Predictive Value of the sFlt-1:PlGF Ratio in Women with Suspected Preeclampsia.

BACKGROUND: The ratio of soluble fms-like tyrosine kinase 1 (sFlt-1) to placental growth factor (PlGF) is elevated in pregnant women before the clinical onset of preeclampsia, but its predictive value in women with suspected preeclampsia is unclear. METHODS: We performed a prospective, multicenter, observational study to derive and validate a ratio of serum sFlt-1 to PlGF that would be predictive of the absence or presence of preeclampsia in the short term in women with singleton pregnancies in whom preeclampsia was suspected (24 weeks 0 days to 36 weeks 6 days of gestation). Primary objectives were to assess whether low sFlt-1:PlGF ratios (at or below a derived cutoff) predict the absence of preeclampsia within 1 week after the first visit and whether high ratios (above the cutoff) predict the presence of preeclampsia within 4 weeks. RESULTS: In the development cohort (500 women), we identified an sFlt-1:PlGF ratio cutoff of 38 as having important predictive value. In a subsequent validation study among an additional 550 women, an sFlt-1:PlGF ratio of 38 or lower had a negative predictive value (i.e., no preeclampsia in the subsequent week) of 99.3% (95% confidence interval [CI], 97.9 to 99.9), with 80.0% sensitivity (95% CI, 51.9 to 95.7) and 78.3% specificity (95% CI, 74.6 to 81.7). The positive predictive value of an sFlt-1:PlGF ratio above 38 for a diagnosis of preeclampsia within 4 weeks was 36.7% (95% CI, 28.4 to 45.7), with 66.2% sensitivity (95% CI, 54.0 to 77.0) and 83.1% specificity (95% CI, 79.4 to 86.3). CONCLUSIONS: An sFlt-1:PlGF ratio of 38 or lower can be used to predict the short-term absence of preeclampsia in women in whom the syndrome is suspected clinically. (Funded by Roche Diagnostics.).

Elecsys® and Kryptor immunoassays for the measurement of sFlt-1 and PlGF to aid preeclampsia diagnosis: are they comparable?

Background For pregnant women with suspected preeclampsia, the soluble fms-like tyrosine-kinase 1 (sFlt-1)/placental growth factor (PlGF) ratio is a biomarker to aid diagnosis. We performed method comparisons between Elecsys® and Kryptor sFlt-1 and PlGF immunoassays and assessed the diagnostic performance for preeclampsia. Methods Serum samples from a case-control study involving 113 pregnant women with preeclampsia/elevated liver enzymes and low platelet count (HELLP) and 270 controls were analyzed. sFlt-1 and PlGF were measured using Roche Elecsys® and BRAHMS Kryptor sFlt-1/PlGF immunoassays. The sFlt-1/PlGF ratios were calculated, and Passing-Bablok regression/Bland-Altman plots were performed. Gestation-specific cut-offs, ≤33 and ≥85/≥110, were assessed. Results Mean (±2 standard deviation [SD]) differences between the Elecsys® and Kryptor values were: sFlt-1, 173.13 pg/mL (6237.66, -5891.40); PlGF, -102.71 pg/mL (186.06, -391.48); and sFlt-1/PlGF, 151.74 (1085.11, -781.63). The Elecsys® and Kryptor immunoassays showed high correlation: Pearson's correlation coefficients were 0.913 (sFlt-1) and 0.945 (PlGF). Slopes were 1.06 (sFlt-1) and 0.79 (PlGF), resulting in ~20% lower values for Kryptor PlGF. Sensitivities and specificities using the sFlt-1/PlGF ≥85 cut-off for early-onset preeclampsia (20 + 0 to 33 + 6 weeks) were 88.1%/100.0% (Elecsys®) and 90.5%/96.2% (Kryptor), respectively, and using the ≥110 cut-off for late-onset preeclampsia (≥34 + 0 weeks) were 51.3%/96.5% (Elecsys®) and 78.9%/90.1% (Kryptor), respectively. Using Elecsys® and Kryptor sFlt-1/PlGF, 0% and 3.8% of women, respectively, were falsely ruled-in for early-onset, and 3.5% and 9.9%, respectively, for late-onset preeclampsia. Conclusions Despite high correlation between the Elecsys® and Kryptor immunoassays, we observed significant differences between sFlt-1/PlGF and PlGF results. Therefore, sFlt-1/PlGF cut-offs validated for Elecsys® immunoassays are not transferable to Kryptor immunoassays.

Multicenter Evaluation of a 0-Hour/1-Hour Algorithm in the Diagnosis of Myocardial Infarction With High-Sensitivity Cardiac Troponin T.

STUDY OBJECTIVE: We aim to prospectively validate the diagnostic accuracy of the recently developed 0-h/1-h algorithm, using high-sensitivity cardiac troponin T (hs-cTnT) for the early rule-out and rule-in of acute myocardial infarction. METHODS: We enrolled patients presenting with suspected acute myocardial infarction and recent (<6 hours) onset of symptoms to the emergency department in a global multicenter diagnostic study. Hs-cTnT (Roche Diagnostics) and sensitive cardiac troponin I (Siemens Healthcare) were measured at presentation and after 1 hour, 2 hours, and 4 to 14 hours in a central laboratory. Patient triage according to the predefined hs-cTnT 0-hour/1-hour algorithm (hs-cTnT below 12 ng/L and Δ1 hour below 3 ng/L to rule out; hs-cTnT at least 52 ng/L or Δ1 hour at least 5 ng/L to rule in; remaining patients to the "observational zone") was compared against a centrally adjudicated final diagnosis by 2 independent cardiologists (reference standard). The final diagnosis was based on all available information, including coronary angiography and echocardiography results, follow-up data, and serial measurements of sensitive cardiac troponin I, whereas adjudicators remained blinded to hs-cTnT. RESULTS: Among 1,282 patients enrolled, acute myocardial infarction was the final diagnosis for 213 (16.6%) patients. Applying the hs-cTnT 0-hour/1-hour algorithm, 813 (63.4%) patients were classified as rule out, 184 (14.4%) were classified as rule in, and 285 (22.2%) were triaged to the observational zone. This resulted in a negative predictive value and sensitivity for acute myocardial infarction of 99.1% (95% confidence interval [CI] 98.2% to 99.7%) and 96.7% (95% CI 93.4% to 98.7%) in the rule-out zone (7 patients with false-negative results), a positive predictive value and specificity for acute myocardial infarction of 77.2% (95% CI 70.4% to 83.0%) and 96.1% (95% CI 94.7% to 97.2%) in the rule-in zone, and a prevalence of acute myocardial infarction of 22.5% in the observational zone. CONCLUSION: The hs-cTnT 0-hour/1-hour algorithm performs well for early rule-out and rule-in of acute myocardial infarction.

Multicenter prospective clinical study to evaluate the prediction of short-term outcome in pregnant women with suspected preeclampsia (PROGNOSIS): study protocol.

BACKGROUND: Preeclampsia is defined as new onset of hypertension and proteinuria at gestational week 20 or after. However, use of these measures to predict preeclampsia before its clinical onset is unreliable, and evidence suggests that preeclampsia, eclampsia, or hemolysis, elevated liver enzymes and low platelet count (HELLP) syndrome may develop without hypertension or proteinuria being evident. Because of its unpredictability, varying clinical presentation and potential adverse outcomes, pregnant women with suspected preeclampsia require intensive monitoring or hospitalization. Beyond preeclampsia diagnosis, there is a high unmet medical need for more reliable predictive markers for preeclampsia to improve maternal and fetal outcomes and reduce unnecessary hospital admissions. An imbalance of circulating angiogenic and antiangiogenic factors, including raised soluble fms-like tyrosine kinase-1 (sFlt-1) and decreased placental growth factor (PlGF), has been found in women diagnosed with preeclampsia and before clinical onset of the disease. The PRediction of short-term Outcome in preGNant wOmen with Suspected preeclampsIa Study (PROGNOSIS) was designed to investigate the use of the sFlt-1/PlGF ratio in the short-term prediction of preeclampsia. METHODS/DESIGN: This global, multicenter, prospective, double-blind, non-interventional study aims to derive and validate cutoffs for the sFlt-1/PlGF ratio, to rule out (for 1 week) or rule in (within 4 weeks) the occurrence of preeclampsia/eclampsia/HELLP syndrome. Eligible participants are women presenting at 24 to <37 weeks' gestation with clinical suspicion of, but not manifest preeclampsia/eclampsia/HELLP syndrome. Clinical assessments, maternal serum sFlt-1/PlGF sampling and documentation of maternal/neonatal outcomes are performed at regular intervals, using strict diagnostic criteria for preeclampsia-related conditions and outcomes. Serum sFlt-1 and PlGF analysis will be performed using fully automated Elecsys® immunoassays. Investigators and participants will remain blinded to the results. Target recruitment is 1000 participants. Health economic analysis is also planned. DISCUSSION: The results of PROGNOSIS will provide the most comprehensive evidence to date on the accuracy of the sFlt-1/PlGF ratio for short-term prediction of preeclampsia/eclampsia/HELLP syndrome. Adoption of the sFlt-1/PlGF test in clinical practice has the potential to reduce the frequency of adverse pregnancy outcomes for both mother and fetus, and decrease healthcare costs associated with unnecessary hospitalization of women with suspected preeclampsia.

Feasibility of using real-world free thyroxine data from the US and Europe to enable fast and efficient transfer of reference intervals from one population to another.

Objectives: The direct approach for determining reference intervals (RIs) is not always practical. This study aimed to generate evidence that a real-world data (RWD) approach could be applied to transfer free thyroxine RIs determined in one population to a second population, presenting an alternative to performing multiple RI determinations. Design and methods: Two datasets (US, n = 10,000; Europe, n = 10,000) were created from existing RWD. Descriptive statistics, density plots and cumulative distributions were produced for each data set and comparisons made. Cumulative probabilities at the lower and upper limits of the RIs were identified using an empirical cumulative distribution function. According to these probabilities, estimated percentiles for each dataset and estimated differences between the two sets of percentiles were obtained by case resampling bootstrapping. The estimated differences were then evaluated against a pre-determined acceptance criterion of ≤7.8% (inter-individual biological variability). The direct approach was used to validate the RWD approach. Results: The RWD approach provided similar descriptive statistics for both populations (mean: US = 16.1 pmol/L, Europe = 16.4 pmol/L; median: US = 15.4 pmol/L, Europe = 15.8 pmol/L). Differences between the estimated percentiles at the upper and lower limits of the RIs fulfilled the pre-determined acceptance criterion and the density plots and cumulative distributions demonstrated population homogeneity. Similar RI distributions were observed using the direct approach. Conclusions: This study provides evidence that a RWD approach can be used to transfer RIs determined in one population to another.

Soluble fms-Like Tyrosine Kinase-1-to-Placental Growth Factor Ratio and Time to Delivery in Women With Suspected Preeclampsia.

OBJECTIVE: To assess the association of a serum soluble fms-like tyrosine kinase 1-to-placental growth factor (sFlt-1-to-PlGF) ratio of greater than 38 with time to delivery and preterm birth. METHODS: Secondary analysis of an observational cohort study that included women 18 years of age or older from 24 to 36 6/7 weeks of gestation at their first study visit with suspected (not confirmed) preeclampsia. Participants were recruited from December 2010 to January 2014 at 30 sites in 14 countries. A total of 1,041 women were included in time-to-delivery analysis and 848 in preterm birth analysis. RESULTS: Women with an sFlt-1-to-PlGF ratio greater than 38 (n=250) had a 2.9-fold greater likelihood of imminent delivery (ie, delivery on the day of the test) (Cox regression hazard ratio 2.9; P<.001) and shorter remaining time to delivery (median 17 [interquartile range 10-26] compared with 51 [interquartile range 30-75] days, respectively; Weibull regression factor 0.62; P<.001) than women with an sFlt-1-to-PlGF ratio of 38 or less, whether or not they developed preeclampsia. For women who did not (n=842) and did develop preeclampsia (n=199), significant correlations were seen between an sFlt-1-to-PlGF ratio greater than 38 and preterm birth (r=0.44 and r=0.46; both P<.001). Among women who did not develop preeclampsia, those who underwent iatrogenic preterm delivery had higher median sFlt-1-to-PlGF ratios at their first visit (35.3, interquartile range 6.8-104.0) than those who did not (8.4, interquartile range 3.4-30.6) or who delivered at term (4.3, interquartile range 2.4-10.9). CONCLUSIONS: In women undergoing evaluation for suspected preeclampsia, a serum sFlt-1-to-PlGF ratio greater than 38 is associated with a shorter remaining pregnancy duration and a higher risk of preterm delivery.

Diagnostic and prognostic implications using age- and gender-specific cut-offs for high-sensitivity cardiac troponin T - Sub-analysis from the TRAPID-AMI study.

OBJECTIVES: To evaluate the impact of age- and gender-specific cut-offs for high-sensitivity cardiac troponin T (hs-cTnT) compared to the general 99th percentile hs-cTnT cut-off on diagnosis and prognosis of acute myocardial infarction (AMI). METHODS: 1282 unselected patients presenting to the emergency department with suspected AMI were enrolled as part of the TRAPID-AMI study. In the present sub-analysis, reclassification of AMI diagnosis was performed by comparing the general hs-cTnT cut-off of 14ng/L to previously proposed age- and gender-dependent hs-cTnT 99th percentile cut-offs (28ng/L for ≥65years, 9ng/L for female and 15.5ng/L for male patients). Patients were further clinically adjudicated into acute coronary syndrome (ACS) and non-ACS. RESULTS: For patients ≥65years, application of age-specified cut-offs resulted in a decrease of AMI from 29.8% to 18.3% in the entire cohort (n=557) and 54.7% to 40.9% in the ACS subcohort (n=225). Using gender-specific cut-offs, AMI-rate increased from 16.6% to 22.6% (entire cohort, n=477) and 62.6% to 71.7% (ACS subcohort, n=99) in women, whereas in men, rates decreased from 23.1% to 21.1% (entire cohort, n=805) and 48.8% to 45.9% (ACS, n=281), respectively. Age-specified cut-offs significantly reclassified patients for outcomes of 1-month and 3-month mortality in the entire and ACS cohort (14.2% net reclassification improvement, p<0.001, respectively). Contrary, no significant differences in outcomes could be found using gender-specific cut-offs. CONCLUSIONS: While influence of gender-specific hs-cTnT cut-offs on diagnostic and prognostic reclassification was only modest in patients with suspected AMI, age-specific cut-offs showed a significant impact and may be considered for further validation.

The Use of Very Low Concentrations of High-sensitivity Troponin T to Rule Out Acute Myocardial Infarction Using a Single Blood Test.

BACKGROUND: Recent single-center and retrospective studies suggest that acute myocardial infarction (AMI) could be immediately excluded without serial sampling in patients with initial high-sensitivity cardiac troponin T (hs-cTnT) levels below the limit of detection (LoD) of the assay and no electrocardiogram (ECG) ischemia. OBJECTIVE: We aimed to determine the external validity of those findings in a multicenter study at 12 sites in nine countries. METHODS: TRAPID-AMI was a prospective diagnostic cohort study including patients with suspected cardiac chest pain within 6 hours of peak symptoms. Blood drawn on arrival was centrally tested for hs-cTnT (Roche; 99th percentile = 14 ng/L, LoD = 5 ng/L). All patients underwent serial troponin sampling over 4-14 hours. The primary outcome, prevalent AMI, was adjudicated based on sensitive troponin I (Siemens Ultra) levels. Major adverse cardiac events (MACE) including AMI, death, or rehospitalization for acute coronary syndrome with coronary revascularization were determined after 30 days. RESULTS: We included 1,282 patients, of whom 213 (16.6%) had AMI and 231 (18.0%) developed MACE. Of 560 (43.7%) patients with initial hs-cTnT levels below the LoD, four (0.7%) had AMI. In total, 471 (36.7%) patients had both initial hs-cTnT levels below the LoD and no ECG ischemia. These patients had a 0.4% (n = 2) probability of AMI, giving 99.1% (95% confidence interval [CI] = 96.7% to 99.9%) sensitivity and 99.6% (95% CI = 98.5% to 100.0%) negative predictive value. The incidence of MACE in this group was 1.3% (95% CI = 0.5% to 2.8%). CONCLUSIONS: In the absence of ECG ischemia, the detection of very low concentrations of hs-cTnT at admission seems to allow rapid, safe exclusion of AMI in one-third of patients without serial sampling. This could be used alongside careful clinical assessment to help reduce unnecessary hospital admissions.

A combination of serum markers for the early detection of colorectal cancer.

PURPOSE: Fecal occult blood testing is recommended as first-line screening to detect colorectal cancer (CRC). We evaluated markers and marker combinations in serum as an alternative to improve the detection of CRC. EXPERIMENTAL DESIGN: Using penalized logistic regression, 6 markers were selected for evaluation in 1,027 samples (301 CRC patients, 143 patients with adenoma, 266 controls, 141 disease controls, and 176 patients with other cancer). The diagnostic performance of each marker and of marker combinations was assessed. RESULTS: To detect CRC from serum samples, we tested 22 biomarkers. Six markers were selected for a marker combination, including the known tumor markers CEA (carcinoembryonic antigen) and CYFRA 21-1 as well as novel markers or markers that are less routinely used for the detection of CRC: ferritin, osteopontin (OPN), anti-p53, and seprase. CEA showed the best sensitivity at 95% specificity with 43.9%, followed by seprase (42.4%), CYFRA 21-1 (35.5%), OPN (30.2%), ferritin (23.9%), and anti-p53 (20.0%). A combination of these markers gave 69.6% sensitivity at 95% specificity and 58.7% at 98% specificity. Focusing on International Union against Cancer (UICC) stages 0-III reduced the sensitivity slightly to 68.0% and 53.3%, respectively. In a subcollective, with matched stool samples (75 CRC cases and 234 controls), the sensitivity of the marker combination was comparable with fecal immunochemical testing (FIT) with 82.4% and 68.9% versus 81.8% and 72.7% at 95% and 98% specificity, respectively. CONCLUSIONS: The performance of the serum marker combination is comparable with FIT. This provides a novel tool for CRC screening to trigger a follow-up colonoscopy for a final diagnosis.