Detection of occult upper gastrointestinal tract bleeding: performance differences in fecal occult blood tests

Diagnostics and Treatment of Peptic Ulcer in Adults (Clinical Guidelines of the Russian Gastroenterological Association, the Russian Society of Colorectal Surgeons, the Russian Endoscopic Society and the Scientific Society for the Clinical Study of Human Microbiome)

Aim. The guidelines set out the modern methods of diagnostics and treatment of peptic ulcer and are created for gastroenterologists, primary care physicians, general practitioners, surgeons, endoscopists.

Key points. The clinical guidelines contain modern views on the etiology and pathogenesis of peptic ulcer, its clinical features, methods of laboratory and instrumental diagnostics, the main approaches to conservative and surgical treatment. They include the criteria for assessment of the quality of medical care, the algorithm of the doctor's actions, as well as information for the patient.

Conclusion. Knowledge of modern methods of diagnostics and therapy of peptic ulcers will contribute to improving the results of its treatment.

Stable iron (58Fe) isotopic measurements in Kenyan toddlers during 3 months of iron supplementation demonstrate that half of the iron absorbed is lost

Increased iron loss may reduce the effectiveness of iron supplementation. The objective of this study was to determine if daily oral iron supplementation increases iron loss, measured using a stable isotope of iron (58Fe). We enrolled and dewormed 24 iron-depleted Kenyan children, 24-27 months of age, whose body iron was enriched and equilibrated with 58Fe given at least 1 year earlier. Over 3 months of supplementation (6 mg iron/kg body weight [BW]/day), mean (±SD) iron absorption was 1.10 (±0.28) mg/day. During supplementation, 0.55 (±0.36) mg iron/day was lost, equal to half of the amount of absorbed iron. Supplementation did not increase faecal haem/porphyrin or biomarkers of enterocyte damage and gut or systemic inflammation. Using individual patient data, we examined iron dose, absorption and loss among all available long-term iron isotopic studies of supplementation. Expressed in terms of body weight, daily iron loss was correlated significantly with iron absorption (Pearson's r = 0.66 [95% confidence interval 0.48-0.78]) but not with iron dose (r = 0.16 [95% CI -0.10-0.40]). The results of this study indicate that iron loss is increased with daily oral iron supplementation and may blunt the efficacy of iron supplements in children. This study was registered at ClinicalTrials.gov as NCT04721964.

Risk factors of tumor invasion and node metastasis in early gastric cancer with undifferentiated component: a multicenter retrospective study on biopsy specimens and clinical data

Background

Early gastric cancer (EGC) with undifferentiated component (UDC) is a more aggressive entity, where the significance of preoperative data to tumor invasion and lymph node metastasis (LNM) remains unclarified.

Methods

A total of 5,020 GC patients undergoing radical gastrectomy in three centers were reviewed, of which, EGC with UDC in preoperative biopsy specimens were enrolled. The histology of biopsy and surgical specimens was graded according to the proportion of UDC and signet ring cells (SRCs). Risk factors of tumor invasion and LNM were evaluated with histological, clinical and demographic data.

Results

Lower body mass index (BMI), melena and larger tumor size were the independent preoperative risk factors of both LNM and LVI, while ulcerative lesion (UL) and the lower third stomach were only correlated with LNM. No relevance was found between the histological features of biopsy specimens and LNM, but SRC or >50% UDC lowered the risk of lymphovascular invasion (LVI) and/or submucosal (SM) invasion. When surgical data (depth of invasion and LVI included) were added, lower BMI, melena and the lower third stomach were still the independent preoperative risk factors of LNM, and LVI, SRC and SM invasion also showed relevance to LNM. The performance of predictive models using pre- or postoperative histological data was comparable.

Conclusions

The preoperative data were significantly relevant to tumor invasion and LNM, showing comparable risk strength with surgical specimens in histology.

Evaluation of the guaiac fecal occult blood test for detection of gastrointestinal bleeding in the rhesus macaque (Macaca mulatta)

BACKGROUND

Gastrointestinal (GI) hemorrhage accompanies several common diseases of rhesus macaques (Macaca mulatta). Guaiac fecal occult blood testing (gFOBT) is a non-invasive means to detect such bleeding in several species; however, there are currently no data indicating reliability of this test to detect GI hemorrhage in macaques.

METHODS

We evaluated sensitivity and specificity of gFOBT to detect simulated and biopsy-associated bleeding in the stomach, duodenum, and colon of 15 rhesus macaques. Fecal samples were analyzed via gFOBT for 72 hours.

RESULTS

Guaiac fecal occult blood testing was more sensitive to detect lower vs upper GI bleeding; sensitivity was volume-dependent in the upper GI tract. Single-test specificity was 95.2%. Repeated fecal collections increased gFOBT sensitivity without affecting specificity.

CONCLUSIONS

Guaiac fecal occult blood testing is a useful screening test for both upper and lower GI bleeding in rhesus macaques. For highest sensitivity, gFOBT should be performed on three fecal samples collected 24 hours apart.

Risk of gastrointestinal cancer in a symptomatic cohort after a complete colonoscopy: Role of faecal immunochemical test

BACKGROUND

Faecal immunochemical test (FIT) has been recommended to assess symptomatic patients for colorectal cancer (CRC) detection. Nevertheless, some conditions could theoretically favour blood originating in proximal areas of the gastrointestinal tract passing through the colon unmetabolized. A positive FIT result could be related to other gastrointestinal cancers (GIC).

AIM

To assess the risk of GIC detection and related death in FIT-positive symptomatic patients (threshold 10 μg Hb/g faeces) without CRC.

METHODS

Post hoc cohort analysis performed within two prospective diagnostic test studies evaluating the diagnostic accuracy of different FIT analytical systems for CRC and significant colonic lesion detection. Ambulatory patients with gastrointestinal symptoms referred consecutively for colonoscopy from primary and secondary healthcare, underwent a quantitative FIT before undergoing a complete colonoscopy. Patients without CRC were divided into two groups (positive and negative FIT) using the threshold of 10 μg Hb/g of faeces and data from follow-up were retrieved from electronic medical records of the public hospitals involved in the research. We determined the cumulative risk of GIC, CRC and upper GIC. Hazard rate (HR) was calculated adjusted by age, sex and presence of significant colonic lesion.

RESULTS

We included 2709 patients without CRC and a complete baseline colonoscopy, 730 (26.9%) with FIT ≥ 10 µgr Hb/gr. During a mean time of 45.5 ± 20.0 mo, a GIC was detected in 57 (2.1%) patients: An upper GIC in 35 (1.3%) and a CRC in 14 (0.5%). Thirty-six patients (1.3%) died due to GIC: 22 (0.8%) due to an upper GIC and 9 (0.3%) due to CRC. FIT-positive subjects showed a higher CRC risk (HR 3.8, 95%CI: 1.2-11.9) with no differences in GIC (HR 1.5, 95%CI: 0.8-2.7) or upper GIC risk (HR 1.0, 95%CI: 0.5-2.2). Patients with a positive FIT had only an increased risk of CRC-related death (HR 10.8, 95%CI: 2.1-57.1) and GIC-related death (HR 2.2, 95%CI: 1.1-4.3), with no differences in upper GIC-related death (HR 1.4, 95%CI: 0.6-3.3). An upper GIC was detected in 22 (0.8%) patients during the first year. Two variables were independently associated: anaemia (OR 5.6, 95%CI: 2.2-13.9) and age ≥ 70 years (OR 2.7, 95%CI: 1.1-7.0).

CONCLUSION

Symptomatic patients without CRC have a moderate risk increase in upper GIC, regardless of the FIT result. Patients with a positive FIT have an increased risk of post-colonoscopy CRC.

Novel Approach to Fecal Occult Blood Testing by Assay of Erythrocyte-Specific microRNA Markers

BACKGROUND

Fecal occult blood testing (FOBT) has historically relied on methods to detect hemoglobin with no fundamental innovations in decades.

AIM

To examine microRNA (miRNA) as a new marker class for FOBT.

METHODS

Candidate miRNA markers were identified by small RNA sequencing of human whole blood compared to colorectal epithelia. Markers were tested in human blood cell subsets and blood from non-human species. We assessed assay linearity in blood spiking and marker stability in stool over incubation experiments. Levels of candidate erythrocyte markers were explored in stools from colorectal cancer (CRC) cases and controls.

RESULTS

Based on small RNA sequencing and validation RT-qPCR, expression level of each of the top blood-enriched markers (hsa-miR-144-3p, 144-5p, 451a, 486-5p, 363-3p, 20b-5p) could perfectly discriminate blood from colorectal epithelia. All six markers arose from and showed specificity to human erythrocytes. Marker levels increased linearly with erythrocyte concentration in saline or stool and demonstrated a broader dynamic range than did immunochemical test for hemoglobin. Degradation of markers occurred in stool but was reduced with preservative buffers. Erythrocyte marker candidates for stool testing were selected in an exploratory set of stools (20 CRC, 40 normal). Candidates were then further tested in a feasibility set (29 CRC, 31 advanced adenoma, and 115 normal); a miRNA panel (hsa-miR-451a, 144-5p, and 200b-3p as normalizer) yielded an AUC of 0.89 (95% CI 0.82-0.95, P < .0001) for CRC.

CONCLUSIONS

A novel miRNA-based approach accurately quantifies fecal blood levels over a broad, clinically relevant range.

Impact of fecal occult blood on obscure gastrointestinal bleeding: Observational study

AIM: To elucidate the association between small bowel diseases (SBDs) and positive fecal occult blood test (FOBT) in patients with obscure gastrointestinal bleeding (OGIB).

METHODS: Between February 2008 and August 2013, 202 patients with OGIB who performed both capsule endoscopy (CE) and FOBT were enrolled (mean age; 63.6 ± 14.0 years, 118 males, 96 previous overt bleeding, 106 with occult bleeding). All patients underwent immunochemical FOBTs twice prior to CE. Three experienced endoscopists independently reviewed CE videos. All reviews and consensus meeting were conducted without any information on FOBT results. The prevalence of SBDs was compared between patients with positive and negative FOBT.

RESULTS: CE revealed SBDs in 72 patients (36%). FOBT was positive in 100 patients (50%) and negative in 102 (50%). The prevalence of SBDs was significantly higher in patients with positive FOBT than those with negative FOBT (46% vs 25%, P = 0.002). In particular, among patients with occult OGIB, the prevalence of SBDs was higher in positive FOBT group than negative FOBT group (45% vs 18%, P = 0.002). On the other hand, among patients with previous overt OGIB, there was no significant difference in the prevalence of SBDs between positive and negative FOBT group (47% vs 33%, P = 0.18). In disease specific analysis among patients with occult OGIB, the prevalence of ulcer and tumor were higher in positive FOBT group than negative FOBT group. In multivariate analysis, only positive FOBT was a predictive factors of SBDs in patients with OGIB (OR = 2.5, 95%CI: 1.4-4.6, P = 0.003). Furthermore, the trend was evident among patients with occult OGIB who underwent FOBT on the same day or a day before CE. The prevalence of SBDs in positive vs negative FOBT group were 54% vs 13% in patients with occult OGIB who underwent FOBT on the same day or the day before CE (P = 0.001), while there was no significant difference between positive and negative FOBT group in those who underwent FOBT two or more days before CE (43% vs 25%, P = 0.20).

CONCLUSION: The present study suggests that positive FOBT may be useful for predicting SBDs in patients with occult OGIB. Positive FOBT indicates higher likelihood of ulcers or tumors in patients with occult OGIB. Undergoing CE within a day after FOBT achieved a higher diagnostic yield for patients with occult OGIB.

Emergency diagnosis of upper gastrointestinal bleeding by detection of haemoglobin in nasogastric aspirate

OBJECTIVE

To determine the accuracy of the Faecal Occult Blood-Transferrin test (FOB-T; Certest Biotec, San Mateo de Gállego, Spain) for detection of blood in nasogastric aspirate, and its emergency diagnostic value for upper gastrointestinal bleeding (UGIB).

METHODS

Nasogastric aspirate was collected from patients with haematemesis on admission to hospital. Haemoglobin was quantified on admission and after 12 h. FOB-T test was used to assess each nasogastric aspirate sample for the presence of haemoglobin and transferrin.

RESULTS

Of 64 patients included in the study, 28 (43.8%) were hospitalized for UGIB based on physical examination, haemoglobin level. 24 were confirmed with endoscopy findings. Four were excluded from study due to lack of endoscopic confirmation. The remaining 36 patients had no clinical evidence of UGIB. FOB-T test findings were positive in 26/60 patients, including all 24 patients with UGIB. The FOB-T test had sensitivity 100%, specificity 94.4%, positive predictive value 92.3% and negative predictive value 100% for UGIB.

CONCLUSIONS

A negative FOB-T test may be sufficient to exclude the possibility of UGIB without other diagnostic tests.

Accuracy of faecal occult blood test and Helicobacter pylori stool antigen test for detection of upper gastrointestinal lesions

OBJECTIVE

Highly sensitive guaiac-based faecal occult blood (Hemoccult SENSA) and Helicobacter pylori stool antigen testing might help detect upper gastrointestinal lesions when appended to a colorectal cancer screening programme with faecal immunochemical testing. We evaluated the diagnostic accuracies of two stool tests in detecting upper gastrointestinal lesions.

DESIGN

Cross-sectional design.

SETTING

Hospital-based and community-based screening settings.

PARTICIPANTS

A hospital-based deviation cohort of 3172 participants to evaluate test performance and a community-based validation cohort of 3621 to verify the findings.

INTERVENTIONS

Three types of stool tests with bidirectional endoscopy as the reference standard.

OUTCOMES

Sensitivity, specificity and positive and negative likelihood ratios.

RESULTS

For detecting upper gastrointestinal lesions in cases with negative immunochemical tests, the sensitivity, specificity, and positive and negative likelihood ratios of the guaiac-based and H pylori antigen tests were 16.3% (95% CI 13.3% to 19.8%), 90.1% (88.9% to 91.2%), 1.64 (1.31 to 2.07), and 0.93 (0.89 to 0.97), respectively, and 52.5% (48.1% to 56.9%), 80.6% (79.0% to 82.1%), 2.71 (2.41 to 3.04) and 0.59 (0.54 to 0.65), respectively. For detecting upper gastrointestinal lesions in cases with normal colonoscopy, the results of the guaiac-based and H pylori antigen tests were 17.9% (14.8% to 21.5%), 90.1% (88.9% to 91.2%), 1.81 (1.45 to 2.26) and 0.91 (0.87 to 0.95), respectively, and 53.1% (48.6% to 57.4%), 80.7% (79.1% to 82.2%), 2.75 (2.45 to 3.08) and 0.58 (0.53 to 0.64), respectively. Within the community, positive predictive values of the immunochemical and H pylori antigen tests were 36.0% (26.0% to 46.0%) and 31.9% (28.3% to 35.5%), respectively, for detecting lower and upper gastrointestinal lesions, which were similar to expected values.

CONCLUSIONS

The H pylori stool antigen test is more accurate than the guaiac-based test in the screening of upper gastrointestinal lesions in a population with high prevalence of H pylori infection and upper gastrointestinal lesions. It is applicable to add the H pylori antigen test to the immunochemical test for pan detection.

TRIAL REGISTRATION

NCT01341197 (ClinicalTrial.gov).

Next-generation stool DNA test accurately detects colorectal cancer and large adenomas

BACKGROUND & AIMS

Technical advances have led to stool DNA (sDNA) tests that might accurately detect neoplasms on both sides of the colorectum. We assessed colorectal neoplasm detection by a next-generation sDNA test and effects of covariates on test performance.

METHODS

We performed a blinded, multicenter, case-control study using archived stool samples collected in preservative buffer from 252 patients with colorectal cancer (CRC), 133 with adenomas ≥ 1 cm, and 293 individuals with normal colonoscopy results (controls); two-thirds were randomly assigned to a training set and one-third to a test set. The sDNA test detects 4 methylated genes, a mutant form of KRAS, and the α-actin gene (as a reference value) using quantitative, allele-specific, real-time target and signal amplification; it also quantifies hemoglobin. We used a logistical model to analyze data.

RESULTS

The sDNA test identified 85% of patients with CRC and 54% of patients with adenomas ≥1 cm with 90% specificity. The test had a high rate of detection for all nonmetastatic stages of CRC (aggregate 87% detection rate for CRC stages I-III). Detection rates increased with adenoma size: 54% ≥ 1 cm, 63% >1 cm, 77% >2 cm, 86% >3 cm, and 92% >4 cm (P < .0001). Based on receiver operating characteristic analysis, the rate of CRC detection was slightly greater for the training than the test set (P = .04), whereas the rate of adenoma detection was comparable between sets. Sensitivities for detection of CRC and adenoma did not differ with lesion site.

CONCLUSIONS

Early-stage CRC and large adenomas can be detected throughout the colorectum and with high levels of accuracy by the sDNA test. Neoplasm size, but not anatomical site, affected detection rates. Further studies are needed to validate the findings in a larger population and optimize the sDNA test.

Esophago-gastro-duodenoscopy is not indicated in patients with positive immunochemical test and nonexplanatory colonoscopy

OBJECTIVES

Patients with positive fecal occult blood test and unrevealing colonoscopy are often advised to undergo esophago-gastro-duodenoscopy (EGD) to exclude a bleeding source in the upper gastrointestinal tract. In this study, we evaluated EGD findings in patients with positive immunochemical fecal occult blood test (I-FOBT) not explained by colonoscopy.

METHODS

Out of 1221 consecutive patients having total colonoscopy after preparing I-FOBT (OC-MICRO, with threshold of 75 or 100 ngHb/ml), we included only patients without colorectal cancer or advanced adenomatous polyp on colonoscopy, who also underwent EGD within 4 months of the fecal blood testing. Findings on EGD were classified as those lesions which are likely or unlikely to bleed.

RESULTS

EGD was performed in 160 patients after a negative colonoscopy. The procedure was performed 1.6 ± 1.4 months after the I-FOBT. Lesion with a bleeding potential was found in 24 patients (15%). In three (12.5%) and two (8.3%) of these patients I-FOBT was positive at the 75 and 100 ngHb/ml threshold, respectively. In 136 patients EGD was normal, and I-FOBT was similarly positive in 16 (11.7%) and 13 patients (9.5%), respectively. The mean fecal hemoglobin was also similar between the groups.

CONCLUSION

Immunological FOBT positivity was not correlated with the finding of lesions, which are likely to bleed on EGD. Thus, EGD is probably not indicated in patients with positive I-FOBT and unrevealing colonoscopy.

Screening for occult abdominal trauma in children with suspected physical abuse

OBJECTIVES

The goals were (1) to determine the prevalence of occult abdominal trauma (OAT) in a sample of children with suspected physical abuse, (2) to assess the frequency of OAT screening, and (3) to assess factors associated with screening.

METHODS

Charts of children evaluated for abusive injury were identified through a search of hospital discharge codes. Identified charts were reviewed to determine whether OAT screening occurred. Data on results of screening tests, abusive injuries identified, family demographic features, and characteristics of the emergency department visit were collected.

RESULTS

Screening occurred for 51 (20%) of 244 eligible children. Positive results were identified for 41% of those screened and 9% of the total sample; 5% of children 12 to 23 months of age had OAT identified through imaging studies. Screening occurred more often in children presenting with probable abusive head trauma (odds ratio [OR]: 20.4 [95% confidence interval [CI]: 3.6-114.6]; P < .01), compared with those presenting with other injuries. Consultation with the child protection team (OR: 8.5 [95% CI: 3.5-20.7]; P < .01) and other subspecialists (OR: 24.3 [95% CI: 7.1-83.3]; P < .01) also increased the likelihood that OAT screening would occur.

CONCLUSIONS

Our findings support OAT screening with liver and pancreatic enzyme measurements for physically abused children. This study also supports the importance of subspecialty input, especially that of a child protection team. Although many identified injuries may not require treatment, their role in confirming or demonstrating increased severity of maltreatment may be critical.

Positive rate comparison between immunological and chemical methods of fecal occult blood test in upper digestive tract bleeding

AIM: To compare the positive rates of immune fecal occult blood test (IFOBT) and chemical fecal occult blood test (CFOBT) in screening upper digestive tract bleeding.

METHODS: A total of 206 consecutive patients who suffered upper digestive tract bleeding and underwent endoscopic examination in our hospital were chosen from July 2006 to March 2007. CFOBT (using o-toluidine) and IFOBT were used to detect fecal occult blood positive rate in the same fecal specimen, and comparison was made between the two methods. The positive rates were also analyzed combined with the clinical data.

RESULTS: The results of IFOBT and CFOBT were not associated with anatomic sites in esophageal and gastric cancer, but associated with the invasion depth in gastric cancer, and they were positively correlated with the largest diameter of gastric cancer (IFOBT: r = 0.30, P = 0.02; CFOBT: r = 0.20, P = 0.04). Meanwhile, IFOBT result showed a positive correlation with the largest diameter of esophageal cancer (r = 0.38, P = 0.01). The positive rate of CFOBT was superior to that of squamous cell carcinoma (SCC) antigen detection in esophageal cancer patients (47.43% vs 20.45%, P < 0.05), and the positive rates of both methods were higher than those of CA125, CEA and CA199 detection. CFOBT was superior to IFOBT in detecting gastric cancer, esophageal cancer, reflux esophagitis and peptic ulcer (50.88% vs 35.09%; 47.73% vs 29.55%; 18.00% vs 6.00%; 60.00% vs 41.82%; all P < 0.05). The total positive rate of IFOBT was lower than that of CFOBT in detecting upper digestive tract bleeding.

CONCLUSION: The IFOBT is not suitable for screening upper digestive tract diseases, but relatively specific for lower digestive tract bleeding.

A comparative study of three fecal occult blood tests in upper gastrointestinal bleeding

The purpose of this study was to evaluate the performance characteristics of three fecal occult blood tests (FOBTs): the chemical o-toluidine test, the immunochemical OC-Hemodia test, and the immunochromatographic Quick Chaser Occult Blood (QCOB) test, which detect human hemoglobin and transferrin simultaneously in cases of upper gastrointestinal (GI) bleeding. Included were 48 FOBT specimens in 48 consecutive admission cases of upper GI bleeding (endoscopy confirmed). We excluded those fecal specimens with an obvious tarry and bloody appearance. The QCOB test revealed the highest positive rates of 33/48 (68.8%), and significantly higher positive rates than that of the OC-Hemodia test and o-toluidine test (p < 0.025 and < 0.01, respectively). In the patient group with upper GI bleeding due to gastric and duodenal ulcers, the QCOB test had higher positive rates (68.6%) than did the o-toluidine test (34.3%) (p < 0.01). There was no fecal specimen that was positive for the o-toluidine test or OC-Hemodia test and was negative for the QCOB test. Our results reveal that the QCOB test has significantly higher positive rates of fecal occult blood than either the OC-Hemodia test or o-toluidine test. The QCOB test is better than the other two tests for detecting occult blood in patients with upper GI bleeding.

Proton pump inhibition prevents gastrointestinal bleeding in ultramarathon runners: a randomised, double blinded, placebo controlled study

BACKGROUND

Ultra-endurance running is emerging as a popular sport in Western industrialised countries. Gastrointestinal bleeding has been reported to be an adverse effect in these runners.

OBJECTIVE

To see if the oral administration of a proton pump inhibitor would reduce the incidence of gastrointestinal bleeding in an ultramarathon.

METHODS

In a randomised, double blinded, placebo controlled study, a prophylactic regimen of three days of an oral proton pump inhibitor (pantoprazole 20 mg) was tested in healthy athletes participating in the Spartathlon ultramarathon. The incidence of gastrointestinal bleeding was assessed by a stool guaiac test.

RESULTS

Results were obtained for 70 healthy volunteers. The data for 20 of 35 runners in the intervention group and 17 of 35 runners in the placebo group were entered into the final analysis. At the end of the ultramarathon, two subjects in the intervention group and 12 in the placebo group had positive stool guaiac tests (risk difference 0.86; 95% confidence interval 0.45 to 0.96; p = 0.001).

CONCLUSION

A short prophylactic regimen of oral proton pump inhibition can successfully decrease the incidence of gastrointestinal bleeding in participants in an ultramarathon.

Stool screening for colorectal cancer: molecular approaches

Assay of molecular markers in stool represents a promising noninvasive approach to screen colorectal cancer. Given that neoplasms exfoliate abundantly into the lumen and that DNA recovered from stool can be assayed with sensitive techniques, there is a strong biologic rationale to pursue this emerging technology. A challenge with DNA-based testing relates to the selection of markers. Because of the molecular heterogeneity of cancer, no single marker has yielded perfect sensitivity. Several combinations of markers in early stool assays have produced high detection rates of both colorectal cancer and advanced adenomas in selected patient groups, but observations from large representative populations are lacking at present. Potential expanded applications of stool DNA testing include detection of supracolonic aerodigestive cancers and of dysplasia in inflammatory bowel disease. Further marker discovery and technologic refinements should translate into improved test performance and fuel a continued evolution with this screening approach.