Lisa Wernroth

Determining vitamin D status: a comparison between commercially available assays.

Background Vitamin D is not only important for bone health but can also affect the development of several non-bone diseases. The definition of vitamin D insufficiency by serum levels of 25-hydroxyvitamin D depends on the clinical outcome but might also be a consequence of analytical methods used for the definition. Although numerous 25-hydroxyvitamin D assays are available, their comparability is uncertain. We therefore aim to investigate the precision, accuracy and clinical consequences of differences in performance between three common commercially available assays. Methodology/Principal Findings Serum 25-hydroxyvitamin D levels from 204 twins from the Swedish Twin Registry were determined with high-pressure liquid chromatography-atmospheric pressure chemical ionization-mass spectrometry (HPLC-APCI-MS), a radioimmunoassay (RIA) and a chemiluminescent immunoassay (CLIA). High inter-assay disagreement was found. Mean 25-hydroxyvitamin D levels were highest for the HPLC-APCI-MS technique (85 nmol/L, 95% CI 81–89), intermediate for RIA (70 nmol/L, 95% CI 66–74) and lowest with CLIA (60 nmol/L, 95% CI 56–64). Using a 50-nmol/L cut-off, 8% of the subjects were insufficient using HPLC-APCI-MS, 22% with RIA and 43% by CLIA. Because of the heritable component of 25-hydroxyvitamin D status, the accuracy of each method could indirectly be assessed by comparison of within-twin pair correlations. The strongest correlation was found for HPLC-APCI-MS (r = 0.7), intermediate for RIA (r = 0.5) and lowest for CLIA (r = 0.4). Regression analyses between the methods revealed a non-uniform variance (p<0.0001) depending on level of 25-hydroxyvitamin D. Conclusions/Significance There are substantial inter-assay differences in performance. The most valid method was HPLC-APCI-MS. Calibration between 25-hydroxyvitamin D assays is intricate.

Biomarkers in Relation to the Effects of Ticagrelor in Comparison With Clopidogrel in Non–ST-Elevation Acute Coronary Syndrome Patients Managed With or Without In-Hospital Revascularization A Substudy From the Prospective Randomized Platelet Inhibition and Patient Outcomes (PLATO) Trial

Background— Risk stratification and the use of specific biomarkers have been proposed for tailoring treatment in patients with non–ST-elevation acute coronary syndrome (NSTE-ACS). We investigated the prognostic importance of high-sensitivity troponin T (hs-TnT), N-terminal pro-brain natriuretic peptide (NT-proBNP), and growth differentiation factor-15 (GDF-15) in relation to randomized treatment (ticagrelor versus clopidogrel) and management strategy (with or without revascularization) in the NSTE-ACS subgroup of the Platelet Inhibition and Patient Outcomes (PLATO) trial. Methods and Results— Of 18 624 patients in the PLATO trial, 9946 had an entry diagnosis of NSTE-ACS and baseline blood samples available. During index hospitalization, 5357 were revascularized, and 4589 were managed without revascularization. Hs-TnT, NT-proBNP, and GDF-15 were determined and assessed according to predefined cutoff levels. Median follow-up was 9.1 months. Increasing levels of hs-TnT were associated with increasing risk of cardiovascular death, myocardial infarction, and stroke in medically managed patients (P<0.001), but not in those managed invasively. NT-proBNP and GDF-15 levels were associated with the same events independent of management strategy. Ticagrelor versus clopidogrel reduced the rate of cardiovascular death, myocardial infarction, and stroke in patients with NSTE-ACS and hs-TnT ≥14.0 ng/L in both invasively and noninvasively managed patients; in patients with hs-TnT <14.0 ng/L, there was no difference between ticagrelor and clopidogrel in the noninvasive group Conclusions— Hs-TnT, NT-proBNP, and GDF-15 are predictors of cardiovascular death, myocardial infarction, and stroke in patients with NSTE-ACS managed noninvasively, and NT-proBNP and GDF-15 also in those managed invasively. Elevated hs-TnT predicts substantial benefit of ticagrelor over clopidogrel both in invasively and noninvasively managed patients, but no apparent benefit was seen at normal hs-TnT. Clinical Trial Registration— URL:http://www.clinicaltrials.gov. Unique identifier: NCT00391872.

F2-Isoprostanes, tocopherols and normal pregnancy

This study investigates oxidative stress and antioxidants in normal human pregnancy and post-partum period. Thirty-seven healthy women with normal pregnancies were included. Both urinary and serum samples were collected throughout the pregnancy and post-partum period. Oxidative stress was estimated by measuring the reliable in vivo marker, namely 8-iso-prostaglandin F2α (8-iso-PGF2α, an F2-isoprostane) and antioxidant status was evaluated by measuring α- and γ-tocopherol in serum samples. Pregnancy was associated with successively increased levels of 8-iso-PGF2α with advancing gestational age. The median post-partum value corresponded to the values observed in early gestation and a significant decrease was observed from late pregnancy to the post-partum period. Lipid-adjusted α- and γ-tocopherol levels decreased with advancing gestational age. This longitudinal study suggests that mild oxidative stress is involved in normal human pregnancy.

Evaluation of predictive markers for patients with advanced colorectal cancer

Abstract Background. To evaluate the predictive and prognostic value of serum and plasma tumor markers, in comparison with clinical and biomedical parameters for response rate (RR), progression-free survival (PFS) and overall survival (OS) among patients with metastatic colorectal cancer (mCRC) treated with combination chemotherapy. Material and methods. One-hundred and six patients with mCRC from three centers, part of a multicenter study, received irinotecan with the Nordic bolus 5-fluorouracil (5-FU) and folinic acid schedule (FLIRI) or the de Gramont schedule (Lv5FU2-IRI). Blood samples for CEA, CA19-9, TPA, TIMP-1, SAA, transthyretin and CRP were taken at baseline and after two, four and eight weeks of treatment. Tumor marker levels at baseline and longitudinally were compared with responses evaluated (CT/MRI) after two and four months of treatment. The correlations to RR, PFS and OS were evaluated with regression analyses. Results. A significant correlation to OS was seen for baseline levels of all markers. In multivariate analyses with clinical parameters, TPA, CRP, SAA and TIMP-1 provided independent information. The baseline values of CEA, TPA and TIMP-1 were also significantly correlated to PFS and TPA to RR. Changes during treatment, i.e. the slope gave with the exception of CA19-9 for OS less information about outcomes. The best correlation to response was seen for CEA, CA19-9 and TPA with AUC values of 0.78, 0.83 and 0.79, respectively, using a combined model based upon an interaction between the slope and the baseline value. Conclusions. Baseline tumor markers together with clinical parameters provide prognostic information about survival in patients with mCRC. The ability of the individual tumor markers to predict treatment response and PFS is limited. Changes in marker levels during the first two months of treatment are less informative of outcome.

Prehospital Trauma Life Support (PHTLS) training of ambulance caregivers and impact on survival of trauma victims

BACKGROUND The Prehospital Trauma Life Support (PHTLS) course has been widely implemented and approximately half a million prehospital caregivers in over 50 countries have taken this course. Still, the effect on injury outcome remains to be established. The objective of this study was to investigate the association between PHTLS training of ambulance crew members and the mortality in trauma patients. METHODS A population-based observational study of 2830 injured patients, who either died or were hospitalized for more than 24 h, was performed during gradual implementation of PHTLS in Uppsala County in Sweden between 1998 and 2004. Prehospital patient records were linked to hospital-discharge records, cause-of-death records, and information on PHTLS training and the educational level of ambulance crews. The main outcome measure was death, on scene or in hospital. RESULTS Adjusting for multiple potential confounders, PHTLS training appeared to be associated with a reduction in mortality, but the precision of this estimate was poor (odds ratio, 0.71; 95% confidence interval, 0.42-1.19). The mortality risk was 4.7% (36/763) without PHTLS training and 4.5% (94/2067) with PHTLS training. The predicted absolute risk reduction is estimated to correspond to 0.5 lives saved annually per 100,000 population with PHTLS fully implemented. CONCLUSIONS PHTLS training of ambulance crew members may be associated with reduced mortality in trauma patients, but the precision in this estimate was low due to the overall low mortality. While there may be a relative risk reduction, the predicted absolute risk reduction in this population was low.

Biomarkers for risk stratification of patients with ST-elevation myocardial infarction treated with primary percutaneous coronary intervention: Insights from the Platelet Inhibition and Patient Outcomes trial

BACKGROUND The incremental prognostic value of admission measurements of biomarkers beyond clinical characteristics and extent of coronary artery disease (CAD) in patients treated with primary percutaneous coronary intervention (PPCI) for ST-elevation myocardial infarction (STEMI) is unclear. METHODS Centrally analyzed plasma for biomarker measurements was available in 5,385 of the STEMI patients treated with PPCI in the PLATO trial. Extent of CAD was graded by operators in association with PPCI. We evaluated the prognostic value of high-sensitivity cardiac troponin T, N-terminal pro-B-type natriuretic peptide (NT-proBNP), and growth differentiation factor 15 (GDF-15) beyond clinical characteristics and extent of CAD using Cox proportional hazards analyses, C-index, and net reclassification improvement (NRI). Outcomes were cardiovascular death (CVD) and spontaneous myocardial infarction (MI). RESULTS Angiographic data on extent of CAD improved the prediction of CVD compared to clinical risk factors alone, increasing the C-index from 0.760 to 0.778, total NRI of 0.31. Biomarker information provided additional prognostic value for CVD beyond clinical risk factors and extent of CAD, C-indices ranging from 0.792 to 0.795 for all biomarkers, but with a higher NRI for NT-proBNP. Extent of CAD and high-sensitivity cardiac troponin T were not associated with spontaneous MI. The prediction of spontaneous MI beyond clinical characteristics and extent of CAD (C-index 0.647) was improved by both NT-proBNP (C-index 0.663, NRI 0.22) and GDF-15 (C-index 0.652, NRI 0.05). CONCLUSIONS Biomarker measurement on admission is feasible and provides incremental risk stratification in patients with STEMI treated with PPCI, with NT-proBNP and GDF-15 being most valuable due to the association with both CVD and spontaneous MI.

Involvement of inflammation in normal pregnancy

To study the role of inflammation throughout normal pregnancy and postpartum, 37 women with normal pregnancies, including normal neonatal outcome, participated. Blood and urine samples were collected from each woman at least six times during pregnancy and postpartum. Plasma levels of interleukin‐6 (IL‐6) and tumor necrosis factor‐α (TNF‐α) and urinary levels of a prostaglandin‐F2α (PGF2α) metabolite were measured. Median, 25th to 75th centile and average change per gestational week of IL‐6, TNF‐α and the PGF2α metabolite were measured. Levels of IL‐6 increased significantly throughout pregnancy and remained high postpartum. No change in TNF‐α could be seen. The PGF2α metabolite levels increased significantly throughout pregnancy and decreased postpartum. These results suggest that mild but significant inflammatory activity is involved in the development of normal pregnancy, which might have important physiological roles.

A longitudinal study of plasma levels of soluble fms-like tyrosine kinase 1 (sFlt1), placental growth factor (PlGF), sFlt1: PlGF ratio and vascular endothelial growth factor (VEGF-A) in normal pregnancy.

Objective. To describe plasma levels of angiogenic (PlGF, VEGF‐A) and anti‐angiogenic (sFlt1) factors as well as the sFlt1:PlGF ratio throughout normal pregnancy and postpartum. Design. Longitudinal prospective study. Setting. One outpatient antenatal clinic in Uppsala, Sweden. Population. Thirty‐seven healthy women with normal pregnancies and normal neonatal outcome were included. Methods. Blood samples were collected from each woman at least six times. Plasma levels of sFlt1, PlGF and VEGF‐A were measured using commercially available ELISA kits. Main outcome measures. Median plasma levels, the 25th to the 75th percentile and the average change per gestational week of sFlt1, PlGF and the sFlt1:PlGF ratio. Results. sFlt1 levels were relatively constant until weeks 29–30, when they increased, reaching a peak at week 40. An increase of 643pg/ml per week was observed from weeks 30 to 40. Postpartum levels were low. PlGF increased by 16pg/ml per week from early pregnancy until weeks 29–30 and thereafter decreased by 14pg/ml per week until week 40. The sFlt1:PlGF ratio decreased from weeks 9–12, was constantly low from weeks 19–20 to 37–38 and then increased to weeks 39–40. VEGF‐A was detectable in only 8% of the samples during pregnancy and in 64% postpartum. Conclusion. This longitudinal study demonstrates how sFlt1, PlGF and the sFlt1:PlGF ratio fluctuate throughout normal pregnancy and postpartum and may serve as a reference against which these factors can be studied in complicated pregnancies. VEGF‐A levels were more often detectable postpartum.

The impact of clinically undiagnosed injuries on survival estimates

Objectives:Missed injury diagnoses may cause potentially preventable deaths. To estimate the effect of clinically undiagnosed injuries on injury-specific survival estimates and the accuracy of an injury severity score. To also estimate the potentially preventable mortality attributable to these injuries. Design, Setting, and Patients:In a nation-wide, population-based study, data were collected from all hospital admissions for injuries in Sweden between 1998 and 2004. We studied 8627 deaths in hospital among 598,137 incident hospital admissions. Measurements and Main Results:New specific-injury categories were added in 7.4% (95% confidence interval [CI] 6.8–8.0) of all deaths with an autopsy rate of 24.2%. It was estimated that this proportion would have increased to 25.1% (95% CI 23.0–27.2), if all deaths had been autopsied. The most pronounced effect of clinically undiagnosed injuries was found for internal organ injury in the abdomen or pelvis, where they reduced the estimated survival from 0.83 to 0.69 (95% CI for the difference: 0.09–0.20). Autopsy diagnoses also revealed substantial bias of survival estimates for vascular injuries in the thorax and crush injuries to the head. The performance of the International Classification of Diseases Injury Severity Score improved when autopsy diagnoses were added to hospital discharge diagnoses. The maximum proportion of injury deaths attributable to missed injuries was estimated to be 6.5%. Conclusions:Maintaining a high autopsy rate and merging accurate hospital discharge data and autopsy data are effective ways to improve the accuracy of survival estimates and mortality prediction models, and to estimate mortality attributable to diagnostic failures.

Fibrinolytic therapy and bleeding complications: risk predictors from RIKS-HIA.

Background Fibrinolytic treatment for ST-elevation myocardial infarction is associated with increased bleeding risk but is still widely used world wide, mainly because of limited access to primary PCI. Objective To analyse contemporary fibrinolytic treatment patterns, in-hospital bleeding risk and prognosis during 2001 to 2006 in unselected Swedish patients. Methods and results The RIKS-HIA registry covers almost all Swedish patients treated for acute coronary syndromes. Major in-hospital bleeding was defined as lethal or intracranial bleeding or bleeding requiring surgery or blood transfusion. Survival status of the 15 373 patients was obtained from the National Cause of Death Register. The number of patients receiving fibrinolysis as reperfusion therapy decreased from 4336 patients in 2001 to 733 in 2006. Cases of major in-hospital bleeding increased from 1.2% (including 0.7% lethal or intracranial) in 2001 to 4.0% (1.1%) in 2006, p<0.001. Higher age, female gender, hypertension, kidney failure, clopidogrel treatment before admission, pre-hospital administration of fibrinolysis and fibrin-specific fibrinolytic agents were identified as predictors for bleeding. Major in-hospital bleeding was the strongest predictor of adverse prognosis with a more than threefold increase in 1-year mortality. Conclusion During 2001 to 2006 the use of fibrinolytic treatment markedly decreased while the incidence of major bleeding complications more than doubled. The latter might in part be explained by increasing use concomitant antiplatelet therapy, pre-hospital treatment and fibrin-specific fibrinolytic agents. Future close monitoring of bleeding complications is warranted, especially when considering the increased use of various combinations of antithrombotic drugs in conjunction with fibrinolysis and the great impact of bleeding on long-term mortality.