Bedside tool for the diagnosis of gastric mucosal lesions prior to endoscopy

Bedside tool for the diagnosis of gastric mucosal lesions prior to endoscopy | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Short Report Bedside tool for the diagnosis of gastric mucosal lesions prior to endoscopy Violet Kayamba, Husna Munshi, Chola Mulenga, Paul Kelly This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-4890061/v1 This work is licensed under a CC BY 4.0 License Status: Published Journal Publication published 18 Mar, 2026 Read the published version in BMC Research Notes → Version 1 posted 10 You are reading this latest preprint version Abstract Objective Diagnosis of upper gastrointestinal (UGI) mucosal lesions is primarily via endoscopy. We investigated the diagnostic accuarcy of the Sanguis-filum (S-filum), a bedside tool for detecting UGI mucosal lesions. Results We tested 200 consenting patients, 112 (56%) females and 88 (44%) males attending for endoscopy at the University Teaching Hospital, Lusaka. Ninety-five (47%) of the patients had visible mucosal lesions; 45 (23%) of them had peptic ulceration, and 9 (5%) had gastric cancer. Ninety-one (46%) S-filum tests were positive. We found an association between positive S-filum results and the presence of mucosal lesions (OR 2.2; 95% CI 1.2–4.1, p = 0.007) but not gastric cancer (OR 3.5; 95% CI 0.7–22, p = 0.09). S-filum was insufficiently sensitive; missing mucosal lesions in 54%, and gastric cancer in 33% of cases. For detection of mucosal lesions, the sensitivity was 56%, specificity 64% with an area under the receiver operating characteristic (ROC) curve of 0.60. For GC, the sensitivity was 67%, the specificity was 64%, with area under the ROC of 0.65. As a screening test prior to endoscopy, the S-filum is not sufficiently accurate for detecting UGI mucosal lesions of GC. Gastric cancer peptic ulcer diagnosis S-filum Figures Figure 1 Introduction The exact prevelence of gastric cancer (GC) in Zambia is unknown but there is evidence that it is increasing [ 1 , 2 ]. GC patient outcomes are very poor in the country, with more than 80% of patients dying within the first year of diagnosis [ 3 ]. One of the reasons for poor outcomes is late case detection resulting from health system limitations and other socioeconomic factors [ 4 ]. In addition, early GC is essentially asymptomatic, but as it progresses, there may be abdominal pain or discomfort. In advnaced stages, alarm symptoms such as weight loss, unexplained anaemia or persistent vomiting develop [ 5 , 6 ]. Several researchers have investigated biomarkers and clinical strategies that might facilitate early GC diagnosis [ 7 , 8 , 9 ]. Many of these strategies require trained personnel, sophisticated equipment and reagents that are not readily available in low-resource settings. Periodic endoscopic surveillance is expensive and in Zambia only available in major cities, leaving out large rural populations [ 10 ]. There is no simple tool or method that can be used in these low-resource settings to determine which patients need endoscopic evaluation for GC. In a previous study, we demonstrated that the presence of free blood in the stomach was associated with GC [ 11 ]. Building on this, we designed a simple tool that we intended to assist healthcare providers in deciding which patients to send for endoscopy. We called it the Sanguis-filum or S-filum (two Latin words meaning blood and string) [ 12 ]. It is a simple bedside tool for detecting the presence of free blood in the stomach. The S-filum was based on the principle that the presence of free blood in the stomach signifies mucosal breaches and alerts health care workers to the need for endoscopic evaluation. The S-filum could be applied by medical personnel with basic training and is therefore easily applicable in rural settings. In this study, we investigated the diagnostic accuracy of the S-filum. Methods This was a cross-sectional diagnostic study [ 13 ] conducted at the University Teaching Hospital in Lusaka, Zambia. Consenting adults above the age of 18 years presenting for upper gastrointestinal endoscopy were enrolled in the study. We excluded those with a history of dysphagia, haematemesis, melena or a previous diagnosis of upper gastrointestinal cancer. Description of the S-filum We previously published details of the S-filum, outlining steps involved in its design and how it was to be applied [ 12 ]. Briefly, the S-filum is a gelatin capsule (capsuline, FL, USA) with an absorbent string coiled inside. The patients swallowed the string-filled gelatine capsule with approximately 50 ml of water, and after 30 minutes, the string was retrieved and tested for the presence of free blood. The string was at least 60 cm long enough to ensure that it reached the gastric lumen. Blood was tested with dissolved guaiacum powder and hydrogen peroxide. A change in color from brown to blue signified a positive test, as previously described [ 12 ]. Study procedure The study procedure was explained to the patients, and informed written consent was obtained for participation. The S-filum test was performed prior to endoscopy, and the results were recorded as positive, negative or indeterminate (intermediate). After the S-filum results were confirmed, endoscopy was performed, and the definitive results regarding the state of the gastric mucosa were recorded. Abnormalities detected in these patients were treated in accordance with the current standard of care. The presence or absence of mucosal lesions was compared with the S-filum results. This enabled the calculation of the specificity, sensitivity, and negative and positive predictive values. In addition, the area under the receiver operating curve (AUC) was calculated. The demographic characteristics of the study participants were collected via interviewer-administered questionnaires. Endoscopy reports were produced in accordance with the standard of care. Data analysis The data were analysed via StataCorp. 2017. Stata Statistical Software: Release 15 . College Station, TX: StataCorp LLC. Categorical variables are presented as proportions, whereas continuous variables are presented as medians and interquartile ranges. To test for associations of the s-filum results with gastric mucosal lesions, we used Fisher’s exact test. Odds ratios with 95% confidence intervals were derived, and p values less than 0.05 were considered statistically significant. The sensitivity, specificity and predictive values were calculated. Results We obtained consent from 210 patients for study participation. Nine of them failed to swallow the capsule, and one declined consent for endoscopy. We, therefore, included 200 patients in the final analysis. Among the patients included, 112 (56%) were female, and 88 (44%) were male. The median age was 40 years (IQR 30–49), and the median body mass index was 24 kg/m 2 (IQR 21–29). The predominant indication for endoscopy was abdominal pain present in 173 (87%) patients, with a reported median duration of 32 weeks (IQR 8–156, Table 1 ). Among the patients with GC, 5 (56%) were female, and 3 (33%) were under 45 years of age. Many had a low body mass index, with a median of 19 kg/m 2, and close to half were from outside Lusaka city (Table 1 ). Diagnostic accuracy of the S-filum for the detection of upper gastrointestinal mucosal lesions Among the patients with gastric mucosal abnormalities, 53 (56%) were positive, and 42 (44%) had negative S-filum results. Among the nine patients with GC, 6 (67%) had positive S-filum results. Three (33%) patients with GC had negative S-filum results. Table 1 Basic characteristics of the enrolled patients stratified by endoscopic diagnosis All patients n = 200 No abnormality on OGD n = 95 Gastric cancer n = 9 Gastric or duodenal ulcer n = 45 Other diagnoses n = 41 Age in years; median (IQR) 40(30–49) 38(30–46) 49(43–60) 42(27–53) 39(32–49) Proportion under 45 years of age 131(69%) 75(71%) 3(33%) 26(58%) 27(66%) Females, n (%) 112(56) 66(63) 5(56) 24(53) 17(41) Body mass index, kg/m 2 ; median (IQR) 24(21–29) 25(23–29) 19(18–19) 24(20–28) 24(21–27) Residence in the capital city (Lusaka) 146(73) 79(75) 4(44) 36(80) 27(66) Level of education • None • Primary • Secondary • Tertiary 8(4) 40(20) 59(30) 93(46) 3(3) 20(19) 30(29) 52(49) 1(11) 5(56) 1(11) 2(22) 2(4) 1(22) 17(38) 16(36) 2(5) 5(12) 11(27) 23(56) Family History of gastric cancer, n (%) 4(2) 0(0) 0(0) 3(7) 0(0) History of abdominal pain, n (%) 173(87) 89(85) 8(89) 39(87) 37(90) History of vomiting, n (%) 42(21) 21(20) 5(56) 8(18) 8(20) Duration of symptoms in weeks; median (IQR) 32(8-156) 52(12–104) 16(8–52) 48(8-208) 16(4-104) History of smoking • Current, n (%) • Former, n (%) 12(6) 23(12) 4(4) 9(9) 2(22) 3(33) 2(4) 3(7) 4(10) 8(20) * Included under “Other diagnoses” are erosions, gastritis, oesophageal varices and candidiasis, oesophagitis, hiatus hernia, healed ulceration and gastric atrophy The sensitivity of S-filum for the detection of upper gastrointestinal mucosal lesions was 56%, with a specificity of 64%, a positive predictive value (PPV) of 58% and a negative predictive value (NPV) of 61%. The area under the receiver operating characteristic (ROC) curve was 0.60 (Table 2 ). For the detection of GC, the sensitivity was 67%, the specificity was 64%, the PPV was 14%, and the NPV was 98%. The area under the ROC curve was 0.65. Using patients with normal endoscopy results as a reference group, univariable analysis revealed an association between S-filum positivity and the presence of mucosal lesions (OR 2.2; 95% CI 1.2–4.1, p = 0.007) and peptic ulceration (OR 2.4; 95% CI 1.1–5.2, p = 0.02). There was no association with GC (OR 3.5; 95% CI 0.7–22, p = 0.09). Other mucosal diagnoses included varices, reflux esophagitis, esophageal candidiasis and gastritis. When these factors were grouped together, they were not associated with S-filum positivity (OR 1.3; 95% CI 0.6–2.8, p = 0.48) (Table 2 ). Table 2 Association between gastric mucosal abnormalities and a positive S-filum test and tests for diagnostic accuracy Total number S-filum positive n (%) S-filum negative n (%) OR; 95% confidence interval P value Sensitivity Specificity Positive predictive value Negative predictive value Area under ROC Normal OGD 105 38 (36) 67 (64) Ref. Ref. Abnormality on OGD 95 53 (56) 42 (44) 2.2 (1.2–4.1) 0.007 56% 64% 58% 61% 0.60 Gastric cancer 9 6 (67) 3 (33) 3.5 (0.7–22) 0.09 67% 64% 14% 98% 0.65 Peptic ulcer 45 26 (58) 19 (42) 2.4 (1.1–5.2) 0.02 58% 64% 41% 78% 0.61 Other diagnoses 41 21 (51) 20 (49) 1.3 (0.6–2.8) 0.48 51% 54% 36% 23% 0.54 Levels of discomfort associated with the S-filum We collected information on the level of discomfort for the S-filum in 190 patients and 145 patients for endoscopy. In 190 (95%) of the patients, endoscopy was unsedated. The median level of discomfort for the S-filum was 2 (IQR 1–4), and it was 7 (IQR 7–9) for endoscopy (Fig. 1 ). There was a statistically significant difference between the two assessments (p < 0.001). Discussion The early diagnosis of GC is a major challenge in many countries, especially in low-resource settings where endoscopy services are scarce. We designed the S-filum as a simple tool that could be used to predict the presence of gastric mucosal lesions before endoscopy and therefore assist in referral decisions [ 12 ]. However, we found that the sensitivity and specificity of the S-filum for detecting mucosal lesions were too low to warrant possible clinical utility. Most importantly, 33% of the GC patients and 44% of the peptic ulcer patients had negative S-filum results, and their lesions were missed by the device. The S-filum was meant for use in a low-resource setting without easy access to endoscopic services. The early diagnosis of gastric lesions is difficult in these settings. Most published studies evaluating gastric juice as a source of nonblood-based liquid biopsies for GC diagnosis have used nucleic acids, metabolites or microbiota as biomarkers [ 14 , 15 ]. These biomarkers require laboratory assays, some of which are sophisticated and are not readily available in low-resource settings. Their general utility would therefore be limited. In addition, analysis of these biomarkers requires a clear understanding of gastric physiology [ 16 ]. There is very limited information on the diagnosis of early gastric cancer in Africa, but the indications are that most tumours are diagnosed late [ 4 , 17 ]. A recent study from Kenya reported that 60% of GC patients had stage III or IV disease at diagnosis [24]. In contrast, 50% of gastric cancer cases in Japan and Korea are early, with the proportion being approximately 20% in Western countries [ 18 ]. Therefore, strategies for early GC diagnosis that focus on low-resource settings are urgently needed. This study was carefully designed to ensure that the individual administering the S-filum was completely independent from the one performing the endoscopy. In addition, the procedure was performed prior to endoscopy to avoid procedure-related trauma, which could have resulted in false positive results. Despite this consideration, the false positive rate was 36% in normal individuals, probably due to minor bleeding that occurred with mildly inflamed gastric mucosa. The false-negative rate of 44% could have resulted from musical lesions that were not bleeding at the time of the test. The S-filum was not able to detect previous bleeds. This is a significant limitation of the device. It is important to understand these limitations, as they affect the accuracy of the S-filum results. The rationale for the use of S-filum is sound, and we are convinced that if the sensitivity could be improved, it could contribute to the early detection of gastric mucosal lesions in low-resource settings. Patients who participated in this study reported minimal discomfort compared with those who underwent endoscopy, suggesting that this approach would be acceptable for routine use. It is possible that there is mucosal bleeding during un-sedated endoscopy, rather than if well sedated, the great majority of the procedures in this study were performed unsedated. This does not, however, explain the low sensitivity of the S-filum. Despite these negative results, there are still other avenues that we have explored to improve the detection of early gastric cancer in low-resource settings. We previously studied serum indicators via the GastroPanel® [ 19 , 20 ] and evaluated unique risk factors that could be used as surrogate markers for screening [ 21 ]. As the use of faecal occult blood testing is not applicable to gastric cancer [ 22 ], we will continue exploring other non-invasive and affordable methods for the diagnosis of gastric cancer. In conclusion, the S-filum is not sufficiently accurate for use as a diagnostic tool for detecting gastric mucosal lesions in the absence of endoscopy. More work needs to be done to discover strategies for the early detection of GC in low-resource settings. Limitations This study is limited by the low number of GC cases that were included. However, the numbers were enough to make reasonable conclusions. The study was conducted among patients coming to a tertiary institution for care. This could have been a biased population. Abbreviations GC Gastric cancer S-filum Sanguis-filum PPV Positive predictive value NPV Negative predictive value (ROC) curve was ROC Receiver operating characteristic Declarations Ethics approval and consent to participate: The study was conducted in accordance with the Declaration of Helsinki and approved by the University of Zambia Biomedical Ethics Committee and the National Health Research Authority, reference number 2446--2021. Written informed consent was obtained from all the subjects involved in the study. Availability of data and material: Data will be available online and upon request Funding: This work was carried out with aid of a grant from UNESCO and the International Development Research Center, Ottawa, Canada. Grant number 108392-001. The views expressed herein do not necessarily represent those of UNESCO, the IDRC or its Board of Directors. Funding was also provided by the European Union (Grant no. DCI-PANAF/2020/420-028), through the African Research Initiative for Scientific Excellence (ARISE), a pilot programme. The ARISE is implemented by the African Academy of Sciences with support from the European Commission and the African Union Commission. The contents of this document are the sole responsibility of the authors and can under no circumstances be regarded as reflecting the position of the European Union, the African Academy of Sciences, or the African Union. Competing interests: The authors declare no conflicts of interest. Author Contributions: Study conceptualisation was performed by VK and PK. VK, HM and CM were involved in data collection, and data analysis was performed by VK. The first draft of the manuscript was written by VK. VK, HM, CM and PK reviewed and edited the manuscript. All authors approved the final version of the manuscript. References Shumba S, Kayamba V. Analysis of the proportion of university teaching hospital gastric cancer data included in the Zambia national cancer registry. Afr Health Sci. 2023 Mar;23(1):438-443. doi: 10.4314/ahs.v23i1.46. Kayamba V, Mubbunu M, Kelly P. Endoscopic diagnosis of gastric and oesophageal cancer in Lusaka, Zambia: a retrospective analysis. BMC Gastroenterol. 2024 Apr 1;24(1):122. doi: 10.1186/s12876-024-03187-x. PMID: 38561688; PMCID: PMC10983744. Asombang AW, Kayamba V, Turner-Moss E, Banda L, Trinkaus K, Colditz G, Mudenda V, Zulu R, Sinkala E, Kelly P. Gastric malignancy survival in Zambia, Southern Africa: A two year follow up study, Medical Journal of Zambia , 2014; 41(1): 13-18. Kayamba, V.; Kelly, P. Delayed referral for diagnostic endoscopy is a contributing factor to late gastric cancer diagnosis in Zambia. Health Press 2019, 3 , 14–19. Matsuoka T, Yashiro M. Novel biomarkers for early detection of gastric cancer. World J Gastroenterol. 2023 May 7;29(17):2515-2533. doi: 10.3748/wjg.v29.i17.2515. Maconi G, Manes G, Porro GB. Role of symptoms in diagnosis and outcome of gastric cancer. World J Gastroenterol. 2008 Feb 28;14(8):1149-55. doi: 10.3748/wjg.14.1149. Xue J, Qin S, Ren N, Guo B, Shi X, Jia E. Extracellular vesicle biomarkers in circulation for the diagnosis of gastric cancer: A systematic review and meta‑analysis. Oncol Lett. 2023 Aug 11;26(4):423. doi: 10.3892/ol.2023.14009. Deng D, Zhang Y, Zhang R, Yi J, Dong J, Sha L, Yan M. Circulating Proteins and Metabolite Biomarkers in Gastric Cancer: A Systematic Review and Meta-analysis. Arch Med Res. 2023 Feb;54(2):124-134. doi: 10.1016/j.arcmed.2022.12.012. Virgilio E, Giarnieri E, Giovagnoli MR, Montagnini M, Proietti A, D'Urso R, Mercantini P, Balducci G, Cavallini M. Gastric Juice MicroRNAs as Potential Biomarkers for Screening Gastric Cancer: A Systematic Review. Anticancer Res. 2018 Feb;38(2):613-616. doi: 10.21873/anticanres.12265. Mwachiro M, Topazian HM, Kayamba V, Mulima G, Ogutu E, Erkie M, Lenga G, Mutie T, Mukhwana E, Desalegn H, Berhe R, Meshesha BR, Kaimila B, Kelly P, Fleischer D, Dawsey SM, Topazian MD. Gastrointestinal endoscopy capacity in Eastern Africa. Endosc Int Open. 2021 Nov 12;9(11):E1827-E1836. doi: 10.1055/a-1551-3343. Kayamba, V.; Zyambo, K.; Kelly, P. Presence of blood in gastric juice: A sensitive marker for gastric cancer screening in a poor resource setting. PLoS ONE 2018, 13 , e0205185. https://doi.org/10.1371/journal.pone.0205185. Kayamba V, Kelly P. Introducing the Sanguis-Filum for Detection of Gastric Mucosal Lesions Prior to Endoscopy: A Study Protocol. Diagnostics (Basel). 2022 May 7;12(5):1160. doi: 10.3390/diagnostics12051160. Mathes T, Pieper D. An algorithm for the classification of study designs to assess diagnostic, prognostic and predictive test accuracy in systematic reviews. Syst Rev. 2019 Sep 3;8(1):226. doi: 10.1186/s13643-019-1131-4. Lopes C, Chaves J, Ortigão R, Dinis-Ribeiro M, Pereira C. Gastric cancer detection by non-blood-based liquid biopsies: A systematic review looking into the last decade of research. United European Gastroenterol J. 2023 Feb;11(1):114-130. doi: 10.1002/ueg2.12328. Yamamoto H, Watanabe Y, Sato Y, Maehata T, Itoh F. Non-Invasive Early Molecular Detection of Gastric Cancers. Cancers (Basel). 2020 Oct 7;12(10):2880. doi: 10.3390/cancers12102880. Herrera-Pariente C, Montori S, Llach J, Bofill A, Albeniz E, Moreira L. Biomarkers for Gastric Cancer Screening and Early Diagnosis. Biomedicines. 2021 Oct 12;9(10):1448. doi: 10.3390/biomedicines9101448. Benamro F, Sartorius B, Clarke DL, Anderson F, Loots E, Olinger L. The spectrum of gastric cancer as seen in a large quaternary hospital in KwaZulu-Natal, South Africa. S Afr Med J. 2017 Jan 30;107(2):130-133. Degu A, Karimi PN, Opanga SA, Nyamu DG. Predictors of survival outcomes among patients with gastric cancer in a leading tertiary, teaching and referral hospital in Kenya. Cancer Med. 2023 Feb;12(4):4147-4160. doi: 10.1002/cam4.5275. Kayamba, V.; Butt, J.; Varga, M.; Shibemba, A.; Piazuelo, M.B.; Wilson, K.T.; Zyambo, K.; Mwakamui, S.; Mulenga, C.; Waterboer, T.; et al. Serum antibodies to Helicobacter pylori antigens are associated with active gastric inflammation but not gastric cancer in patients seen at the University Teaching Hospital in Lusaka, Zambia. Malawi Med. J. 2022, 34 , 17-24 https://dx.doi.org/10.4314/mmj.v34i1.4. Kayamba, V.; Shibemba, A.; Zyambo, K.; Heimburger, D.C.; Morgan, D.; Kelly, P. HIV related hypochlorhydria does not appear to respond to anti-retroviral therapy in Zambian adults: A case control study. Pan Afr. Med. J. 2018, 31 , 128. https://doi.org/10.11604/pamj.2018.31.128.11850. Kayamba V, Zyambo K, Mulenga C, Mwakamui S, Tembo MJ, Shibemba A, Heimburger DC, Atadzhanov M, Kelly P. Biomass Smoke Exposure Is Associated With Gastric Cancer and Most likely, Mediated Via Oxidative Stress and DNA Damage: A Case‒Control Study. JCO Glob Oncol. 2020 Mar;6:532-541. doi: 10.1200/GO.20.00002. Nakama, H.; Zhang, B. Immunochemical fecal occult blood test is inadequate for screening test of stomach cancer. Dig. Dis. Sci. 2000, 45 , 2195–2198. Additional Declarations No competing interests reported. Cite Share Download PDF Status: Published Journal Publication published 18 Mar, 2026 Read the published version in BMC Research Notes → Version 1 posted Editorial decision: Revision requested 12 Feb, 2026 Reviews received at journal 26 Jan, 2026 Reviewers agreed at journal 14 Jan, 2026 Reviews received at journal 05 Nov, 2024 Reviewers agreed at journal 24 Oct, 2024 Reviewers invited by journal 14 Oct, 2024 Editor invited by journal 14 Aug, 2024 Editor assigned by journal 12 Aug, 2024 Submission checks completed at journal 12 Aug, 2024 First submitted to journal 10 Aug, 2024 You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. 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Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-4890061","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Short Report","associatedPublications":[],"authors":[{"id":347475772,"identity":"f83ef855-35d6-4758-84a4-fe8119064baa","order_by":0,"name":"Violet Kayamba","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAAv0lEQVRIiWNgGAWjYDACZgYGA4YCBjkGBh6StBgwGJOgBQwMGBIbiNZicJz5QMEHA5v0DcfPHnzwgcFOTreBkJbDbAmGMwzScjecyUs2nMGQbGx2gIAWyWYeA2Meg8O5Gw7kmEnzMBxI3Eaklv/pBuffEKmFnxms5UCCwQ1ibeFnBvsl2XDmjTfGIAZhv7DxHz5m8KHCTp7vfI7hAyBDjqAWkC4DEKkAVmlAWDkIMD8AkfINxKkeBaNgFIyCEQgAXgw7wKdrj9kAAAAASUVORK5CYII=","orcid":"","institution":"University of Zambia School of Medicine","correspondingAuthor":true,"prefix":"","firstName":"Violet","middleName":"","lastName":"Kayamba","suffix":""},{"id":347475773,"identity":"a9febc57-c1d1-4e85-a48c-244e2937529d","order_by":1,"name":"Husna Munshi","email":"","orcid":"","institution":"University of Zambia School of Medicine","correspondingAuthor":false,"prefix":"","firstName":"Husna","middleName":"","lastName":"Munshi","suffix":""},{"id":347475774,"identity":"4b35be92-f091-4975-b701-ff9296b53c4a","order_by":2,"name":"Chola Mulenga","email":"","orcid":"","institution":"University of Zambia School of Medicine","correspondingAuthor":false,"prefix":"","firstName":"Chola","middleName":"","lastName":"Mulenga","suffix":""},{"id":347475775,"identity":"220fc142-83d7-454a-bdd1-42b468d50053","order_by":3,"name":"Paul Kelly","email":"","orcid":"","institution":"Blizard Institute, Queen Mary University of London","correspondingAuthor":false,"prefix":"","firstName":"Paul","middleName":"","lastName":"Kelly","suffix":""}],"badges":[],"createdAt":"2024-08-10 05:23:33","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-4890061/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-4890061/v1","draftVersion":[],"editorialEvents":[{"content":"https://doi.org/10.1186/s13104-026-07777-8","type":"published","date":"2026-03-18T15:58:27+00:00"}],"editorialNote":"","failedWorkflow":false,"files":[{"id":66096497,"identity":"b98c8088-7c8d-4951-a402-58d7fe126f10","added_by":"auto","created_at":"2024-10-07 15:57:37","extension":"jpg","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":23851,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eComparison between levels of discomfort during S-filum testing and endoscopy. Levels of discomfort estimated from zero to ten, with ten signifying the highest level of discomfort. **** indicates \u003c/strong\u003e\u003cem\u003e\u003cstrong\u003eP \u003c/strong\u003e\u003c/em\u003e\u003cstrong\u003evalue is less than 0.001\u003c/strong\u003e\u003c/p\u003e","description":"","filename":"BMCSfilumfigure1.jpg","url":"https://assets-eu.researchsquare.com/files/rs-4890061/v1/4f488d7288a69c9dd8a5a1e9.jpg"},{"id":105223366,"identity":"d1028e09-58d5-46ad-ae8d-12b8fcee4ecf","added_by":"auto","created_at":"2026-03-23 16:05:32","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":752694,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-4890061/v1/81ebd1ad-b32c-4d17-8115-71bad1ff852b.pdf"}],"financialInterests":"No competing interests reported.","formattedTitle":"Bedside tool for the diagnosis of gastric mucosal lesions prior to endoscopy","fulltext":[{"header":"Introduction","content":"\u003cp\u003eThe exact prevelence of gastric cancer (GC) in Zambia is unknown but there is evidence that it is increasing [\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e, \u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e]. GC patient outcomes are very poor in the country, with more than 80% of patients dying within the first year of diagnosis [\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e]. One of the reasons for poor outcomes is late case detection resulting from health system limitations and other socioeconomic factors [\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e]. In addition, early GC is essentially asymptomatic, but as it progresses, there may be abdominal pain or discomfort. In advnaced stages, alarm symptoms such as weight loss, unexplained anaemia or persistent vomiting develop [\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e, \u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eSeveral researchers have investigated biomarkers and clinical strategies that might facilitate early GC diagnosis [\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e, \u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e, \u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e]. Many of these strategies require trained personnel, sophisticated equipment and reagents that are not readily available in low-resource settings. Periodic endoscopic surveillance is expensive and in Zambia only available in major cities, leaving out large rural populations [\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e]. There is no simple tool or method that can be used in these low-resource settings to determine which patients need endoscopic evaluation for GC.\u003c/p\u003e \u003cp\u003eIn a previous study, we demonstrated that the presence of free blood in the stomach was associated with GC [\u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e]. Building on this, we designed a simple tool that we intended to assist healthcare providers in deciding which patients to send for endoscopy. We called it the Sanguis-filum or S-filum (two Latin words meaning blood and string) [\u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e]. It is a simple bedside tool for detecting the presence of free blood in the stomach. The S-filum was based on the principle that the presence of free blood in the stomach signifies mucosal breaches and alerts health care workers to the need for endoscopic evaluation. The S-filum could be applied by medical personnel with basic training and is therefore easily applicable in rural settings.\u003c/p\u003e \u003cp\u003eIn this study, we investigated the diagnostic accuracy of the S-filum.\u003c/p\u003e"},{"header":"Methods","content":"\u003cp\u003eThis was a cross-sectional diagnostic study [\u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e] conducted at the University Teaching Hospital in Lusaka, Zambia. Consenting adults above the age of 18 years presenting for upper gastrointestinal endoscopy were enrolled in the study. We excluded those with a history of dysphagia, haematemesis, melena or a previous diagnosis of upper gastrointestinal cancer.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec4\" class=\"Section2\"\u003e \u003ch2\u003eDescription of the S-filum\u003c/h2\u003e \u003cp\u003eWe previously published details of the S-filum, outlining steps involved in its design and how it was to be applied [\u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e]. Briefly, the S-filum is a gelatin capsule (capsuline, FL, USA) with an absorbent string coiled inside. The patients swallowed the string-filled gelatine capsule with approximately 50 ml of water, and after 30 minutes, the string was retrieved and tested for the presence of free blood. The string was at least 60 cm long enough to ensure that it reached the gastric lumen. Blood was tested with dissolved guaiacum powder and hydrogen peroxide. A change in color from brown to blue signified a positive test, as previously described [\u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e].\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec5\" class=\"Section2\"\u003e \u003ch2\u003eStudy procedure\u003c/h2\u003e \u003cp\u003eThe study procedure was explained to the patients, and informed written consent was obtained for participation. The S-filum test was performed prior to endoscopy, and the results were recorded as positive, negative or indeterminate (intermediate). After the S-filum results were confirmed, endoscopy was performed, and the definitive results regarding the state of the gastric mucosa were recorded. Abnormalities detected in these patients were treated in accordance with the current standard of care. The presence or absence of mucosal lesions was compared with the S-filum results. This enabled the calculation of the specificity, sensitivity, and negative and positive predictive values. In addition, the area under the receiver operating curve (AUC) was calculated. The demographic characteristics of the study participants were collected via interviewer-administered questionnaires. Endoscopy reports were produced in accordance with the standard of care.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec6\" class=\"Section2\"\u003e \u003ch2\u003eData analysis\u003c/h2\u003e \u003cp\u003eThe data were analysed via StataCorp. 2017. \u003cem\u003eStata Statistical Software: Release 15\u003c/em\u003e. College Station, TX: StataCorp LLC. Categorical variables are presented as proportions, whereas continuous variables are presented as medians and interquartile ranges. To test for associations of the s-filum results with gastric mucosal lesions, we used Fisher\u0026rsquo;s exact test. Odds ratios with 95% confidence intervals were derived, and \u003cem\u003ep\u003c/em\u003e values less than 0.05 were considered statistically significant. The sensitivity, specificity and predictive values were calculated.\u003c/p\u003e \u003c/div\u003e"},{"header":"Results","content":"\u003cp\u003e We obtained consent from 210 patients for study participation. Nine of them failed to swallow the capsule, and one declined consent for endoscopy. We, therefore, included 200 patients in the final analysis. Among the patients included, 112 (56%) were female, and 88 (44%) were male. The median age was 40 years (IQR 30\u0026ndash;49), and the median body mass index was 24 kg/m\u003csup\u003e2\u003c/sup\u003e (IQR 21\u0026ndash;29). The predominant indication for endoscopy was abdominal pain present in 173 (87%) patients, with a reported median duration of 32 weeks (IQR 8\u0026ndash;156, Table\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e). Among the patients with GC, 5 (56%) were female, and 3 (33%) were under 45 years of age. Many had a low body mass index, with a median of 19 kg/m\u003csup\u003e2,\u003c/sup\u003e and close to half were from outside Lusaka city (Table\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e).\u003c/p\u003e \u003cdiv id=\"Sec8\" class=\"Section2\"\u003e \u003ch2\u003eDiagnostic accuracy of the S-filum for the detection of upper gastrointestinal mucosal lesions\u003c/h2\u003e \u003cp\u003eAmong the patients with gastric mucosal abnormalities, 53 (56%) were positive, and 42 (44%) had negative S-filum results. Among the nine patients with GC, 6 (67%) had positive S-filum results. Three (33%) patients with GC had negative S-filum results.\u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab1\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 1\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eBasic characteristics of the enrolled patients stratified by endoscopic diagnosis\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"6\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c6\" colnum=\"6\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eAll patients\u003c/p\u003e \u003cp\u003en\u0026thinsp;=\u0026thinsp;200\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eNo abnormality on OGD\u003c/p\u003e \u003cp\u003en\u0026thinsp;=\u0026thinsp;95\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003eGastric cancer\u003c/p\u003e \u003cp\u003en\u0026thinsp;=\u0026thinsp;9\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c5\"\u003e \u003cp\u003eGastric or duodenal ulcer\u003c/p\u003e \u003cp\u003en\u0026thinsp;=\u0026thinsp;45\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c6\"\u003e \u003cp\u003eOther diagnoses\u003c/p\u003e \u003cp\u003en\u0026thinsp;=\u0026thinsp;41\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eAge in years; median (IQR)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e40(30\u0026ndash;49)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e38(30\u0026ndash;46)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e49(43\u0026ndash;60)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e42(27\u0026ndash;53)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e39(32\u0026ndash;49)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eProportion under 45 years of age\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e131(69%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e75(71%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e3(33%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e26(58%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e27(66%)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eFemales, n (%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e112(56)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e66(63)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e5(56)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e24(53)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e17(41)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eBody mass index, kg/m\u003csup\u003e2\u003c/sup\u003e; median (IQR)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e24(21\u0026ndash;29)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e25(23\u0026ndash;29)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e19(18\u0026ndash;19)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e24(20\u0026ndash;28)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e24(21\u0026ndash;27)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eResidence in the capital city (Lusaka)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e146(73)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e79(75)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e4(44)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e36(80)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e27(66)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eLevel of education\u003c/p\u003e \u003cp\u003e\u0026bull; None\u003c/p\u003e \u003cp\u003e\u0026bull; Primary\u003c/p\u003e \u003cp\u003e\u0026bull; Secondary\u003c/p\u003e \u003cp\u003e\u0026bull; Tertiary\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e8(4)\u003c/p\u003e \u003cp\u003e40(20)\u003c/p\u003e \u003cp\u003e59(30)\u003c/p\u003e \u003cp\u003e93(46)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e3(3)\u003c/p\u003e \u003cp\u003e20(19)\u003c/p\u003e \u003cp\u003e30(29)\u003c/p\u003e \u003cp\u003e52(49)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e1(11)\u003c/p\u003e \u003cp\u003e5(56)\u003c/p\u003e \u003cp\u003e1(11)\u003c/p\u003e \u003cp\u003e2(22)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e2(4)\u003c/p\u003e \u003cp\u003e1(22)\u003c/p\u003e \u003cp\u003e17(38)\u003c/p\u003e \u003cp\u003e16(36)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e2(5)\u003c/p\u003e \u003cp\u003e5(12)\u003c/p\u003e \u003cp\u003e11(27)\u003c/p\u003e \u003cp\u003e23(56)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eFamily History of gastric cancer, n (%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e4(2)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0(0)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0(0)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e3(7)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e0(0)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eHistory of abdominal pain, n (%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e173(87)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e89(85)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e8(89)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e39(87)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e37(90)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eHistory of vomiting, n (%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e42(21)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e21(20)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e5(56)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e8(18)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e8(20)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eDuration of symptoms in weeks; median (IQR)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e32(8-156)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e52(12\u0026ndash;104)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e16(8\u0026ndash;52)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e48(8-208)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e16(4-104)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eHistory of smoking\u003c/p\u003e \u003cp\u003e\u0026bull; Current, n (%)\u003c/p\u003e \u003cp\u003e\u0026bull; Former, n (%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e12(6)\u003c/p\u003e \u003cp\u003e23(12)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e4(4)\u003c/p\u003e \u003cp\u003e9(9)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e2(22)\u003c/p\u003e \u003cp\u003e3(33)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e2(4)\u003c/p\u003e \u003cp\u003e3(7)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e4(10)\u003c/p\u003e \u003cp\u003e8(20)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003cp\u003e* Included under \u0026ldquo;Other diagnoses\u0026rdquo; are erosions, gastritis, oesophageal varices and candidiasis, oesophagitis, hiatus hernia, healed ulceration and gastric atrophy\u003c/p\u003e \u003cp\u003eThe sensitivity of S-filum for the detection of upper gastrointestinal mucosal lesions was 56%, with a specificity of 64%, a positive predictive value (PPV) of 58% and a negative predictive value (NPV) of 61%. The area under the receiver operating characteristic (ROC) curve was 0.60 (Table\u0026nbsp;\u003cspan refid=\"Tab2\" class=\"InternalRef\"\u003e2\u003c/span\u003e). For the detection of GC, the sensitivity was 67%, the specificity was 64%, the PPV was 14%, and the NPV was 98%. The area under the ROC curve was 0.65.\u003c/p\u003e \u003cp\u003eUsing patients with normal endoscopy results as a reference group, univariable analysis revealed an association between S-filum positivity and the presence of mucosal lesions (OR 2.2; 95% CI 1.2\u0026ndash;4.1, p\u0026thinsp;=\u0026thinsp;0.007) and peptic ulceration (OR 2.4; 95% CI 1.1\u0026ndash;5.2, p\u0026thinsp;=\u0026thinsp;0.02). There was no association with GC (OR 3.5; 95% CI 0.7\u0026ndash;22, p\u0026thinsp;=\u0026thinsp;0.09). Other mucosal diagnoses included varices, reflux esophagitis, esophageal candidiasis and gastritis. When these factors were grouped together, they were not associated with S-filum positivity (OR 1.3; 95% CI 0.6\u0026ndash;2.8, p\u0026thinsp;=\u0026thinsp;0.48) (Table\u0026nbsp;\u003cspan refid=\"Tab2\" class=\"InternalRef\"\u003e2\u003c/span\u003e).\u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab2\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 2\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eAssociation between gastric mucosal abnormalities and a positive S-filum test and tests for diagnostic accuracy\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"11\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c6\" colnum=\"6\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c7\" colnum=\"7\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c8\" colnum=\"8\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c9\" colnum=\"9\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c10\" colnum=\"10\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c11\" colnum=\"11\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eTotal number\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eS-filum positive\u003c/p\u003e \u003cp\u003en (%)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003eS-filum negative\u003c/p\u003e \u003cp\u003en (%)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c5\"\u003e \u003cp\u003eOR; 95% confidence interval\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c6\"\u003e \u003cp\u003eP value\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c7\"\u003e \u003cp\u003eSensitivity\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c8\"\u003e \u003cp\u003eSpecificity\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c9\"\u003e \u003cp\u003ePositive predictive value\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c10\"\u003e \u003cp\u003eNegative predictive value\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c11\"\u003e \u003cp\u003eArea under ROC\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eNormal OGD\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e105\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e38 (36)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e67 (64)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003eRef.\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003eRef.\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c10\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c11\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eAbnormality on OGD\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e95\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e53 (56)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e42 (44)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e2.2 (1.2\u0026ndash;4.1)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e0.007\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e56%\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e64%\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e \u003cp\u003e58%\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c10\"\u003e \u003cp\u003e61%\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c11\"\u003e \u003cp\u003e0.60\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eGastric cancer\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e9\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e6 (67)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e3 (33)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e3.5 (0.7\u0026ndash;22)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e0.09\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e67%\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e64%\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e \u003cp\u003e14%\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c10\"\u003e \u003cp\u003e98%\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c11\"\u003e \u003cp\u003e0.65\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003ePeptic ulcer\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e45\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e26 (58)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e19 (42)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e2.4 (1.1\u0026ndash;5.2)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e0.02\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e58%\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e64%\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e \u003cp\u003e41%\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c10\"\u003e \u003cp\u003e78%\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c11\"\u003e \u003cp\u003e0.61\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eOther diagnoses\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e41\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e21 (51)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e20 (49)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e1.3 (0.6\u0026ndash;2.8)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e0.48\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e51%\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e54%\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e \u003cp\u003e36%\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c10\"\u003e \u003cp\u003e23%\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c11\"\u003e \u003cp\u003e0.54\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec9\" class=\"Section2\"\u003e \u003ch2\u003eLevels of discomfort associated with the S-filum\u003c/h2\u003e \u003cp\u003e \u003cdiv class=\"BlockQuote\"\u003e \u003cp\u003eWe collected information on the level of discomfort for the S-filum in 190 patients and 145 patients for endoscopy. In 190 (95%) of the patients, endoscopy was unsedated. The median level of discomfort for the S-filum was 2 (IQR 1\u0026ndash;4), and it was 7 (IQR 7\u0026ndash;9) for endoscopy (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e). There was a statistically significant difference between the two assessments (p\u0026thinsp;\u0026lt;\u0026thinsp;0.001).\u003c/p\u003e \u003c/div\u003e \u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003c/div\u003e"},{"header":"Discussion","content":"\u003cp\u003e \u003cdiv class=\"BlockQuote\"\u003e \u003cp\u003eThe early diagnosis of GC is a major challenge in many countries, especially in low-resource settings where endoscopy services are scarce. We designed the S-filum as a simple tool that could be used to predict the presence of gastric mucosal lesions before endoscopy and therefore assist in referral decisions [\u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e]. However, we found that the sensitivity and specificity of the S-filum for detecting mucosal lesions were too low to warrant possible clinical utility. Most importantly, 33% of the GC patients and 44% of the peptic ulcer patients had negative S-filum results, and their lesions were missed by the device.\u003c/p\u003e \u003cp\u003eThe S-filum was meant for use in a low-resource setting without easy access to endoscopic services. The early diagnosis of gastric lesions is difficult in these settings. Most published studies evaluating gastric juice as a source of nonblood-based liquid biopsies for GC diagnosis have used nucleic acids, metabolites or microbiota as biomarkers [\u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e, \u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e]. These biomarkers require laboratory assays, some of which are sophisticated and are not readily available in low-resource settings. Their general utility would therefore be limited. In addition, analysis of these biomarkers requires a clear understanding of gastric physiology [\u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e]. There is very limited information on the diagnosis of early gastric cancer in Africa, but the indications are that most tumours are diagnosed late [\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e, \u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e]. A recent study from Kenya reported that 60% of GC patients had stage III or IV disease at diagnosis [24]. In contrast, 50% of gastric cancer cases in Japan and Korea are early, with the proportion being approximately 20% in Western countries [\u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e]. Therefore, strategies for early GC diagnosis that focus on low-resource settings are urgently needed.\u003c/p\u003e \u003cp\u003eThis study was carefully designed to ensure that the individual administering the S-filum was completely independent from the one performing the endoscopy. In addition, the procedure was performed prior to endoscopy to avoid procedure-related trauma, which could have resulted in false positive results. Despite this consideration, the false positive rate was 36% in normal individuals, probably due to minor bleeding that occurred with mildly inflamed gastric mucosa. The false-negative rate of 44% could have resulted from musical lesions that were not bleeding at the time of the test. The S-filum was not able to detect previous bleeds. This is a significant limitation of the device. It is important to understand these limitations, as they affect the accuracy of the S-filum results.\u003c/p\u003e \u003cp\u003eThe rationale for the use of S-filum is sound, and we are convinced that if the sensitivity could be improved, it could contribute to the early detection of gastric mucosal lesions in low-resource settings. Patients who participated in this study reported minimal discomfort compared with those who underwent endoscopy, suggesting that this approach would be acceptable for routine use. It is possible that there is mucosal bleeding during un-sedated endoscopy, rather than if well sedated, the great majority of the procedures in this study were performed unsedated. This does not, however, explain the low sensitivity of the S-filum.\u003c/p\u003e \u003cp\u003eDespite these negative results, there are still other avenues that we have explored to improve the detection of early gastric cancer in low-resource settings. We previously studied serum indicators via the GastroPanel\u0026reg; [\u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e19\u003c/span\u003e, \u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e20\u003c/span\u003e] and evaluated unique risk factors that could be used as surrogate markers for screening [\u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e21\u003c/span\u003e]. As the use of faecal occult blood testing is not applicable to gastric cancer [\u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e22\u003c/span\u003e], we will continue exploring other non-invasive and affordable methods for the diagnosis of gastric cancer.\u003c/p\u003e \u003c/div\u003e \u003c/p\u003e \u003cp\u003eIn conclusion, the S-filum is not sufficiently accurate for use as a diagnostic tool for detecting gastric mucosal lesions in the absence of endoscopy. More work needs to be done to discover strategies for the early detection of GC in low-resource settings.\u003c/p\u003e \u003cdiv id=\"Sec11\" class=\"Section2\"\u003e \u003ch2\u003eLimitations\u003c/h2\u003e \u003cp\u003eThis study is limited by the low number of GC cases that were included. However, the numbers were enough to make reasonable conclusions. The study was conducted among patients coming to a tertiary institution for care. This could have been a biased population.\u003c/p\u003e \u003c/div\u003e"},{"header":"Abbreviations","content":"\u003cp\u003eGC \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp;\u0026nbsp;Gastric cancer\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eS-filum \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp;\u0026nbsp;Sanguis-filum\u003c/p\u003e\n\u003cp\u003ePPV\u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp;Positive predictive value\u003c/p\u003e\n\u003cp\u003eNPV\u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp;\u0026nbsp;Negative predictive value\u0026nbsp;(ROC) curve was\u003c/p\u003e\n\u003cp\u003eROC\u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp;\u0026nbsp;Receiver operating characteristic\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u0026nbsp;\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003e\u003cstrong\u003eEthics approval and consent to participate:\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe study was conducted in accordance with the Declaration of Helsinki and approved by the University of Zambia Biomedical Ethics Committee and the National Health Research Authority, reference number\u0026nbsp;2446--2021.\u0026nbsp;Written informed consent was obtained from all the subjects involved in the study.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAvailability of data and material:\u003c/strong\u003e Data will be available online and upon request\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eFunding:\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThis work was carried out with aid of a grant from UNESCO and the International Development Research Center, Ottawa, Canada. Grant number 108392-001. The views expressed herein do not necessarily represent those of UNESCO, the IDRC or its Board of Directors. Funding was also provided by the European Union\u0026nbsp;(Grant no. DCI-PANAF/2020/420-028), through the African Research Initiative for Scientific Excellence (ARISE), a pilot programme.\u0026nbsp;The\u0026nbsp;ARISE is implemented by the African Academy of Sciences with support from the European Commission and the African Union Commission.\u0026nbsp;The contents of this document are the sole responsibility of\u0026nbsp;the authors\u0026nbsp;and can under no circumstances be regarded as reflecting the position of the European Union, the African Academy of Sciences, or the African Union.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eCompeting interests:\u0026nbsp;\u003c/strong\u003eThe authors declare no conflicts of interest.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAuthor Contributions:\u003c/strong\u003e Study conceptualisation was performed by VK and PK. VK, HM and CM were involved in data collection, and data analysis was performed by VK. The first draft of the manuscript was written by VK. VK, HM, CM and PK reviewed and edited the manuscript. All authors approved the final version of the manuscript.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\n\u003cli\u003eShumba S, Kayamba V. Analysis of the proportion of university teaching hospital gastric cancer data included in the Zambia national cancer registry. Afr Health Sci. 2023 Mar;23(1):438-443. doi: 10.4314/ahs.v23i1.46.\u003c/li\u003e\n\u003cli\u003eKayamba V, Mubbunu M, Kelly P. Endoscopic diagnosis of gastric and oesophageal cancer in Lusaka, Zambia: a retrospective analysis. BMC Gastroenterol. 2024 Apr 1;24(1):122. doi: 10.1186/s12876-024-03187-x. PMID: 38561688; PMCID: PMC10983744.\u003c/li\u003e\n\u003cli\u003eAsombang AW, Kayamba V, Turner-Moss E, Banda L, Trinkaus K, Colditz G, Mudenda V, Zulu R, Sinkala E, Kelly P. Gastric malignancy survival in Zambia, Southern Africa: A two year follow up study, \u003cem\u003eMedical Journal of Zambia\u003c/em\u003e, 2014; 41(1): 13-18.\u003c/li\u003e\n\u003cli\u003eKayamba, V.; Kelly, P. Delayed referral for diagnostic endoscopy is a contributing factor to late gastric cancer diagnosis in Zambia. \u003cem\u003eHealth Press\u003c/em\u003e 2019, \u003cem\u003e3\u003c/em\u003e, 14\u0026ndash;19.\u003c/li\u003e\n\u003cli\u003eMatsuoka T, Yashiro M. Novel biomarkers for early detection of gastric cancer. World J Gastroenterol. 2023 May 7;29(17):2515-2533. doi: 10.3748/wjg.v29.i17.2515.\u003c/li\u003e\n\u003cli\u003eMaconi G, Manes G, Porro GB. Role of symptoms in diagnosis and outcome of gastric cancer. World J Gastroenterol. 2008 Feb 28;14(8):1149-55. doi: 10.3748/wjg.14.1149.\u003c/li\u003e\n\u003cli\u003eXue J, Qin S, Ren N, Guo B, Shi X, Jia E. Extracellular vesicle biomarkers in circulation for the diagnosis of gastric cancer: A systematic review and meta‑analysis. Oncol Lett. 2023 Aug 11;26(4):423. doi: 10.3892/ol.2023.14009.\u003c/li\u003e\n\u003cli\u003eDeng D, Zhang Y, Zhang R, Yi J, Dong J, Sha L, Yan M. Circulating Proteins and Metabolite Biomarkers in Gastric Cancer: A Systematic Review and Meta-analysis. Arch Med Res. 2023 Feb;54(2):124-134. doi: 10.1016/j.arcmed.2022.12.012.\u003c/li\u003e\n\u003cli\u003eVirgilio E, Giarnieri E, Giovagnoli MR, Montagnini M, Proietti A, D\u0026apos;Urso R, Mercantini P, Balducci G, Cavallini M. Gastric Juice MicroRNAs as Potential Biomarkers for Screening Gastric Cancer: A Systematic Review. Anticancer Res. 2018 Feb;38(2):613-616. doi: 10.21873/anticanres.12265.\u003c/li\u003e\n\u003cli\u003eMwachiro M, Topazian HM, Kayamba V, Mulima G, Ogutu E, Erkie M, Lenga G, Mutie T, Mukhwana E, Desalegn H, Berhe R, Meshesha BR, Kaimila B, Kelly P, Fleischer D, Dawsey SM, Topazian MD. Gastrointestinal endoscopy capacity in Eastern Africa. Endosc Int Open. 2021 Nov 12;9(11):E1827-E1836. doi: 10.1055/a-1551-3343.\u003c/li\u003e\n\u003cli\u003eKayamba, V.; Zyambo, K.; Kelly, P. Presence of blood in gastric juice: A sensitive marker for gastric cancer screening in a poor resource setting.\u003cem\u003e PLoS ONE \u003c/em\u003e2018, \u003cem\u003e13\u003c/em\u003e, e0205185. https://doi.org/10.1371/journal.pone.0205185.\u003c/li\u003e\n\u003cli\u003eKayamba V, Kelly P. Introducing the Sanguis-Filum for Detection of Gastric Mucosal Lesions Prior to Endoscopy: A Study Protocol. Diagnostics (Basel). 2022 May 7;12(5):1160. doi: 10.3390/diagnostics12051160.\u003c/li\u003e\n\u003cli\u003eMathes T, Pieper D. An algorithm for the classification of study designs to assess diagnostic, prognostic and predictive test accuracy in systematic reviews. Syst Rev. 2019 Sep 3;8(1):226. doi: 10.1186/s13643-019-1131-4.\u003c/li\u003e\n\u003cli\u003eLopes C, Chaves J, Ortig\u0026atilde;o R, Dinis-Ribeiro M, Pereira C. Gastric cancer detection by non-blood-based liquid biopsies: A systematic review looking into the last decade of research. United European Gastroenterol J. 2023 Feb;11(1):114-130. doi: 10.1002/ueg2.12328.\u003c/li\u003e\n\u003cli\u003eYamamoto H, Watanabe Y, Sato Y, Maehata T, Itoh F. Non-Invasive Early Molecular Detection of Gastric Cancers. Cancers (Basel). 2020 Oct 7;12(10):2880. doi: 10.3390/cancers12102880.\u003c/li\u003e\n\u003cli\u003eHerrera-Pariente C, Montori S, Llach J, Bofill A, Albeniz E, Moreira L. Biomarkers for Gastric Cancer Screening and Early Diagnosis. Biomedicines. 2021 Oct 12;9(10):1448. doi: 10.3390/biomedicines9101448.\u003c/li\u003e\n\u003cli\u003eBenamro F, Sartorius B, Clarke DL, Anderson F, Loots E, Olinger L. The spectrum of gastric cancer as seen in a large quaternary hospital in KwaZulu-Natal, South Africa. S Afr Med J. 2017 Jan 30;107(2):130-133.\u003c/li\u003e\n\u003cli\u003eDegu A, Karimi PN, Opanga SA, Nyamu DG. Predictors of survival outcomes among patients with gastric cancer in a leading tertiary, teaching and referral hospital in Kenya. Cancer Med. 2023 Feb;12(4):4147-4160. doi: 10.1002/cam4.5275.\u003c/li\u003e\n\u003cli\u003eKayamba, V.; Butt, J.; Varga, M.; Shibemba, A.; Piazuelo, M.B.; Wilson, K.T.; Zyambo, K.; Mwakamui, S.; Mulenga, C.; Waterboer, T.; et al. Serum antibodies to \u003cem\u003eHelicobacter pylori\u003c/em\u003e antigens are associated with active gastric inflammation but not gastric cancer in patients seen at the University Teaching Hospital in Lusaka, Zambia. \u003cem\u003eMalawi Med. J. \u003c/em\u003e2022,\u003cem\u003e 34\u003c/em\u003e, 17-24 https://dx.doi.org/10.4314/mmj.v34i1.4.\u003c/li\u003e\n\u003cli\u003eKayamba, V.; Shibemba, A.; Zyambo, K.; Heimburger, D.C.; Morgan, D.; Kelly, P. HIV related hypochlorhydria does not appear to respond to anti-retroviral therapy in Zambian adults: A case control study.\u003cem\u003e Pan Afr. Med. J. \u003c/em\u003e2018, \u003cem\u003e31\u003c/em\u003e, 128. https://doi.org/10.11604/pamj.2018.31.128.11850.\u003c/li\u003e\n\u003cli\u003eKayamba V, Zyambo K, Mulenga C, Mwakamui S, Tembo MJ, Shibemba A, Heimburger DC, Atadzhanov M, Kelly P. Biomass Smoke Exposure Is Associated With Gastric Cancer and Most likely, Mediated Via Oxidative Stress and DNA Damage: A Case‒Control Study. JCO Glob Oncol. 2020 Mar;6:532-541. doi: 10.1200/GO.20.00002.\u003c/li\u003e\n\u003cli\u003eNakama, H.; Zhang, B. Immunochemical fecal occult blood test is inadequate for screening test of stomach cancer.\u003cem\u003e \u003c/em\u003e\u003cem\u003eDig. Dis. Sci.\u003c/em\u003e\u003cem\u003e \u003c/em\u003e2000, \u003cem\u003e45\u003c/em\u003e, 2195\u0026ndash;2198.\u003c/li\u003e\n\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":false,"highlight":"","institution":"","isAcceptedByJournal":true,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"bmc-research-notes","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"resn","sideBox":"Learn more about [BMC Research Notes](http://bmcresnotes.biomedcentral.com)","snPcode":"","submissionUrl":"https://www.editorialmanager.com/resn/default.aspx","title":"BMC Research Notes","twitterHandle":"@BMC_series","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"em","reportingPortfolio":"BMC Series","inReviewEnabled":true,"inReviewRevisionsEnabled":true},"keywords":"Gastric cancer, peptic ulcer, diagnosis, S-filum","lastPublishedDoi":"10.21203/rs.3.rs-4890061/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-4890061/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003ch2\u003eObjective\u003c/h2\u003e \u003cp\u003eDiagnosis of upper gastrointestinal (UGI) mucosal lesions is primarily via endoscopy. We investigated the diagnostic accuarcy of the Sanguis-filum (S-filum), a bedside tool for detecting UGI mucosal lesions.\u003c/p\u003e\u003ch2\u003eResults\u003c/h2\u003e \u003cp\u003eWe tested 200 consenting patients, 112 (56%) females and 88 (44%) males attending for endoscopy at the University Teaching Hospital, Lusaka. Ninety-five (47%) of the patients had visible mucosal lesions; 45 (23%) of them had peptic ulceration, and 9 (5%) had gastric cancer. Ninety-one (46%) S-filum tests were positive. We found an association between positive S-filum results and the presence of mucosal lesions (OR 2.2; 95% CI 1.2\u0026ndash;4.1, p\u0026thinsp;=\u0026thinsp;0.007) but not gastric cancer (OR 3.5; 95% CI 0.7\u0026ndash;22, p\u0026thinsp;=\u0026thinsp;0.09). S-filum was insufficiently sensitive; missing mucosal lesions in 54%, and gastric cancer in 33% of cases. For detection of mucosal lesions, the sensitivity was 56%, specificity 64% with an area under the receiver operating characteristic (ROC) curve of 0.60. For GC, the sensitivity was 67%, the specificity was 64%, with area under the ROC of 0.65. As a screening test prior to endoscopy, the S-filum is not sufficiently accurate for detecting UGI mucosal lesions of GC.\u003c/p\u003e","manuscriptTitle":"Bedside tool for the diagnosis of gastric mucosal lesions prior to endoscopy","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2024-10-07 15:57:32","doi":"10.21203/rs.3.rs-4890061/v1","editorialEvents":[{"type":"communityComments","content":0},{"type":"decision","content":"Revision requested","date":"2026-02-12T10:42:15+00:00","index":"","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2026-01-26T09:01:18+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"180587170332839588641944006782516036976","date":"2026-01-14T11:35:27+00:00","index":"hide","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2024-11-06T00:27:47+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"122556339361311640063167683423282637647","date":"2024-10-25T00:35:53+00:00","index":"hide","fulltext":""},{"type":"reviewersInvited","content":"","date":"2024-10-14T06:00:18+00:00","index":"","fulltext":""},{"type":"editorInvited","content":"","date":"2024-08-14T12:04:17+00:00","index":"","fulltext":""},{"type":"editorAssigned","content":"","date":"2024-08-12T06:50:47+00:00","index":"","fulltext":""},{"type":"checksComplete","content":"","date":"2024-08-12T06:50:10+00:00","index":"","fulltext":""},{"type":"submitted","content":"BMC Research Notes","date":"2024-08-10T05:21:03+00:00","index":"","fulltext":""}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"bmc-research-notes","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"resn","sideBox":"Learn more about [BMC Research Notes](http://bmcresnotes.biomedcentral.com)","snPcode":"","submissionUrl":"https://www.editorialmanager.com/resn/default.aspx","title":"BMC Research Notes","twitterHandle":"@BMC_series","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"em","reportingPortfolio":"BMC Series","inReviewEnabled":true,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"1d417436-08c4-49a2-a5e9-401e138a6a1c","owner":[],"postedDate":"October 7th, 2024","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"published-in-journal","subjectAreas":[],"tags":[],"updatedAt":"2026-03-23T16:01:53+00:00","versionOfRecord":{"articleIdentity":"rs-4890061","link":"https://doi.org/10.1186/s13104-026-07777-8","journal":{"identity":"bmc-research-notes","isVorOnly":false,"title":"BMC Research Notes"},"publishedOn":"2026-03-18 15:58:27","publishedOnDateReadable":"March 18th, 2026"},"versionCreatedAt":"2024-10-07 15:57:32","video":"","vorDoi":"10.1186/s13104-026-07777-8","vorDoiUrl":"https://doi.org/10.1186/s13104-026-07777-8","workflowStages":[]},"version":"v1","identity":"rs-4890061","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-4890061","identity":"rs-4890061","version":["v1"]},"buildId":"qtupq5eGEP_6zYnWcrvyt","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}