Risk-stratification of febrile African children at risk of sepsis using sTREM-1 as basis for a rapid triage test

Identifying febrile children at risk of sepsis in low-resource settings can improve survival, but recognition triage tools are lacking. Here we test the hypothesis that measuring circulating markers of immune and endothelial activation may identify children with sepsis at risk of all-cause mortality. In a prospective cohort study of 2,502 children in Uganda, we show that Soluble Triggering Receptor Expressed on Myeloid cells-1 (sTREM-1) measured at first clinical presentation, had high predictive accuracy for subsequent in-hospital mortality. sTREM-1 had the best performance, versus 10 other markers, with an AUROC for discriminating children at risk of death of 0.893 in derivation (95% CI 0.843–0.944) and 0.901 in validation (95% CI 0.856–0.947) cohort. sTREM-1 cutoffs corresponding to a negative likelihood ratio (LR) of 0.10 and a positive LR of 10 classified children into low (1,306 children, 53.1%), intermediate (942, 38.3%) and high (212, 8.6%) risk zones. The estimated incidence of death was 0.5%, 3.9%, and 31.8%, respectively, suggesting sTREM-1 could be used to risk-stratify febrile children. These findings do not attempt to derive a risk prediction model, but rather define sTREM-1 cutoffs as the basis for rapid triage test for all cause fever syndromes in children in low-resource settings.

Risk-stratification of HPV-positive women with low-grade cytology by FAM19A4/miR124-2 methylation and HPV genotyping

Background The introduction of primary HPV screening has doubled the number of colposcopy referrals because of the direct referral of HPV-positive women with a borderline or mild dyskaryosis (BMD) cytology (ASC-US/LSIL) triage test. Further risk-stratification is warranted to improve the efficiency of HPV-based screening. Methods This study evaluated the discriminative power of FAM19A4/miR124-2 methylation, HPV16/18 genotyping and HPV16/18/31/33/45 genotyping in HPV-positive women with BMD (n = 294) in two Dutch screening trials. Absolute CIN3+ risks and colposcopy referrals within one screening round were calculated. Results Methylation analysis discriminated well, yielding a CIN3+ risk of 33.1% after a positive result and a CIN3+ risk of 9.8% after a negative result. HPV16/18 and HPV16/18/31/33/45 genotyping resulted in a 27.6% and 24.6% CIN3+ risk after a positive result, and a 13.2% and 9.1% CIN3+ risk after a negative result. Colposcopy referral percentages were 41.2%, 43.2%, and 66.3% for FAM19A4/miR124-2 methylation, HPV16/18 and HPV16/18/31/33/45 genotyping, respectively. The CIN3+ risk after a negative result could be lowered to 2.8% by combining methylation and extended genotyping, at the expense of a higher referral percentage of 75.5%. Conclusion The use of FAM19A4/miR124-2 methylation and/or HPV genotyping in HPV-positive women with BMD can lead to a substantial reduction in the number of direct colposcopy referrals.

C-reactive protein as a triage tool for adults with presumptive pulmonary tuberculosis in South Africa: a prospective cohort study

Background: Identification of an accurate, low-cost triage test for pulmonary TB among people presenting to healthcare facilities is an urgent global research priority. We assessed the diagnostic accuracy and clinical utility of C-reactive protein (CRP) for TB triage among symptomatic adult outpatients, irrespective of HIV status. Methods: We prospectively enrolled adults reporting at least one (for people with HIV) or two (for people without HIV) symptoms of cough, fever, night sweats, or weight loss at two TB clinics in Cape Town, South Africa. Participants provided sputum for culture and Xpert MTB/RIF Ultra. We evaluated the diagnostic accuracy of CRP (measured using a laboratory-based assay) against a TB-culture reference standard as the area under the receiver operating characteristic curve (AUROC) and sensitivity and specificity at pre-specified thresholds. We assessed clinical utility using decision curve analysis, benchmarked against WHO recommendations. Results: Of 932 included individuals, 255 (27%) had culture-confirmed TB and 389 (42%) were living with HIV. CRP demonstrated an AUROC of 0.80 (95% confidence interval 0.77-0.83), with sensitivity 93% (89-95%) and specificity 54% (50-58%) using a primary cut-off of ≥10mg/L. Performance was similar among people with HIV to those without. In decision curve analysis, CRP-based triage offered greater clinical utility than confirmatory testing for all up to a number willing to test threshold of 20 confirmatory tests per true positive TB case diagnosed. Conclusions: CRP approached the WHO-defined minimum performance for a TB triage test and showed evidence of clinical utility among symptomatic outpatients, irrespective of HIV status.

Diagnostic accuracy of the Cepheid 3-gene host response fingerstick blood test in a prospective, multi-site study: interim results

Background The development of a fast and accurate, non-sputum-based point-of-care triage test for tuberculosis (TB) would have a major impact on combating the TB burden worldwide. A new fingerstick blood test has been developed by Cepheid (the Xpert-MTB-Host Response (HR)-Prototype), which generates a ‘TB score’ based on mRNA expression of 3 genes. Here we describe the first prospective findings of the MTB-HR prototype. Methods Fingerstick blood from adults presenting with symptoms compatible with TB in South Africa, The Gambia, Uganda and Vietnam was analysed using the Cepheid GeneXpert MTB-HR prototype. Accuracy of the Xpert MTB-HR cartridge was determined in relation to GeneXpert Ultra results and a composite microbiological score (GeneXpert Ultra and liquid culture) with patients classified as having TB or other respiratory diseases (ORD). Results When data from all sites (n=75 TB, 120 ORD) were analysed, the TB score discriminated between TB and ORD with an AUC of 0·94 (CI, 0·91-0·97), sensitivity of 87% (CI, 77-93%) and specificity of 94% (88-97%). When sensitivity was set at 90% for a triage test, specificity was 86% (CI, 75-97%). These results were not influenced by HIV status or geographical location. When evaluated against a composite microbiological score (n=80 TB, 111 ORD), the TB score was able to discriminate between TB and ORD with an AUC of 0·88 (CI, 0·83-0·94), 80% sensitivity (CI, 76-85%) and 94% specificity (CI, 91-96%). Conclusions Our interim data indicate the Cepheid MTB-HR cartridge reaches the minimal target product profile for a point of care triage test for TB using fingerstick blood, regardless of geographic area or HIV infection status.

Prospective validation of host transcriptomic biomarkers for pulmonary tuberculosis by real-time PCR

We tested performance of host-blood transcriptomic tuberculosis (TB) signatures for active case-finding. Among 20,207 HIV-uninfected and 963 HIV-infected adults screened; 2,923 and 861 were enrolled from five South African communities. Eight signatures were measured by microfluidic RT-qPCR and participants were microbiologically-investigated for pulmonary TB at baseline, and actively surveilled for incident disease through 15 months. Diagnostic AUCs for 61 HIV-uninfected (weighted-prevalence 1.1%) and 10 HIV-infected (prevalence 1.2%) prevalent TB cases for the 8 signatures were 0.63-0.79 and 0.65-0.88, respectively. Thereafter, 24 HIV-uninfected and 9 HIV-infected participants progressed to incident TB (1.1 and 1.0 per 100 person-years, respectively). Prognostic AUCs through 15-months follow-up were 0.49-0.66 and 0.54-0.81, respectively. Prognostic performance for incident TB occurring within 6-12 months in HIV-negative participants was higher for all signatures. None of the signatures met WHO Target Product Profile criteria for a triage test to diagnose asymptomatic TB; most signatures met the criteria for symptomatic TB. Prognostic accuracy of most signatures for incident TB within six months of testing met the criteria for an incipient TB test.

Evaluation of the diagnostic performance of laboratory-based c-reactive protein as a triage test for active pulmonary tuberculosis

Introduction A highly sensitive triage test that captures most symptomatic patients at increased likelihood of having pulmonary tuberculosis (PTB) would ‘rule-out’ lower-risk patients from expensive confirmatory testing. Although studies have assessed the diagnostic accuracy of a C-reactive protein (CRP) triage test for PTB in HIV+ patients, limited data are available from HIV- cohorts. Materials and methods In this retrospective case-control study, 765 serum samples were selected from FIND’s biobank. Each sample had been collected from an adult presenting with respiratory symptomatology to district hospitals in South Africa and referral hospitals in Cambodia, Peru, Georgia and Vietnam between 2007–2017. Serum CRP measurements were obtained using a laboratory-based assay. CRP cutoff-points of ≥8mg/L and ≥10mg/L were predefined as a positive triage test result. The PTB reference standard was two contemporaneously collected sputum liquid culture results. Results CRP demonstrated an overall sensitivity for PTB of 79.8% (95%CI 75.5–83.5) and 77.7% (95%CI 73.4–81.6) for cutoff-points of 8mg/L and 10mg/L respectively. Specificity was 62.8% (95%CI 57.8–67.6%) and 66.6% (95%CI 61.1–70.7) respectively. Area-under-the-curve using Receiver Operating Characteristic analysis was 0.77 (95%CI 0.74–0.81). Threshold analysis showed optimal CRP cutoff-points were higher in HIV+ than HIV- participants. An algorithm in which CRP triage was followed by confirmatory Xpert MTB/Rif testing achieved a sensitivity of 75.1% (95%CI 69.0–80.4%) whilst decreasing Xpert usage by 40.6%. Discussion CRP may not meet the challenge of a catch-all TB triage test. However, it shows promise in HIV+ individuals. Further research is required in a prospective study using point-of-care platforms to further evaluate its capabilities.

Faecal immunochemical tests safely enhance rational use of resources during the assessment of suspected symptomatic colorectal cancer in primary care: systematic review and meta-analysis

ObjectiveImplementation of faecal immunochemical tests (FIT) as a triage test in primary healthcare may improve the efficiency of referrals without missing cases of colorectal cancer (CRC). We aim to summarise the performance characteristics of FITs for CRC in symptomatic patients presenting to primary healthcare.DesignWe performed a systematic literature review of Medline and EMBASE databases from May 2018 to November 2020. Previous related systematic searches were also adapted to this aim and completed with reference screening. We identified studies performed on adult patients consulting for abdominal symptoms in primary care which reported data such that the FIT diagnostic performance parameters for CRC could be obtained. Bivariate models were used to synthesise available evidence. Meta-regression analysis was performed to evaluate the causes of heterogeneity.ResultsTwenty-three studies (69 536 participants) were included (CRC prevalence 0.3%–6.2%). Six studies (n=34 691) assessed FIT as rule in test (threshold of ≥150 µg Hb/g faeces) showing a sensitivity of 64.1% (95% CI 57.8% to 69.9%) and a specificity of 95.0% (95% CI 91.2% to 97.2%). A threshold of 10 µg/g (15 studies; n=48 872) resulted in a sensitivity of 87.2% (95% CI 81.0% to 91.6%) and a specificity of 84.4% (95% CI 79.4% to 88.3%) for CRC. At a 20 µg Hb/g faeces threshold (five studies; n=24 187) less than one additional CRC would be missed per 1000 patients investigated compared with 10 µg Hb/g faeces threshold (CRC prevalence 2%).ConclusionFIT is the test of choice to evaluate patients with new-onset lower gastrointestinal symptoms in primary healthcare.

Development of EndoScreen Chip, a Microfluidic Pre-Endoscopy Triage Test for Esophageal Adenocarcinoma

The current endoscopy and biopsy diagnosis of esophageal adenocarcinoma (EAC) and its premalignant condition Barrett’s esophagus (BE) is not cost-effective. To enable EAC screening and patient triaging for endoscopy, we developed a microfluidic lectin immunoassay, the EndoScreen Chip, which allows sensitive multiplex serum biomarker measurements. Here, we report the proof-of-concept deployment for the EAC biomarker Jacalin lectin binding complement C9 (JAC-C9), which we previously discovered and validated by mass spectrometry. A monoclonal C9 antibody (m26 3C9) was generated and validated in microplate ELISA, and then deployed for JAC-C9 measurement on EndoScreen Chip. Cohort evaluation (n = 46) confirmed the expected elevation of serum JAC-C9 in EAC, along with elevated total serum C9 level. Next, we asked if the small panel of serum biomarkers improves detection of EAC in this cohort when used in conjunction with patient risk factors (age, body mass index and heartburn history). Using logistic regression modeling, we found that serum C9 and JAC-C9 significantly improved EAC prediction from AUROC of 0.838 to 0.931, with JAC-C9 strongly predictive of EAC (vs. BE OR = 4.6, 95% CI: 1.6–15.6, p = 0.014; vs. Healthy OR = 4.1, 95% CI: 1.2–13.7, p = 0.024). This proof-of-concept study confirms the microfluidic EndoScreen Chip technology and supports the potential utility of blood biomarkers in improving triaging for diagnostic endoscopy. Future work will expand the number of markers on EndoScreen Chip from our list of validated EAC biomarkers.

Evaluation of Triage Tests When Existing Test Capacity Is Constrained: Application to Rapid Diagnostic Testing in COVID-19

Objectives A triage test is used to determine which patients will undergo an existing or “reference” test. This article explores the potential value of using triage tests before reference tests when the capacity of the reference test is constrained. Methods We developed a simple model with inputs: prevalence, sensitivity, specificity, and reference test capacity. We included a case study of rapid diagnostic tests for SARS-CoV-2 antigens used as triage tests before a reference polymerase chain reaction test. Performance data were obtained from an evaluation performed by an academic center on 425 samples from testing centers in the United Kingdom and Germany. Results When reference test capacity is constrained, the use of a triage test leads to a relative expansion of the population tested and cases identified; both are higher with a high-specificity triage test. When reference test capacity is not constrained, the potential advantages of introducing a triage test can be assessed using a standard cost-utility framework, balancing the utility of the reduction in the number of reference tests required against the disutility of missed cases associated with the use of a lower-sensitivity triage test. In the constrained case, the advantage of a triage testing strategy in terms of population covered and cases identified is reduced as the prevalence increases. In the unconstrained case, the reduction in reference tests required is reduced and the number of cases missed increase as the prevalence rises. Conclusion When the availability of the reference test is constrained, tests added in a triage position do not need high levels of accuracy to increase the number of cases diagnosed. This has implications in many disease areas, including COVID-19. Twitter: Lower-accuracy #COVID19 tests can still be useful, according to a new article, “Evaluation of Triage Tests When Existing Test Capacity Is Constrained: Application to Rapid Diagnostic Testing in COVID-19,” co-authored by @janetbouttell & @NeilSHawkins @HEHTAGlasgow @MedDecMak There is much emphasis on high-accuracy #COVID19 tests, but lower-accuracy tests have their place, according to a new study on triage tests when test capacity is constrained, co-authored by @janetbouttell & @NeilSHawkins @HEHTAGlasgow @MedDecMak A new study, co-authored by @janetbouttell & @NeilSHawkins @HEHTAGlasgow, has shown that when there is limited capacity of high-accuracy #COVID19 diagnostic tests, triage testing strategies can increase the population covered and the number of #COVID19 cases identified. @MedDecMak

MO948CHANGES OF SOLUBLE UROKINASE PLASMINOGEN ACTIVATOR RECEPTOR (SUPAR) AFTER CADAVERIC KIDNEY TRANSPLANTATION AND ASSOCIATION WITH KIDNEY FUNCTION

Background and Aims The soluble urokinase plasminogen activator receptor (suPAR), a marker of podocyte injury, has been implicated in pathogenesis of various kidney diseases, especially in focal segmental glomerulosclerosis. It correlates to the activation level of immune system. SuPAR predicted all course mortality in hemodialysis patients, but was not tested as a prognostic biomarker in kidney transplant patients. The aim of this study was to evaluate changes of suPAR concentration after kidney transplantation and to test its relation to graft function. Method We examined patients, who underwent cadaveric kidney transplantation (Tx) from 2019/05/23 to 2020/07/30 in the Hospital of Lithuanian University of Health Sciences. We evaluated level of suPAR biomarker before Tx, 12 days after Tx and 3 months after Tx. We used the suPARnostic Quick Triage test by ViroGates (Medtech, Denmark) for testing suPAR concentration. The suPARnostic Quick Triage test is based on the lateral flow principle. The device consists of a nitrocellulose membrane with two immobilized antibody zones and a running buffer with gold particles. The quantitative results are read by the aLF Reader with a detection interval of 2-15 ng/mL suPAR. Data on serum creatinine level and eGFR were collected at the same time points. Creatinine was tested using Analyzer AU680, Beckman Coulter, USA (Kinetic Jaffe traceable to the IDMS reference method). The statistical data analysis was performed using SPSS 23.0 software. Results 35 patients were included into the study, 57% of men and 43% of woman. Mean age of patients - 47±13.5 years. Mean suPAR level before transplantation was 8.7±4.2 ng/ml. It was a trend towards lower mean suPAR level 12 days after Tx (5.9±2.8 ng/ml, p=0.1) as compared to before Tx. It was significant decrease of suPAR level 3 months after Tx (3.9±1.1 ng/ml, p=0.003) as compared to before Tx. There was no suPAR relation to patient’s age. Serum creatinine and eGFR did not correlate with suPAR levels measured at the same time (before Tx, 12 days, and 3 months after Tx). We did not find relation between suPAR level before transplantation and creatinine level and eGFR 12 days after Tx. We found a significant negative correlation between suPAR level before transplantation and creatinine level 3 months after transplantation (r = -0.4, p = 0.049), but not eGFR 3 months after Tx. In a group of patients with eGFR ≥45 ml/min/1.73m2 3 months after transplantation mean suPAR level before Tx (9.5±4.3 ng/ml), after 12 days (5.8±2.6 ng/ml), and 3 months after Tx (3.8±0.87 ng/ml) was not different than in group of patients with eGFR < 45 ml/min/1.73m2 (8±4.1 ng/ml, 5.2±3.5 ng/ml, 3.9±1.5 ng/ml accordingly), p>0.05. Conclusion There was a significant gradual decrease of suPAR levels during 3 months after transplantation. No correlation of suPAR levels and transplanted kidney function was confirmed. A larger study is needed to assess whether suPAR could predict long term outcomes in kidney transplantation.