The phenotypic spectrum of proximal 6q deletions based on a large cohort derived from social media and literature reports.

Proximal 6q (6q11-q15) deletions are extremely rare and little is known about their phenotypic consequences. Since parents and caregivers now use social media to seek information on rare disorders, the Chromosome 6 Project has successfully collaborated with a Facebook group to collect data on individuals worldwide. Here we describe a cohort of 20 newly identified individuals and 25 literature cases with a proximal 6q deletion. Microarray results and phenotype data were reported directly by parents via a multilingual online questionnaire. This led to phenotype descriptions for five subregions of proximal 6q deletions; comparing the subgroups revealed that 6q11q14.1 deletions presented less severe clinical characteristics than 6q14.2q15 deletions. Gastroesophageal reflux, tracheo/laryngo/bronchomalacia, congenital heart defects, cerebral defects, seizures, and vision and respiratory problems were predominant in those with 6q14.2q15 deletions. Problems related to connective tissue (hypermobility, hernias and foot deformities) were predominantly seen in deletions including the COL12A1 gene (6q13). Congenital heart defects could be linked to deletions of MAP3K7 (6q15) or TBX18 (6q14.3). We further discuss the role of ten genes known or assumed to be related to developmental delay and/or autism (BAI3, RIMS1, KCNQ5, HTR1B, PHIP, SYNCRIP, HTR1E, ZNF292, AKIRIN2 and EPHA7). The most influential gene on the neurodevelopmental phenotype seems to be SYNCRIP (6q14.3), while deletions that include more than two of these genes led to more severe developmental delay. We demonstrate that approaching individuals via social media and collecting data directly from parents is a successful strategy, resulting in better information to counsel families.

Accuracy, Precision, and Trending Ability of Electrical Cardiometry Cardiac Index versus Continuous Pulmonary Artery Thermodilution Method: A Prospective, Observational Study.

INTRODUCTION: Evaluation of accuracy, precision, and trending ability of cardiac index (CI) measurements using the Aesculon™ bioimpedance electrical cardiometry (Aesc) compared to the continuous pulmonary artery thermodilution catheter (PAC) technique before, during, and after cardiac surgery. METHODS: A prospective observational study with fifty patients with ASA 3-4. At six time points (T), measurements of CI simultaneously by continuous cardiac output pulmonary thermodilution and thoracic bioimpedance and standard hemodynamics were performed. Analysis was performed using Bland-Altman, four-quadrant plot, and polar plot methodology. RESULTS: CI obtained with pulmonary artery thermodilution and thoracic bioimpedance ranged from 1.00 to 6.75 L min-1 and 0.93 to 7.25 L min-1, respectively. Bland-Altman analysis showed a bias between CIBIO and CIPAC of 0.52 liters min-1 m-2, with LOA of [-2.2; 1.1] liters min-1 m-2. Percentage error between the two techniques was above 30% at every time point. Polar plot methodology and 4-quadrant analysis showed poor trending ability. Skin incision had no effect on the results. CONCLUSION: CI obtained by continuous PAC and CI obtained by Aesculon bioimpedance are not interchangeable in cardiac surgical patients. No effects of skin incision were found. International clinical trial registration number is ISRCTN26732484.

Does public disclosure of quality indicators influence hospitals' inclination to enhance results?

OBJECTIVE: The national guideline on oesophageal carcinoma's recommendation of a minimum number of 10 resections per year and the intervention of the Dutch Health Care Inspectorate have highlighted hospitals' 'need to score' on the public quality indicator for the annual number of oesophageal resections. To determine whether low-volume hospitals are inclined to adjust their numbers, we studied the difference between the reported and actual numbers of oesophageal resections in 2005 and 2006. DESIGN: A retrospective cohort study. Hospitals were asked to submit all operative reports on resections from 2005 to 2006. Two pairs of evaluators independently labelled all anonymous operative reports from the selected hospitals as resection or non-resection. SETTING: Hospitals in the Netherlands. PARTICIPANTS: Ten hospitals that reported 10 or 11 resections in 2006, or an average of fewer than 10 resections per year in the period 2003-2006. INTERVENTIONS: None. MAIN OUTCOME MEASURE(S): Difference between the reported and actual numbers of oesophageal resections in 2005 and 2006. RESULTS: Oesophageal resection criteria were not met in 7% of the 179 operative reports from the 10 selected hospitals. The difference between the reported and actual numbers of resections in 2005 was not significant, while in 2006 it was. Of the hospitals studied, 70% actually performed fewer resections than they reported. CONCLUSION: Our results support the assumption that low-volume hospitals are inclined to adjust their numbers when, because outcomes are public, pressure to report a sufficient number is high. So, external verification of data is essential when this 'need to score' is high.

Obstetric interventions for babies born before 28 weeks of gestation in Europe: results of the MOSAIC study.

OBJECTIVE: To describe obstetric intervention for extremely preterm births in ten European regions and assess its impact on mortality and short term morbidity. DESIGN: Prospective observational cohort study. SETTING: Ten regions from nine countries participating in the 'Models of Organising Access to Intensive Care for Very Preterm Babies in Europe' (MOSAIC) project. POPULATION: All births from 22 to 29 weeks of gestation (n = 4146) in 2003, excluding terminations of pregnancy. METHODS: Comparison of three obstetric interventions (antenatal corticosteroids, antenatal transfer and caesarean section for fetal indication) rates at 22-23, 24-25 and 26-27 weeks to that at 28-29 weeks and the association of the level of intervention with pregnancy outcome. MAIN OUTCOME MEASURES: Use of antenatal corticosteroids, antenatal transfer and caesarean section by two-week gestational age groups as well as a composite score of these three interventions. Outcomes included stillbirth, in-hospital mortality and intraventricular haemorrhage (IVH) grades III and IV and/or periventricular leucomalacia (PVL) and bronchopulmonary dysplasia (BPD). RESULTS: There were large differences between regions in interventions for births at 22-23 and 24-25 weeks. Differences were most pronounced at 24-25 weeks; in some regions these babies received the same care as babies of 28-29 weeks, whereas elsewhere levels of intervention were distinctly lower. Before 26 weeks and especially at 24-25 weeks, there was an association between the composite intervention score and mortality. No association was observed at 26-27 weeks. For survivors at 24-25 weeks, the intervention score was associated with higher rates of BPD, but not with IVH or PVL. CONCLUSIONS: There are large differences between European regions in obstetric practices at the lower limit of viability and these are related to outcome, especially at 24-25 weeks.

[The usefulness of the hospital standardized mortality ratio as an indicator of hospital mortality]. / Het gestandaardiseerde ziekenhuissterftecijfer (HSMR) bruikbaar voor het volgen van ziekenhuissterfte.

In 2007, a patient safety programme was started to reduce hospital mortality in the Netherlands. The hospital standardized mortality ratio (HSMR) seems to be a promising indicator for monitoring the reduction of hospital mortality within hospitals. It is questionable, however, whether the HSMR can be used to compare the performance of hospitals. It has been shown that certain specialized procedures such as percutaneous transluminal coronary angioplasty (PTCA) and open heart surgery have an impact on the HSMR. Although this hampers a fair comparison between cardiac centres and general hospitals, the HSMR may still indicate whether a cardiac centre could improve its performance. Moreover, the impact of cardiac procedures on the HSMR is relatively modest, which shows that it is a robust indicator to monitor the intended decrease of hospital mortality on a national scale.

[At the limits of viability: Dutch referral policy for premature birth too reserved]. / Op de grens van levensvatbaarheid: Nederlands verwijsbeleid bij vroeggeboorte te terughoudend.

OBJECTIVE: Evaluation of policy and treatment of deliveries at the limits of viability in the Netherlands and resulting survival figures. DESIGN: Cohort study. METHOD: Within the framework of the European 'Models of organising access to intensive care for very preterm births in Europe' (MOSAIC) study, data was collected on all 512 births in 2003 (terminations excluded) following 22-31 weeks gestation in the catchment areas of the perinatal centres in Nijmegen and Utrecht, the Netherlands. RESULTS: Gynaecologists and neonatologists practised a reserved policy for the active treatment of pregnancies under 25 weeks (5/77; 6%); all infants died. At 25 weeks, an active obstetric policy was used in one quarter of pregnancies, but none of the infants survived. Even at 26 weeks pregnancy, the obstetric policy was reserved and the mortality relatively high (9/31; 29%). From the neonatal deaths, 86 out of 92 (93%) were preceded by a decision either not to start or to discontinue treatment. CONCLUSION: Dutch obstetricians and neonatologists practised a reserved policy at the limits of neonatal viability. There is more need for active antenatal transfer to perinatal centres for those at the lower limit of neonatal viability to enable well-balanced decisions to take place. The parents' wishes should always be taken into account.

Lower mortality but higher neonatal morbidity over a decade in very preterm infants.

Better perinatal care has led to better survival of very preterm children, but may or may not have increased the number of children with cerebral and pulmonary morbidity. We therefore investigated the relationship between changes in perinatal care during one decade, and short-term outcome in very preterm infants. Perinatal risk factors and their effects on 28-day and in-hospital mortality, and on intraventricular haemorrhage and bronchopulmonary dysplasia (BPD) in survivors, were compared in two surveys of very preterm singleton infants in the Netherlands. Between 1983 and 1993, 28-day mortality decreased from 52.1% to 31.8% in infants of 25-27 weeks' gestation and from 15.2% to 11.3% in infants of 28-31 weeks' gestation. The incidence of intraventricular haemorrhage in survivors did not change (44.4% and 43.3% in infants of 25-27 weeks' gestation, and 29.0% and 24.0% in infants of 28-31 weeks' gestation). The incidence of BPD in survivors increased from 40.3% to 60.0% in infants of 25-27 weeks' gestation and remained similar in infants of 28-31 weeks' gestation (8.5% and 9.8% respectively). In multivariable analysis, higher mortality was associated with congenital malformation, low gestational age, low birthweight, no administration of steroids before birth, low Apgar scores and intraventricular haemorrhage, in 1983 as well in 1993, and with male gender in 1993. The effect of maternal age on mortality diminished significantly between 1983 and 1993. Intraventricular haemorrhage in surviving children was associated with low gestational age and artificial ventilation, both in 1983 and in 1993. The effect of artificial ventilation on the incidence of intraventricular haemorrhage diminished significantly between 1983 and 1993. BPD was associated with low gestational age and artificial ventilation, both in 1983 and in 1993, and with low birthweight and caesarean section in 1993. We conclude that the better survival of very preterm infants, especially of those of 25-27 weeks' gestation, has been accompanied by a similar incidence (and thus with an increased absolute number) of children with intraventricular haemorrhage and by an increased incidence of children with BPD.

Outcome of perinatal care for very preterm infants at 5 years of age: a comparison between 1983 and 1993.

Perinatal mortality in very preterm infants has decreased by up to 50% during the last decades. Studies of changes of long-term outcome are inconclusive. We studied the visual, auditory, neuromotor, cognitive and behavioural development of two geographically defined populations of very preterm, singleton infants, born in 1983 and in 1993, and analysed the relationship between perinatal risk factors and outcomes. The incidence of disabling cerebral palsy increased from 6.0% to 11.1% (OR 2.45 [95% CI 1.11, 5.38]). Impaired vision and strabismus decreased significantly, presumably by continuous monitoring of pO(2). Hearing problems, the need for special education and the incidence of behavioural problems did not change over time. The proportion of children who showed optimal performance in every developmental domain increased from 29.5% in 1983 to 43.2% in 1993. Cerebral palsy was associated with male gender in 1983, with low Apgar score and intraventricular haemorrhage in 1993, and with seizures both in 1983 and in 1993. The intensiveness of neonatal treatment has increased, leading to the survival of many more healthy infants, but at the cost of more infants with cerebral damage. Modern perinatal care is no longer limited by the devastating effects of pulmonary problems as it was in the past, but fails to safeguard cerebral integrity in very preterm infants.

Is paediatric assessment of motor development of very preterm and low-birthweight children appropriate?

AIM: To determine whether paediatricians that examine, in regular clinical practice, very preterm and very-low-birthweight children at 5 y of age detect neurological impairments and functional motor problems in these children. METHODS: We compared a paediatric judgement, a standardized neurological examination (Touwen examination) and a screening of motor development (Denver Developmental Screening Test; DDST) with the Movement ABC in 396 5-y-old very preterm and low-birthweight children. RESULTS: The Movement ABC detected clinically important motor disorders in 20.5% and borderline disturbances in 22.5% of the children. Compared to the Movement ABC, the sensitivity of the paediatric judgement was 0.19, Touwen examination 0.62 and DDST 0.52; the negative predictive values were 0.61, 0.74 and 0.69, respectively. CONCLUSION: Paediatric assessment of motor development in 5-y-old very preterm and low-birthweight children generally is not sensitive enough to detect functional motor problems. The Movement ABC should be added to the assessment of the motor development of very preterm and low-birthweight children at 5 y of age.

The compangle: a new goniometer for joint angle measurements of the hand. A technical note.

The accuracy of joint angle measurement of the hand may be negatively influenced by joint swelling, deformation and other obstacles. We developed an alternative goniometer with clear ergonomic advantages, especially for the measurement of small joints. This new concept of goniometry is described and preliminary results on the reliability of the measurements are presented. The intraclass correlation coefficients (ICCs) and the standard error of measurements (SEMs) of the alternative goniometer are greater respectively smaller than a conventional goniometer, indicating a better intratester reliability.

Is attrition bias a problem in neonatal follow-up?

AIM: To assess whether attrition rate influences outcome in the follow-up of very preterm infants. STUDY DESIGN: In a national follow-up study of infants born alive in 1983 in the Netherlands with a gestational age less than 32 weeks and/or a birth weight less than 1500 g, outcome was assessed separately for adolescents who responded early or late to a follow-up invitation at age 14 years. Neonatal data and outcome results of earlier assessments from early and late responders were compared to those of non-responders by univariate and nominal (polytomous logistic) regression analysis. SUBJECTS: There were 723 (76%) early responders, 130 (14%) late responders and 109 (11%) non-responders. RESULTS: We found significantly more non-Dutch origin and more disabilities and school problems at age 10 years in late- and especially in non-responders. At age 14 years, the health utility index was significantly lower in late responders compared to early responders. School outcome did not show difference in relation to the response groups. CONCLUSION: The results suggest that the incidence of adverse outcome in very preterm infants is underestimated when follow-up is incomplete and hence response rate is not a negligible problem in the assessment of late outcome. Therefore, follow-up studies should include a drop-out analysis to enable comparison to other studies.

Catch-up growth up to ten years of age in children born very preterm or with very low birth weight.

BACKGROUND: Improved survival due to advances in neonatal care has brought issues such as postnatal growth and development more to the focus of our attention. Most studies report stunting in children born very preterm and/or small for gestational age. In this article we study the growth pattern of these children and aim to identify factors associated with postnatal catch-up growth. METHODS: 1338 children born with a gestational age <32 weeks and/or a birth weight of <1500 grams were followed during a Dutch nationwide prospective study (POPS). Subgroups were classified as appropriate for gestational age and <32 weeks (AGA) or small for gestational age (<32 wks SGA and > or =32 wks SGA). Data were collected at different intervals from birth until 10 years for the 962 survivors and compared to reference values. The correlation between several factors and growth was analysed. RESULTS: At 10 years the AGA children had attained normal height, whereas the SGA group demonstrated stunting, even after correction for target height (AGA: 0.0 SDS; SGA <32 wks: -0.29SDS and > or =32 wks: -0.13SDS). Catch-up growth was especially seen in the SGA children with a fast initial weight gain. BMI was approximately 1 SD below the population reference mean. CONCLUSION: At 10 years of age, children born very preterm AGA show no stunting. However, many children born SGA, especially the very preterm, show persistent stunting. Early weight gain seems an important prognostic factor in predicting childhood growth.

Ethnic differences in congenital malformations in the Netherlands: analyses of a 5-year birth cohort.

Congenital malformations are among the major causes of perinatal mortality and morbidity at present. Research into the ethnic diversity of congenital malformations can form a basis both for aetiological studies and for health care advice and planning. This study compared the overall prevalence of congenital malformations, the prevalence in different organ systems and of several specific malformations between different maternal ethnic groups in the Netherlands using a 5-year national birth cohort (1996-2000) containing 881 800 births. Maternal ethnic groups considered were Dutch; Mediterranean (Moroccan/Turkish); other European; Black; Hindu and Asian. Mediterranean women had a 20% higher risk of having a child with a congenital malformation than Dutch women (age-adjusted OR = 1.21 [95% CI 1.16, 1.27]). They showed an increased risk of malformations in several organ systems such as the central nervous system and sensory organs, the urogenital system and skin and abdominal wall. Further, they had an increased risk of the group of chromosomal malformations/multiple malformations/syndromes. For the specific group of multiple malformations the maternal age adjusted OR was 1.80 [95% CI 1.47, 2.20]. The Black group showed a significantly increased risk of skeletal and muscular malformations (age adjusted OR = 1.76 [95% CI 1.53, 2.02]) with a sixfold increased risk of polydactyly compared with the Dutch group. For Mediterranean women, the largest and fastest growing group of immigrants in the Netherlands, this study demonstrated an increased risk of congenital malformations.

Changes in neonatology: comparison of two cohorts of very preterm infants (gestational age <32 weeks): the Project On Preterm and Small for Gestational Age Infants 1983 and the Leiden Follow-Up Project on Prematurity 1996-1997.

OBJECTIVE: To determine changes in peri- and neonatal care concerning neonatal mortality and morbidity by comparing 2 cohorts of very prematurely born infants (gestational age [GA] <32 weeks), 1 from the 1980s and 1 from the 1990s. METHODS: The Leiden Follow-Up Project on Prematurity (LFUPP-1996/97), a regional, prospective study, includes all infants who were born alive after a GA <32 weeks in 1996 and 1997 in the Dutch health regions Leiden, The Hague, and Delft. The Project On Preterm and Small for Gestational Age Infants (POPS-1983), a national, prospective study from the presurfactant era, includes all liveborn infants <32 weeks' GA and/or <1500 g from 1983 (n = 1338). For comparison, infants from the POPS-1983 cohort with a GA <32 weeks from the same Dutch health regions were selected (n = 102). RESULTS: The absolute number of preterm births in the study region increased by 30%: 102 in 1983 to on average of 133 in 1996-1997. Centralization of perinatal care improved: the percentage of extrauterinely transported infants decreased from 61% in 1983 to 35% in 1996-1997. A total of 182 (73%) of the LFUPP-1996/97 infants were treated antenatally with glucocorticosteroids compared with 6 (6%) of the POPS-1983 infants. A total of 112 (42%) of the LFUPP-1996/97 infants received surfactant. In-hospital mortality decreased from 30% in the 1980s to 11% in the 1990s. Mortality of the extremely preterm infants (<27 weeks) decreased from 76% to 33%. The incidence of respiratory distress syndrome remained the same: approximately 60% in both groups. Mortality from respiratory distress syndrome, however, decreased from 29% to 8%. The incidence of bronchopulmonary dysplasia increased from 6% to 19%. For the surviving infants, the average length of stay in the hospital and the mean number of NICU days stayed approximately the same ( approximately 67 days total admission time and 44 NICU days in both groups); including the infants who died, the mean NICU admission time increased from 27 days in the 1980s to 41 days in the 1990s. Equal percentages of adverse outcome (dead or an abnormal general condition) at the moment of discharge from hospital were found (+/-40% in both groups). CONCLUSIONS: An increase in the absolute number of very preterm births in this study region was found, leading to a greater burden on the regional NICUs. Improvements in peri- and neonatal care have led to an increased survival of especially extremely preterm infants. However, increased survival has resulted in more morbidity, mainly bronchopulmonary dysplasia, at the moment of discharge from the hospital.

Development and evaluation of a follow up assessment of preterm infants at 5 years of age.

BACKGROUND: Long term follow up shows a high frequency of developmental disturbances in preterm survivors of neonatal intensive care formerly considered non-disabled. AIMS: To develop and validate an assessment tool that can help paediatricians to identify before 6 years of age which survivors have developmental disturbances that may interfere with normal education and normal life. METHODS: A total of 431 very premature infants, mean gestational age 30.2 weeks, mean birth weight 1276 g, were studied at age 5 years. Children with severe handicaps were excluded. The percentage of children with a correctly identified developmental disturbance in the domains cognition, speech and language development, neuromotor development, and behaviour were determined. RESULTS: The follow up instrument classified 67% as optimal and 33% as at risk or abnormal. Of the children classified as at risk or abnormal, 60% had not been identified at earlier follow up assessments. The combined set of standardised tests identified a further 30% with mild motor, cognitive, or behavioural disturbances. The paediatrician's assessment had a specificity of 88% (95% CI 83-93%), a sensitivity of 48% (95% CI 42-58%), a positive predictive value of 85% (95% CI 78-91%), and a negative predictive value of 55% (95% CI 49-61%). CONCLUSIONS: Even after standardised and thorough assessment, paediatricians may overlook impairments for cognitive, motor, and behavioural development. Long term follow up studies that do not include detailed standardised tests for multiple domains, especially fine motor domain, may underestimate developmental problems.

Periconceptional folic acid use and the prevalence of neural tube defects in The Netherlands.

OBJECTIVE: To study the effect of increased folic acid intake on the prevalence of neural tube defects (NTD) in The Netherlands. STUDY DESIGN: Using the capture-recapture method, the prevalence of NTD was estimated on the basis of five different registries on births affected by NTD. RESULTS: Total prevalence over the 1988-1998 period varied between 1.43 and 1.96 per 1000 live and still births. No decrease in total prevalence was found to have taken place during that period. Scrutiny of the last 2 years, 1997 and 1998, in which increased folic acid intake might be expected to have had an effect, did not give any indication that the prevalence of NTD was falling. CONCLUSIONS: A decrease in the Dutch prevalence of NTD during the study period could not be demonstrated due to the relatively small number of women using folic acid periconceptionally. This does not mean automatically that periconceptional folic acid use is ineffective in reducing the Dutch prevalence of NTD. Further monitoring is needed.

Congenital malformations in 4224 children conceived after IVF.

BACKGROUND: The percentage of children born after IVF will continue to increase due to demographic changes such as increasing maternal age and new developments in assisted reproduction techniques. IVF conceptions may carry an increased risk of congenital malformations. METHODS: We compared overall and specific congenital malformation rates calculated for IVF children (n = 4224) and naturally conceived children (n = 314 605), using records from the same Dutch national database for the years 1995 and 1996 and controlling for confounding maternal factors. RESULTS: The overall crude odds ratio (OR) for the risk of any malformation for IVF children compared with naturally conceived children was 1.20 [95% confidence interval (CI): 1.01-1.43]. After correction for differences in maternal age, parity and ethnicity between the IVF and control population the OR was 1.03 (95% CI: 0.86-1.23). The crude OR for IVF children appeared higher for the cardiovascular organ system and for several specific minor congenital malformations. However, these could be chance findings due to comparison of many malformation categories or may result from remaining differences in ascertaining malformations between IVF and naturally conceived children. CONCLUSIONS: The small increase in overall congenital malformations observed in the IVF children appears to be attributable to differences in maternal characteristics and not to any aspect of the IVF procedure.

Randomised clinical trial on the effect of the Dutch obstetric peer review system.

The project "Obstetric Peer Review Interventions" (Verloskundige Onderlinge Kwaliteitsspiegeling Interventies, VOKSINT) was set-up in The Netherlands in 1994. It provided annual comparison data (quality ranking, league tables) for secondary care obstetric departments adjusted for population differences, based on the data registered in the Perinatal Database of The Netherlands (Landelijke Verloskunde Registratie, LVR). The aim of the so-called VOKS reports was to influence obstetricians' interventions in such a way that they led to a more homogeneous policy. To assess this influence, a trial was set-up, with departments randomly assigned to be or not to be informed about the VOKS results. Obstetric intervention rates and the morbidity of newborns including neonatal neurological examinations (NNEs) were assessed. Obstetric intervention rates were similar in the report group and the control group. Practice in the report group became more homogeneous (adjusted for population differences) than in the control departments, but this was only statistically significant for term caesarean section.

The reliability of perinatal and neonatal mortality rates: differential under-reporting in linked professional registers vs. Dutch civil registers.

Official Dutch perinatal mortality rates are based on birth and death certificates. These civil registration data are not detailed enough for international comparisons or extensive epidemiological research. In this study, we linked and extrapolated three national, incomplete, professional registers from midwives, obstetricians and paediatricians, containing detailed perinatal information. This linkage and extrapolation resulted in one detailed professional database which is representative of all Dutch births and from which gestational age-specific perinatal mortality rates could be calculated. The reliability of these calculated mortality rates was established by comparing them with the rates derived from the national civil registers. The professional database reported more perinatal deaths and fewer late neonatal deaths than the civil registers. The under-reporting in the civil registers amounted to 1.2 fewer perinatal deaths per 1000 births and was most apparent in immature newborns. We concluded that under-reporting of perinatal and neonatal deaths depends on the data source used. Mortality rates for the purpose of national and international comparison should, therefore, be defined with caution. This study also demonstrated that combining different incomplete professional registers can result in a more reliable database containing detailed perinatal information. Such databases can be used as the basis for extensive perinatal epidemiological research.

Behavioural problems in children who weigh 1000 g or less at birth in four countries.

BACKGROUND: The increased survival chances of extremely low-birthweight (ELBW) infants (weighing <1000 g at birth) has led to concern about their behavioural outcome in childhood. In reports from several countries with different assessments at various ages, investigators have noted a higher frequency of behavioural problems in such infants, but cross-cultural comparisons are lacking. Our aim was to compare behavioural problems in ELBW children of similar ages from four countries. METHODS: We prospectively studied 408 ELBW children aged 8-10 years, whose parents completed the child behaviour checklist. The children came from the Netherlands, Germany, Canada, and USA. The checklist provides a total problem score consisting of eight narrow-band scales. Of these, two (aggressive and delinquent behaviour) give a broad-band externalising score, three (anxious, somatic, and withdrawn behaviour) give a broad-band internalising score, and three (social, thought, and attention problems) indicate difficulties fitting neither broad-band dimension. For each cohort we analysed scores in ELBW children and those in normal- birthweight controls (two cohorts) or national normative controls (two cohorts). Across countries, we assessed deviations of the ELBW children from normative or control groups. FINDINGS: ELBW children had higher total problem scores than normative or control children, but this increase was only significant in European countries. Narrow-band scores were raised only for the social, thought, and attention difficulty scales, which were 0.5-1.2 SD higher in ELBW children than in others. Except for the increase in internalising scores recorded for one cohort, ELBW children did not differ from normative or control children on internalising or externalising scales. INTERPRETATION: Despite cultural differences, types of behavioural problems seen in ELBW children were very similar in the four countries. This finding suggests that biological mechanisms contribute to behavioural problems of ELBW children.