Development and Validation of a Dynamically Updated Prediction Model for Attrition From Marine Recruit Training.

ABSTRACT: Dijksma, I, Hof, MHP, Lucas, C, and Stuiver, MM. Development and validation of a dynamically updated prediction model for attrition from Marine recruit training. J Strength Cond Res 36(9): 2523-2529, 2022-Whether fresh Marine recruits thrive and complete military training programs, or fail to complete, is dependent on numerous interwoven variables. This study aimed to derive a prediction model for dynamically updated estimation of conditional dropout probabilities for Marine recruit training. We undertook a landmarking analysis in a Cox proportional hazard model using longitudinal data from 744 recruits from existing databases of the Marine Training Center in the Netherlands. The model provides personalized estimates of dropout from Marine recruit training given a recruit's baseline characteristics and time-varying mental and physical health status, using 21 predictors. We defined nonoverlapping landmarks at each week and developed a supermodel by stacking the landmark data sets. The final supermodel contained all but one a priori selected baseline variables and time-varying health status to predict the hazard of attrition from Marine recruit training for each landmark as comprehensive as possible. The discriminative ability (c-index) of the prediction model was 0.78, 0.75, and 0.73 in week one, week 4 and week 12, respectively. We used 10-fold cross-validation to train and evaluate the model. We conclude that this prediction model may help to identify recruits at an increased risk of attrition from training throughout the Marine recruit training and warrants further validation and updates for other military settings.

Growth patterns from birth to overweight at age 5-6 years of children with various backgrounds in socioeconomic status and country of origin: the ABCD study.

INTRODUCTION: Children from minority groups are at increased risk of overweight. This study compared BMI growth patterns from birth onwards of boys and girls with overweight at 5-6 years, according to socioeconomic status (SES) and country of origin, in order to gain more insight into the critical periods of growth to overweight. METHODS: A total of 3714 singletons of the multi-ethnic ABCD study were included. Within children with overweight at age 5-6 years (N = 487, prevalence boys: 11.6%, girls: 14.6%), BMI growth patterns from birth onwards (12.8 serial measurements; SD = 3.1) were compared between children from European (69.4%) and non-European mothers (30.6%), and between children from low (20.8%), mid (37.0%) or high SES (42.2%), based on maternal educational level. RESULTS: BMI growth to overweight did not differ between children of European or non-European mothers, but it did differ according to maternal SES. Children with overweight in the low and mid SES group had a lower BMI in the first 2 years of life, an earlier adiposity rebound and increased in BMI more rapidly after age 2, resulting in a higher BMI at age 7 years compared to children with overweight in the high SES group [∆BMI (kg/m2 ) between high and low SES: boys 1.43(95%CI:0.16;3.01) and girls 1.91(0.55;3.27)]. CONCLUSION: Children with overweight from low SES have an early adiposity rebound and accelerated growth to a higher BMI at age 5-6 years compared to children with overweight from the high SES group. These results imply that timing of critical periods for overweight development is earlier in children with a low socioeconomic background as compared to other children.

The high risk for type 2 diabetes among ethnic minority populations is not explained by low-grade inflammation.

Our aim was to identify whether low-grade inflammation, reflected by C-reactive protein (CRP), explains the higher risk for incident type 2 diabetes (T2D) among ethnic minorities. We included 837 Dutch, 712 South-Asian Surinamese, 797 African Surinamese, 804 Ghanaian, 817 Turkish and 778 Moroccan origin participants of the HELIUS study (Amsterdam, the Netherlands). We used multiple linear regression to assess ethnic differences in CRP levels. We determined the association of CRP with T2D and the modifying effect of ethnicity by cox regression, and compared hazard ratios for the association between ethnicity and T2D before and after adjustment for CRP. CRP levels were higher in ethnic minority groups than in Dutch origin participants. CRP was associated with a higher T2D incidence, similarly across ethnic groups (overall HR per SD 1.38 [95% CI 1.14; 1.68]). However, the association was attenuated and no longer statistically significant after adjustment for adiposity measures (HR 1.11 [95% CI 0.90; 1.37]). CRP accounted for a very small part of the ethnic differences in T2D, but only in models unadjusted for adiposity. Low-grade inflammation does not substantially contribute to the higher risk of T2D among ethnic minority populations compared to the Dutch.

From population reference to national standard: new and improved birthweight charts.

BACKGROUND: Antenatal detection of intrauterine growth restriction remains a major obstetrical challenge, with the majority of cases not detected before birth. In these infants with undetected intrauterine growth restriction, the diagnosis must be made after birth. Clinicians use birthweight charts to identify infants as small-for-gestational-age if their birthweights are below a predefined threshold for gestational age. The choice of birthweight chart strongly affects the classification of small-for-gestational-age infants and has an impact on both research findings and clinical practice. Despite extensive literature on pathological risk factors associated with small-for-gestational-age, controversy exists regarding the exclusion of affected infants from a reference population. OBJECTIVE: This study aims to identify pathological risk factors for abnormal fetal growth, to quantify their effects, and to use these findings to calculate prescriptive birthweight charts for the Dutch population. MATERIALS AND METHODS: We performed a retrospective cross-sectional study, using routinely collected data of 2,712,301 infants born in The Netherlands between 2000 and 2014. Risk factors for abnormal fetal growth were identified and categorized in 7 groups: multiple gestation, hypertensive disorders, diabetes, other pre-existing maternal medical conditions, maternal substance (ab)use, medical conditions related to the pregnancy, and congenital malformations. The effects of these risk factors on mean birthweight were assessed using linear regression. Prescriptive birthweight charts were derived from live-born singleton infants, born to ostensibly healthy mothers after uncomplicated pregnancies and spontaneous onset of labor. The Box-Cox-t distribution was used to model birthweight and to calculate sex-specific percentiles. The new charts were compared to various existing birthweight and fetal-weight charts. RESULTS: We excluded 111,621 infants because of missing data on birthweight, gestational age or sex, stillbirth, or a gestational age not between 23 and 42 weeks. Of the 2,599,640 potentially eligible infants, 969,552 (37.3%) had 1 or more risk factors for abnormal fetal growth and were subsequently excluded. Large absolute differences were observed between the mean birthweights of infants with and without these risk factors, with different patterns for term and preterm infants. The final low-risk population consisted of 1,629,776 live-born singleton infants (50.9% male), from which sex-specific percentiles were calculated. Median and 10th percentiles closely approximated fetal-weight charts but consistently exceeded existing birthweight charts. CONCLUSION: Excluding risk factors that cause lower birthweights results in prescriptive birthweight charts that are more akin to fetal-weight charts, enabling proper discrimination between normal and abnormal birthweight. This proof of concept can be applied to other populations.

Does maternal pre-pregnancy overweight or obesity influence offspring's growth patterns from birth up to 7years? The ABCD-study.

BACKGROUND: Maternal pre-pregnancy overweight is known to program offspring for adverse health outcomes later in life. AIMS: To investigate how growth patterns of weight, height and BMI from birth to 7years differ according to maternal pre-pregnancy weight (normal weight, overweight and obesity), with specific attention for sex differences. STUDY DESIGN: Prospective multi-ethnic ABCD-study. SUBJECTS: 3805 mother-child pairs were included. Self-reported maternal pre-pregnancy body mass index was categorized into: normal weight (18.5-25kg/m2; n=3354), overweight (25-30kg/m2; n=711) and obesity (≥30kg/m2; n=241). OUTCOME MEASURES: Population-specific growth patterns were used to compute SD-scores for weight, height and BMI (on average 12.7 (SD=2.6) measurements for each child) for term born boys and girls separately. Mixed effect models were fitted to these SD-scores to determine the effect of pre-pregnancy BMI category on postnatal growth, corrected for maternal characteristics. RESULTS: Compared to children of mothers with normal weight before pregnancy, children of overweight mothers grew faster in weight and BMI (boys and girls) and children of obese mothers grew faster in height (only girls), weight and BMI (boys and girls) during the first years of life. The differences seemed to increase with age and were in general larger in girls. CONCLUSION: Maternal overweight and obesity impact on offspring's weight, height and BMI growth pattern with increasing differences when children age. Effects were in general stronger for girls. These results suggest that a healthy weight before pregnancy may be beneficial for optimal weight, height and BMI growth in the offspring.

The Effect of Interpregnancy Interval on the Recurrence Rate of Spontaneous Preterm Birth: A Retrospective Cohort Study.

Objective We assessed, in women with a previous spontaneous preterm birth, the effect of interpregnancy interval on the subsequent preterm birth rate. Design Retrospective cohort study. Setting A nationwide longitudinal dataset of the the Netherlands Perinatal Registry. Population Women with three sequential singleton pregnancies between 1999 and 2009 and a spontaneous preterm birth <37 weeks in the first pregnancy. Methods We evaluated the impact of interpregnancy interval on the course of the next pregnancies. Antenatal death and/or congenital abnormalities were excluded. Conventional and conditional logistic regression analysis were applied. We adjusted for maternal age, ethnicity, socioeconomic status, artificial reproductive techniques, and year of birth. Main Outcome Measures Outcomes studied were preterm birth <37 weeks, <32 weeks, low birth weight <2500 g, and small for gestational age <10th percentile. Results Among 2,361 women with preterm birth in the first pregnancy, logistic regression analysis indicated a significant effect of a short interpregnancy interval (0-5 mo) on recurrent preterm birth <37 weeks (odds ratio [OR], 2.22; 95% confidence interval [CI], 1.62-3.05), <32 weeks (OR, 2.90; 95% CI, 1.43-5.87), and low birth weight (OR, 2.69; 95% CI, 1.79-4.03). In addition, a long interval (≥60 mo) had a significant effect on preterm birth <37 weeks (OR, 2.19; 95% CI, 1.29-3.74). Conditional logistic regression analysis confirmed the effect of a short interval on the recurrence of preterm birth rate <37 weeks and low birth weight. Conclusion In women with a previous spontaneous preterm birth, a short interpregnancy interval has a strong impact on the risk of preterm birth before 37 weeks and low birth weight in the next pregnancy, irrespective of the type of analysis performed.

Association between infancy BMI peak and body composition and blood pressure at age 5-6 years.

INTRODUCTION: The development of overweight is often measured with the body mass index (BMI). During childhood the BMI curve has two characteristic points: the adiposity rebound at 6 years and the BMI peak at 9 months of age. In this study, the associations between the BMI peak and body composition measures and blood pressure at age 5-6 years were investigated. METHODS: Measurements from the Amsterdam Born Children and their Development (ABCD) study were available for this study. Blood pressure (systolic and diastolic) and body composition measures (BMI, waist-to-height ratio, fat percentage) were gathered during a health check at about 6 years of age (n = 2822). All children had multiple BMI measurements between the 0-4 years of age. For boys and girls separately, child-specific BMI peaks were extracted from mixed effect models. Associations between the estimated BMI peak and the health check measurements were analysed with linear models. In addition, we investigated the potential use of the BMI at 9 months as a surrogate measure for the magnitude of the BMI peak. RESULTS: After correction for the confounding effect of fetal growth, both timing and magnitude of the BMI peak were significantly and positively associated (p<0.001) with all body composition measures at the age of 5-6 years. The BMI peak showed no direct association with blood pressure at the age 5-6 year, but was mediated by the current BMI. The correlation between the magnitude of the BMI peak and BMI at 9 months was approximately 0.93 and similar associations with the measures at 5-6 years were found. CONCLUSION: The magnitude of the BMI peak was associated with body composition measures at 5-6 years of age. Moreover, the BMI at 9 months could be used as surrogate measure for the magnitude of the BMI peak.

Which patients benefit most from primary surgery or neoadjuvant chemotherapy in stage IIIC or IV ovarian cancer? An exploratory analysis of the European Organisation for Research and Treatment of Cancer 55971 randomised trial.

BACKGROUND: To investigate whether biomarkers consisting of baseline characteristics of advanced stage ovarian cancer patients can help in identifying subgroups of patients who would benefit more from primary surgery or neoadjuvant chemotherapy. METHODS: We used data of the European Organisation for Research and Treatment of Cancer (EORTC) 55971 trial in which 670 patients were randomly assigned to primary surgery or neoadjuvant chemotherapy. The primary outcome was overall survival. Ten baseline clinical and pathological characteristics were selected as potential biomarkers. Using Subpopulation Treatment Effect Pattern Plots (STEPP), biomarkers with a statistically significant qualitative additive interaction with treatment were considered as potentially informative for treatment selection. We also combined selected biomarkers to form a multimarker treatment selection rule. FINDINGS: The size of the largest metastatic tumour and clinical stage were significantly associated with the magnitude of the benefit from treatment, in terms of five-year survival (p for interaction: 0.008 and 0.016, respectively). Stage IIIC patients with metastatic tumours ⩽45 mm benefited more from primary surgery while stage IV patients with metastatic tumours >45 mm benefited more from neoadjuvant chemotherapy. In stage IIIC patients with larger metastatic tumours and in stage IV patients with less extensive metastatic tumours both treatments were equally effective. We estimated that by selecting treatments for patients based on largest metastatic tumour and clinical stage, the potential five-year survival rate in the population of treated patients would be 27.3% (95% confidence interval (CI) 21.9-33.0), 7.8% higher than if all were treated with primary surgery, and 5.6% higher if all were treated with neoadjuvant chemotherapy. INTERPRETATION: Although survival was comparable after primary surgery and neoadjuvant chemotherapy in the overall group of patients with ovarian cancer in the EORTC 55971 trial, we found in this exploratory analysis that patients with stage IIIC and less extensive metastatic tumours had higher survival with primary surgery, while patients with stage IV disease and large metastatic tumours had higher survival with neoadjuvant chemotherapy. For patients who did not meet these criteria, both treatment options led to comparable survival rates.

Recurrence risk of preterm birth in subsequent singleton pregnancy after preterm twin delivery.

OBJECTIVE: The purpose of this study was to investigate the recurrence risk of preterm birth (<37 weeks' gestation) in a subsequent singleton pregnancy after a previous nulliparous preterm twin delivery. STUDY DESIGN: We included 1957 women who delivered a twin gestation and a subsequent singleton pregnancy from the Netherlands Perinatal Registry. We compared the outcome of subsequent singleton pregnancy of women with a history of preterm delivery to the pregnancy outcome of women with a history of term twin delivery. RESULTS: Preterm birth in the twin pregnancy occurred in 1075 women (55%) vs 882 women (45%) who delivered at term. The risk of subsequent spontaneous singleton preterm birth was significantly higher after preterm twin delivery (5.2% vs 0.8%; odds ratio, 6.9; 95% confidence interval, 3.1-15.2). CONCLUSION: Women who deliver a twin pregnancy are at greater risk for delivering prematurely in a subsequent singleton pregnancy.