Evaluation of biomarkers for treatment selection using individual participant data from multiple clinical trials.

Biomarkers that predict treatment effects may be used to guide treatment decisions, thus improving patient outcomes. A meta-analysis of individual participant data (IPD) is potentially more powerful than a single-study data analysis in evaluating markers for treatment selection. Our study was motivated by the IPD that were collected from 2 randomized controlled trials of hypertension and preeclampsia among pregnant women to evaluate the effect of labor induction over expectant management of the pregnancy in preventing progression to severe maternal disease. The existing literature on statistical methods for biomarker evaluation in IPD meta-analysis have evaluated a marker's performance in terms of its ability to predict risk of disease outcome, which do not directly apply to the treatment selection problem. In this study, we propose a statistical framework for evaluating a marker for treatment selection given IPD from a small number of individual clinical trials. We derive marker-based treatment rules by minimizing the average expected outcome across studies. The application of the proposed methods to the IPD from 2 studies in women with hypertension in pregnancy is presented.

The FIGO Stage IVA Versus IVB of Ovarian Cancer: Prognostic Value and Predictive Value for Neoadjuvant Chemotherapy.

OBJECTIVE: The revised version of the International Federation of Gynaecology and Obstetrics (FIGO) staging system (2014) for epithelial ovarian cancer includes a number of changes. One of these is the division of stage IV into 2 subgroups. Data on the prognostic and predictive significance of this classification are scarce. The effect of neoadjuvant chemotherapy (NACT) versus primary debulking surgery (PDS) in relation to the subclassification of FIGO stage IV is also unknown. METHODS: We used data of the EORTC 55971 trial, in which 670 patients with previous stage IIIC or IV epithelial ovarian cancer were randomly assigned to PDS or NACT; 160 patients had previous stage IV. Information on previous FIGO staging and presence of pleural effusion with positive cytology were used to classify tumors as either stage IVA or IVB. We tested the association between stage IVA/IVB and survival to evaluate the prognostic value and interactions between stage, treatment, and survival to evaluate the predictive performance. RESULTS: Among the 160 participants with previous stage IV disease, 103 (64%) were categorized as stage IVA and 57 (36%) as stage IVB tumors. Median overall survival was 24 months in FIGO stage IVA and 31 months in stage IVB patients (P = 0.044). Stage IVB patients treated with NACT had 9 months longer median overall survival compared with IVB patients undergoing PDS (P = 0.025), whereas in IVA patients, no significant difference was observed (24 vs 26 months, P = 0.48). CONCLUSIONS: The reclassification of FIGO stage IV into stage IVA or IVB was not prognostic as expected. Compared with stage IVA patients, stage IVB patients have a better overall survival and may benefit more from NACT.

Development and evaluating multimarker models for guiding treatment decisions.

BACKGROUND: Despite the growing interest in developing markers for predicting treatment response and optimizing treatment decisions, an appropriate methodology to identify, combine and evaluate such markers has been slow to develop. We propose a step-by-step strategy for analysing data from existing randomised trials with the aim of identifying a multi-marker model for guiding decisions about treatment. METHODS: We start with formulating the treatment selection problem, continue with defining the treatment threshold, prepare a list of candidate markers, develop the model, apply the model to estimate individual treatment effects, and evaluate model performance in the study group of patients who meet the trial eligibility criteria. In this process, we rely on some well-known techniques for multivariable prediction modelling, but focus on predicting benefit from treatment, rather than outcome itself. We present our approach using data from a randomised trial in which 808 women with multiple pregnancy were assigned to cervical pessary or control, to prevent adverse perinatal outcomes. Overall, cervical pessary did not reduce the risk of adverse perinatal outcomes. RESULTS: The treatment threshold was zero. We had a preselected list of 5 potential markers and developed a logistic model including the markers, treatment and all marker-by-treatment interaction terms. The model was well calibrated and identified 35% (95% confidence interval (CI) 32 to 39%) of the trial participants as benefitting from pessary insertion. We estimated that the risk of adverse outcome could be reduced from 13.5 to 8.1% (5.4% risk reduction; 95% CI 2.1 to 8.6%) through model-based selective pessary insertion. The next step is external validation upon existence of independent trial data. CONCLUSIONS: We suggest revisiting existing trials data to explore whether differences in treatment benefit can be explained by differences in baseline characteristics of patients. This could lead to treatment selection tools which, after validation in comparable existing trials, can be introduced into clinical practice for guiding treatment decisions in future patients.

Genomic markers to tailor treatments: waiting or initiating?

The decade since the publication of the Human Genome Project draft has ended with the discovery of hundreds of genomic markers related to diseases and phenotypes. However, the project has not yet delivered on its promise to tailor treatments for individuals. The number of genomic markers in clinical practice is very small. The number of markers to guide treatment decisions is even smaller. In order to speed up discovery and validation of genomic treatment selection markers, we call for considering the brilliant potential of randomized clinical trials. If biomedical research community can collaborate in organizing large-scale consortium of clinical trials associated with well-designed biobanks, these studies would soon act as huge laboratories for investigating genomic medicine; a big step forward towards personalizing medicine.

Gene-environment Interaction on the Risk of Type 2 Diabetes Among Ethnic Minority Populations Living in Europe and North America: A Systematic Review.

BACKGROUND: The body of evidence on gene-environment interaction (GEI) related to type 2 diabetes (T2D) has grown in the recent years. However, most studies on GEI have sought to explain variation within individuals of European ancestry and results among ethnic minority groups are inconclusive. OBJECTIVE: To investigate any interaction between a gene and an environmental factor in relation to T2D among ethnic minority groups living in Europe and North America. METHODS: We systematically searched Medline and EMBASE databases for the published literature in English up to 25th March 2019. The screening, data extraction and quality assessment were performed by reviewers independently. RESULTS: 1068 studies identified through our search, of which nine cohorts of six studies evaluating several different GEIs were included. The mean follow-up time in the included studies ranged from 5 to 25.7 years. Most studies were relatively small scale and few provided replication data. All studies included in the review included ethnic minorities from North America (Native-Americans, African- Americans, and Aboriginal Canadian), none of the studies in Europe assessed GEI in relation to T2D incident in ethnic minorities. The only significant GEI among ethnic minorities was HNF1A rs137853240 and smoking on T2D incident among Native-Canadians (Pinteraction = 0.006). CONCLUSION: There is a need for more studies on GEI among ethnicities, broadening the spectrum of ethnic minority groups being investigated, performing more discovery using genome-wide approaches, larger sample sizes for these studies by collaborating efforts such as the InterConnect approach, and developing a more standardized method of reporting GEI studies are discussed.

Tubal flushing with oil- or water-based contrast medium: can we identify markers that indicate treatment benefit?

STUDY QUESTION: Can we identify patient characteristics that distinguish which ovulatory infertile women undergoing hysterosalpingography (HSG) benefit more or less from flushing with oil-based contrast medium compared to water-based contrast medium? SUMMARY ANSWER: In ovulatory infertile women, HSG with oil-based contrast medium resulted in higher 6-month ongoing pregnancy and live birth rates as compared to HSG with water-based contrast medium and this treatment effect was independent of characteristics of the couple. WHAT IS KNOWN ALREADY: We recently showed that in infertile women undergoing HSG, flushing with oil-based contrast medium resulted in more ongoing pregnancies than flushing with water-based contrast medium. STUDY DESIGN SIZE DURATION: We used data from our randomized clinical trial (RCT) in which 1,119 ovulatory infertile women undergoing HSG during fertility work-up were randomized for use of oil-based (N = 557) or water-based (N = 562) contrast medium. PARTICIPANTS/MATERIALS SETTING METHODS: We built logistic regression models to predict ongoing pregnancy and live birth (secondary outcome) as a function of the specific contrast, the specific marker, and marker-by-contrast-interaction. Markers considered were female age, maternal ethnicity, female smoking, body mass index (BMI), duration of infertility, infertility being primary or secondary, sperm quality, and previous appendectomy. MAIN RESULTS AND THE ROLE OF CHANCE: The 6-month ongoing pregnancy rates in the overall population were 39.7% after use of oil-based contrast versus 29.1% after use of water-based contrast medium [relative risk (RR), 1.37; 95% confidence interval (CI), 1.16-1.61; P < 0.001]. Among the studied baseline characteristics, BMI (P = 0.002) and semen volume (P = 0.02) were statistically significant prognosticators. The treatment effect of oil-based contrast was stronger in women with a BMI ≤30 kg/m2 [RR, 1.54; 95% CI, 1.23-1.92; P = 0.002], and in women whose partner had a semen volume >3 ml [RR, 1.77; 95% CI, 1.28-2.46; P = 0.02]. Also, in women who smoked, the treatment effect of flushing with oil was stronger, but this interaction did not reach statistical significance (P = 0.066). We found no positive effect of oil-based contrast in obese women. We found similar but weaker associations for live birth, which was probably due to lower number of events resulting in less power. LIMITATIONS REASONS FOR CAUTION: The RCT was restricted to infertile ovulatory women younger than 39 years of age without endocrinological disorders and at low risk for tubal pathology. Our results should not be generalized to infertile women who do not share these features. WIDER IMPLICATIONS OF THE FINDINGS: All infertile, ovulatory women younger than 39 years with a low risk for tubal pathology will benefit from an HSG with oil-based contrast; therefore, this should be offered to them after fertility work-up. STUDY FUNDING/COMPETING INTERESTS: The original H2Oil RCT was an investigator-initiated study that was funded by the two academic institutions (AMC and VUmc) of the Amsterdam UMC. The study displayed in this paper was funded by an unconditional research grant from Guerbet. B.W.M. is supported by an NHMRC Practitioner Fellowship (GNT1082548). K.D. reports consultancy for Guerbet, during the conduct of the study, and also reports research grants from Guerbet. C.B.L. reports grants from Guerbet, during the conduct of the study, and grants from Ferring, grants from Merck, and personal fees from Ferring, outside the submitted work. P.H. reports grants from Guerbet, during the conduct of the study, and grants from Ferring and Merck, outside the submitted work. V.M. reports receiving travel and speakers fee as well as research grants from Guerbet. B.W.M. reports consultancy for ObsEva, Merck, Merck KGaA, and Guerbet, and research grants from Guerbet and Merck. The other authors have no conflict of interest to declare. TRIAL REGISTRATION NUMBER: NTR 3270 www.trialregister.nl. TRIAL REGISTRATION DATE: 1 February 2012. DATE OF FIRST PATIENT'S ENROLMENT: 3 February 2012.

Premature ejaculation and serum leptin level: a diagnostic case-control study.

INTRODUCTION: Premature ejaculation (PE) is regarded as the most common male sexual disorder. To date, there is no accurate and objective diagnostic test for PE. AIM: To determine the diagnostic value of serum leptin level for PE. METHODS: In a case-control design, the serum leptin level of 46 PE patients referred to our outpatient clinic were determined and compared with 44 control patients referred to the same clinic with the complaint of nephrolithiasis. PE was defined based on the Diagnostic and Statistical Manual of Mental Disorders IV criteria and an intravaginal ejaculatory latency time of less than a minute. MAIN OUTCOME MEASURES: Serum leptin level and presence of PE. RESULTS: The PE patients had significantly higher serum leptin levels (8.3+/-3 ng/mL) than the controls (3.3+/-1 ng/mL) (P<0.001). Sensitivity and specificity for the test as a predictive diagnostic tool for PE were 80.4% and 97.7%, respectively, at the cutoff value of 6.3 ng/mL. CONCLUSIONS: According to our results, leptin level in patients with PE was significantly higher than in the control subjects. More studies are necessary to determine the value of serum leptin as a diagnostic tool for PE.

A randomized trial of ceftriaxone versus trimethoprim-sulfamethoxazole to prevent ventriculoperitoneal shunt infection.

BACKGROUND AND PURPOSE: Shunt infection represents a particularly morbid condition, which can also result in mortality. In order to decrease the high morbidity and mortality rates, prevention is an essential step. The purpose of this study was to compare the prophylactic use of ceftriaxone and trimethoprim-sulfamethoxazole (SXT) for the prevention of ventriculoperitoneal (VP) shunt infection. METHODS: In this prospective, single-institution, randomized clinical trial, 107 children with hydrocephalus and an indication for shunting were randomly assigned to prophylaxis with ceftriaxone (n = 50) or SXT (55), each administered as a single dose during anesthesia and two divided doses postoperatively. Patients were followed up for at least one year. RESULTS: The mean age of patients was 15 months, and 85% were aged 6 months or younger. During the first postoperative year, meningitis occurred in 13.5% of patients receiving ceftriaxone and 14.5% of the SXT group, with no statistically significant difference between the groups. Younger age, presence of cerebrospinal fluid leakage and aqueductal stenosis as a cause of hydrocephalus showed significant correlation with meningitis occurrence on univariate analysis. However, only the latter 2 factors were associated with meningitis on multivariate analysis. The risk of shunt infection did not correlate with the gender of the patient, time of VP shunt surgery, or duration of hospitalization for shunting. CONCLUSION: Ceftriaxone and SXT showed similar efficacy in preventing shunt infection. Cerebrospinal fluid leakage before or after VP shunt placement and aqueductal stenosis were independent risk factors for meningitis after VP shunt.

The cerebral arterial circle (circulus arteriosus cerebri): an anatomical study in fetus and infant samples.

BACKGROUND: Many studies have investigated the variations in the anatomy of each segment of the cerebral arterial circle while a few have addressed the variations of the cerebral arterial circle as a whole. METHODS: Thirty brains of recently deceased Iranian infants and fetuses were dissected. The dissection process was filmed and digitized so as to be readily available for further studies. The variations of the circle as a whole and segmental variations were evaluated. RESULTS: Variants with uni- and bilateral hypoplasia of posterior communicating arteries (PcoAs) were the most common in our study, similar to previous works. No aplasia of the precommunicating part of the anterior cerebral artery (A1), the precommunicating part of the posterior cerebral artery (P1) and anterior communicating artery was seen. Hypoplasia of the right and left PcoA was observed in 8 and 5 cases, respectively. Aplasia of the right PcoA was found in 16.6% and of the left PcoA in 3.3%. CONCLUSION: In this study, we confirmed the previously described finding that the symmetrical, circular configuration of the circulus arteriosus cerebri is present in only about 42.1%. The main differences between the fetal and adult disposition are the diameter of the PcoA and the circular part of the posterior cerebral artery. According to previous studies, the fetal brain older than 4 months has anatomical characteristics very similar to the adult's circle; our finding was mostly similar to adult samples as most samples were from infants, not fetuses.

The predictive value of extensor grip test for the effectiveness of treatment for tennis elbow.

OBJECTIVE: To compare the effectiveness of 5 different modalities, and determine the usefulness of recently proposed extensor grip test (EGT) in predicting the response to treatment. METHODS: In a randomized controlled clinical trial, 92 of 98 tennis elbow patients in Sina Hospital Tehran, Iran between 2006 and 2007 fulfilled the trial entry criteria. Among these patients 56 (60.9%) had positive EGT result. The stratified EGT result, were randomly allocated to 5 treatment groups: brace, physiotherapy, brace plus physiotherapy, injection, and injection plus physiotherapy. RESULTS: Patients with a positive EGT result had better response to treatments. Among them, injection plus physiotherapy was the most successful, then brace plus physiotherapy, physiotherapy, and brace injection was the worst treatment modality. Response to treatment was comparable in all groups between EGT positive and negative patients except bracing, in which positive EGT was correlated with a dramatic response to treatment. CONCLUSION: In all patients, injection plus physiotherapy and then brace plus physiotherapy is recommended, but in EGT negatives, bracing seems to be of no use. Injection alone is not recommended in either group.

The impact of low serum triglyceride on LDL-cholesterol estimation.

Most clinical laboratories directly measure serum triglyceride, total cholesterol, and high- density lipoprotein cholesterol. They indirectly calculate low-density lipoprotein cholesterol value using the Friedewald equation. Although high serum triglyceride (>400 mg/dL or 4.52 mmol/L) devaluates low-density lipoprotein cholesterol calculation by using this formula, effects of low serum triglyceride (<100 mg/dL or 1.13 mmol/L) on its accuracy is less defined.Two hundred thirty serum samples were assayed during a one-year period. In 115 samples, the triglyceride level was below 100 mg/dL and in 115 samples from age- and sex-matched patients the triglyceride level was 150 - 350 mg/dL (1.69 - 3.95 mmol/L). In both groups total cholesterol was above 250 mg/dL (6.46 mmol/L). On each sample, total cholesterol, high-density lipoprotein cholesterol, and triglyceride were directly measured in duplicate and low-density lipoprotein cholesterol measured directly and calculated with Friedewald equation as well. Statistical analysis showed that when triglyceride is <100 mg/dL, calculated low- density lipoprotein cholesterol is significantly overestimated (average :12.17 mg/dL or 0.31 mmol/L), where as when triglyceride is between 150 and 300 mg/dL no significant difference between calculated and measured low-density lipoprotein cholesterol is observed. In patients with low serum triglyceride and undesirably high total cholesterol levels, Friedewald equation may overestimate low-density lipoprotein cholesterol concentration and it should be either directly assayed or be calculated by a modified Friedewald equation. Using linear regression modeling, we propose a modified equation.

Intelligence quotient in children with meningomyeloceles: a case-control study.

OBJECT: Meningomyelocele (MMC) is a common central nervous system birth defect. As one of many problems facing patients with MMC, learning disabilities are often overlooked. The aim of this study was to evaluate IQs in a group of children with MMCs and determine if a correlation exists between intelligence level and the presence of an MMC and/or its complications. METHODS: A case-control study was conducted at the Children's Hospital Medical Center in Tehran, Iran, from December 2004 through December 2005. The patient group included 50 children with MMC from 5 to 12 years of age who were referred to the authors' institution for treatment of complications or for follow up after surgery for MMC closure. The patient group was individually matched for age and sex with a control group of 50 children referred to the hospital for other reasons and who did not have MMC or other neurological abnormalities. The IQs in all children in this study were evaluated using the Ravens Progressive Matrices test. The children in both groups were similar in the socioeconomic status of the family (p = 0.347) and educational status of the father (p = 0.117) and mother (p = 0.439). Patient age at the time of surgery for MMC closure varied from 1 day to 96 months (mean 4.1 months). Only 20% of the patients with MMC could walk with a normal gait. Forty-six percent of the patients had undergone placement of a ventriculoperitoneal shunt, and half of these patients experienced shunt-related complications; 72% of the children in the patient group were completely incontinent for both urine and feces. The IQ results obtained in the patient group ranged from 73 to 134 with a mean (+/- standard deviation) of 96.62 +/- 13.01. In the control group the IQ range was 70 to 128, and the mean was 104.82 +/- 12.30. Compared with the control group there was a statistically significant correlation between having an MMC and having a lower IQ (p < 0.001, paired t-test). CONCLUSIONS: Although the average IQ in the patient group was significantly lower than that in the control group, it is important to note that all children in the patient group had an average or above-average IQ. In contrast with the results reported in other studies, earlier repair of the MMC, the presence of a shunt or shunt-related complications, walking difficulty, and the spinal level of the lesion did not correlate significantly with IQs. Therefore, the lower IQ and reduced cognitive levels noted in these patients result from the disease process itself and not from the associated complications.

Impact of fasting on shockwave lithotripsy in renal stones: a randomized controlled trial.

PURPOSE: We evaluated the impact of fasting on the effectiveness of shockwave lithotripsy (SWL) in patients with renal calculi. PATIENTS AND METHODS: The study was a randomized controlled trial for patients with renal stones. Between May 2005 and November 2006, patients (n = 97) with a single radio-opaque renal stone (7-21 mm) who were candidates for SWL were enrolled. Patients were randomized to fasting (F, n = 49) and nonfasting (NF, n = 48) groups. F group patients were asked to fast for 12 hours before SWL. Urine specific gravity (SG) was measured after fasting. All patients were monitored every 2 weeks until complete stone clearance. Treatment effectiveness was defined as complete clearance up to 3 months. RESULTS: There were 32 men in the F group and 28 men in the NF group. The mean age was 37.9 +/- 8.5 years in the F group and 39.1 +/- 7.7 years in the NF group. The mean body mass index was 22.8 +/- 2.5 and 23.1 +/- 2.6 in F and NF patients, respectively. The urine SG in the F group (1.036 +/- 0.004) was significantly higher than in the NF group (1.013 +/- 0.004; P < 0.001). At 3-month follow-up, the overall stone-free rate using SWL was 86.1% in the F group, which was higher than the rate of 72.9% in the NF group; however, the difference was not statistically significant (P = 0.16). CONCLUSION: Fasting significantly changes the urine SG but does not have a significant impact on the effectiveness of SWL for isolated renal stones.

The prenatal ultrasonographic detection of myelomeningocele in patients referred to Children's Hospital Medical Center: a cross sectional study.

BACKGROUND: To find out about the prenatal diagnosis rate of myelomeningocele (MMC) by ultrasound scan in patients referred to the Children's Hospital Medical Center in Tehran, Iran from July 2004 to July 2005. METHODS: We included 140 children born with MMC and who were referred for management, surgery and treatment of complications associated with it. The ultrasound reports were examined. Data on sex, age, location of MMC, time of prenatal ultrasound and the trimester in which the diagnosis was made along with the results of the diagnosis (MMC, hydrocephalus, or both), were collected. RESULTS: Among the studied patients, 136 (97.1%) cases had prenatal ultrasound, amongst those, 58 (42.6%) sonographic evaluations were diagnostic for hydrocephalus and/or MMC. The prenatal ultrasound was positive for MMC in 16 (11.8%), hydrocephalus in 25 (18.4%) and both MMC and hydrocephalus in 17 (12.5%) cases. Among all cases with prenatal diagnosis of MMC, 3.4% were detected in the first, 31% in the second and 65.5% in the third trimester. Thoracic/thoracolumbar lesions were found prenatally in 40% of cases, which is significantly higher than the detection rate of other locations including cervical/cervicothoracic and lumbar/lumbosacral/sacral regions diagnosed only in 0% and 21% of cases respectively. CONCLUSION: There is a large difference between the detection rate of our population (24.3%) compared to others (68%). Pregnant women should have an ultrasound at 20-22 week for detection of congenital anomalies including MMC.

Can we identify subfertile couples that benefit from immediate in vitro fertilisation over intrauterine insemination?

OBJECTIVE: Available treatment options in couples with unexplained or mild male subfertility are intrauterine insemination with controlled ovarian hyperstimulation (IUI-COH) and in vitro fertilisation (IVF). IUI-COH is a less invasive treatment that is often used before proceeding with IVF. Yet as the IVF success rates might be higher and time to pregnancy shorter, expedited access to IVF might be the preferred option. To identify couples that could benefit from immediate IVF over IUI-COH, we assessed whether female age, duration of subfertility or prewash total motile count (TMC) can help to identify couples that would benefit from IVF over IUI-COH. STUDY DESIGN: We performed a secondary data-analysis of a multicentre open-label randomised controlled trial in three university and six teaching hospitals in the Netherlands. 116 couples with unexplained or mild male subfertility were randomised to one cycle of IVF with elective single embryo transfer with subsequent frozen-thawed embryo transfers or 3 cycles of IUI-COH. The primary outcome was an ongoing pregnancy within 4 months after randomisation. Our aim was to explore a possible differential effect of specific markers on the effectiveness of treatment. We chose to therefore assess female age, duration of subfertility and TMC as these have previously been identified as predictors. For each prognostic factor we developed a logistic regression model to predict ongoing pregnancy with that prognostic factor, treatment and a factor-by-treatment interaction term. RESULTS: Female age and duration of subfertility were not associated with better ongoing pregnancy chances after IVF compared to IUI-COH (p-value for interaction=0.65 and 0.26, respectively). Only when TMC was lower than 110 (×10(6)spermatozoa/mL), the probability of ongoing pregnancy was higher in women allocated to IVF (p-value for interaction=0.06). CONCLUSION: In couples with unexplained or mild male subfertility, a low TMC might lead to higher pregnancy rates after IVF than after IUI-COH. This finding needs to be validated in a larger trial before it can be applied in clinical practice.

Uroflowmetry nomogram in Iranian children aged 7 to 14 years.

BACKGROUND: As the voiding habits of Iranian children differs from other children because of some cultural and religious considerations, we aimed to establish normal reference values of urinary flow rates in Iranian children between 7 to 14 years of age. METHODS: Eight hundred and two uroflowmetry studies were performed on children with no history of a renal, urological, psychological or neurological disorder, between the ages 7 and 14. Five hundred twenty five studies from 192 girls and 335 boys were considered in this study excluding the staccato/interrupted voiding pattern or voided volume less than 20 ml. The voiding volume, the maximum and average urinary flow rates were extensively analyzed. RESULTS: The maximal and average urine flow rate nomograms were plotted for both girls and boys. Mean maximum urine flow rate was 19.9 (ml/sec) for boys and 23.5 (ml/sec) for girls with a mean voided volume of 142 (ml) for boys and 147 (ml) for girls. Flow rates showed a close association with voiding volume in both sexes. The maximum and average flow rates were higher in girls than in boys, and they showed a significant increase in flow rates with increasing age, where boys did not. The mean maximum urine flow rates (19.9 ml/sec for boys and 23.5 ml/sec for girls) were found to be higher in this study than other studies. CONCLUSION: Nomograms of maximal and average flow rates of girls and boys are presented in centile form, which can help the physician to evaluate the response to medical or surgical treatment and be useful for the screening of lower urinary tract disturbances in children, for a wide range of voided volumes.

Relevance of individual participant data meta-analysis for studies in obstetrics: delivery versus expectant monitoring for hypertensive disorders of pregnancy.

Like many other research subjects in obstetrics, research on immediate delivery versus expectant monitoring for women with hypertensive disorders of pregnancy faces certain challenges when it comes to interpretation and generalisation of the results; relatively rare outcomes are studied, in a clinically heterogeneous population, while the clinical practice in some countries has dictated that studies in term pregnancy were completed before earlier gestational ages could be studied. This has resulted in multiple smaller studies, some studying surrogate outcome measures, with different in- and exclusion criteria, and without enough power for reliable subgroup analyses. All this complicates the generation of definitive answers and implementation of the results into clinical practice. Performing multiple studies and subsequently pooling their results in a meta-analysis can be a way to overcome the difficulties of studying relatively rare outcomes and subgroups with enough power, as well as a solution to reach a final answer on questions involving an uncertain and possibly harmful intervention. However, in the case of the current studies on delivery versus expectant monitoring in women with hypertensive disorders of pregnancy, differences regarding eligibility criteria, outcome measures and subgroup definitions make it difficult to pool their results in an aggregate meta-analysis. Individual patient data meta-analysis (IPDMA) has the potential to overcome these challenges, because it allows for flexibility regarding the choice of endpoints and standardisation of inclusion and exclusion criteria across studies. In addition, it has more statistical power for informative subgroup analyses. We therefore propose an IPDMA on immediate delivery versus expectant monitoring for hypertensive disorders of pregnancy, and advocate the use of IPDMA for research questions in obstetrics that face similar challenges.