), followed by double-contrast barium enema (BE) or sigmoidoscopy. Our study was to assess patterns and trends of colorectal cancer (CRC) diagnostic testing within 2 years after iFOBT. We analyzed both iFOBT results and claims data provided by employee health insurance societies in Japan from 2005 to 2010. 25,596 enrollees underwent iFOBT screening. The positive rate was 5.1%. 32.3% of those positive underwent diagnostic tests and 1.0% (12 patients) were confirmed as having cancer. The most common test was optical colonoscopy (77.2% of total tests), followed by BE (16.2%). From 2006 to 2009, the rate of optical colonoscopy for females increased from 55% to 82% and that of BE declined from 36% to 12%, while no significant changes were seen for males. Only one-third of those who tested positive underwent diagnostic test in the 2 years following screening iFOBT. As official guidelines for diagnostic testing of CRC recommend, optical colonoscopy is now the most commonly used diagnostic test after positive iFOBT result for enrollees in employee health insurance societies in Japan.