Carol Dezateux

How active are our children? Findings from the Millennium Cohort Study

Objective To describe levels of physical activity, sedentary time and adherence to Chief Medical Officers (CMO) physical activity guidelines among primary school-aged children across the UK using objective accelerometer-based measurements. Design Nationally representative prospective cohort study. Setting Children born across the UK, between 2000 and 2002. Participants 6497 7-year-old to 8-year-old singleton children for whom reliable accelerometer data were available for at least 10 h a day for at least 2 days. Main outcome measures Physical activity in counts per minute (cpm); time spent in sedentary and moderate-to-vigorous intensity physical activity (MVPA); proportion of children meeting CMO guidelines (≥60 min/day MVPA); average daily steps. Explanatory measures Gender, ethnicity, maternal current/most recent occupation, lone parenthood status, number of children in the household and country/region of residence. Results The median daily physical activity level was 595 cpm (IQR 507, 697). Children spent a median of 60 min (IQR 47–76) in MVPA/day and were sedentary for a median of 6.4 h/day (IQR 6–7). Only 51% met CMO guidelines, with girls (38%) less active than boys (63%). Children took an average of 10 229 (95% CI (8777 to 11 775)) steps each day. Children of Indian ethnicity were significantly less active overall than all other ethnic groups. Children of Bangladeshi origin and those living in Northern Ireland were least likely to meet CMO guidelines. Conclusions Only half of 7-year-old children in the UK achieve recommended levels of physical activity, with significant gender, ethnic and geographic variations. Longitudinal studies are needed to better understand the relevance of these (in)activity patterns for long-term health and well-being. In the meantime population-wide efforts to boost physical activity among young people are needed which are likely to require a broad range of policy interventions.

Developmental dysplasia of the hip

In its severest form, developmental dysplasia of the hip is one of the most common congenital malformations. The pathophysiology and natural history of the range of morphological and clinical disorders that constitute developmental dysplasia of the hip are poorly understood. Neonatal screening programmes, based on clinical screening examinations, have been established for more than 40 years but their effectiveness remains controversial. Whereas systematic sonographic imaging of newborn and young infants has afforded insights into normal and abnormal hip development in early life, we do not clearly understand the longer-term outcomes of developmental hip dysplasia, its contribution to premature degenerative hip disorders in adult life, and the benefits and harms of newborn screening. High quality studies of the adult outcomes of developmental hip dysplasia and the childhood origins of early degenerative hip disease are needed, as are randomised trials to assess the effectiveness and safety of neonatal screening and early treatment.

The effect of parental smoking on lung function and development during infancy.

Abstract:  While the adverse effects of parental smoking on respiratory health during childhood are well recognized, its potential impact on early lung development is less clear. This review summarizes current evidence on the effect of parental smoking on lung function during infancy. It is difficult to separate the effects of pre‐ and postnatal exposure, since the majority of mothers who smoke in pregnancy (currently around 30% worldwide) continue to do so thereafter. Nevertheless, measurements undertaken prior to any postnatal exposure have consistently demonstrated significant changes in tidal flow patterns in infants whose mothers smoked in pregnancy. While there is, as yet, no convincing evidence from studies in human infants that smoking during pregnancy is associated with increased airway responsiveness at birth, many studies have demonstrated a reduction in forced expiratory flows (on average by 20%) in infants exposed to parental smoking. While maternal smoking during pregnancy remains the most significant source of such exposure and is likely to be responsible for diminished airway function in early life, continuing postnatal tobacco smoke exposure will increase the risk of respiratory infections, the combination of both being responsible for the two‐ to fourfold increased risk of wheezing illnesses observed during the first year of life in infants whose parents smoke. These findings emphasize the need to keep infants in a smoke‐free environment both before and after birth, not least because of growing awareness that airway function in later life is largely determined by that during foetal development and early infancy.

Airway function in infants newly diagnosed with cystic fibrosis.

The lung function of infants with cystic fibrosis is often reduced shortly after diagnosis. We measured the airway function of newly diagnosed infants to test whether this reduction is independent of clinically recognised lower respiratory illness. We compared the airway function of 33 infants with cystic fibrosis and 87 healthy controls after adjustment for sex, age, bodyweight and length, and exposure to maternal smoking. Airway function was significantly reduced in children with cystic fibrosis, even in those without clinically recognised previous lower respiratory illness. Our findings raise important questions about the onset and natural history of impaired airway function in infants with cystic fibrosis.

Surgery for congenital dislocation of the hip in the UK as a measure of outcome of screening

BACKGROUND Universal clinical screening for congenital dislocation of the hip to detect hip instability in neonates was introduced in the UK as a national policy in 1969, but its effectiveness is not known. We aimed to assess the extent to which surgery for congenital dislocation of the hip is the result of a failure of detection through screening or follows non-surgical treatment after detection by screening. METHODS We established a national orthopaedic surveillance scheme and used routine hospital data for inpatients for 20% of births in the UK (Scotland and the Northern and Wessex regions) to ascertain the number of children aged under 5 years per 1000 livebirths who had received at least one operative procedure for congenital dislocation of the hip from April, 1993, to April, 1994. Estimates of the incidence of operative procedures were adjusted for under-ascertainment by capture-recapture techniques. FINDINGS The ascertainment-adjusted incidence of a first operative procedure for congenital dislocation of the hip in the UK was 0.78 per 1000 livebirths (95% CI 0.72-0-84). Congenital dislocation of the hip had not been detected by routine screening in 222 (70%) of 318 children reported to the national orthopaedic surveillance scheme. In 112 (35%) children the diagnosis was made primarily as a result of parental concern. 67 (21%) children had previously received non-surgical treatment. In Scotland and the Northern and Wessex regions, 81 cases were notified to the national orthopaedic surveillance scheme, 62 cases were identified only through routine hospital data on inpatients, and an estimated 20 cases were not identified by either source, making a total of 163 cases. Thus, 81 (50%) of these 163 cases were identified by surveillance, 125 (77%) by routine data, and 143 (88%) by both sources. INTERPRETATION The incidence of a first operative procedure for congenital dislocation of the hip in the UK was similar to that reported before screening was introduced. In most children who received surgery, congenital dislocation of the hip was not detected by screening. Formal evaluation of current and alternative screening policies, including universal primary ultrasound imaging, is needed.

Airway function at one year: association with premorbid airway function, wheezing, and maternal smoking

BACKGROUND Impaired growth and development of the respiratory system during fetal and early postnatal life may have important implications for lung development and later lung health. The aim of this study was to examine the association of diminished premorbid airway function, prior wheezing, and maternal smoking with airway function at 1 year of age. METHODS Respiratory function was measured at the end of the first year in 100 of 108 healthy term infants (93%) in whom similar measurements had been undertaken prior to any respiratory illness at 8 weeks. Physician diagnosed wheezing episodes were identified retrospectively from medical records. RESULTS At 1 year specific airway conductance during end expiration (sGawee; /s/kPa) was significantly diminished in those infants with prior wheezing (95% CI wheeze/no wheeze –0.76 to –0.14), mothers who smoked (95% CI smoke/no smoke –0.81 to –0.27), a family history of asthma (95% CI family history/no family history –0.62 to 0.00), or diminished premorbid sGawee (95% CI –0.13 to –0.43/s/kPa per unit reduction sGawee at 8 weeks). In a multivariate model only maternal smoking and diminished premorbid sGaweewere independently associated with diminished sGawee at 1 year. CONCLUSIONS Diminished airway function at the end of the first year appears to be mediated by impaired airway development during early life as well as by exposure to maternal smoking. These findings are consistent with the hypothesis that, at a population level, diminished premorbid airway function provides the link between wheezing lower respiratory illness and diminished airway function at 1 year. Maternal smoking remains an important and avoidable cause of impaired airway development and function in infancy.

Ultrasonography in the diagnosis and management of developmental hip dysplasia (UK Hip Trial): clinical and economic results of a multicentre randomised controlled trial

BACKGROUND Clinical screening aims to identify and treat neonatal hip instability associated with increased risk of hip displacement, but risks failures of diagnosis and treatment (abduction splinting), iatrogenic effects, and costs to parents and health services. Our objectives were to assess clinical effectiveness and net cost of ultrasonography compared with clinical assessment alone, to provide guidance for management of infants with clinical hip instability. METHODS Infants with clinical hip instability were recruited from 33 centres in UK and Ireland and randomised to either ultrasonographic hip examination (n=314) or clinical assessment alone (n=315). The primary outcome was appearance on hip radiographs by 2 years. Secondary outcomes included surgical treatment, abduction splinting, level of mobility, resource use, and costs. Analysis was by intention to treat. FINDINGS Protocol compliance was high, and radiographic information was available for 91% of children by 12-14 months and 85% by 2 years. By age 2 years, subluxation, dislocation, or acetabular dysplasia were identified by radiography on one or both hips of 21 children in each of the groups (relative risk 1.00; 95% CI 0.56-1.80). Fewer children in the ultrasonography group had abduction splinting in the first 2 years than did those in the no-ultrasonography group (0.78; 0.65-0.94; p=0.01). Surgical treatment was required by 21 infants in the ultrasonography group (6.7%) and 25 (7.9%) in the no-ultrasonography group (0.84; 0.48-1.47). One child from the ultrasonography group and four from the no-ultrasonography group were not walking by 2 years (0.25; 0.03-2.53; p=0.37). Infants in the ultrasonography group incurred significantly higher ultrasound costs over the first 2 years (pound 42 vs pound 23, mean difference pound 19, 95% CI 11-27); total hospital costs were lower for those infants, but the difference was not significant. INTERPRETATION The use of ultrasonography in infants with screen-detected clinical hip instability allows abduction splinting rates to be reduced, and is not associated with an increase in abnormal hip development, higher rates of surgical treatment by 2 years of age, or significantly higher health-service costs.

Quality control methods in accelerometer data processing: defining minimum wear time.

Background When using accelerometers to measure physical activity, researchers need to determine whether subjects have worn their device for a sufficient period to be included in analyses. We propose a minimum wear criterion using population-based accelerometer data, and explore the influence of gender and the purposeful inclusion of children with weekend data on reliability. Methods Accelerometer data obtained during the age seven sweep of the UK Millennium Cohort Study were analysed. Children were asked to wear an ActiGraph GT1M accelerometer for seven days. Reliability coefficients(r) of mean daily counts/minute were calculated using the Spearman-Brown formula based on the intraclass correlation coefficient. An r of 1.0 indicates that all the variation is between- rather than within-children and that measurement is 100% reliable. An r of 0.8 is often regarded as acceptable reliability. Analyses were repeated on data from children who met different minimum daily wear times (one to 10 hours) and wear days (one to seven days). Analyses were conducted for all children, separately for boys and girls, and separately for children with and without weekend data. Results At least one hour of wear time data was obtained from 7,704 singletons. Reliability increased as the minimum number of days and the daily wear time increased. A high reliability (r = 0.86) and sample size (n = 6,528) was achieved when children with ≥ two days lasting ≥10 hours/day were included in analyses. Reliability coefficients were similar for both genders. Purposeful sampling of children with weekend data resulted in comparable reliabilities to those calculated independent of weekend wear. Conclusion Quality control procedures should be undertaken before analysing accelerometer data in large-scale studies. Using data from children with ≥ two days lasting ≥10 hours/day should provide reliable estimates of physical activity. It’s unnecessary to include only children with accelerometer data collected during weekends in analyses.

Differences in risk factors for partial and no immunisation in the first year of life: prospective cohort study

Abstract Objective To compare demographic, social, maternal, and infant related factors associated with partial immunisation and no immunisation in the first year of life in the United Kingdom. Design Prospective cohort study. Setting Sample of electoral wards in England, Wales, Scotland, and Northern Ireland, stratified by measures of ethnic composition and social disadvantage. Participants 18 488 infants born between September 2000 and January 2002, resident in the UK and eligible to receive child benefit (a universal benefit available to all families) at age 9 months. Main outcome measure Immunisation status at 9 months of age, defined as fully immunised, partially immunised, or not immunised. Results Overall in the UK, 3.3% of infants were partially immunised and 1.1% were unimmunised; these rates were highest in England (3.6% and 1.3%, respectively; P < 0.01). Residence in ethnic or disadvantaged wards, larger family size, lone or teenaged parenthood, maternal smoking in pregnancy, and admission to hospital by 9 months of age were independently associated with partial immunisation status. In contrast, a higher proportion of mothers of unimmunised infants were educated to degree level or above (1.9%), were older (3.1%), or were of black Caribbean ethnicity (4.7%). Conclusions Mothers of unimmunised infants differ in terms of age and education from those of partially immunised infants. Interventions to reduce incomplete immunisation in infancy need different approaches.

National cross sectional study of detection of congenital and infantile cataract in the United Kingdom: role of childhood screening and surveillance

Objectives: To determine the mode of detection and timing of ophthalmic assessment of a nationally representative group of children with congenital and infantile cataract. Design: Cross sectional study. Setting: United Kingdom. Subjects: All children born in the United Kingdom and aged 15 years or under in whom congenital or infantile cataract was newly diagnosed between October 1995 and September 1996. Main outcome measures: Proportion of cases detected through routine ocular examination and proportion assessed by an ophthalmologist by 3 months and 1 year of age. Results: Data were complete for 235 (95%) of 248 children identified. Of these, 83 (35%) were detected at the routine newborn examination and 30 (12%) at the 6-8 week examination; 82 children presented symptomatically. 137 (57%) children had been assessed by an ophthalmologist by the age of 3 months but 78 (33%) were not examined until after 1 year of age. In 91 cases the childs carers suspected an eye defect before cataract was diagnosed. Conclusions: A substantial proportion of children with congenital and infantile cataract are not diagnosed by 3 months of age, although routine ocular examination of all newborn and young infants is recommended nationally. Strategies to achieve earlier detection through screening and surveillance are required.