FEV1 is a stronger mortality predictor than FVC in patients with moderate COPD and with an increased risk for cardiovascular disease.

Purpose: Chronic obstructive pulmonary disease (COPD) is one of the leading causes of death worldwide. Impaired lung function is associated with heightened risk for death, cardiovascular events, and COPD exacerbations. However, it is unclear if forced expiratory volume in one second (FEV1) and forced vital capacity (FVC) differ in predictive value. Patients and Methods: Data from 16,485 participants in the Study to Understand Mortality and Morbidity (SUMMIT) in COPD were analyzed. Patients were grouped into quintiles for each lung function parameter (FEV1 %predicted, FVC %predicted, FEV1/FVC). The four highest quintiles (Q2-Q5) were compared to the lowest (Q1) to assess their relationship with all-cause mortality, cardiovascular events, and moderate-to-severe and severe exacerbations. Cox-regression was used, adjusted for age, sex, ethnicity, body-mass index, smoking status, previous exacerbations, cardiovascular disease, treatment, and modified Medical Research Council dyspnea score. Results: Compared to Q1 (<53.5% FEV1 predicted), increasing FEV1 quintiles (Q2 53.5-457.5% predicted, Q3 57.5-461.6% predicted, Q4 61.6-465.8% predicted, and Q5 ≥65.8%) were all associated with significantly decreased all-cause mortality (20% (4-34%), 28% (13-40%), 23% (7-36%), and 30% (15-42%) risk reduction, respectively). In contrast, a significant risk reduction (21% (4-35%)) was seen only between Q1 and Q5 quintiles of FVC. Neither FEV1 nor FVC was associated with cardiovascular risk. Increased FEV1 and FEV1/FVC quintiles were also associated with the reduction of moderate-to-severe and severe exacerbations while, surprisingly, the highest FVC quintile was related to the heightened exacerbation risk (28% (8-52%) risk increase). Conclusion: Our results suggest that FEV1 is a stronger predictor for all-cause mortality than FVC in moderate COPD patients with heightened cardiovascular risk and that subjects with moderate COPD have very different risks.

First trimester maternal serum placental growth factor levels in twin pregnancies.

BACKGROUND: An understanding of the normal behavior of biochemical markers in twin pregnancies is necessary in order to offer prenatal screening to this subgroup. This study investigates the levels of first trimester maternal serum placental growth factor (PlGF) in twin and singleton pregnancies. METHODS: The PlGF concentrations were measured by an automated assay in the first trimester maternal serum of 440 dichorionic twin, 116 monochorionic twin, and 607 singleton pregnancy samples thawed from frozen storage. RESULTS: The PlGF concentrations in singleton levels were predicted by gestational age, maternal ethnicity, and smoking status. Following the correction for these variables, PlGF levels were, on average, 41% higher in dichorionics, but only 16% higher in monochorionics, compared to singleton pregnancies. CONCLUSIONS: First trimester maternal serum PlGF levels are increased in twin pregnancies compared with singleton pregnancies, but to less of an extent than is common with other screening markers, especially in monochorionic twins.

The association between gestational diabetes mellitus and first trimester aneuploidy screening markers.

OBJECTIVE: To establish whether maternal serum first trimester concentrations of PAPP-A and free hCGß are altered in pregnancies that subsequently are diagnosed by an oral glucose tolerance test (OGTT) with gestational diabetes mellitus (GDM). METHODS: Over the period 2009 and 2011, the results for women who had first trimester screening for aneuploidy were matched with those having an oral glucose tolerance test at 22-26 weeks for suspected GDM. Free hCGß, PAPP-A and NT MoMs were compared amongst the group having an OGTT with confirmed GDM and those in which GDM was not confirmed. A second comparison group consisted of all non-aneuploidy singleton pregnancies in which no OGTT was performed. RESULTS: During the three-year period, 27,660 singleton pregnancies were screened of which 7429 cases had an OGTT of which 870 cases were classed as GDM by WHO criteria. There was a significant 7-9% reduction in both PAPP-A and free hCGß MoM in the GDM group compared with either the OGTT non-GDM group or the remaining pregnancies with no known risk factors for evidence of GDM. There was no difference in the NT measurements. CONCLUSIONS: First trimester concentrations of PAPP-A and free hCGß are reduced in pregnancies that subsequently are diagnosed with GDM and may be useful in further screening algorithms for this disorder although the sensitivity alone is quite poor.

Evaluation of a dried blood spot assay to measure prenatal screening markers pregnancy-associated plasma protein a and free ß-subunit of human chorionic gonadotropin.

BACKGROUND: First-trimester prenatal screening for aneuploidy by use of dried blood spots (DBSs) may offer practical benefits in settings where the instability of intact human chorionic gonadotropin (hCG) is problematic. We evaluated a DBS pregnancy-associated plasma protein A (PAPP-A) and free ß-subunit of hCG (free hCGß) dual assay and compared it to serum screening. METHODS: Hematocrit-corrected DBS PAPP-A and free-hCGß concentrations were measured and compared with serum concentrations in 252 first-trimester samples. Serum intact hCG was also measured and, with serum free hCGß, was used to fit a model to predict serum-equivalent DBS free-hCGß concentrations. In a separate experiment, we investigated the effects of temperature and relative humidity during the blood spot drying process. RESULTS: The DBS assay for PAPP-A performed similarly to the serum assay, whereas free-hCGß DBS measurements were consistently higher than in serum. Purifying blood spots of intact hCG suggested that the free-hCGß DBS assay is measuring a composite of free hCGß and additional ß-subunits from intact hCG. The drying experiment showed that increased temperature and relative humidity during the drying process resulted in increased free hCGß and reduced PAPP-A. CONCLUSIONS: Despite measuring additional free hCGß compared to the serum assay, DBS analysis has a role in first-trimester combined screening for trisomy 21.

Accuracy of self-reported smoking status in first trimester aneuploidy screening.

OBJECTIVES: To review the accuracy of self-reporting of smoking status in our first trimester screening population and to assess the levels of pregnancy-associated plasma protein-A (PAPP-A) and free-ß human chorionic gonadotropin (free-hCGß) in women who were classified for smoking status by serum cotinine concentrations and self-reporting. METHODS: Cotinine concentration was determined in the stored serum 696 self-reported smokers and 442 self-reported non-smokers. PAPP-A and free-hCGß multiples of the medians (MoMs) determined at screening were reverted to uncorrected for self-reported smoking status. RESULTS: A total of 21.7% of those self-reporting as non-smokers had increased serum cotinine concentrations (using a cut-off of 13.7 ng/mL), indicating a positive smoking status. This under-reporting meant that serum PAPP-A and free-hCGß MoMs were greater reduced in smokers classified by cotinine levels (17.2% and 9.7%) than in those classified by self-reporting (14.6% and 2.8%). Women who were classified as smokers at conception but had stopped at some time afterwards did not have significantly reduced marker MoMs to non-smokers. CONCLUSIONS: Self-reporting results in under-representation of smoking in our population, resulting in a significant bias and inflated screen-positive rates.

Correction of first trimester biochemical aneuploidy screening markers for smoking status: influence of gestational age, maternal ethnicity and cigarette dosage.

OBJECTIVE: To examine the gestational age, maternal ethnicity and cigarette dosage effects of the reduction of maternal serum pregnancy-associated plasma protein A (PAPP-A) and free-ß human chorionic gonadotrophin (free hCGß) in smokers. METHODS: Maternal serum PAPP-A and free hCGß corrected for confounders, excluding smoking, in first trimester smokers and nonsmokers were compared by gestational age, maternal ethnicity and cigarette dosage. A small set of second trimester smokers and nonsmoker controls were analysed for PAPP-A along with free hCGß and assessed for gestational age effects of smoking. RESULTS: Pregnancy-associated plasma protein A reduction by smoking in the first trimester was not influenced by gestational age, however free hCGß levels were only significantly reduced in weeks 12 and 13 in smokers. Ethnicity and cigarette dosage were also found to influence the reduction of both makers in smokers in the first trimester. In second trimester smokers, PAPP-A was found to be reduced by less and free hCGß reduced by more than in the first trimester, although no second trimester gestational age effect on smoking was found. CONCLUSIONS: Current methods of correcting for smoking status may be an oversimplification of a more complex subject.

Effect of gestational age on first trimester maternal serum prenatal screening correction factors for ethnicity and IVF conception.

OBJECTIVE: The aim of this study is to investigate gestational age effects of maternal ethnicity and in vitro fertilization (IVF) pregnancy correction factors of first trimester trisomy 21 screening markers pregnancy associated plasma protein A (PAPP-A) and free-ß human chorionic gonadotropin (free hCGß) in a large dataset. METHODS: Data from 205,341 normal singleton pregnancies were retrieved, and PAPP-A and free hCGß concentrations were converted to multiples of the medians (MoMs) uncorrected for either maternal ethnicity or IVF pregnancy. Log(10) transformed MoMs were plotted against gestational age in each group to examine gestational age effects RESULTS: Significant gestational age effects were found for correction factors for PAPP-A in Afro-Caribbean, South Asian and East Asian, and for free hCGß in Afro-Caribbean and IVF pregnancy. CONCLUSIONS: Current single correction factors for PAPP-A and free hCGß based on maternal ethnicity and IVF pregnancy are inappropriate, and future screening algorithms need to take into account the change in effect of these factors with gestational age.

Analytical goal setting in aneuploidy screening: within person biological variability of first trimester biochemical markers.

OBJECTIVE: To determine the average within person biological variability of free-ß human chorionic gonadotrophin (free hCGß), intact hCG and pregnancy-associated plasma protein A (PAPP-A), and to establish analytical goals for the measurement of these markers when used in first trimester screening. METHODS: Free hCGß, PAPP-A and intact hCG were measured on paired first trimester samples collected during the same pregnancy. Results were converted to Multiple of the Median (MoMs).The overall total variation at each day log was determined from a correlation of the marker MoMs in the log domain. Biological variation was calculated after taking into account analytical variation. RESULTS: The within person biological variability for free hCGß varied from 1.30% at 2 days separation to 5.25% at 5 days. For PAPP-A this was 1.96% and 5.03%, respectively, and for intact hCG this was 14.59% and 21.09%. All markers exhibit a rapid increase in biological variability as the time separation increased. CONCLUSIONS: Setting analytical goals for precision of measurement of first trimester biochemical markers from within person biological variability would suggest that free hCGß and PAPP-A needs to be measured with a precision of 2.5%, targets close to those set empirically by the Fetal Medicine Foundation and achieved in practice by some analytical system in routine use.

The stability of free-ß human chorionic gonadotrophin and pregnancy-associated plasma protein-A in first trimester dried blood spots.

OBJECTIVES: To determine the stability of first trimester free-ß human chorionic gonadotrophin (free-ß hCG) and pregnancy-associated plasma protein-A (PAPP-A) in dried blood spots (DBSs) under typical storage conditions. METHODS: First trimester maternal blood was spotted onto filter paper and left to dry. DBSs were analysed for PAPP-A and free-ß hCG using an AutoDELFIA dual assay at t = 0. Cards were stored at one of - 20 °C, refrigerator temperature, room temperature or 30 °C and reanalysed at set future time points. RESULTS: Free-ß hCG was stable (<10% change in concentration) under all temperatures tested for at least 35 days. PAPP-A was stable at - 20 °C and refrigerator temperature for at least 35 days. However, PAPP-A levels decreased by 10% at 4.1 days at room temperature and at 3.9 days at 30 °C. Longer-term storage at - 20 °C and refrigerator temperature showed that both PAPP-A and free-ß hCG levels were significantly decreased by 107 and 244 days. CONCLUSIONS: Free-ß hCG stability is greatly improved in DBS compared to serum storage; however PAPP-A stability is decreased in the DBS medium. Despite this DBS, screening may not necessitate such strict storage and transportation rules compared to serum screening programmes.

The relationship between maternal body mass, smoking status and ethnicity and first trimester nuchal translucency thickness.

OBJECTIVE: To investigate the existence of a relationship between maternal body mass, maternal ethnicity and maternal smoking status and nuchal translucency (NT) in the first trimester of pregnancy. METHODS: NT measurements from 130 339 euploid, singleton pregnancies were converted to NT multiples of the median (MoM) and delta NT using expected medians determined using regression analysis. Relationships between maternal body mass index (BMI), maternal weight, maternal ethnicity and maternal smoking status and NT MoM and delta NT were examined. RESULTS: NT increased with gestational age. Uncorrected NT MoM and delta NT demonstrated small but significant positive relationships with either maternal BMI or maternal weight. Both NT MoM and delta NT were slightly, but significantly, increased in smokers compared to non-smokers and Afro-Caribbean compared to Caucasians, and slightly, but significantly, decreased in Asians compared to Caucasians. CONCLUSION: Although statistically significant, all the changes reported are likely to be too small to be relevant in terms of correcting in prenatal screening.

Maternal plasma levels of follistatin-related gene protein in the first trimester of pregnancies with Down syndrome.

OBJECTIVE: To determine maternal plasma levels of follistatin-related gene protein (FLRG) in the first trimester of pregnancy and assess its potential role as a marker for prenatal screening of Down syndrome. METHODS: Maternal plasma levels of FLRG were determined in 100 pregnant women with normal fetuses in their first trimester of pregnancy (i.e. 11th to 15th weeks). These results were compared with 20 cases with Down syndrome fetuses, taking into consideration clinical and demographic variables, such as maternal age, maternal weight, gestational age, smoking status and ethnicity. RESULTS: Maternal plasma median of FLRG in the normal population was 1.41 ng/mL with 95% confidence interval (CI) of 1.37-1.70 and interquartile range (IQR) of 0.88, during the 11th to 15th weeks of pregnancy. Maternal age and weight were the only variables significantly related to FLRG levels (p = 0.030 and 0.020, respectively). Only maternal and gestational ages were related to Down syndrome (p = 0.039 and 0.006, respectively). Maternal plasma levels of FLRG were not significantly different in the presence of Down syndrome fetuses compared to normal population (p = 0.63). CONCLUSION: FLRG can be successfully detected in maternal plasma in the first trimester of pregnancy. However, its levels are not significantly altered in the presence of Down syndrome fetuses.

PAPP-A and free ss-hCG stability in first trimester serum using PerkinElmer AutoDELFIA and DELFIA Xpress systems.

BACKGROUND: In this study we aim to investigate the stability of free-beta-hCG and PAPP-A over time in serum and whole blood in typical routine temperatures. METHODS: Serum pools were stored under the following temperatures: 30 degrees C, room temperature, refrigerator temperature and -20 degrees C, for up to 240 days. Stability of the markers in whole blood was examined in a shorter study and compared to serum. Samples were analysed using the AutoDELFIA and DELFIA Xpress analysers. RESULTS: On the AutoDELFIA, considering a 10% change acceptable, PAPP-A levels are stable in serum for 142 days at refrigerator temperature, 37 days at room temperature and 20 days at 30 degrees C. Free-beta hCG is stable in serum for 94 days at refrigerator temperature, 3 days at room temperature and 12 h at 30 degrees C. There was no significant change with either analyte after -20 degrees C storage for up to 240 days or after six repeated freeze-thaw cycles. In whole blood, free-beta hCG levels increased more rapidly compared to serum, especially at 30 degrees C. CONCLUSION: Normal handling of samples is only likely to minimally effect the risk assessment of chromosomal anomalies. However, careful attention should be paid to minimise the increase of free-beta hCG levels in samples shipped as whole blood.

Is maternal renal disease a cause of elevated free beta-hCG in first trimester aneuploidy screening?

OBJECTIVE: To asses whether supra elevated levels of maternal serum free beta hCG in the first trimester are associated with impaired renal function. METHOD: A cohort of 553 women with maternal serum free beta-hCG greater than 5 multiple of median (MoM) with a single euploid fetus was matched with a control of the same maternal age (+/-1 year), ethnic origin and with a free beta-hCG within the range 0.50-1.50 MoM. Screening samples were analysed for serum creatinine and estimated glomerular filtration rate was calculated. Renal function in the two groups was compared. The database was examined to find outcomes registered as known renal disease amongst the high free beta-hCG group. RESULTS: In the group with a supra elevated free beta-hCG MoM there was a significant reduction in estimated glomerular filtration rate (eGFR) (122.85, 95% CI 120.43-124.74 vs 118.80, 95% CI 114.90-121.59; p = 0.009) suggesting a small but increased risk of renal disease. CONCLUSIONS: The presence of renal disease should also be considered as one potential cause of supra elevated levels of free beta-hCG in addition to the possibility of paternally derived triploidy and trisomy 21.

First trimester maternal serum placental protein 13 for the prediction of pre-eclampsia in women with a priori high risk.

OBJECTIVE: To evaluate whether first trimester maternal serum PP13 can predict pre-eclampsia among women with a priori high risk. METHOD: This was a nested case-control study. Women less than 14 weeks' gestation at increased risk of developing pre-eclampsia were recruited. Venous blood samples were assayed for PP13 using enzyme-linked immunosorbent assay. PP13 multiples of median (MoM) were calculated and adjusted for body mass index, ethnicity, smoking, maternal age and parity. For each case of pre-eclampsia (n = 42), five controls were randomly selected. PP13 levels were compared between women who developed pre-eclampsia and controls using the Wilcoxon rank sum test. Sensitivity and false-positive rates were derived from receiver operating characteristic curves. RESULTS: Women who developed pre-eclampsia had significantly lower (P < 0.001) PP13 MoMs compared with controls. PP13 MoMs for controls and pre-eclampsia cases were 1.0 (range 0.0-10.0) and 0.4 (range 0.0-7.0), respectively (P < 0.001). At a MoM cutoff of 0.53, for a false-positive rate of 10%, sensitivity was 50% for pre-eclampsia at term (>37 weeks), 62% for preterm pre-eclampsia (<37 weeks) and 71% for early-onset pre-eclampsia (<34 weeks). CONCLUSION: First trimester PP13 can predict pre-eclampsia in women at increased a priori risk and predicts early-onset better than late-onset disease.

The impact of fetal gender on first trimester nuchal translucency and maternal serum free beta-hCG and PAPP-A MoM in normal and trisomy 21 pregnancies.

OBJECTIVE: To investigate if fetal sex has an impact on 1st trimester combined screening for aenuploidy. METHODS: We studied the first trimester PAPP-A, free beta-human chorionic gonadatropin (beta-hCG) and nuchal translucency levels in 56,024 normal, singleton pregnancies with known fetal sex at birth. We also examined the distributions in 722 pregnancies with trisomy 21 of known fetal sex. RESULTS: We have found a 14.74% increase in first trimester maternal serum (MS) median free beta-hCG MoM, 6.25% increase of PAPP-A and a 9.41% decrease in delta NT, when the fetus was female. Analysis of data has shown that women carrying a female fetus were 1.084 times more likely to be in the 'at risk' group than those carrying a male fetus. In examining data from 722 pregnancies in which the fetus was affected by trisomy 21, we observed a similar 20.8% increase in free beta-hCG MoM, 5.7% increase in PAPP-A and a 12% decrease in delta NT when the fetus was female. Amongst the trisomy 21 cases, 88.8% of male trisomy 21 cases were detected compared with 91.2% in female cases, this difference was not statistically significant. Correcting for fetal sex redressed the balance in screen-positive rate between the sexes and had a minimal impact on detection rate. CONCLUSION: Correcting for fetal sex may be a worthwhile consideration. A cost-benefit analysis would be required to determine if it is feasible to introduce fetal gender assignment into the routine first trimester scan for the purpose of marker correction and whether this would have any significant impact.

The effect of Rhesus status on first-trimester pregnancy screening markers free beta human chorionic gonadotropin, pregnancy-associated plasma protein-A and nuchal translucency.

OBJECTIVE: To examine whether maternal Rhesus status has any effect on the levels of first-trimester markers free beta-human chorionic gonadotropin (beta-hCG), pregnancy-associated plasma protein-A (PAPP-A) and nuchal translucency (NT). METHODS: First-trimester free-beta-hCG and PAPP-A levels from pregnant women attending three hospitals in Kent were converted into MoMs and corrected for maternal weight, ethnicity, and smoking status. Maternal Rhesus status data were merged with screening data and free-beta-hCG and PAPP-A medians multiples of medians (MoMs) and NT from the Rhesus positive and Rhesus negative group were compared. RESULTS: Totally, 15 045 normal, singleton pregnancies were retrieved with full records. Altogether, 16.0% of the population were Rhesus negative. There was no difference between the medians MoMs of both free-beta-hCG nor PAPP-A nor NT in the two Rhesus status groups (p > 0.05). Demographic analysis on the distribution of Rhesus status in different ethnic origins showed that Caucasians have lower percentages of RhD-positive antigen compared to Asians and Afro-Caribbeans. CONCLUSION: Maternal Rhesus status does not influence the levels of free-beta-hCG and PAPP-A in the first trimester of pregnancy in this almost exclusively Caucasian population studied; therefore correction for maternal Rhesus status is not suggested.

First trimester intact hCG as an early marker of trisomy 21: a promise unrecognised?

BACKGROUND: An initial study of trisomy 21 cases showed that prior to 10 weeks, maternal serum levels of intact hCG in the early first trimester are lower than normal. Here we further study the levels prior to and after 10 weeks of gestation to further establish whether or not the intact hCG is effective as a very early screening marker. METHODS: Fifty-nine samples from pregnancies with trisomy 21 were identified, 31 were collected between the sixth and ninth weeks of gestation and 28 after the tenth week. A series of 629 gestational age-matched samples collected during the same period formed the control group. Intact hCG was measured by a DELFIA assay. RESULTS: The multiples of the median (MoM) in cases (n = 31) collected prior to 10 weeks were 0.79 (CI 0.62-0.98) at a median gestation of 9.1 weeks. Prior to 9 weeks (n = 14) the median was 0.774 (CI 0.54-1.09) at a median gestation of 8.5 weeks. Modelling the detection rate for a 3 or 5% false-positive rate when screening using intact hCG, free beta-hCG and PAPP-A at 8-10 weeks of gestation indicated that 71 or 77% of cases would be detected. CONCLUSION: More data are needed to establish a secure MoM for intact hCG in pregnancies prior to 10 weeks, before it could be considered a suitable screening marker.

First-trimester maternal placental protein 13 levels in pregnancies resulting in adverse outcomes.

BACKGROUND: In a previous study, reduced levels of maternal serum placental protein 13 (PP13) in the first trimester have been correlated with adverse pregnancy outcomes. The objective of this study was to compare first-trimester PP13 levels in control pregnancies with pregnancies resulting in one or more of the following adverse outcomes: intrauterine growth restriction (IUGR), small and very small (3rd, 5th, 10th centile) for gestational age (SGA), low (<1.5 and < 2.5 kg) birth weight (LBW), macrosomia (the > 90th centile), large birth weight (>4.5 kg), preterm (35-36 weeks) and very early (<34 weeks) delivery (PTD), and intrauterine fetal demise (IUFD). METHODS: Maternal serum samples from 1940, 11 to 14 weeks singleton pregnancies, were assayed for PP13 and the concentrations were corrected for gestational age, maternal weight, smoking status, and ethnic origin. A comparison of the levels of PP13 in 364 controls and 1576 adverse outcome categories was made. PP13 levels were expressed in terms of both concentration and multiple of medians (MoMs). RESULTS: Comparison of PP13 MoMs from SGA, PTD, and low birth weight samples with control pregnancy samples showed no statistically significant difference. In macrosomic pregnancies (>90th centile), levels of PP13 were significantly higher than controls (p = 0.0263) although the number of cases in this study was small. CONCLUSION: Decreased levels of PP13 were not significantly correlated with the studied adverse pregnancy outcomes of IUGR, PTD low birth weight, and IUFD. Further studies are required to evaluate if measurement of PP13 has any value in the early assessment of pregnancies.