Linear hair growth rates in preschool children.

BACKGROUND: Human scalp hair is a validated bio-substrate for monitoring various exposures in childhood including contextual stressors, environmental toxins, prescription or non-prescription drugs. Linear hair growth rates (HGR) are required to accurately interpret hair biomarker concentrations. METHODS: We measured HGR in a prospective cohort of preschool children (N = 266) aged 9-72 months and assessed demographic factors, anthropometrics, and hair protein content (HPC). We examined HGR differences by age, sex, race, height, hair pigment, and season, and used univariable and multivariable linear regression models to identify HGR-related factors. RESULTS: Infants below 1 year (288 ± 61 µm/day) had slower HGR than children aged 2-5 years (p = 0.0073). Dark-haired children (352 ± 52 µm/day) had higher HGR than light-haired children (325 ± 50 µm/day; p = 0.0019). Asian subjects had the highest HGR overall (p = 0.016). Younger children had higher HPC (p = 0.0014) and their HPC-adjusted HGRs were slower than older children (p = 0.0073). Age, height, hair pigmentation, and HPC were related to HGR in multivariable regression models. CONCLUSIONS: We identified age, height, hair pigment, and hair protein concentration as significant determinants of linear HGRs. These findings help explain the known hair biomarker differences between children and adults and aid accurate interpretation of hair biomarker results in preschool children. IMPACT: Discovery of hair biomarkers in the past few decades has transformed scientific disciplines like toxicology, pharmacology, epidemiology, forensics, healthcare, and developmental psychology. Identifying determinants of hair growth in children is essential for accurate interpretation of hair biomarker results in pediatric clinical studies. Childhood hair growth rates define the time-periods of biomarker incorporation into growing hair, essential for interpreting the biomarkers associated with environmental exposures and the mind-brain-body connectome. Our study describes age-, sex-, and height-based distributions of linear hair growth rates and provides determinants of linear hair growth rates in a large population of children. Age, height, hair pigmentation, and hair protein content are determinants of hair growth rates and should be accounted for in child hair biomarkers studies. Our findings on hair protein content and linear hair growth rates may provide physiological explanations for differences in hair growth rates and biomarkers in preschool children as compared to adults.

Stress Symptoms Among Children and Their Parents After ICU Hospitalization.

Objective: Child survival after intensive care unit (ICU) hospitalization has increased, yet many children experience acute stress that may precipitate mental/behavioral health comorbidities. Parents report stress after their child's hospitalization. Little is known about the individual and family characteristics that may moderate intergenerational relationships of acute stress. Design: Following ICU admission at a large academic medical center, a prospective cross-sectional cohort study assessed the associations between intergenerational characteristics and acute stress among children and families. Patients: Parent-child dyads (N = 88) were recruited from the pediatric ICU and pediatric cardiovascular ICU (CVICU) following ICU discharge. Eligible children were between 8 and 18 years old with ICU stays longer than 24 hours. Children with developmental delays were excluded. Caregivers were proficient in English or Spanish. Surveys were collected before hospital discharge. Measurements/Main Results: The primary outcome was "child stress" defined as a score≥17, measured by the Children's Revised Impact of Events Scale (CRIES-8). "Parent stress" was defined as an elevated composite score on the Stanford Acute Stress Reaction Questionnaire. We used validated scales to assess the child's clinical and family social characteristics. Acute stress was identified in 34 (39.8%) children and 50 (56.8%) parents. In multivariate linear regression analyses adjusting for social characteristics, parent stress was associated with increased risk of child stress (adjusted odds ratio 2.58, 95% confidence interval 0.69, 4.46, p < .01). In unadjusted analyses, Hispanic ethnicity was associated with greater child stress. In adjusted analyses, race, income, ICU length of stay, and language were not associated with child stress and did not moderate the parent-child stress relationship. Conclusions: Parent stress is closely correlated with child stress during ICU hospitalization. Hispanic ethnicity may be associated with increased risk for child stress, but further studies are required to define the roles of other social and clinical measures.

Association of Continuous Opioids and/or Midazolam During Early Mechanical Ventilation with Survival and Sensorimotor Outcomes at Age 2 Years in Premature Infants: Results from the French Prospective National EPIPAGE 2 Cohort.

OBJECTIVE: To evaluate the association of early continuous infusions of opioids and/or midazolam with survival and sensorimotor outcomes at age 2 years in very premature infants who were ventilated. STUDY DESIGN: This national observational study included premature infants born before 32 weeks of gestation intubated within 1 hour after birth and still intubated at 24 hours from the French EPIPAGE 2 cohort. Infants only treated with bolus were excluded. Treated infants received continuous opioid and/or midazolam infusion started before 7 days of life and before the first extubation. Naive infants did not receive these treatments before the first extubation, or received them after the first week of life, or never received them. This study compared treated (n = 450) vs naive (n = 472) infants by using inverse probability of treatment weighting after multiple imputation in chained equations. The primary outcomes were survival and survival without moderate or severe neuromotor or sensory impairment at age 2 years. RESULTS: Survival at age 2 years was significantly higher in the treated group (92.5% vs 87.9%, risk difference, 4.7%; 95% CI, 0.3-9.1; P = .037), but treated and naive infants did not significantly differ for survival without moderate or severe neuromotor or sensory impairment (86.6% vs 81.3%; risk difference, 5.3%; 95% CI -0.3 to 11.0; P = .063). These results were confirmed by sensitivity analyses using 5 alternative models. CONCLUSIONS: Continuous opioid and/or midazolam infusions in very premature infants during initial mechanical ventilation that continued past 24 hours of life were associated with improved survival without any difference in moderate or severe sensorimotor impairments at age 2 years.

The newborn infant parasympathetic evaluation index for acute procedural pain assessment in preterm infants.

BACKGROUND: Accurate assessments of pain in hospitalized preterm infants present a major challenge in improving the short- and long-term consequences associated with painful experiences. We evaluated the ability of the newborn infant parasympathetic evaluation (NIPE) index to detect acute procedural pain in preterm infants. METHODS: Different painful and stressful interventions were prospectively observed in preterm infants born at 25 + 0 to 35 + 6 weeks gestation. Pain responses were measured using the composite Premature Infant Pain Profile Revised (PIPP-R) scale, the NIPE index, and skin conductance responses (SCR). Outcome measures were correlations between the NIPE index, the PIPP-R score, and the SCR. Sensitivity/specificity analyses tested the accuracy of the NIPE index and SCR. RESULTS: Two hundred and fifty-four procedures were recorded in 90 preterm infants. No significant correlation was found between PIPP-R and the NIPE index. PIPP-R and SCR were positively correlated (r = 0.27, P < 0.001), with stronger correlations for painful procedures (r = 0.68, P < 0.001) and especially for skin-breaking procedures (r = 0.82, P < 0.001). The NIPE index and SCR had high sensitivity and high negative predictive values to predict PIPP-R > 10, especially for skin-breaking painful procedures. CONCLUSIONS: We found no significant correlation between the NIPE index and PIPP-R during routine painful or stressful procedures in preterm infants. IMPACT: Exposure to repetitive pain can lead to neurodevelopmental sequelae. Behavior-based pain scales have limited clinical utility, especially for preterm infants. New devices for monitoring physiological responses to pain have not been validated sufficiently in preterm infants. This study found that the NIPE index was not significantly correlated to the validated PIPP-R scale during acute procedural pain. Secondary analysis of this study showed that NIPE index and SCRs may help to exclude severe pain in preterm infants. In clinical practice, measurements of physiological parameters should be combined with behavior-based scales for multidimensional pain assessments.

The social ecology of childhood and early life adversity.

An increasing prevalence of early childhood adversity has reached epidemic proportions, creating a public health crisis. Rather than focusing only on adverse childhood experiences (ACEs) as the main lens for understanding early childhood experiences, detailed assessments of a child's social ecology are required to assess "early life adversity." These should also include the role of positive experiences, social relationships, and resilience-promoting factors. Comprehensive assessments of a child's physical and social ecology not only require parent/caregiver surveys and clinical observations, but also include measurements of the child's physiology using biomarkers. We identify cortisol as a stress biomarker and posit that hair cortisol concentrations represent a summative and chronological record of children's exposure to adverse experiences and other contextual stressors. Future research should use a social-ecological approach to investigate the robust interactions among adverse conditions, protective factors, genetic and epigenetic influences, environmental exposures, and social policy, within the context of a child's developmental stages. These contribute to their physical health, psychiatric conditions, cognitive/executive, social, and psychological functions, lifestyle choices, and socioeconomic outcomes. Such studies must inform preventive measures, therapeutic interventions, advocacy efforts, social policy changes, and public awareness campaigns to address early life adversities and their enduring effects on human potential. IMPACT: Current research does not support the practice of using ACEs as the main lens for understanding early childhood experiences. The social ecology of early childhood provides a contextual framework for evaluating the long-term health consequences of early life adversity. Comprehensive assessments reinforced with physiological measures and/or selected biomarkers, such as hair cortisol concentrations to assess early life stress, may provide critical insights into the relationships between early adversity, stress axis regulation, and subsequent health outcomes.

Demographic and psychosocial factors associated with hair cortisol concentrations in preschool children.

BACKGROUND: Early life stress has enduring effects on physical and mental health. Hair cortisol concentrations (HCCs) reflect exposures to contextual stressors in early life, but are understudied in preschool children. METHODS: Hair samples from children (N = 693) during clinic visits (CVs) scheduled at 1-4 years (CV1-CV4) were measured using validated assay methods for HCC. RESULTS: HCCs were highest at CV1 and decreased at CV2-CV4, with no sex differences. Black children had higher HCC than White/other children; these differences persisted even after adjusting for socioeconomic factors. Bivariable analyses showed significant effects on HCC for Black race, with specific demographic and psychosocial factors at different ages. Multivariable analyses showed that higher HCC at CV1 were associated with Black race and male sex; at CV2 with Black race, lower maternal self-esteem, socioeconomic adversity, and the child's risk for developmental delay; at CV3 with Black race; at CV4 with maternal depression and the child's prior HCC values. CONCLUSIONS: HCCs were higher in Black children than White/other races; differences were related to maternal factors, socioeconomic adversity, and the child's risk for developmental delay. Public health measures to reduce disparities between Blacks and other races must also consider the long-term effects of chronic stress in early life.

COVID-19 PICU guidelines: for high- and limited-resource settings.

BACKGROUND: Fewer children than adults have been affected by the COVID-19 pandemic, and the clinical manifestations are distinct from those of adults. Some children particularly those with acute or chronic co-morbidities are likely to develop critical illness. Recently, a multisystem inflammatory syndrome (MIS-C) has been described in children with some of these patients requiring care in the pediatric ICU. METHODS: An international collaboration was formed to review the available evidence and develop evidence-based guidelines for the care of critically ill children with SARS-CoV-2 infection. Where the evidence was lacking, those gaps were replaced with consensus-based guidelines. RESULTS: This process has generated 44 recommendations related to pediatric COVID-19 patients presenting with respiratory distress or failure, sepsis or septic shock, cardiopulmonary arrest, MIS-C, those requiring adjuvant therapies, or ECMO. Evidence to explain the milder disease patterns in children and the potential to use repurposed anti-viral drugs, anti-inflammatory or anti-thrombotic therapies are also described. CONCLUSION: Brief summaries of pediatric SARS-CoV-2 infection in different regions of the world are included since few registries are capturing this data globally. These guidelines seek to harmonize the standards and strategies for intensive care that critically ill children with COVID-19 receive across the world. IMPACT: At the time of publication, this is the latest evidence for managing critically ill children infected with SARS-CoV-2. Referring to these guidelines can decrease the morbidity and potentially the mortality of children effected by COVID-19 and its sequalae. These guidelines can be adapted to both high- and limited-resource settings.

Discovering Pain in Newborn Infants.

Randomised Trial of Fentanyl Anesthesia in Preterm Babies Undergoing Surgery: Effects on the Stress Response. By Anand KJ, Sippell WG, and Aynsley-Green A. Lancet 1987; 1:243-8. Reprinted with permission.In a randomised controlled trial, preterm babies undergoing ligation of a patent ductus arteriosus were given nitrous oxide and D-tubocurarine, with (n = 8) or without (n = 8) the addition of fentanyl (10 µg/kg intravenously) to the anesthetic regimen. Major hormonal responses to surgery, as indicated by changes in plasma adrenaline, noradrenaline, glucagon, aldosterone, corticosterone, 11-deoxycorticosterone, and 11-deoxycortisol levels, in the insulin/glucagon molar ratio, and in blood glucose, lactate, and pyruvate concentrations were significantly greater in the nonfentanyl than in the fentanyl group. The urinary 3-methylhistidine/creatinine ratios were significantly greater in the nonfentanyl group on the second and third postoperative days. Compared with the fentanyl group, the nonfentanyl group had circulatory and metabolic complications postoperatively. The findings indicate that preterm babies mount a substantial stress response to surgery under anesthesia with nitrous oxide and curare and that prevention of this response by fentanyl anesthesia may be associated with an improved postoperative outcome.

Measuring socioeconomic adversity in early life.

AIM: Early life adversity leads to enduring effects on physical and mental health, school performance and other outcomes. We sought to identify potentially modifiable factors associated with socioeconomic adversity in early life. METHODS: We enrolled 1503 pregnant women aged 16-40 years, without pregnancy complications or pre-existing conditions from Shelby County, Tennessee. Social, familial and economic variables were analysed using principal components (PCs) analyses to generate the Socioeconomic Adversity Index (SAI). This was replicated using the National Survey of Children's Health (NSCH). Health and social outcomes were compared across the quintile groups defined by SAI values at the county, state and national levels. RESULTS: Significant differences occurred across the SAI Quintile-1 to Quintile-5 groups in marital status, household structure, annual income, education and health insurance. Significantly worse health and social outcomes occurred in the lower versus higher SAI quintiles, including maternal depression, parental incarceration, child's birthweight and potential for child abuse. Maternal age and race also differed significantly across the SAI quintiles. CONCLUSION: Modifiable factors contributing to socioeconomic adversity in early life included marital status, household structure, annual income, education and health insurance. Those exposed to greater socioeconomic adversity as defined by SAI values had significantly worse maternal and child outcomes.

Cognitive Development One Year After Infantile Critical Pertussis.

OBJECTIVES: Pertussis can cause life-threatening illness in infants. Data regarding neurodevelopment after pertussis remain scant. The aim of this study was to assess cognitive development of infants with critical pertussis 1 year after PICU discharge. DESIGN: Prospective cohort study. SETTING: Eight hospitals comprising the Eunice Kennedy Shriver National Institute for Child Health and Human Development Collaborative Pediatric Critical Care Research Network and 18 additional sites across the United States. PATIENTS: Eligible patients had laboratory confirmation of pertussis infection, were less than 1 year old, and were admitted to the PICU for at least 24 hours. INTERVENTIONS: The Mullen Scales of Early Learning was administered at a 1-year follow-up visit. Functional status was determined by examination and parental interview. MEASUREMENTS AND MAIN RESULTS: Of 196 eligible patients, 111 (57%) completed the Mullen Scales of Early Learning. The mean scores for visual reception, receptive language, and expressive language domains were significantly lower than the norms (p < 0.001), but not fine and gross motor domains. Forty-one patients (37%) had abnormal scores in at least one domain and 10 (9%) had an Early Learning Composite score 2 or more SDs below the population norms. Older age (p < 0.003) and Hispanic ethnicity (p < 0.008) were associated with lower mean Early Learning Composite score, but presenting symptoms and PICU course were not. CONCLUSIONS: Infants who survive critical pertussis often have neurodevelopmental deficits. These infants may benefit from routine neurodevelopmental screening.

Defining pain in newborns: need for a uniform taxonomy?

A framework for defining pain terms such as acute, persistent, prolonged or chronic pain to newborns was derived from the scientific literature on neonatal pain assessments, previous attempts to define chronic pain and the clinical and neurophysiological features of neonatal pain. This novel framework incorporates the temporal features, localising characteristics, and secondary effects of the pain experienced, as well as the behavioural and physiological response patterns of newborns. CONCLUSION: Although not evidence-based, this framework provides an initial starting point for defining commonly used neonatal pain terms. It will require future revision/refinement based on the accumulating evidence for non-acute pain.

Assessment of continuous pain in newborns admitted to NICUs in 18 European countries.

AIM: Continuous pain occurs routinely, even after invasive procedures, or inflammation and surgery, but clinical practices associated with assessments of continuous pain remain unknown. METHODS: A prospective cohort study in 243 neonatal intensive care units (NICUs) from 18 European countries recorded the frequency of pain assessments, use of mechanical ventilation, sedation, analgesia or neuromuscular blockade for each neonate for up to 28 days after NICU admission. RESULTS: Only 2113 of 6648 (31.8%) of neonates received assessments of continuous pain, occurring variably among tracheal ventilation (TrV, 46.0%), noninvasive ventilation (NiV, 35.0%) and no ventilation (NoV, 20.1%) groups (p < 0.001). Daily assessments for continuous pain occurred in only 10.4% of all neonates (TrV: 14.0%, NiV: 10.7%, NoV: 7.6%; p < 0.001). More frequent assessments of continuous pain occurred in NICUs with pain guidelines, nursing champions and surgical admissions (all p < 0.01), and for newborns <32 weeks gestational age, those requiring ventilation, or opioids, sedatives-hypnotics, general anaesthetics (O-SH-GA) (all p < 0.001), or surgery (p = 0.028). Use of O-SH-GA drugs increased the odds for pain assessment in the TrV (OR:1.60, p < 0.001) and NiV groups (OR:1.40, p < 0.001). CONCLUSION: Assessments of continuous pain occurred in less than one-third of NICU admissions and daily in only 10% of neonates. NICU clinical practices should consider including routine assessments of continuous pain in newborns.

Regulation of inflammatory biomarkers by intravenous methylprednisolone in pediatric ARDS patients: Results from a double-blind, placebo-controlled randomized pilot trial.

OBJECTIVE: A double-blind, randomized controlled trial showed that low-dose glucocorticoid therapy in pediatric ARDS patients is feasible and may improve both ventilation and oxygenation indices in these patients. However, the molecular mechanisms underlying potential changes in outcomes remain unclear. Based on these clinical findings, this study was designed to examine the effects of intravenous methylprednisolone on circulating inflammatory biomarkers in pediatric ARDS patients. DESIGN: Double-blind, placebo-controlled randomized trial with blood collection on study entry and day 7. SETTING: Tertiary care children's hospital. PATIENTS: Children (0-18years) with ARDS undergoing mechanical ventilation. INTERVENTIONS: 35 children were randomized within 72h of mechanical ventilation. The glucocorticoid group received methylprednisolone 2mg/kg loading dose followed by 1mg/kg/day continuous infusion from days 1 to 7. Both groups were ventilated following the ARDSnet recommendations. WBC and differential cell counts, plasma cytokines and CRP levels, and coagulation parameters were analyzed on days 0 and 7. RESULTS: At study entry, the placebo group had higher IL-15 and basophil levels. On day 7, in comparison to study entry, the placebo group had lower IL-1α, IFN-γ and IL-10 levels. The glucocorticoid group had lower INF-α, IL-6, IL-10, MCP-1, G-CSF and GM-CSF levels, and higher IL-17α levels on day 7 in comparison to study entry. Total and differential cell counts remained unchanged within the placebo group between days 0 and 7, whereas in the glucocorticoid group total WBC and platelets counts were increased on day 7. Pearson's correlation studies within the placebo and glucocorticoid groups revealed positive and negative correlations between cytokine levels, cell counts, coagulation parameters and relevant clinical parameters of disease severity identified in our previous study. Multiple regression models identified several cytokines as predictors for alterations in clinical parameters of disease severity. CONCLUSION: This pilot study shows the feasibility of simultaneously measuring multiple inflammatory cytokines, cell counts and coagulation parameters in pediatric ARDS patients. We report statistical models that may be useful for future, larger trials to predict ARDS severity and outcomes.

Research as a Standard of Care in the PICU.

OBJECTIVES: Excellence in clinical care coupled with basic and applied research reflects the maturation of a medical subspecialty, advances that field, and provides objective data for identifying best practices. PICUs are uniquely suited for conducting translational and clinical research. In addition, multiple investigations have reported that a majority of parents are interested in their children's participation in clinical research, even when the research offers no direct benefit to their child. However, such activity may generate ethical conflict with bedside care providers trying to acutely identify the best approach for an individual critically ill child. Ultimately, this conflict may diminish enthusiasm for the generation of scientific evidence that supports the application of evidence-based medicine into PICU clinical standard work. Accordingly this review endeavors to provide an overview of current state PICU clinical research strengths, liabilities, opportunities, and barriers and contrast this with an established pediatric hematology-oncology iterative research model that constitutes a learning healthcare system. DATA SOURCES, DATA EXTRACTION, AND DATA SYNTHESIS: Narrative review of medical literature published in English. CONCLUSIONS: Currently, most PICU therapy is not evidence based. Developing a learning healthcare system in the PICU integrates clinical research into usual practice and fosters a culture of evidence-based learning and continual care improvement. As PICU mortality has significantly decreased, identification and validation of patient-centered, clinically relevant research outcome measures other than mortality is essential for future clinical trial design. Because most pediatric critical illness may be classified as rare diseases, participation in research networks will facilitate iterative, collaborative, multiinstitutional investigations that over time identify the best practices to improve PICU outcomes. Despite real ethical challenges, critically ill children and their families should have the opportunity to participate in translational/clinical research whenever feasible.

The validity and reliability of the EValuation of INtervention Scale: preliminary report.

AIM: Pain management is a priority for infants receiving neonatal care as they undergo many necessary painful and stressful interventions, which are associated with negative short- or long-term consequences. This study aims to validate the content, and test the reliability, of the EValuation of INtervention Scale (EVIN), which is designed to evaluate the use of widely recommended nonpharmacological strategies to reduce neonatal pain and stress during procedures. METHODS: The content of the EVIN was validated with multidisciplinary participation (N = 80), and consistency was established via observations on preterm infants (N = 12, at 31-34 weeks' gestation) during interventions in a neonatal unit. A revised scale was tested for inter-rater reliability with observations of invasive (blood sampling, N = 16) and noninvasive (nappy change, N = 18) interventions. The intraclass correlation coefficient (ICC) was used to determine inter-rater reliability. SPSS (PASW Statistics) version 18 was used for analysis. RESULTS: Very good intraclass correlation coefficients (>0.8) for both invasive (0.962) and noninvasive procedures (0.970) were achieved. CONCLUSION: These results indicate that the EVIN is suitable for the evaluation of nonpharmacological support during painful or stressful interventions.

Does noninvasive electrical stimulation of acupuncture points reduce heelstick pain in neonates?

AIM: Noninvasive electrical stimulation at acupuncture points (NESAP) for analgesia is used in children, but has not been widely studied in neonates. The purpose of this study was to determine whether NESAP alone or in combination with sucrose relieved heelstick pain in neonates. METHODS: Term neonates (n = 162) receiving routine heelsticks for newborn screening were enrolled following parental consent. All infants received facilitated tucking and non-nutritive sucking. Neonates were randomised to standard care, sucrose, NESAP or sucrose plus NESAP. NESAP (3.5 mA, 10 Hz) or sham was administered over four acupuncture points. The Premature Infant Pain Profile (PIPP), heart rate variability (HRV) and salivary cortisol were used to measure heelstick pain. RESULTS: PIPP scores among all four treatment groups increased during heelstick, F (9,119) = 1.95, p = 0.05 and NESAP therapy had no significant effect on PIPP scores. However, PIPP scores from baseline to heelstick increased the most in the two groups not receiving sucrose (p < 0.01). Mean PIPP scores remained below five during the heelstick in all four groups, indicating minimal or no pain. Differences in HRV and salivary cortisol among groups were insignificant. CONCLUSION: NESAP at 3.5 mA, 10 Hz is not effective in relieving pain during heelsticks in neonates.

Inverse Relationship between Cardio-Ankle Vascular Index and Body Mass Index in Healthy Children.

OBJECTIVE: To establish reference scores for cardio-ankle vascular index (CAVI), a noninvasive measure of vascular function, which reflects the stiffness of arteries, in healthy children, to test for racial and ethnic differences, and to compare CAVI scores between overweight and normal weight children. STUDY DESIGN: Subjects included 292 children aged 10-18 years: 100 non-Hispanic whites, 89 non-Hispanic blacks, and 103 Hispanics. Subjects were grouped as normal weight (body mass index [BMI] <85th percentile for age) and overweight (BMI >85th percentile for age). Blood pressure (BP) and CAVI scores were measured in all subjects. RESULTS: After controlling for age, sex, and BMI, normal weight black males had a higher CAVI score (indicating stiffer arteries) in comparison with Hispanic males and white males (5.53 ± 0.15 vs 5.13 ± 0.15 vs 5.02 ± 0.15, P = .04). BMI had an inverse association on the CAVI score (r = -0.335, P < .0001). In multivariable analysis, BMI and average CAVI scores were significant predictors of each other (R(2) = 0.37, P < .0001, R(2) = 0.21, P < .0001). There was no significant correlation between CAVI scores and resting BP values, confirming that CAVI scores were independent of concurrent BP values. CONCLUSIONS: Significant differences in vascular function exist among ethnic groups of children. Overweight children had lower CAVI scores, suggestive of vascular adaptation to obesity in early life. CAVI, by providing a noninvasive measure of vascular health, may help identify children at increased risk for cardiovascular disease.

Methodological Considerations for Hair Cortisol Measurements in Children.

BACKGROUND: Hair cortisol levels are used increasingly as a measure for chronic stress in young children. We propose modifications to the current methods used for hair cortisol analysis to more accurately determine reference ranges for hair cortisol across different populations and age groups. METHODS: The authors compared standard (finely cutting hair) versus milled methods for hair processing (n = 16), developed a 4-step extraction process for hair protein and cortisol (n = 16), and compared liquid chromatography-mass spectrometry (LC-MS) versus enzyme-linked immunosorbent assays (ELISAs) for measuring hair cortisol (n = 28). The extraction process included sequential incubations in methanol and acetone, repeated twice. Hair protein was measured through spectrophotometric ratios at 260/280 nm to indicate the hair dissolution state using a BioTek plate reader and dedicated software. Hair cortisol was measured using an ELISA assay kit. Individual (n = 13), pooled hair samples (n = 12) with high, intermediate, and low cortisol values, and the ELISA assay internal standards (n = 3) were also evaluated by LC-MS. RESULTS: Milled and standard methods showed highly correlated hair cortisol (rs = 0.951, P < 0.0001) and protein values (rs = 0.902, P = 0.0002), although higher yields of cortisol and protein were obtained from the standard method in 13 of 16 and 14 of 16 samples, respectively (P < 0.05). Four sequential extractions yielded additional amounts of protein (36.5%, 27.5%, 30.5%, 3.1%) and cortisol (45.4%, 31.1%, 15.1%, 0.04%) from hair samples. Cortisol values measured by LC-MS and ELISA were correlated (rs = 0.737; P < 0.0001), although cortisol levels [median (interquartile range)] detected in the same samples by LC-MS [38.7 (14.4-136) ng/mL] were lower than that by ELISA [172.2 (67.9-1051) ng/mL]. LC-MS also detected cortisone, which comprised of 13.4% (3.7%-25.9%) of the steroids detected. CONCLUSIONS: Methodological studies suggest that finely cutting hair with sequential incubations in methanol and acetone, repeated twice, extracts greater yields of cortisol than does milled hair. Based on these findings, at least 3 incubations may be required to extract most of the cortisol in human hair samples. In addition, ELISA-based assays showed greater sensitivity for measuring hair cortisol levels than LC-MS-based assays.