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Dive into the research topics where Brent C. Opmeer is active.

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Featured researches published by Brent C. Opmeer.


Human Reproduction Update | 2011

AMH and AFC as predictors of excessive response in controlled ovarian hyperstimulation: a meta-analysis

Simone L. Broer; Madeleine Dólleman; Brent C. Opmeer; Bart C.J.M. Fauser; B.W. Mol; F.J. Broekmans

BACKGROUND Anti-Mullerian hormone (AMH) is a marker of ovarian reserve status and represents a good predictor of ovarian response to ovarian hyperstimulation. The aim of this study was to assess the accuracy of AMH and antral follicle count (AFC) as predictors of an excessive response in IVF/ICSI treatment. METHODS A systematic review and meta-analysis of the existing literature was performed. Studies were included if 2 × 2 tables for the outcome excessive response in IVF patients in relation to AMH/AFC could be constructed. Using a bivariate meta-analytic model, both summary point estimates for sensitivity and specificity were calculated, as well as summary ROC curves. Clinical value was analysed by calculating post-test probabilities of excessive response at optimal cut-off levels, as well as the corresponding abnormal test rates. RESULTS Nine studies reporting on AMH and five reporting on AFC were found. Summary estimates of sensitivity and specificity for AMH were 82 and 76%, respectively, and 82 and 80%, respectively, for AFC. Comparison of the summary estimates and ROC curves for AMH and AFC showed no statistical difference. Abnormal test rates for AMH and AFC amounted to ∼14 and 16%, respectively, at cut-off levels where test performance is optimal [likelihood ratio for a positive result (LR + ) > 8], with a post-test probability of ± 70%. CONCLUSIONS Both AMH and AFC are accurate predictors of excessive response to ovarian hyperstimulation. Moreover, both tests appear to have clinical value. This opens ways to explore the potential of individualized FSH dose regimens based on ovarian reserve testing.


Obstetrics & Gynecology | 2010

Endometrial thickness measurement for detecting endometrial cancer in women with postmenopausal bleeding: a systematic review and meta-analysis

Anne Timmermans; Brent C. Opmeer; Khalid S. Khan; Lucas M. Bachmann; E. Epstein; T Justin Clark; Janesh Gupta; Shagaf H. Bakour; Thierry Van den Bosch; Helena C. van Doorn; Sharon Cameron; M. Gabriella Giusa; Salvatore Dessole; F. Paul H. L. J. Dijkhuizen; Gerben ter Riet; Ben Willem J. Mol

OBJECTIVE: To estimate the accuracy of endometrial thickness measurement in the detection of endometrial cancer among women with postmenopausal bleeding with individual patient data using different meta-analytic strategies. DATA SOURCES: Original data sets of studies detected after reviewing the included studies of three previous reviews on this subject. An additional literature search of published articles using MEDLINE databases was preformed from January 2000 to December 2006 to identify articles reporting on endometrial carcinoma and sonographic endometrial thickness measurement in women with postmenopausal bleeding. METHODS OF STUDY SELECTION: We identified 90 studies reporting on endometrial thickness measurements and endometrial carcinoma in women with postmenopausal bleeding. TABULATION, INTEGRATION, AND RESULTS: We contacted 79 primary investigators to obtain the individual patient data of their reported studies, of which 13 could provide data. Data on 2,896 patients, of which 259 had carcinoma, were included. Several approaches were used in the analyses of the acquired data. First, we performed receiver operator characteristics (ROC) analysis per study, resulting in a summary area under the ROC curve (AUC) calculated as a weighted mean of AUCs from original studies. Second, individual patient data were pooled and analyzed with ROC analyses irrespective of study with standardization of distributional differences across studies using multiples of the median and by random effects logistic regression. Finally, we also used a two-stage procedure, calculating sensitivities and specificities for each study and using the bivariate random effects model to estimate summary estimates for diagnostic accuracy. This resulted in rather comparable ROC curves with AUCs varying between 0.82 and 0.84 and summary estimates for sensitivity and specificity located along these curves. These curves indicated a lower AUC than previously reported meta-analyses using conventional techniques. CONCLUSION: Previous meta-analyses on endometrial thickness measurement probably have overestimated its diagnostic accuracy in the detection of endometrial carcinoma. We advise the use of cutoff level of 3 mm for exclusion of endometrial carcinoma in women with postmenopausal bleeding.


Human Reproduction Update | 2014

Endometrial thickness and pregnancy rates after IVF: a systematic review and meta-analysis

Annemieke Kasius; Janine G. Smit; Helen L. Torrance; Marinus J.C. Eijkemans; Ben Willem J. Mol; Brent C. Opmeer; Frank J. Broekmans

BACKGROUND Thin endometrium on ultrasound in the course of ovarian hyperstimulation has been thought to be associated with poor success rates after IVF, even in the absence of prior intrauterine surgery or infection. To assess the clinical significance of endometrial thickness (EMT) for IVF outcome, we performed a systematic review and meta-analysis. METHODS The electronic databases Pubmed, Cochrane and Embase were searched up to October 2013 for articles that studied the association between EMT and IVF outcome. The articles had to be written in the English or Dutch language. Studies were included if two-by-two tables for EMT and pregnancy rates could be constructed. Study quality was scored using the Strengthening the Reporting of Observational Studies in Epidemiology (STROBE) checklist. Summary receiver operating characteristic (sROC) curves were estimated to assess the accuracy of EMT in the prediction of pregnancy. In addition, odds ratios (ORs) with 95% confidence intervals (CIs) were calculated using a Mantel-Haenszel random effect model expressing the association between EMT and pregnancy chances. Meta-regression was performed to determine if female age and number of oocytes at retrieval interacted in the estimated effect of EMT on IVF outcome. RESULTS A total of 1170 studies was retrieved by the search. The overall quality of the 22 studies included in the review and meta-analysis was moderate. The estimated sROC curve indicated a virtually absent discriminatory capacity of EMT in the prediction of pregnancy. A thin endometrium (≤ 7 mm) was observed in only 2.4% of the reported cases (260/10 724). In these cases a trend towards lower ongoing pregnancy and live birth rates for women with EMT ≤ 7 mm was observed [OR 0.38 (95% CI 0.09-1.5)]. The probability of clinical pregnancy for an EMT ≤ 7 mm was significantly lower compared with cases with EMT > 7 mm [23.3% versus 48.1%, OR 0.42 (95% CI 0.27-0.67)]. Positive and negative predictive values for the outcome of clinical pregnancy 77 and 48%, respectively. The relationship between the number of oocytes and female age on the one hand and pregnancy on the other hand was very weak making correction for these variables unfeasible. CONCLUSIONS Current data indicate that EMT has a limited capacity to identify women who have a low chance to conceive after IVF. The frequently reported cut-off of 7 mm is related to a lower chance of pregnancy, but occurs infrequently. The use of EMT as a tool to decide on cycle cancellation, freezing of all embryos or refraining from further IVF treatment seems not to be justified based on the current meta-analysis. Further research is needed to investigate the real independent significance of EMT in IVF.


Human Reproduction Update | 2014

Systematic review and meta-analysis of intrauterine adhesions after miscarriage: prevalence, risk factors and long-term reproductive outcome

Angelo B. Hooker; Marike Lemmers; Andreas L. Thurkow; Martijn W. Heymans; Brent C. Opmeer; Hans A.M. Brölmann; Ben Willem J. Mol; Judith A.F. Huirne

BACKGROUND Approximately 15-20% of all clinically confirmed pregnancies end in a miscarriage. Intrauterine adhesions (IUAs) are a possible complication after miscarriage, but their prevalence and the contribution of possible risk factors have not been elucidated yet. In addition, the long-term reproductive outcome in relation to IUAs has to be elucidated. METHODS We systematically searched the literature for studies that prospectively assessed the prevalence and extent of IUAs in women who suffered a miscarriage. To be included, women diagnosed with a current miscarriage had to be systematically evaluated within 12 months by hysteroscopy after either spontaneous expulsion or medical or surgical treatment. Studies that included women with a history of recurrent miscarriage only or that evaluated the IUAs after elective abortion or beyond 12 months after the last miscarriage were not included. Subsequently, long-term reproductive outcomes after expectant (conservative), medical or surgical management were assessed in women with and without post-miscarriage IUAs. RESULTS We included 10 prospective studies reporting on 912 women with hysteroscopic evaluation within 12 months of miscarriage and 8 prospective studies, including 1770 women, reporting long-term reproductive outcome. IUAs were detected in 183 women, resulting in a pooled prevalence of 19.1% [95% confidence interval (CI): 12.8-27.5%]. The extent of IUAs was reported in 124 women (67.8%) and was mild, moderate and severe respectively in 58.1, 28.2 and 13.7% of cases. Relative to women with one miscarriage, women with two or three or more miscarriages showed an increased risk of IUAs by a pooled OR of 1.41 and 2.1, respectively. The number of dilatation and curettage (D&C) procedures seemed to be the main driver behind these associations. A total of 150 congenital and acquired intrauterine abnormalities were encountered in 675 women, resulting in a pooled prevalence of 22.4% (95% CI: 16.3-29.9%). Similar reproductive outcomes were reported subsequent to conservative, medical or surgical management for miscarriage, although the numbers of studies and of included women were limited. No studies reported long-term reproductive outcomes following post-miscarriage IUAs. CONCLUSIONS IUAs are frequently encountered, in one in five women after miscarriage. In more than half of these, the severity and extent of the adhesions was mild, with unknown clinical relevance. Recurrent miscarriages and D&C procedures were identified as risk factors for adhesion formation. Congenital and acquired intrauterine abnormalities such as polyps or fibroids were frequently identified. There were no studies reporting on the link between IUAs and long-term reproductive outcome after miscarriage, while similar pregnancy outcomes were reported subsequent to conservative, medical or surgical management. Although this review does not allow strong clinical conclusions on treatment management, it signals an important clinical problem. Treatment strategies are proposed to minimize the number of D&C in an attempt to reduce IUAs.


PLOS Medicine | 2012

Induction of Labor versus Expectant Management in Women with Preterm Prelabor Rupture of Membranes between 34 and 37 Weeks: A Randomized Controlled Trial

David van der Ham; Sylvia M. C. Vijgen; Jan G. Nijhuis; Johannes J. van Beek; Brent C. Opmeer; Antonius L.M. Mulder; Rob Moonen; Mariet Groenewout; Marielle van Pampus; Gerald Mantel; Kitty W. M. Bloemenkamp; Wim van Wijngaarden; Marko Sikkema; Monique C. Haak; Paula Pernet; Martina Porath; Jan Molkenboer; Simone Kuppens; Anneke Kwee; Michael Kars; Mallory Woiski; Martin Weinans; Hajo I. J. Wildschut; Bettina M.C. Akerboom; Ben Willem J. Mol; Christine Willekes

In a randomized controlled trial David van der Ham and colleagues investigate induction of labor versus expectant management for women with preterm prelabor rupture of membranes.


British Journal of Obstetrics and Gynaecology | 2012

Glucose challenge test for detecting gestational diabetes mellitus: a systematic review

M van Leeuwen; Louwerse; Brent C. Opmeer; J Limpens; Mj Serlie; Jb Reitsma; Bwj Mol

Please cite this paper as: van Leeuwen M, Louwerse M, Opmeer B, Limpens J, Serlie M, Reitsma J, Mol B. Glucose challenge test for detecting gestational diabetes mellitus: a systematic review. BJOG 2012;119:393–401.


American Journal of Obstetrics and Gynecology | 2008

Clinical factors to predict the outcome of external cephalic version : a metaanalysis

Marjolein Kok; Jeltsje S. Cnossen; Lonneke Gravendeel; Joris A. M. van der Post; Brent C. Opmeer; Ben Willem J. Mol

OBJECTIVE The objective of the study was to systematically review the medical literature reporting on potential clinical prognosticators for the outcome of external cephalic version (ECV). STUDY DESIGN Medline, EMBASE, and Cochrane Central Register of Controlled Trials were searched. Studies reporting on potential clinical prognosticators and ECV success rates that allowed construction of a 2 x 2 table were selected. RESULTS We detected 53 primary articles reporting on 10,149 women. Multiparity (P >/= 1.00; odds ratio [OR], 2.5; 95% confidence interval [CI], 2.3-2.8), nonengagement of the breech (OR, 9.4; 95% CI, 6.3-14), a relaxed uterus (OR, 18; 95% CI, 12-29), a palpable fetal head (OR, 6.3; 95% CI, 4.3-9.2), and maternal weight less than 65 kg (OR, 1.8; 95% CI, 1.2-2.6) were predictors for successful external cephalic version. CONCLUSION Success of an ECV attempt is associated with clinical factors. This should be taken into account in the counseling of women prior to an ECV attempt.


JAMA | 2013

Effect of Maintenance Tocolysis With Nifedipine in Threatened Preterm Labor on Perinatal Outcomes A Randomized Controlled Trial

Carolien Roos; Marc Spaanderman; Ewoud Schuit; Kitty W. M. Bloemenkamp; Antoinette C. Bolte; Jérôme Cornette; Johannes J. Duvekot; Jim van Eyck; Maureen Franssen; Christianne J.M. de Groot; Joke H. Kok; Anneke Kwee; Ashley Merien; Bas Nij Bijvank; Brent C. Opmeer; Martijn A. Oudijk; Marielle van Pampus; Dimitri Papatsonis; Martina Porath; Hubertina C. J. Scheepers; Sicco Scherjon; Krystyna M. Sollie; Sylvia M. C. Vijgen; Christine Willekes; Ben Willem J. Mol; Joris A. M. van der Post; Fred K. Lotgering

IMPORTANCE In threatened preterm labor, maintenance tocolysis with nifedipine, after an initial course of tocolysis and corticosteroids for 48 hours, may improve perinatal outcome. OBJECTIVE To determine whether maintenance tocolysis with nifedipine will reduce adverse perinatal outcomes due to premature birth. DESIGN, SETTING, AND PARTICIPANTS APOSTEL-II (Assessment of Perinatal Outcome with Sustained Tocolysis in Early Labor) is a double-blind, placebo-controlled trial performed in 11 perinatal units including all tertiary centers in The Netherlands. From June 2008 to February 2010, women with threatened preterm labor between 26 weeks (plus 0 days) and 32 weeks (plus 2 days) gestation, who had not delivered after 48 hours of tocolysis and a completed course of corticosteroids, were enrolled. Surviving infants were followed up until 6 months after birth (ended August 2010). INTERVENTION Randomization assigned 406 women to maintenance tocolysis with nifedipine orally (80 mg/d; n = 201) or placebo (n = 205) for 12 days. Assigned treatment was masked from investigators, participants, clinicians, and research nurses. MAIN OUTCOME MEASURES Primary outcome was a composite of adverse perinatal outcomes (perinatal death, chronic lung disease, neonatal sepsis, intraventricular hemorrhage >grade 2, periventricular leukomalacia >grade 1, or necrotizing enterocolitis). Analyses were completed on an intention-to-treat basis. RESULTS Mean (SD) gestational age at randomization was 29.2 (1.7) weeks for both groups. Adverse perinatal outcome was not significantly different between groups: 11.9% (24/201; 95% CI, 7.5%-16.4%) for nifedipine vs 13.7% (28/205; 95% CI, 9.0%-18.4%) for placebo (relative risk, 0.87; 95% CI, 0.53-1.45). CONCLUSIONS AND RELEVANCE In patients with threatened preterm labor, nifedipine-maintained tocolysis did not result in a statistically significant reduction in adverse perinatal outcomes when compared with placebo. Although the lower than anticipated rate of adverse perinatal outcomes in the control group indicates that a benefit of nifedipine cannot completely be excluded, its use for maintenance tocolysis does not appear beneficial at this time. TRIAL REGISTRATION trialregister.nl Identifier: NTR1336.


British Journal of Obstetrics and Gynaecology | 2010

Estimating the risk of gestational diabetes mellitus: a clinical prediction model based on patient characteristics and medical history

M van Leeuwen; Brent C. Opmeer; E. J. K. Zweers; E. van Ballegooie; H. G. ter Brugge; H.W. de Valk; G. H. A. Visser; Ben Willem J. Mol

Objective  To develop a clinical prediction rule that can help the clinician to identify women at high and low risk for gestational diabetes mellitus (GDM) early in pregnancy in order to improve the efficiency of GDM screening.


Obstetrics & Gynecology | 2014

Predictive value of cervical length measurement and fibronectin testing in threatened preterm labor

Gert Jan Van Baaren; Jolande Y. Vis; Femke F. Wilms; Martijn A. Oudijk; Anneke Kwee; Martina Porath; Guid Oei; H. C. J. Scheepers; Marc Spaanderman; Kitty Bloemenkamp; M.C. Haak; Antoinette C. Bolte; Caroline J. Bax; Jérôme Cornette; Johannes J. Duvekot; Bas W.A. Nij Bijvanck; Jim van Eyck; Maureen Franssen; Krystyna M. Sollie; Frank Vandenbussche; Mallory Woiski; William A. Grobman; Joris A. M. van der Post; Patrick M M Bossuyt; Brent C. Opmeer; Ben Willem J. Mol

OBJECTIVE: To estimate the performance of combining cervical length measurement with fetal fibronectin testing in predicting delivery in women with symptoms of preterm labor. METHODS: We conducted a prospective nationwide cohort study in all 10 perinatal centers in The Netherlands. Women with symptoms of preterm labor between 24 and 34 weeks of gestation with intact membranes were included. In all women, qualitative fibronectin testing (0.050-microgram/mL cutoff) and cervical length measurement were performed. Logistic regression was used to predict spontaneous preterm delivery within 7 days after testing. A risk less than 5%, corresponding to the risk for women with a cervical length of at least 25 mm, was considered as low risk. RESULTS: Between December 2009 and August 2012, 714 women were enrolled. Fibronectin results and cervical length were available for 665 women, of whom 80 (12%) delivered within 7 days. Women with a cervical length of at least 30 mm or with a cervical length between 15 and 30 mm with a negative fibronectin result were at low risk (less than 5%) of spontaneous delivery within 7 days. Fibronectin testing in case of a cervical length between 15 and 30 mm additionally classified 103 women (15% of the cohort) as low risk and 36 women (5% of the cohort) as high risk. CONCLUSION: Cervical length measurement, combined with fetal fibronectin testing in case of a cervical length between 15 and 30 mm, improves identification of women with a low risk to deliver spontaneously within 7 days. LEVEL OF EVIDENCE: II

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Maureen Franssen

University Medical Center Groningen

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B.W. Mol

University of Adelaide

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