The Wheezing Illnesses Study Leidsche Rijn (WHISTLER): rationale and design

Early-Life Risk Factors for Carotid Intima-Media Thickness and Carotid Stiffness in Adolescence

Importance

Atherogenesis starts during childhood, making childhood and adolescence an important window of opportunity to prevent atherosclerotic cardiovascular disease later in life.

Objective

To identify early-life risk factors for preclinical atherosclerosis in adolescence.

Design, Setting, and Participants

This cohort study is part of the ongoing Wheezing Illness Study in Leidsche Rijn (WHISTLER) prospective birth cohort study, which includes 3005 healthy newborns born between December 2001 and December 2012 in the Leidsche Rijn area of Utrecht, the Netherlands. Eligible participants included those from the WHISTLER cohort who visited the clinic between March 2019 and October 2020 for adolescent follow-up. This study's analyses were performed in January 2024.

Exposures

Early-life growth was assessed at birth to 6 months, 5 years, and 12 to 16 years. Abdominal ultrasonography determined abdominal subcutaneous adipose tissue (SAT) and visceral adipose tissue (VAT) depth. Blood pressure (BP) percentiles and body mass index (BMI) z scores were used.

Main Outcomes and Measures

Carotid ultrasonography was performed at age 12 to 16 years to assess carotid intima-media thickness (cIMT) and the distensibility coefficient (DC), established measures of preclinical atherosclerosis. Multivariable linear regression models were used to identify early-life risk factors for cIMT and DC in adolescence.

Results

In total, 232 adolescents (median [IQR] age, 14.9 [13.7-15.8] years; 121 female [52.2%]) were included. More postnatal weight gain (B = 12.34; 95% CI, 2.39 to 22.39), higher systolic BP at 5 years (B = 0.52; 95% CI, 0.02 to 1.01), more VAT at 5 years (B = 3.48; 95% CI, 1.55 to 5.40), and a larger change in VAT between 5 and 12 to 16 years (B = 3.13; 95% CI, 1.87 to 4.39) were associated with a higher cIMT in adolescence. A higher BMI (B = -2.70, 95% CI,-4.59 to -0.80) and VAT at 5 years (B = -0.56; 95% CI, -0.87 to -0.25), as well as a larger change in BMI between 5 and 12 to 16 years (B = -3.63; 95% CI, -5.66 to -1.60) were associated with a higher carotid stiffness in adolescence. On the contrary, a larger change in SAT between 5 and 12 to 16 years (B = 0.37; 95% CI, 0.16 to 0.58) was associated with a higher carotid DC in adolescence.

Conclusions and Relevance

In this cohort study of 232 participants, early-life growth parameters, and particularly abdominal VAT development, were associated with a higher cIMT and carotid stiffness in adolescence. These findings suggest that assessment of adipose tissue development during childhood can aid characterization of lifetime risk trajectories and tailoring of cardiovascular prevention and risk management strategies.

Physical activity, sedentary behaviour, and childhood asthma: a European collaborative analysis

OBJECTIVES

To investigate the associations of physical activity (PA) and sedentary behaviour in early childhood with asthma and reduced lung function in later childhood within a large collaborative study.

DESIGN

Pooling of longitudinal data from collaborating birth cohorts using meta-analysis of separate cohort-specific estimates and analysis of individual participant data of all cohorts combined.

SETTING

Children aged 0-18 years from 26 European birth cohorts.

PARTICIPANTS

136 071 individual children from 26 cohorts, with information on PA and/or sedentary behaviour in early childhood and asthma assessment in later childhood.

MAIN OUTCOME MEASURE

Questionnaire-based current asthma and lung function measured by spirometry (forced expiratory volume in 1 s (FEV1), FEV1/forced vital capacity) at age 6-18 years.

RESULTS

Questionnaire-based and accelerometry-based PA and sedentary behaviour at age 3-5 years was not associated with asthma at age 6-18 years (PA in hours/day adjusted OR 1.01, 95% CI 0.98 to 1.04; sedentary behaviour in hours/day adjusted OR 1.03, 95% CI 0.99 to 1.07). PA was not associated with lung function at any age. Analyses of sedentary behaviour and lung function showed inconsistent results.

CONCLUSIONS

Reduced PA and increased sedentary behaviour before 6 years of age were not associated with the presence of asthma later in childhood.

Childhood infection burden, recent antibiotic exposure and vascular phenotypes in preschool children

BACKGROUND

Severe childhood infection has a dose-dependent association with adult cardiovascular events and with adverse cardiometabolic phenotypes. The relationship between cardiovascular outcomes and less severe childhood infections is unclear.

AIM

To investigate the relationship between common, non-hospitalised infections, antibiotic exposure, and preclinical vascular phenotypes in young children.

DESIGN

A Dutch prospective population-derived birth cohort study.

METHODS

Participants were from the Wheezing-Illnesses-Study-Leidsche-Rijn (WHISTLER) birth cohort. We collected data from birth to 5 years on antibiotic prescriptions, general practitioner (GP)-diagnosed infections, and monthly parent-reported febrile illnesses (0-1 years). At 5 years, carotid intima-media thickness (CIMT), carotid artery distensibility, and blood pressure (BP) were measured. General linear regression models were adjusted for age, sex, smoke exposure, birth weight z-score, body mass index, and socioeconomic status.

RESULTS

Recent antibiotic exposure was associated with adverse cardiovascular phenotypes; each antibiotic prescription in the 3 and 6 months prior to vascular assessment was associated with an 18.1 μm (95% confidence interval, 4.5-31.6, p = 0.01) and 10.7 μm (0.8-20.5, p = 0.03) increase in CIMT, respectively. Each additional antibiotic prescription in the preceding 6 months was associated with an 8.3 mPa-1 decrease in carotid distensibility (-15.6- -1.1, p = 0.02). Any parent-reported febrile episode (compared to none) showed weak evidence of association with diastolic BP (1.6 mmHg increase, 0.04-3.1, p = 0.04). GP-diagnosed infections were not associated with vascular phenotypes.

CONCLUSIONS

Recent antibiotics are associated with adverse vascular phenotypes in early childhood. Mechanistic studies may differentiate antibiotic-related from infection-related effects and inform preventative strategies.

Tracking Mental Wellbeing of Dutch Adolescents During the First Year of the COVID-19 Lockdown: A Longitudinal Study

PURPOSE

Adolescents might be susceptible to the effects of the COVID-19 lockdown. We assessed changes in mental wellbeing throughout the first year of the pandemic and compared these with prepandemic levels.

METHODS

This five-wave prospective study among Dutch adolescents aged 12-17 years used data collected before the pandemic (n = 224) (T0), in May (T1), July (T2), and October 2020 (T3), and in February 2021 (T4). Generalized estimating equations were used to assess the association between stringency of the lockdown with mental wellbeing.

RESULTS

Adolescents had a lower life satisfaction during the first full lockdown (T1) [adjusted β: -0.36, 95% confidence interval (CI): -0.58 to -0.13], during the partial lockdown (T3) (adjusted β: -0.37, 95% CI: -0.63 to -0.12), and during the second full lockdown (T4) (adjusted β: -0.79, 95% CI: -1.07 to -0.52) compared to before the pandemic (T0). Adolescents reported more internalizing symptoms during only the second full lockdown (T4) (adjusted β: 2.58, 95% CI: 0.41-4.75). During the pandemic [at T1 (adjusted β: 0.29, 95% CI: 0.20-0.38), T2 (adjusted β: 0.36, 95% CI: 0.26-0.46), T3 (adjusted β: 0.33, 95% CI: 0.22-0.45), and T4 (adjusted β: 0.20, 95% CI: 0.07-0.34)], adolescents reported a better psychosomatic health, partly attributable to less trouble falling asleep (p < .01).

DISCUSSION

The COVID-19 lockdown measures have had both a negative and positive impact on mental wellbeing of Dutch adolescents. However, mental wellbeing was most impacted during the second full lockdown compared to before the pandemic.

The PROactive cohort study: rationale, design, and study procedures

Children with a chronic condition face more obstacles than their healthy peers, which may impact their physical, social-emotional, and cognitive development. The PROactive cohort study identifies children with a chronic disease at high risk of debilitating fatigue, decreased daily life participation and psychosocial problems, as well as children who are resilient and thrive despite the challenges of growing up with a chronic condition. Both groups will teach us how we can best support children, adolescents and parents to adapt to and manage a disease, as well as tailor interventions to their specific needs.

This cohort follows a continuous longitudinal design. It is based at the Wilhelmina Children’s Hospital (WKZ) in the Netherlands and has been running since December 2016. Children with a chronic condition (e.g. cystic fibrosis, juvenile idiopathic arthritis, chronic kidney disease, or congenital heart disease) as well children with medically unexplained fatigue or pain in a broad age range (2–18 years) are included, as well as their parent(s). Data are collected from parents (of children between 2 and 18 years) and children (8–18 years), as well as data from their electronic health record (EHR). Primary outcome measures are fatigue, daily life participation, and psychosocial well-being, all assessed via patient- and proxy-reported outcome measures. Generic biological/lifestyle, psychological, and social factors were assessed using clinical assessment tools and questionnaires. In the PROactive cohort study the research assessment is an integrated part of clinical care. Children are included when they visit the outpatient clinic and are followed up annually.

The Impact of the COVID-19 Outbreak on Mental Wellbeing in Children with a Chronic Condition Compared to Healthy Peers

The aim of this study was to assess the impact of the COVID-19 pandemic on the mental wellbeing of children 8-18 years old with chronic conditions, by comparing pandemic data with pre-pandemic data and with healthy peers. Data were obtained from two ongoing longitudinal cohorts: the PROactive cohort study following children with a chronic condition, and the WHISTLER population cohort. Mental wellbeing was assessed by three indicators: life satisfaction, internalising symptoms, and psychosomatic health. The stringency of the COVID-19-related lockdown was considered a moderating factor. Data on chronic patients were recorded before (n = 934, 65% girls) and during (n = 503, 61% girls) the pandemic, and compared to healthy peers during the pandemic (n = 166, 61% girls). Children with a chronic condition reported lower life satisfaction, but no clinically relevant changes in internalising symptoms or psychosomatic health, during the pandemic compared to before. In comparison to healthy peers, children with a chronic condition experienced decreased life satisfaction and psychosomatic health, but internalising symptoms did not differ between groups during the COVID-19 pandemic. The lockdown stringency was negatively associated with all indicators of mental wellbeing-worse life satisfaction, more internalising symptoms, and more psychosomatic symptoms.

Birth cohort studies using symptom diaries for assessing respiratory diseases–a scoping review

Background

Respiratory infections are the most frequent health problem in childhood leading to morbidity and socioeconomic burden. Studying symptoms of respiratory infections in home based settings requires dedicated prospective cohort studies using diaries. However, no information is available on which birth cohort studies using symptom diary data. A review of birth cohort studies with available symptom diary data, follow-up data, and bio samples is needed to support research collaborations and create potential synergies.

Methods

We conducted a scoping review of birth cohort studies using diaries for the collection of respiratory symptoms. The scoping review was conducted in accordance with the PRISMA Extension. We searched the electronic databases PubMed, Embase, Web of science and CINAHL (last search November 2020) resulting in 5872 records (based on title and abstract screening) eligible for further screening.

Results

We examined 735 records as full text articles and finally included 57 according to predefined inclusion criteria. We identified 22 birth cohort studies that collect(ed) data on respiratory symptoms using a symptom diary starting at birth. Numbers of participants ranged from 129 to 8677. Eight studies collected symptom diary information only for the first year of life, nine for the first two years or less and six between three and six years. Most of the cohorts collected biosamples (n = 18) and information on environmental exposures (n = 19).

Conclusion

Information on respiratory symptoms with daily resolution was collected in several birth cohorts, often including related biosamples, and these data and samples can be used to study full spectrum of infections, particularly including those which did not require medical treatment.

Gender-Specific Changes in Life Satisfaction After the COVID-19-Related Lockdown in Dutch Adolescents: A Longitudinal Study

PURPOSE

The purposes of this study were to assess whether mental well-being has changed after introduction of the lockdown measures compared with that before, whether this change differs between boys and girls, and whether this change is associated with COVID-19-related concerns.

METHODS

This is a two-wave prospective study among Dutch adolescents using data collected up to one year before the COVID-19 pandemic (n = 224) and 5-8 weeks after the first introduction of lockdown measures (n = 158). Mental well-being was assessed by three indicators: life satisfaction, internalizing symptoms, and psychosomatic health. General linear model repeated-measures analysis of variance was used to assess whether mental well-being has changed and if this differed by sex. Univariate linear regressions were used to assess associations between COVID-19-related concerns and a change in mental well-being.

RESULTS

Life satisfaction decreased (η2p = .079, p < .001), but no change in internalizing symptoms was observed (η2p = .014, p = .14), and psychosomatic health increased (η2p = .194, p < .001) after the introduction of lockdown measures. Boys scored significantly better on all mental health indicators compared with girls at baseline and follow-up. However, boys' life satisfaction significantly decreased at the follow-up (η2p = .038, p = .015), whereas girls' life satisfaction did not change. Concerns about COVID-19 were significantly associated with a lower life satisfaction and more internalizing symptoms.

CONCLUSIONS

Adolescents', especially boys', life satisfaction decreased during the lockdown. They reported no change in internalizing symptoms and an improved psychosomatic health. Adolescents' mental well-being is expected to vary during the COVID-19 pandemic and should continue to be monitored.

Risk factors for atopic diseases and recurrent respiratory tract infections in children

INTRODUCTION

The simultaneously increased prevalence of atopic diseases and decreased prevalence of infectious diseases might point to a link between the two entities. Past work mainly focused on either atopic diseases or recurrent infections. We aim to investigate whether risk factors for atopic diseases (ie, asthma, allergic rhinitis, atopic dermatitis, and/or food allergy) differ from risk factors for recurrent respiratory tract infections (RRTIs) in children.

METHODS

Cross-sectional data were used from 5517 children aged 1 to 18 years who participated in an Electronic Portal for children between 2011 and 2019. Univariable/multivariable logistic regression analyses were performed to determine risk factors for any atopic disease and RRTIs.

RESULTS

Children aged ≥5 years were more likely to have any atopic disease (adjusted odds ratio [OR]: 1.50-2.77) and less likely to have RRTIs (OR: 0.68-0.84) compared to children aged less than 5 years. Female sex (OR: 0.72; 95% confidence interval [CI]: 0.63-0.81), low birth weight (OR: 0.74; 95% CI: 0.57-0.97) and dog ownership (OR: 0.79; 95% CI: 0.66-0.95) reduced the odds of any atopic disease, but not of RRTIs. Daycare attendance (OR: 1.22; 95% CI: 1.02-1.47) was associated with RRTIs, but not with atopic diseases. A family history of asthma, allergic rhinitis, atopic dermatitis, and RRTIs was significantly associated with the same entity in children, with OR varying from 1.58 (95% CI: 1.35-1.85) in allergic rhinitis to 2.20 (95% CI: 1.85-2.61) in asthma.

CONCLUSION

Risk factors for atopic diseases are distinct from risk factors for RRTIs, suggesting that the changing prevalence of both entities is not related to shared risk factors.

Defining asthma in children: how well do parents, doctors and spirometry agree?

Background

Because diagnosing asthma in school-aged children is challenging, a variety of proxies for asthma are used in clinical practice and research settings as indicators of this disease. We aimed to provide insight into the agreement between various asthma indicators based on parental report, medical diagnosis and spirometry.

Methods

Children from the WHISTLER birth cohort performed spirometry and were followed up with parental ISAAC (International Study of Asthma and Allergies in Childhood) questionnaires about asthma at 5 and 8 years of age. Medical data were extracted from primary care records. We compared 15 asthma indicators based on parental report, medical diagnosis and spirometry using positive agreement, κ statistics and latent class cluster analysis.

Results

At 5 years of age, 1007 children completed a study visit, while 803 children visited at 8 years of age. Depending on the indicator, the responder and child's age, the asthma prevalence ranged from 0.2% to 26.6%. Cluster analysis revealed classes related to the presence of recent symptoms and a decreased lung function. Agreement between parents and doctors was generally low with κ coefficients ranging from 0.07 (recent wheeze) to 0.52 (recent asthma medication). Additionally, parental report showed to be sensitive to recall bias over time.

Conclusions

Dependent on the asthma indicator, the responder and the age of the child, substantial differences in agreement were observed between commonly used indicators associated with asthmatic disease in school-aged children. Most agreement between parents and doctors was seen for objective and recent indicators such as the recent use of asthma medication. We advocate caution when literature with different asthma indicators is compared.

A variety of clinical definitions are used as indicators of asthma. There are substantial differences in agreement between parents, doctors and lung function. Caution is needed when literature with different asthma indicators is compared.https://bit.ly/2VxDH8p

Relations between air pollution and vascular development in 5-year old children: a cross-sectional study in the Netherlands

BACKGROUND

Air pollution has been shown to promote cardiovascular disease in adults. Possible mechanisms include air pollution induced changes in arterial wall function and structure. Atherosclerotic vascular disease is a lifelong process and childhood exposure may play a critical role. We investigated whether air pollution is related to arterial wall changes in 5-year old children. To this aim, we developed an air pollution exposure methodology including time-weighted activity patterns improving upon epidemiological studies which assess exposure only at residential addresses.

METHODS

The study is part of an existing cohort study in which measurements of carotid artery intima-media thickness, carotid artery distensibility, elastic modulus, diastolic and systolic blood pressure have been obtained. Air pollution assessments were based on annual average concentration maps of Particulate Matter and Nitrogen Oxides at 5 m resolution derived from the European Study of Cohorts for Air Pollution Effects. We defined children's likely primary activities and for each activity we calculated the mean air pollution exposure within the assumed area visited by the child. The exposure was then weighted by the time spent performing each activity to retrieve personal air pollution exposure for each child. Time spent in these activities was based upon a Dutch mobility survey. To assess the relation between the vascular status and air pollution exposure we applied linear regressions in order to adjust for potential confounders.

RESULTS

Carotid artery distensibility was consistently associated with the exposures among the 733 5-years olds. Regression analysis showed that for air pollution exposures carotid artery distensibility decreased per standard deviation. Specifically, for NO2, carotid artery distensibility decreased by - 1.53 mPa- 1 (95% CI: -2.84, - 0.21), for NOx by - 1.35 mPa- 1 (95% CI: -2.67, - 0.04), for PM2.5 by - 1.38 mPa- 1 (95% CI: -2.73, - 0.02), for PM10 by - 1.56 mPa- 1 (95% CI: -2.73, - 0.39), and for PM2.5absorbance by - 1.63 (95% CI: -2.30, - 0.18). No associations were observed for the rest outcomes.

CONCLUSIONS

The results of this study support the view that air pollution exposure may reduce arterial distensibility starting in young children. If the reduced distensibility persists, this may have clinical relevance later in life. The results of this study further stress the importance of reducing environmental pollutant exposures.

Excess early postnatal weight gain and blood pressure in healthy young children

Blood pressure (BP) tracks from childhood to adulthood, and early BP trajectories predict cardiovascular disease risk later in life. Excess postnatal weight gain is associated with vascular changes early in life. However, to what extent it is associated with children's BP is largely unknown. In 853 healthy 5-year-old children of the Wheezing-Illnesses-Study-Leidsche-Rijn (WHISTLER) birth cohort, systolic (SBP) and diastolic BP (DBP) were measured, and z scores of individual weight gain rates adjusted for length gain rates were calculated using at least two weight and length measurements from birth until 3 months of age. Linear regression analyses were conducted to investigate the association between weight gain rates adjusted for length gain rates and BP adjusted for sex and ethnicity. Each standard deviation increase in weight gain rates adjusted for length gain rates was associated with 0.9 mmHg (95% CI 0.3, 1.5) higher sitting SBP after adjustment for confounders. Particularly in children in the lowest birth size decile, high excess weight gain was associated with higher sitting SBP values compared to children with low weight gain rates adjusted for length gain rates. BMI and visceral adipose tissue partly explained the association between excess weight gain and sitting SBP (β 0.5 mmHg, 95% CI -0.3, 1.3). Weight gain rates adjusted for length gain rates were not associated with supine SBP or DBP. Children with excess weight gain, properly adjusted for length gain, in the first three months of life, particularly those with a small birth size, showed higher sitting systolic BP at the age of 5 years.

The association between a genetic risk score for allergy and the risk of developing allergies in childhood-Results of the WHISTLER cohort

BACKGROUND

Several genetic variants have been associated with the susceptibility to allergic disease in adults, but it remains unclear whether these genetic variants are also associated with the onset of allergic disease early in life. The aim of this study was to develop a genetic risk score (GRS) for allergy based on findings in adults and study its predictive capacity for allergy in children.

METHODS

A GRS was constructed based on 10 SNPs previously associated with allergies in adults. The GRS was tested in children who participated in a population-based newborn cohort (WHISTLER) and were followed from birth to school age. Logistic regression analysis was used to study the association between the GRS and the parental-reported allergies at age 5 (based on a reported allergy to ≥1 of the following allergens: pollen, house dust mites, or pets). A Cox regression model was used to study the association between GRS and a physician-diagnosed allergy during follow-up (allergic conjunctivitis, allergic rhinitis, and eczema/dermatitis). Cohen's kappa coefficient was calculated to study the agreement between physician-diagnosed allergy and parental-reported allergy at age 5.

RESULTS

The GRS was significantly associated with parental-reported allergy (odds ratio: 15.9, 95% confidence interval (CI): 1.07-233.73) at age 5, as well as with a physician-diagnosed allergy during follow-up (hazard ratio: 1.89, 95% CI: 1.05-3.41). The overall agreement between physician-diagnosed and parental-reported allergies was 70.5% (kappa: 0.10, 95% CI: 0.03-0.18).

CONCLUSIONS

An adult-derived GRS for allergy predicts the risk of developing allergies in childhood.

Cardiovascular and Metabolic Health of 74 Children From Women Previously Diagnosed With Polycystic Ovary Syndrome in Comparison With a Population-Based Reference Cohort

Women with polycystic ovary syndrome (PCOS) have compromised cardiovascular health profiles and an increased risk of pregnancy complications. In order to evaluate potential consequences, we aim to compare the cardiovascular and metabolic health of the children from women with PCOS with a population-based reference cohort. We included children from women with PCOS between the age of 2.5 to 4 years (n = 42) and 6 to 8 years (n = 32). The reference groups consisted of 168 (3-4 years old) and 130 children (7-8 years old). In an extensive cardiovascular screening program, we measured anthropometrics and blood pressure (all children), heart function and vascular rigidity (young children), metabolic laboratory assessment and carotid intima thickness (old age-group). Results showed that young PCOS offspring have a significantly lower diastolic blood pressure (β = 2.3 [95% confidence interval, CI: 0.5-4.0]) and higher aortic pulse pressure (β = -1.4 [95% CI: -2.5 to -0.2]), compared to the reference population. Furthermore, a higher left ventricle internal diameter but a lower tissue Doppler imaging of the right wall in systole compared to the reference group was found. Older offspring of women with PCOS presented with a significantly lower breast and abdominal circumference, but higher triglycerides (β = -0.1 [95% CI: -0.2 to -0.1]), LDL-cholesterol (β = -0.4 [95% CI: -0.6 to -0.1]), and higher carotid intima-media thickness (β = -31.7 [95% CI: -46.6 to -16.9]) compared to the reference group. In conclusion, we observe subtle but distinct cardiovascular and metabolic abnormalities already at an early age in PCOS offspring compared to a population-based reference group, despite a lower diastolic blood pressure, breast, and abdominal circumference. These preliminary findings require confirmation in independent data sets.

Detecting Acute Otitis Media Symptom Episodes Using a Mobile App: Cohort Study

BACKGROUND

Population cohort studies are useful to study infectious diseases episodes not attended by health care services, but conventional paper diaries and questionnaires to capture cases are prone to noncompliance and recall bias. Use of smart technology in this setting may improve case finding.

OBJECTIVE

The objective of our study was to validate an interactive mobile app for monitoring occurrence of acute infectious diseases episodes in individuals, independent of health care seeking, using acute otitis media (AOM) symptom episodes in infants as a case study. We were interested in determining participant compliance and app performance in detecting and ascertaining (parent-reported) AOM symptom episodes with this novel tool compared with traditional methods used for monitoring study participants.

METHODS

We tested the InfectieApp research app to detect AOM symptom episodes. In 2013, we followed 155 children aged 0 to 3 years for 4 months. Parents recorded the presence of AOM symptoms in a paper diary for 4 consecutive months and completed additional disease questionnaires when AOM symptoms were present. In 2015 in a similar cohort of 69 children, parents used an AOM diary and questionnaire app instead.

RESULTS

During conventional and app-based recording, 93.13% (17,244/18,516) and 94.56% (7438/7866) of symptom diaries were returned, respectively, and at least one symptom was recorded for 32.50% (n=5606) and 43.99% (n=3272) of diary days (P<.01). The incidence of AOM symptom episodes was 605 and 835 per 1000 child-years, respectively. Disease questionnaires were completed for 59% (17/29) of episodes when participants were using conventional recording, compared with 100% (18/18) for app-based recording.

CONCLUSIONS

The use of the study's smart diary app improved AOM case finding and disease questionnaire completeness. For common infectious diseases that often remain undetected by health care services, use of this technology can substantially improve the accurateness of disease burden estimates.

Long-chain polyunsaturated fatty acids in infant formula and cardiovascular markers in childhood

To investigate whether children who consumed infant formula supplemented with long-chain polyunsaturated fatty acids (LCPUFAs) had a more favourable cardiovascular profile than children who consumed formula without these fatty acids, we used the Wheezing Illnesses Study Leidsche Rijn, a birth cohort that included 2,468 newborns between 2001 and 2014. Data on infant feeding were obtained by questionnaires. At age 5, blood pressure, carotid intima-media thickness (CIMT), and carotid distension were measured. We used multivariable linear regression analysis to compare levels of cardiovascular markers in formula-fed children born before and after the LCPUFA supplementation. To account for secular trends, we compared levels of cardiovascular markers in a control group of breastfed children from the same cohort born before and after the supplementation. Formula-fed children born after the LCPUFA supplementation (n = 48) had no different systolic blood pressure (-2.58 mmHg, 95% confidence interval, CI [-5.5, 0.30]), diastolic blood pressure (-0.13 mmHg, 95% CI [-2.3, 2.1]), or carotid distension (24.8 MPa^-1 , 95% CI [-47.1, 96.6]) and had a higher CIMT (18.6 μm, 95% CI [3.7, 33.5]) than formula-fed children born before the supplementation (n = 163). In the control group, children born after the LCPUFA supplementation (n = 98) had no different systolic- or diastolic-blood pressure, or CIMT, and a higher carotid distension than children born before the supplementation (n = 142). In conclusion, children who consumed infant formula supplemented with LCPUFAs did not have a more favourable cardiovascular profile in early childhood than children who consumed formula without LCPUFAs.

Feasibility and characteristics of arterial stiffness measurement in preschool children

Background

Arterial stiffness is an important predictor of cardiovascular risk in adult life. Increased arterial stiffness can also be present in children and may be associated with several other cardiovascular risk factors. Until now, however, we know little about measuring arterial stiffness in preschool children. In this study, we assessed the feasibility of measuring arterial stiffness in preschool children and explored possible determinants related to arterial stiffness at this age.

Methods

We studied 168 healthy children, aged 3.3–4.1 years, who were recruited from a prospective birth cohort. We measured arterial stiffness, expressed in aortic pulse wave velocity and augmentation index, using a non-invasive oscillometric device (Arteriograph). We measured anthropometry and recorded other determinants using a questionnaire.

Results

In 100 children (59.5%) at least one valid arterial stiffness measurement was obtained. Of these infants, 89 had at least two valid measurements and 73 infants had at least three valid measurements. The mean aortic pulse wave velocity was 5.56 m/s (SD 0.77), and the mean augmentation index of the aorta was 19.7 m/s (SD 7.0). The augmentation index was significantly inversely associated with body height, with a regression coefficient of –0.78 (m/s)/cm (95% confidence interval –1.13 to –0.42). The augmentation index was not significantly associated with age, sex or (birth) weight.

Conclusion

The feasibility of measuring arterial stiffness in preschool children using the Arteriograph is moderate. We identified height as the most important determinant of the augmentation index in preschool children.

Antenatal coffee and tea consumption and the effect on birth outcome and hypertensive pregnancy disorders

BACKGROUND AND OBJECTIVE

Coffee and tea are commonly consumed during pregnancy. While several of their components, like caffeine, have strong pharmacological effects, the effect on the unborn fetus remains unclear. Caffeine intake has been associated with abortion, preterm birth and fetal growth restriction, but a general consensus on caffeine restriction is still lacking. We aimed to investigate antenatal coffee, tea and caffeine consumption and the effect on birth weight and length, gestational age at birth and hypertensive disorders in pregnancy.

METHODS

A total of 936 healthy pregnancies from the WHISTLER birth cohort with data on coffee and tea consumption were included. Maternal and child characteristics as well as antenatal coffee and tea consumption were obtained through postpartum questionnaires. Reported consumption was validated using available preconceptional data. Caffeine intake was calculated from coffee and tea consumption. Linear and logistic regression was used to assess the association with birth outcome and hypertensive disorders.

RESULTS

After adjustment for smoking and maternal age, a daily consumption of more than 300mg of caffeine compared to less than 100mg of caffeine was significantly associated with an increased gestational age (linear regression coefficient = 2.00 days, 95%CI = 0.12-4.21, P = 0.03). Tea consumption was significantly related to a higher risk of pregnancy induced hypertension (OR = 1.13, 95%CI = 1.04-1.23, P = 0.004). No associations concerning coffee consumption or birth weight and birth length were observed.

CONCLUSIONS

Daily caffeine consumption of more than 300mg is possibly associated with an increase in gestational age at birth. A possible relation between high tea consumption and increased risk for pregnancy induced hypertension warrants further research. For most outcomes, we found no significant associations with coffee or tea intake.

Acute Otitis Media During Infancy: Parent-reported Incidence and Modifiable Risk Factors

BACKGROUND

Age at exposure to acute otitis media (AOM) risk factors such as day care attendance, lack of breastfeeding and tobacco smoke is little studied but important for targeting AOM prevention strategies. Moreover, studies are typically restricted to clinically diagnosed AOM, while a significant subset can occur outside the health care system, depending on the country setting. This study aims to determine risk factor exposure and effect of its timing within the first year of life on parent-reported AOM symptom episodes.

METHODS

In the WHeezing and Illnesses STudy LEidsche Rijn birth-cohort study, 1056 children were prospectively followed during their first year of life. Group day care attendance, breastfeeding and tobacco smoke exposure were recorded monthly and parent-reported AOM symptoms daily. Generalized estimating equations were used to estimate the association between the time-varying risk factors and AOM symptom episodes, while correcting for confounding by indication.

RESULTS

The first-year incidence rate of parent-reported AOM was 569/1000 child-years [95% confidence interval (CI): 523-618]. Children who attended day care had higher odds of developing AOM symptom episodes compared with those not attending (odds ratio: 5.0; 95% CI: 2.6-9.6). Tobacco smoke exposure and (a history of) breastfeeding were not associated with AOM. Test for interaction revealed that the effect of day care increased with each month younger in age.

CONCLUSIONS

First-year day care attendance is a major risk factor for AOM symptom episodes among infants in the community. This adjusted effect estimate is higher than previously reported and is age-dependent. AOM prevention strategies in day care facilities should therefore focus in particular on the youngest age groups.

E-health and consultation rates for respiratory illnesses in infants: a randomised clinical trial in primary care

BACKGROUND

It is assumed that clear and complete information on the internet can reduce healthcare consumption.

AIM

We assessed in a randomised clinical trial whether a personalised online parent information program on infant respiratory symptoms can reduce primary care utilisation.

DESIGN AND SETTING

Randomised clinical trial in primary healthcare centres in a new residential area in the Netherlands.

METHOD

A web-based program (WHISTLER-online) was developed for parents that offered general information on childhood respiratory disease and personalised risk assessments. Parents of infants who enrolled from June 2009 to June 2012 in WHISTLER, an ongoing population-based birth cohort, were randomly allocated to 'WHISTLER-online' or 'usual care'. Information about, first, consultations and, second, associated prescriptions for respiratory symptoms during the first year of life was collected from the electronic patient files.

RESULTS

A total of 323 infants were randomly assigned to WHISTLER-online and 322 to usual care, and 314 and 305, respectively, were analysed. Of the parents, 70% used WHISTLER-online, and 99% of them judged it to be clear and useful information. There were differences neither in consultation rates for respiratory symptoms (incidence rate ratio 0.96 [95% CI = 0.85 to 1.09, P = 0.532]) nor in associated drug prescriptions.

CONCLUSION

Although parents greatly appreciate the provided facilities, a personalised e-support program on respiratory illnesses in infants does not substantially reduce healthcare utilisation.

Impact of Early-Onset Acute Otitis Media on Multiple Recurrences and Associated Health Care Use

OBJECTIVE

To quantify the critical age period of first episode of acute otitis media (AOM) and its consequences for AOM recurrences and AOM health care use.

STUDY DESIGN

Children enrolled in the Wheezing-Illnesses-STudy-LEidsche-Rijn cohort with at least 1 episode of AOM documented in their primary care health record before 2 years of age were followed until 6 years of age. Data on episodes of AOM and associated primary care consultations, antibiotic prescriptions, and specialist referrals were retrieved. Regression models assessed the presence and shape of the associations between age of first AOM and subsequent episodes of AOM and health care use.

RESULTS

A total of 796 of 2026 children (39%) experienced a first AOM before 2 years of age. Each month decrease in age at first AOM in the first 2 years of life increased the risk of developing recurrent AOM (≥3 AOM episodes in 6 months or ≥ 4 in 1 year) linearly by 6% (adjusted risk ratio: 1.06; 95% CI: 1.02-1.10). For first AOM occurring before 9 months, the cumulative 6-year primary care consultation rate increased by 8% (adjusted incidence rate ratio: 1.08; 95% CI: 1.03-1.15) and the associated specialist referral increased by 16% (adjusted risk ratio: 1.16; 95% CI: 1.07-1.27) for each month decrease in age. No associations were found between age at first AOM and total AOM episodes or antibiotic prescriptions.

CONCLUSIONS

The association between earlier age of first AOM and recurrent AOM as well as total health care use during childhood is particularly strong before 9 months of age.

Antibiotic Treatment for First Episode of Acute Otitis Media Is Not Associated with Future Recurrences

OBJECTIVE

Antibiotic treatment of acute otitis media (AOM) has been suggested to increase the risk of future AOM episodes by causing unfavorable shifts in microbial flora. Because current evidence on this topic is inconclusive and long-term follow-up data are scarce, we wanted to estimate the effect of antibiotic treatment for a first AOM episode occurring during infancy on AOM recurrences and AOM-related health care utilization later in life.

METHODS

We obtained demographic information and risk factors from data of the Wheezing Illnesses Study Leidsche Rijn, a prospective birth cohort study in which all healthy newborns born in Leidsche Rijn (between 2001 and 2012), The Netherlands, were enrolled. These data were linked to children's primary care electronic health records up to the age of four. Children with at least one family physician-diagnosed AOM episode before the age of two were included in analyses. The exposure of interest was the prescription of oral antibiotics (yes vs no) for a child's first AOM episode before the age of two years.

RESULTS

848 children were included in analyses and 512 (60%) children were prescribed antibiotics for their first AOM episode. Antibiotic treatment was not associated with an increased risk of total AOM recurrences (adjusted rate ratio: 0.94, 95% CI: 0.78-1.13), recurrent AOM (≥3 episodes in 6 months or ≥4 in one year; adjusted risk ratio: 0.79, 95% CI: 0.57-1.11), or with increased AOM-related health care utilization during children's first four years of life.

CONCLUSIONS

Oral antibiotic treatment of a first AOM episode occurring during infancy does not affect the number of AOM recurrences and AOM-related health care utilization later in life. This information can be used when weighing the pros and cons of various AOM treatment options.

Analysis of recruitment in a pragmatic observational study on C-reactive protein point-of-care testing in primary care

INTRODUCTION

Failure to recruit all eligible study patients can lead to biased results. Little is known on selective patient recruitment in studies on implementation of diagnostic devices.

OBJECTIVES

The aim of this observational study was to measure recruitment of patients in an implementation study in primary care on use of point-of-care (POC) C-reactive protein (CRP) and to evaluate recruitment bias and its impact on the study endpoint.

METHODS

In a cross-sectional observational study on POC CRP implementation and related antibiotics prescribing, we compared included patients with all eligible patients to assess the representativeness of the included subjects. Eligible patients were adults presenting with acute cough in primary care between March and September 2012. The frequency of POC CRP testing and the proportion of prescribed antibiotics were compared between recruited and non-recruited patients. As measure of bias, odds ratios (ORs) with accompanying 95% confidence intervals (CIs) for the association between CRP level (<20 mg/l or not) and antibiotic prescribing were computed.

RESULTS

Of all 1473 eligible patients 348 (24%) were recruited. In recruited patients, POC CRP tests were conducted and antibiotics prescribed more frequently as compared to non-recruited patients (81% versus 6% and 44% versus 29%, respectively). The ORs were 18.2 (95%CI: 9.6-34.3), 30.5 (95%CI: 13.2-70.3) and 3.8 (95%CI: 0.9-14.8) respectively in all eligible patients, the recruited and the non-recruited patients.

CONCLUSION

Selective recruitment resulted in an overestimation of POC CRP test use and antibiotic prescribing.

C-reactive protein point-of-care testing and associated antibiotic prescribing

BACKGROUND

In clinical trials, the potential of point-of-care (POC) C-reactive protein (CRP) tests was demonstrated in decreasing antibiotic prescribing in adults with acute cough in general practice, but effects of implementation are unknown.

OBJECTIVE

To determine the overall effect of POC CRP testing on antibiotic prescribing rate in general practice.

METHODS

In an observational study, GPs were instructed to use POC CRP in adults with acute cough following current guidelines. After routine history taking and physical examination, they reported whether they intended to prescribe antibiotics ('pre-test decision'). They reported their revised decision after receiving the POC CRP test result ('post-test decision'). Primary outcome was the percentage of patients in whom the GP changed his or her decision to prescribe antibiotics. Secondary outcome was the difference between 'pre-test' and 'post-test' antibiotic prescribing % at group level.

RESULTS

A total of 40 GPs enrolled 939 patients, 78% of whom were tested for CRP. GPs changed their decision after POC CRP testing in 200 patients (27%). Antibiotic prescribing before and after CRP testing did not differ ('pre-test' 31%, 'post-test' 28%; 95% confidence interval of difference -7 to 1). In 41% of the tested patients, the indication for testing was in accordance with the guidelines.

CONCLUSION

POC CRP influenced GPs to change their decision about antibiotic prescribing in patients with acute cough. POC CRP testing does not reduce overall antibiotic prescribing by GPs who already have a low antibiotic prescribing rate.

E-health and health care behaviour of parents of young children: a qualitative study

OBJECTIVE

Internet plays a huge role in providing information about health care problems. However, it is unknown how parents use and perceive the internet as a source of information and how this influences health care utilisation when it comes to common complaints in infants. The objective was to evaluate the perception parents have on the role of internet in providing health care information on common symptoms in infants and its effects on health care utilisation.

DESIGN

A qualitative design was chosen.

SETTING AND SUBJECTS

Parents were recruited from a population-based birth-cohort and selected purposefully.

MAIN OUTCOME MEASURES

Semi-structured interviews were used to receive information of parents' ideas. Thematic coding and constant comparison were used for interview transcript analysis.

RESULTS

Ten parents were interviewed. Parents felt anxious and responsible when their child displayed common symptoms, and appeared to be in need of information. They tried to obtain information from relatives, but more so from the internet, because of its accessibility. Nevertheless, information found on the internet had several limitations, evoked new doubts and insecurity and although parents compared information from multiple sources, only the physician was able to take away the insecurity. The internet did not interfere in the decision to consult the physician.

CONCLUSIONS

Parents need information about their children's symptoms and the internet is a major resource. However, only physicians could take away their symptom-related doubts and insecurities and internet information did not play a role in parental decision making. Information gathered online may complement the information from physicians, rather than replace it. Key points Internet plays an increasing role in providing health care information but it is unknown how this influences health care utilisation. Our study suggests that: Parents need information about their children's symptoms and the internet is a major resource. However, only physicians could take away their symptom-related doubts and insecurities. Internet information did not play a role in parental decision making.

First-year Daycare and Incidence of Acute Gastroenteritis

BACKGROUND

Daycare attendance has been associated with increased acute gastroenteritis (AGE) incidence in the first years of life. We investigated the effects of first-year daycare attendance on AGE incidence and primary care contact rate up to age 6 years.

METHODS

Children enrolled in the Wheezing Illnesses Study Leidsche Rijn cohort were managed until age 6 years. Data on primary care diagnosed AGE episodes and number of associated contacts per episode were collected from health records. Children were categorized according to first year daycare attendance and age-month at entry when applicable. Generalized estimating equations were used to assess associations between first-year daycare and AGE incidence or primary care contact rate.

RESULTS

A total of 1344 out of 2220 children (83%) attended daycare before age 1 year. Overall, the 6-year primary care AGE incidence rate (IR) among first-year daycare attendees and nonattendees was comparable (IR: 12.2/100 vs 13.3/100 child-years). First-year daycare attendees had a higher AGE incidence during the first year (IRR: 1.13; 95% confidence interval: 1.06-1.21) and lower during the third to sixth year of age compared with nonattendees (P < .001). The daycare-associated increase in AGE incidence was most pronounced during the first 12 months after enrollment into daycare and demonstrated clear seasonality. A similar pattern was observed for primary care contact rate per AGE episode.

CONCLUSIONS

First-year daycare attendance advances the timing of AGE infections, resulting in increased AGE disease burden in the first year and relative protection thereafter. Protection against AGE infection persists at least up to age 6 years. Future studies should address whether this protective effect persists during later childhood.

Lack of Impact of Body Mass Index at Young Age on Otitis Media Occurrence During Preschool Years: Wheezing Illnesses Study Leidsche Rijn Cohort Study

Using data on weight and height at 6 and 11 months of age and primary care electronic health records data from 1960 children participating in the Wheezing Illnesses Study Leidsche Rijn birth cohort study, we found that body mass index at 6 and 11 months of age was not associated with otitis media occurrence during the first 4 years of life.

Maternal use of probiotics during pregnancy and effects on their offspring's health in an unselected population

Probiotics are used by women in the perinatal period and may improve balance of microbiota, with possible health benefits for both mother and baby. Characteristics and (health) behaviour patterns of mothers using probiotics during pregnancy, and health effects on their offspring, were investigated. Differences between mothers using probiotics during pregnancy and those who did not, were assessed. In total, 341 out of 2491 (13.7%) mothers reported use of probiotics during pregnancy. There were no significant differences in maternal features (gestation, age, ethnicity, education) between users and non-users. Logistic regression analyses showed that consumption of probiotics was significantly associated with use of homeopathic products [odds ratio (OR) 1.65, 95% confidence interval (CI) 1.17-2.33, p = 0.005], maternal history of smoking (OR 1.72, 95% CI 1.25-2.37, p = 0.001) and paternal history of smoking (OR 1.39, 95% CI 1.01-1.89, p = 0.05). Common disease symptoms during the first year of life in the offspring did not differ between both groups.

CONCLUSION

The use of probiotics or other health-related products without doctor's prescription during pregnancy might point to compensation for types of less favourable behaviour. Probiotic use during pregnancy does not seem to induce positive health effects in the offspring in an unselected population.

WHAT IS KNOWN

Aberrant microbiota compositions have been detected during critical periods when early programming occurs including pregnancy and early neonatal life. Probiotics modulate intestinal microbiota composition and are associated with positive health effects.

WHAT IS NEW

The use of probiotics or other health-related products without doctor's prescription during pregnancy is associated with and might point to compensation for types of less favourable behaviour. Probiotic use during pregnancy does not induce positive health effects in the offspring in this unselected population.

Relation Between Circulating Inflammatory Chemokines and Vascular Characteristics in Healthy, Young Children

BACKGROUND

Atherosclerosis begins in childhood with the occurrence of inflammatory vascular wall alterations that are detectable with B-mode ultrasound. Chemokines appear to be involved in the development of these alterations given that they occur early in the atherosclerotic pathway as mediators of vascular inflammation. However, this has not extensively been investigated. Therefore, we studied in healthy young children whether chemokines monocyte chemotactic protein 1 (MCP-1), regulated on activation normal T-cell expressed and secreted (RANTES), and vascular and intercellular adhesion molecules (VCAM and ICAM) related to vascular characteristics of the carotid artery.

METHODS AND RESULTS

We obtained demography, anthropometry, and overnight fasting plasma of 139 eight-year-old children of the Wheezing Illnesses Study Leidsche Rijn birth cohort. Carotid intima-media thickness (CIMT), distensibility, and Young's Elastic Modulus (YEM) of the common carotid artery were measured sonographically. Chemokine plasma levels were assessed using a multiplex assay. We studied the relation between the chemokines and vascular characteristics using multivariable linear regression analyses with adjustments for sex, systolic blood pressure, homeostasis model assessment of insulin resistance, triglycerides, low-density lipoprotein- and high-density lipoprotein-cholesterol. Of the studied chemokines, RANTES related to common carotid distensibility and YEM. One standard deviation increase in RANTES level related to a 5.45-MPA(-1) (95% confidence interval [CI], -9.43, -1.39; P=0.01) decrease in distensibility and to a 5.55-kPa increase in YEM (95% CI, 0.40, 10.85; P=0.03). RANTES did not relate to CIMT. MCP-1, VCAM, and ICAM did not relate to any of the studied vascular characteristics.

CONCLUSION

RANTES appears to be involved in the development of preatherosclerotic inflammatory vascular alterations already in healthy, young children. This may provide further insight into the early-life origins of atherosclerosis.

Maternal body mass index, neonatal lung function and respiratory symptoms in childhood

Recent studies have shown that maternal obesity is associated with increased risk of wheezing in the offspring. We assessed whether impaired neonatal lung function could explain this association. We measured neonatal lung function in 2606 children of our prospective birth cohort. Information about daily symptoms of wheezing was obtained using questionnaires. Consultations and prescriptions for wheezing illnesses were derived from general practitioner patient files. Higher maternal body mass index (BMI) was associated with increased risk of wheezing in the first year of life and more consultations and prescriptions for wheezing illnesses until the age of 5 years. Lung function could partially explain the association with wheezing in the first year of life. Adding respiratory resistance to the model decreased the incidence rate ratio from 1.023 (95% CI 1.008-1.039) to 1.015 (95% CI 0.998-1.032). Anthropometrics of the 5-year-olds largely explained the association with consultations. Intermediates or confounders could not explain the association with prescriptions. There is an association between higher maternal BMI and increased risk of wheezing illnesses. In the first year of life, it is largely explained by an impaired lung function in early life, especially in children of nonatopic mothers. At the age of 5 years, infant lung function is of minor influence in this association.

Parent-reported symptoms of acute otitis media during the first year of life: what is beneath the surface?

Background

Most estimates of the incidence of acute otitis media (AOM) are based on general practitioner (GP) or pediatrician diagnoses. It is likely that these figures underestimate the community incidence of AOM since parents do not visit their doctor every time their child suffers from acute ear symptoms. The impact of these symptom episodes may be substantial since they affect the child’s quality of life and parents’ productivity.

Methods

To determine AOM symptoms in the community, we measured parent-reported AOM symptoms daily for 12 consecutive months in 1,260 children participating in a prospective birth cohort in the Netherlands. The mean age of these children was at study enrollment 0.9 months (standard deviation 0.6). A parent-reported AOM symptom episode was defined as fever (temperature 38˚C or above) plus at least one of the following symptoms: ear pain and ear discharge. These febrile AOM symptom episodes were linked to GP-consultations and diagnoses in the GP electronic health records.

Results

With an estimated 624 parent-reported symptom episodes per 1,000 child-years (95% CI: 577 to 674) incidence of febrile AOM symptoms during the child’s first year is high. The GP was consulted in half of these symptom episodes and AOM was diagnosed in 49% of these consultations.

Conclusions and Relevance

The incidence of febrile AOM symptoms in the first year of life is high in Dutch children and leads to a GP-consultation in only half of the cases. This suggests that AOM symptomatology in the community is underestimated when focusing on GP-diagnosed AOM episodes alone, since a considerable proportion of febrile AOM symptom episodes are treated symptomatically by parents at home and do not come to the attention of the GP. Having data on community AOM symptomatology available for each country is important when the potential impact of preventive and therapeutic interventions for AOM are studied.

Breast-feeding and health consequences in early childhood: is there an impact of time-dependent confounding?

BACKGROUND

Estimated effects of breast-feeding on childhood health vary between studies, possibly due to confounding by baseline maternal and child characteristics. Possible time-dependent confounding has received little consideration. Our aim was to evaluate the impact of such confounding.

METHODS

We estimated the relationship between cumulative exclusive breast-feeding up to 6 months and wheezing, rash and body mass index (BMI) at 12 months [in the Whistler cohort (n = 494) and PROBIT (n = 11,463)], and wheezing, rash, asthma, hay fever, eczema, allergy and BMI at age 6.5 years (PROBIT). We adjusted for time-dependent confounding by weight, length, rash, respiratory illness and day care attendance using marginal structural models (MSMs).

RESULTS

Weight and day care attendance appeared potential time-dependent confounders, since these predicted breast-feeding status and were influenced by previous breast-feeding. However, adjustment for time-dependent confounders did not markedly change the estimated associations. For example, in PROBIT the adjusted increase in BMI at 12 months per 1-month increase in exclusive breast-feeding was 0.04 (95% CI -0.09 to 0.01) using logistic regression and -0.06 (95% CI -0.11 to -0.01) using MSM. In Whistler, these estimates were each -0.05 (95% CI -0.10 to 0.00).

CONCLUSIONS

In two cohort studies, there was little evidence of time-dependent confounding by weight, length, rash, respiratory illness or day care attendance of the effects of breast-feeding on early childhood health.

Allergies are associated with arterial changes in young children

BACKGROUND

Inflammation is important in atherosclerosis development. Whether common causes of inflammation, such as allergies and infections, already exert this influence in early childhood is unknown. The objective of this study was to investigate the association between both allergies and infections with children's vasculature.

DESIGN

This was a longitudinal study in a general population cohort.

METHODS

In 390 five-year-olds of the WHISTLER (Wheezing-Illnesses-Study-LEidsche-Rijn) birth cohort, carotid intima-media thickness (CIMT) and arterial stiffness were obtained ultrasonographically. Physician-diagnosed allergies and infections and recent prescriptions of systemic antihistamines and antibiotics were obtained, as well as parental history of allergies. General linear regression was performed with vascular characteristics as dependent variables and measures of inflammation as independent variables.

RESULTS

Having both a positive parental history of allergy and an allergy diagnosis showed 15.0 µm (95% confidence interval (CI): 2.3-27.8, p = 0.02) larger CIMT than not having such history and diagnosis. Having a positive parental history of allergy only showed 11.9 µm (0.87-23.0, p = 0.04) larger CIMT. Recent use of antihistamines and antibiotics showed 18.8 µm (1.6-35.9, p = 0.03) and 16.1 µm (4.5-27.7, p = 0.01) larger CIMT, respectively. Childhood infections were not clearly related to vascular parameters. Neither allergy nor infections were associated with arterial stiffness.

CONCLUSION

An allergic predisposition is already associated with thicker arterial walls in early childhood.

Extracellular vesicle protein CD14 relates to common carotid intima-media thickness in eight-year-old children

BACKGROUND

Atherosclerosis is a process that begins in childhood, develops over decades and underlies the majority of cardiovascular events in adulthood. Previously, we demonstrated in adults with cardiovascular disease that levels of extracellular vesicle (EV) proteins CD14, Serpin F2 and cystatin C predict vascular outcome. Here, we study for the first time whether these EV proteins are related to vascular characteristics in healthy, young children.

METHODS AND RESULTS

In 141 eight-year old children of the Wheezing-Illnesses-Studie-LEidsche-Rijn birth cohort, anthropometrics and blood pressure were measured. In addition, common carotid intima-media thickness, carotid distensibility and carotid Young's elastic modulus were obtained non-invasively using ultrasound imaging. A fasting lipid spectrum was obtained and EVs were isolated from plasma. Levels of EV proteins CD14, Serpin F2 and cystatin C were measured using a multiplex assay. In a multivariable linear regression model we assessed the relation between these EV proteins and the selected vascular characteristics. Of the studied EV proteins, CD14 levels were positively related to common carotid intima-media thickness (log transformed, beta = 7.31 ln(mm)/(ng/mg) (1.24, 13.38), p = 0.02). EV proteins Serpin F2 and cystatin C were not related to common carotid intima-media thickness. In addition, we found no relation between all three EV proteins and carotid distensibility or carotid Young's elastic modulus.

CONCLUSION

In healthy eight-year old children, extracellular vesicle protein CD14 levels seem positively related to common carotid intima-media thickness. This would point towards inflammatory vascular alterations inflicted by extracellular vesicle protein CD14 already in early life and warrants further investigation.

Impact of early daycare on healthcare resource use related to upper respiratory tract infections during childhood: prospective WHISTLER cohort study

BACKGROUND

Daycare attendance is an established risk factor for upper respiratory tract infections (URTI) and acute otitis media (AOM). Whether this results in higher use of healthcare resources during childhood remains unknown. We aim to assess the effect of first year daycare attendance on the timing and use of healthcare resources for URTI and AOM episodes during early childhood.

METHODS

In the Wheezing-Illnesses-STudy-LEidsche-Rijn birth cohort, 2,217 children were prospectively followed up to age six years. Children were categorized according to first-year daycare attendance (yes versus no) and age at entry when applicable (age 0 to 2 months, 3 to 5 months and 6 to 12 months). Information on general practitioner (GP) diagnosed URTI and AOM, GP consultations, antibiotic prescriptions and specialist referral was collected from medical records. Daycare attendance was recorded by monthly questionnaires during the first year of life.

RESULTS

First-year daycare attendees and non-attendees had similar total six-year rates of GP-diagnosed URTI and AOM episodes (59/100 child-years, 95% confidence interval 57 to 61 versus 56/100 child-years, 53 to 59). Daycare attendees had more GP-diagnosed URTI and AOM episodes before the age of one year and fewer beyond the age of four years than non-attendees (Pinteraction <0.001). Daycare attendees had higher total six-year rates for GP consultation (adjusted rate ratio 1.15, 1.00 to 1.31) and higher risk for specialist referrals (hazard ratio: 1.43, 1.01 to 2.03). The number of antibiotic prescriptions in the first six years of life was only significantly increased among children who entered daycare between six to twelve months of age (rate ratio 1.32, 1.04 to 1.67). This subgroup of child-care attendees also had the highest overall URTI and AOM incidence rates, GP consultation rates and risk for specialist referral.

CONCLUSIONS

Children who enter daycare in the first year of life, have URTI and AOM at an earlier age, leading to higher use of healthcare resources compared to non-attendees, especially when entering daycare between six to twelve months. These findings emphasize the need for improved prevention strategies in daycare facilities to lower infection rates at the early ages.

Nocturnal wheeze measurement in preschool children

RATIONALE

Wheezing is a very common symptom in preschool children. Nocturnal wheezing is present in many asthmatic patients, due to enhanced airflow limitation overnight. We assessed the prevalence of nocturnal wheezing in young children and correlated this with respiratory system resistance and history of wheezing symptoms.

METHODS

Using a continuous overnight recording of respiratory sounds we analyzed wheeze rate (ratio between wheezing time and recorded breathing time), oxygen saturation and heart rate during one night in 59 three-year-old children of an ongoing birth cohort study, the WHISTLER-project. We associated the nocturnal measurements with the patient's history of wheezing symptoms and with measurement of respiratory system resistance (Rint).

RESULTS

Analysis of wheeze rate was successful in 44 children. The overall wheeze rate of these children was low, with the highest wheeze rate of 0.63% measured by the tracheal sensor during expiration. In total, 21/44 children had a wheeze rate of ≥ 5% during at least 1 min. There was no statistically significant difference in wheeze rate between the children with and without a history of wheezing. The wheeze rate of the tracheal sensor had a significant correlation with Rint (correlation coefficients of inspiration and expiration: 0.308 and 0.382, P-values 0.05 and 0.01, respectively).

CONCLUSIONS

Overall, the wheeze rate in young children is low, but seems to increase over nighttime. Almost 50% of the children have sporadic wheeze during the night. Although higher nocturnal wheeze rates are related to increased respiratory system resistance, it is not related to clinical wheezing symptoms.

Effect of physical activity on vascular characteristics in young children

BACKGROUND

Physical activity has long been proposed as an important modifiable cardiovascular risk factor in adults. We assessed whether physical activity already has an effect on childhood vasculature.

METHODS

In the Wheezing-Illnesses-Study-in-Leidsche-Rijn birth cohort, we performed vascular ultrasound to measure carotid intima-media thickness (cIMT) and functional properties (distensibility, elastic modulus) at 5 and 8 years of age. Child typical physical activities were inquired using a questionnaire completed by parents. Linear regression was used with physical activity level, expressed as a standardized value of time-weighted metabolic equivalent (MET) as the independent variable and vascular properties as dependent variables with further confounder adjustment and evaluation for possible body mass index and sex effect modifications.

RESULTS

In 595 5-year-old children and in 237 of those who had reached the age of 8 years, we did not find statistically significant associations between total time-weighted MET and each vascular parameter, neither in pooled nor stratified analysis. However, sport activities were associated with thinner cIMT (-3.20 µm/SD, 95% CI -6.34, -0.22, p = 0.04) at 5 years of age; a similar pattern was seen for organized sport. This effect was strongest in children in the highest body mass index tertile (-5.38 µm/SD, 95% CI -10.54, -0.19, p = 0.04). At the age of 8 years, higher sport level tended to be associated with higher vascular distensibility (2.64 × 10(3) kPa/SD, 95% CI -0.18, 5.45, p = 0.07) although this was not statistically significant.

CONCLUSIONS

Sport activity may have beneficial effects on arteries of young children, particularly those with higher relative body weight.

Increased risk of wheeze and decreased lung function after respiratory syncytial virus infection

Background

A relationship between hospitalization for respiratory syncytial virus (RSV) bronchiolitis and asthma development has been suggested in case-control studies.

Objective

The aim of this study was to assess the risk of current wheeze, asthma, and lung function at school age in infants previously hospitalized for RSV bronchiolitis compared to non-hospitalized children.

Methods

For this study, data from a prospective birth cohort of unselected, term-born infants (n = 553), of whom 4 (0.7%) were hospitalized for RSV bronchiolitis, and a prospective patient cohort of 155 term infants hospitalized for RSV bronchiolitis were used. Respiratory outcomes at age 6 in children hospitalized for RSV bronchiolitis were compared to non-hospitalized children.

Results

The risk of current wheeze was higher in hospitalized patients (n = 159) compared to non-hospitalized children (n = 549) (adjusted odds ratio (OR) 3.2 (95% CI 1.2–8.1). Similarly, the risk of current asthma, defined as a doctor’s diagnosis of asthma plus current symptoms or medication use, was higher in hospitalized patients (adjusted OR 3.1 (95% CI 1.3–7.5). Compared to non-hospitalized children, RSV bronchiolitis hospitalization was associated with lower lung function (mean difference FEV1% predicted −6.8 l (95% CI (−10.2 to −3.4).

Conclusions and Clinical Relevance

This is the first study showing that hospitalization for RSV bronchiolitis during infancy is associated with increased risk of wheezing, current asthma, and impaired lung function as compared to an unselected birth cohort at age 6.

Longitudinal follow-up of the relationship between dietary intake and growth and development in the Lifeways cross-generation cohort study 2001-2013

In this paper we will review evidence on the early life and familial influences on childhood growth and development, with particular reference to the Lifeways cross-generation cohort study in the Republic of Ireland. The Lifeways cross-generation cohort study was established in 2001-2013 through two maternity hospitals in the Republic of Ireland and was one of many new cohort studies established worldwide in the millennium period. Mothers were recruited at first booking visit, completing a self-administered questionnaire, which included a 147 item semi-quantitative FFQ. Longitudinal follow-up is ongoing in 2013, with linkage data to hospital and general practice records and examination of children when aged 5 and 9 years. The study is one of very few containing data on grandparents of both lineages with at least one grandparent recruited at baseline. There have been consistent associations between parental and grandparental health status characteristics and children's outcomes, including infant birth-weight, BMI when child was aged 5 years and childhood wheeze or asthma when child was aged 3 and aged 5 years. In conclusion, empirical evidence to date shows consistent familial and cross-generational patterns, particularly in the maternal line.

Human rhinovirus and wheezing: short and long-term associations in children

OBJECTIVES

Human rhinoviruses (HRVs) have been suggested to play a role in the development of childhood wheezing. However, whether HRV is causally related to the development of wheezing or HRV-associated wheeze is merely an indicator of disease susceptibility is unclear. Our aim was to study the role of HRV during infancy in the development of lower respiratory disease during infancy and childhood.

METHODS

In a population-based birth cohort, during the 1st year of life, nose and throat swabs were collected on a monthly basis, regardless of any symptoms. Polymerase chain reaction was used to detect an extensive panel of respiratory pathogens. Lung function was measured before 2 months of age. Information on respiratory symptoms was collected by daily questionnaires and electronic patient files.

RESULTS

1425 samples were collected in 140 infants. Both the presence of (single or multiple) pathogens (HRV equal to other pathogens) and increased respiratory system resistance were significantly associated with lower respiratory symptoms during infancy. HRV presence during infancy was not associated with the risk of wheezing at age 4, but every HRV episode with wheezing increased the risk of wheezing at age 4 (odds ratio 1.9, 1.1-3.5). This association weakened after adjustment for lung function (odds ratio 1.4, 0.7-2.9).

CONCLUSIONS

HRV and other viruses are associated with lower respiratory symptoms during infancy, as well as a high presymptomatic respiratory system resistance. HRV presence during infancy is not associated with childhood wheezing, but wheeze during a HRV episode is an indicator of children at high risk for childhood wheeze, partly because of a reduced neonatal lung function.

Pregnancy and birth cohort resources in europe: a large opportunity for aetiological child health research

BACKGROUND

During the past 25 years, many pregnancy and birth cohorts have been established. Each cohort provides unique opportunities for examining associations of early-life exposures with child development and health. However, to fully exploit the large amount of available resources and to facilitate cross-cohort collaboration, it is necessary to have accessible information on each cohort and its individual characteristics. The aim of this work was to provide an overview of European pregnancy and birth cohorts registered in a freely accessible database located at http://www.birthcohorts.net.

METHODS

European pregnancy and birth cohorts initiated in 1980 or later with at least 300 mother-child pairs enrolled during pregnancy or at birth, and with postnatal data, were eligible for inclusion. Eligible cohorts were invited to provide information on the data and biological samples collected, as well as the timing of data collection.

RESULTS

In total, 70 cohorts were identified. Of these, 56 fulfilled the inclusion criteria encompassing a total of more than 500,000 live-born European children. The cohorts represented 19 countries with the majority of cohorts located in Northern and Western Europe. Some cohorts were general with multiple aims, whilst others focused on specific health or exposure-related research questions.

CONCLUSION

This work demonstrates a great potential for cross-cohort collaboration addressing important aspects of child health. The web site, http://www.birthcohorts.net, proved to be a useful tool for accessing information on European pregnancy and birth cohorts and their characteristics.

Inflammatory phenotypes underlying uncontrolled childhood asthma despite inhaled corticosteroid treatment: rationale and design of the PACMAN2 study

BACKGROUND

The diagnosis of childhood asthma covers a broad spectrum of pathological mechanisms that can lead to similarly presenting clinical symptoms, but may nonetheless require different treatment approaches. Distinct underlying inflammatory patterns are thought to influence responsiveness to standard asthma medication.

METHODS/DESIGN

The purpose of the PACMAN2 study is to identify inflammatory phenotypes that can discriminate uncontrolled childhood asthma from controlled childhood asthma by measures in peripheral blood and exhaled air. PACMAN2 is a nested, case-control follow-up study to the ongoing pharmacy-based "Pharmacogenetics of Asthma medication in Children: Medication with Anti-inflammatory effects" (PACMAN) study. The original PACMAN cohort consists of children aged 4-12 years with reported use of asthma medication. The PACMAN2 study will be conducted within the larger PACMAN cohort, and will focus on detailed phenotyping of a subset of the PACMAN children. The selected participants will be invited to a follow-up visit in a clinical setting at least six months after their baseline visit based on their adherence to usage of inhaled corticosteroids, their asthma symptoms in the past year, and their age (≥ 8 years). During the follow-up visit, current and long-term asthma symptoms, medication use, environmental factors, medication adherence and levels of exhaled nitric oxide will be reassessed. The following measures will also be examined: pulmonary function, exhaled volatile organic compounds, as well as inflammatory markers in peripheral blood and blood plasma. Comparative analysis and cluster-analyses will be used to identify markers that differentiate children with uncontrolled asthma despite their use of inhaled corticosteroids (ICS) (cases) from children whose asthma is controlled by the use of ICS (controls).

DISCUSSION

Asthmatic children with distinct inflammatory phenotypes may respond differently to anti-inflammatory therapy. Therefore, by identifying inflammatory phenotypes in children with the PACMAN2 study, we may greatly impact future personalised treatment strategies, uncover new leads for therapeutic targets and improve the design of future clinical studies in the assessment of the efficacy of novel therapeutics.

Referrals for recurrent respiratory tract infections including otitis media in young children

OBJECTIVE

(a) To establish whether disease-related, child-related, and physician-related factors are independently associated with specialist referral in young children with recurrent RTI, and (b) to evaluate whether general practitioners (GPs) follow current guidelines regarding these referrals.

METHODS

Electronic GP records of children under 24 month of age, born 2002-2008, were reviewed for RTI episodes using ICPC codes. Child-related factors were extracted from the prospective WHISTLER birth-cohort in which a considerable part of children had been enrolled. To evaluate guideline adherence, referral data were compared to national guideline recommendations.

RESULTS

Consultations for 2532 RTI episodes (1041 children) were assessed. Seventy-eight children were referred for recurrent RTI (3.1% of RTI episodes; 7.5% of children). Disease factors were the main determinants of referral: number (OR 1.7 [CI 1.7-1.7]) and severity of previous RTI episodes (OR 2.2 [CI 1.6-2.8]), and duration of RTI episode (OR 1.7 [CI 1.7-1.8]). The non-disease factors daycare attendance (OR 1.3 [CI 1.0-1.7]) and 5-10 years working experience as a GP compared with <5 years (OR 0.37 [CI 0.27-0.50]) were also associated. Fifty-seven percent of referrals for recurrent RTI were made in accordance with national guidelines.

CONCLUSIONS

Referral of children for recurrent RTI was primarily determined by frequency, severity, and duration of RTIs; the influence of non-disease factors was limited. Just over half of referrals were made in accordance with guidelines.

The expert network and electronic portal for children with respiratory and allergic symptoms: rationale and design

Data on baseline characteristics of children with asthma to predict individual treatment responses are lacking. We aimed to set up a data-collection system which can easily fill this gap in clinical practice.A web-based application was developed, named 'Portal for children with respiratory and allergic symptoms', hereafter called Electronic Portal (EP). It contains health- and disease-related questionnaires on respiratory- and allergic diseases. All patients, 1-18 years of age, with respiratory- and/or allergic complaints are invited to enter the EP before their first visit. By using the EP large amounts of data, gathered during routine patient care can be used for research purposes. This may help to further investigate the different treatment related asthma phenotypes and will be helpful to monitor risk factors for other atopic diseases and respiratory infections.

Effect of endotoxin and allergens on neonatal lung function and infancy respiratory symptoms and eczema

BACKGROUND

Exposure to endotoxin and allergens in house dust has been found to be associated with childhood wheeze and asthma. Neonatal lung function is rarely examined in relation to this exposure.

OBJECTIVES

To assess the association between exposure to endotoxin, house dust mite and cat allergens and neonatal lung function, and respiratory symptoms and eczema in infancy.

METHODS

In the Wheezing Illnesses Study Leidsche Rijn (WHISTLER) birth cohort study, levels of endotoxin, house dust mite allergens, and cat allergen have been measured in dust samples collected in the child's home. Lung function was measured before age 2 months, and respiratory symptoms and eczema were recorded in a daily diary during the first year of life. Associations of lung function (N = 302), respiratory symptoms (N = 361), and eczema (N = 342) with endotoxin and allergen levels have been studied by means of linear and logistic regression, respectively.

RESULTS

Mattress dust endotoxin was associated with a significant increase in neonatal respiratory compliance [adjusted mean difference (95% confidence interval) 2.31 (0.33; 4.29) ml/kPa per interquartile range increase in exposure] and a non-significant decrease in neonatal airway resistance [0.32 (-0.77; 0.14) kPa/l/s]. There were no associations between allergen exposure and neonatal lung function and respiratory symptoms.

CONCLUSIONS

Environmental exposure to endotoxin may have an important role in the development of lung function.

Parental blood pressure is related to vascular properties of their 5-year-old offspring

BACKGROUND

Adolescent offspring of hypertensive parents have increased carotid intima media thickness (CIMT) and arterial stiffness compared with offspring of normotensives. We assessed whether systolic blood pressure (SBP) of both parents is associated with the vasculature of their offspring as early as in childhood.

METHODS

In the first 306 5-year-old children of the Wheezing-Illnesses-Study-Leidsche-Rijn birth cohort, CIMT, distensibility, and elastic modulus (EM) were obtained ultrasonographically. In 204 of 306 (67%) children, complete data on both maternal and paternal SBP were obtained from the linked database of the Utrecht Health Project.

RESULTS

CIMT of the children was 0.58 µm (95% confidence interval (CI): 0.14, 1.0) greater with every 1-mm Hg higher maternal SBP. Maternal SBP and children's distensibility and EM were more strongly associated, negative and positive respectively, with increasing paternal SBP and vice versa (P value-for-interaction: 0.003 and 0.001, respectively). CIMT of children of whom both parents were in the highest SBP tertile was 17.9 µm (95% CI: 4.0, 31.9) greater compared with the CIMT of children of whom neither one of the parents had a SBP in the highest tertile. For EM and distensibility, these estimates were 20.1 kPa (95% CI: 1.1, 39.2) and -11.6 1/Mpa (95%-CI: -22.9, -0.31), respectively.

CONCLUSIONS

Higher maternal SBP is related to thicker arterial walls in their 5-year-old offspring. If both parents have higher SBP, the arterial wall of their offspring is thicker and stiffer.