An international comparison of retinopathy of prematurity grading performance within the Benefits of Oxygen Saturation Targeting II trials

Purpose

To investigate whether the observed international differences in retinopathy of prematurity (ROP) treatment rates within the Benefits of Oxygen Saturation Targeting (BOOST) II trials might have been caused by international variation in ROP disease grading.

Methods

Groups of BOOST II trial ophthalmologists in UK, Australia, and New Zealand (ANZ), and an international reference group (INT) used a web based system to grade a selection of RetCam images of ROP acquired during the BOOST II UK trial. Rates of decisions to treat, plus disease grading, ROP stage grading, ROP zone grading, inter-observer variation within groups and intra-observer variation within groups were measured.

Results

Forty-two eye examinations were graded. UK ophthalmologists diagnosed treat-requiring ROP more frequently than ANZ ophthalmologists, 13.9 (3.49) compared to 9.4 (4.46) eye examinations, P=0.038. UK ophthalmologists diagnosed plus disease more frequently than ANZ ophthalmologists, 14.1 (6.23) compared to 8.5 (3.24) eye examinations, P=0.021. ANZ ophthalmologists diagnosed stage 2 ROP more frequently than UK ophthalmologists, 20.2 (5.8) compared to 12.7 (7.1) eye examinations, P=0.026. There were no other significant differences in the grading of ROP stage or zone. Inter-observer variation was higher within the UK group than within the ANZ group. Intra-observer variation was low in both groups.

Conclusions

We have found evidence of international variation in the diagnosis of treatment-requiring ROP. Improved standardisation of the diagnosis of treatment-requiring ROP is required. Measures might include improved training in the grading of ROP, using an international approach, and further development of ROP image analysis software.

Perinatal health services organization for preterm births: a multinational comparison

OBJECTIVE

To explore population characteristics, organization of health services and comparability of available information for very low birth weight or very preterm neonates born before 32 weeks' gestation in 11 high-income countries contributing data to the International Network for Evaluating Outcomes of Neonates (iNeo).

STUDY DESIGN

We obtained population characteristics from public domain sources, conducted a survey of organization of maternal and neonatal health services and evaluated the comparability of data contributed to the iNeo collaboration from Australia, Canada, Finland, Israel, Italy, Japan, New Zealand, Spain, Sweden, Switzerland and UK.

RESULTS

All countries have nationally funded maternal/neonatal health care with >90% of women receiving prenatal care. Preterm birth rate, maternal age, and neonatal and infant mortality rates were relatively similar across countries. Most (50 to >95%) between-hospital transports of neonates born at non-tertiary units were conducted by designated transport teams; 72% (8/11 countries) had designated transfer and 63% (7/11 countries) mandate the presence of a physician. The capacity of 'step-down' units varied between countries, with capacity for respiratory care available in <10% to >75% of units. Heterogeneity in data collection processes for benchmarking and quality improvement activities were identified.

CONCLUSIONS

Comparability of healthcare outcomes for very preterm low birth weight neonates between countries requires an evaluation of differences in population coverage, healthcare services and meta-data.

Hypertensive disorders of pregnancy and outcomes of preterm infants of 24 to 28 weeks' gestation

OBJECTIVE

To examine the relationship between hypertensive disorders of pregnancy (HDPs) and mortality and major morbidities in preterm neonates born at 24 to 28 weeks of gestation.

STUDY DESIGN

Using an international cohort, we retrospectively studied 27 846 preterm neonates born at 24⁰ to 28⁶ weeks of gestation during 2007 to 2010 from 6 national neonatal databases. The incidence of HDP was compared across countries, and multivariable logistic regression analyses were conducted to examine the association of HDP and neonatal outcomes including mortality to discharge, bronchopulmonary dysplasia, severe brain injury, necrotizing enterocolitis and treated retinopathy of prematurity.

RESULTS

The incidence of HDP in the entire cohort was 13% (range 11 to 16% across countries). HDP was associated with reduced odds of mortality (adjusted odds ratio (aOR) 0.77; 95% confidence interval (CI) 0.67 to 0.88), severe brain injury (aOR 0.74; 95% CI 0.62 to 0.89) and treated retinopathy (aOR 0.82; 95% CI 0.70 to 0.96), but increased odds of bronchopulmonary dysplasia (aOR 1.16; 95% CI 1.05 to 1.27).

CONCLUSIONS

In comparison with neonates born to mothers without HDP, neonates of HDP mothers had lower odds of mortality, severe brain injury and treated retinopathy, but higher odds of bronchopulmonary dysplasia. The impact of maternal HDP on newborn outcomes was inconsistent across outcomes and among countries; therefore, further international collaboration to standardize terminology, case definition and data capture is warranted.

Neonatal renal vein thrombosis and prothrombotic risk

A case of extensive deep venous thrombosis in a four a day old infant was presented. Unusually this patient was shown to be heterozygous for three thrombophilia genes; Factor V Leiden, prothrombin and antithrombin gene mutations, the latter being novel.

CONCLUSION

There are no randomized controlled trials to guide management in deep venous thrombosis in the newborn but knowledge of the prothrombotic risk factors may help direct treatment.

Vitamin A supplementation to prevent mortality and short and long-term morbidity in very low birthweight infants

BACKGROUND

Vitamin A is necessary for normal lung growth and the ongoing integrity of respiratory tract epithelial cells. Preterm infants have low vitamin A status at birth and this has been associated with increased risk of developing chronic lung disease. Several studies have been undertaken to assess whether vitamin A supplementation beyond that routinely given in multivitamin preparations can reduce the incidence of this outcome.

OBJECTIVES

To assess the benefit and risk of supplementation with vitamin A in very low birthweight infants.

SEARCH STRATEGY

Searches were made of the Oxford Database of Perinatal Trials, MEDLINE up to November 2006, Cochrane Central Register of Controlled Trials Register (CENTRAL, The Cochrane Library, Issue 4, 2006), and Science Citation Index. The reference lists of relevant trials, recent issues of paediatric and nutrition journals, abstracts and proceedings from relevant conferences in the English language were hand searched.

SELECTION CRITERIA

Randomised controlled trials which compared the effects of supplemental vitamin A with standard vitamin A regimes in infants with birthweight </= 1500 g and reported clinical outcomes (death, chronic lung disease or bronchopulmonary dysplasia, long-term neurodevelopmental status) and/or vitamin A concentrations were considered for the review, as were trials which compared vitamin A dosing regimes and reported biochemical outcomes (retinol concentrations at 28 days).

DATA COLLECTION AND ANALYSIS

Data on mortality, requirement for supplemental oxygen at one month of age and at 36 weeks postmenstrual age, retinopathy of prematurity, nosocomial sepsis and follow-up at 18 to 22 months, as well as retinol concentrations at 28 days in trials comparing dosage regimes, were excerpted by both reviewers independently. Data analysis was conducted according to the standards of the Cochrane Neonatal Review Group.

MAIN RESULTS

Eight eligible trials comparing vitamin A supplementation with standard regimes were identified, one having a much larger sample size than the others combined. The meta-analysis suggests supplementation with vitamin A is beneficial in reducing death or oxygen requirement at one month of age [typical RR 0.93 (95% CI 0.88, 0.99), RD -0.05 ( 95% CI -0.10, -0.01), NNT 20 (10, 100) and oxygen requirement at 36 weeks postmenstrual age [typical RR 0.87 (95% CI 0.77, 0.98), RD -0.08 ( 95% CI -0.14, -0.01), NNT 13 (7, 100)], and trends towards reduction in oxygen requirement in survivors at one month of age [typical RR 0.93 (95% CI 0.86, 1.01) and death or oxygen requirement at 36 weeks postmenstrual age [typical RR 0.91 (95% CI 0.82, 1.00)]. Meta-analysis of the three studies from which data on retinopathy of prematurity are available suggests a trend towards reduced incidence in vitamin A supplemented infants. Neurodevelopmental assessment of 85% of surviving infants participating in the largest trial showed no differences in outcome between supplementation and placebo groups at 18 to 22 months corrected age.

AUTHORS' CONCLUSIONS

Supplementing very low birthweight infants with vitamin A is associated with a reduction in death or oxygen requirement at one month of age and oxygen requirement among survivors at 36 weeks postmenstrual age, with this latter outcome being confined to infants with birthweight less than 1000 g. Whether clinicians decide to utilise repeat intramuscular doses of vitamin A to prevent chronic lung disease may depend upon the local incidence of this outcome and the value attached to achieving a modest reduction in this outcome, balanced against the lack of other proven benefits and the acceptability of treatment. Information on long-term neurodevelopmental status suggests no evidence of either benefit or harm from the intervention. The benefits, in terms of vitamin A status, safety and acceptability of delivering vitamin A in an intravenous emulsion compared with repeat intramuscular injections, should be assessed in a further trial.

Variation in rates of severe retinopathy of prematurity among neonatal intensive care units in the Australian and New Zealand Neonatal Network

AIM

To analyse variations in rates of severe retinopathy of prematurity (ROP) among neonatal intensive care units (NICUs) in the Australian and New Zealand Neonatal Network (ANZNN), adjusting for sampling variability and for case mix.

METHODS

25 NICUs were included in the study of 2105 infants born at less than 29 weeks in 1998 and 1999, who survived to 36 weeks post-menstrual age and were examined for ROP. The observed NICU rates of severe ROP were adjusted for case mix using logistic regression on gestation, weight for gestational age and sex, and for sampling variability using shrinkage estimates. The corrected rate in the best 20% of NICUs was identified and NICU variations in rates were compared with those in 2000-1.

RESULTS

The overall (unadjusted) rate of severe ROP in the NICUs was 9.6% (interquartile range 5.4-12.8%). After adjusting for both case mix and sampling variability there remained significant variation among the NICUs. 20% of NICUs had a rate of severe ROP </=5.9%. Variation in rates among NICUs showed a similar pattern in both time periods. If the overall network rate was reduced to 5.9%, the 20th centile of the adjusted rates, there would be 79 fewer cases in a 2 year period, in contrast with 26 fewer if rates in the two units with excess rates improved to the average.

CONCLUSIONS

Considerable variation in rates of severe ROP among NICUs remained after adjustment for case mix and sampling variability. These data will facilitate investigation of potentially better practices associated with a reduced risk of severe ROP.

Infants in a neonatal intensive care unit: parental response

OBJECTIVE

To compare the psychosocial functioning of the parents (mother and father) of infants admitted to a neonatal intensive care unit (NICU) with the parents of infants born at term and not admitted to the NICU.

DESIGN

Random sample of NICU parents and term non-NICU parents were assessed across a variety of psychiatric and psychosocial measures shortly after the birth of their infant.

SETTING

Christchurch Women's Hospital, New Zealand. Labour ward and level III NICU.

PARTICIPANTS

A total of 447 parents (242 mothers; 205 fathers) with an infant admitted to a regional NICU during a 12 month period; 189 parents (100 mothers; 89 fathers) with infants born at term and not requiring NICU admission.

MAIN OUTCOME MEASURES

Depression and anxiety symptoms, psychosocial functioning.

RESULTS

Overall, levels of anxiety and depression were low in both parent groups. Compared with control parents, a higher percentage of NICU parents had clinically relevant anxiety and were more likely to have had a previous NICU admission and be in a lower family income bracket. Infant prematurity was associated with higher levels of symptomatology in both NICU mothers and fathers.

CONCLUSIONS

Specific interventions are not needed for most parents who have an infant admitted to the NICU as they appear to adapt relatively successfully. Infant prematurity impacts negatively on the father as well as the mother. Consequently these parents may benefit from increased clinical attention.

Vitamin C supplementation in very preterm infants: a randomised controlled trial

OBJECTIVE

To determine whether regulating vitamin C (ascorbic acid: AA) intake to achieve higher or lower plasma concentrations was associated with improved clinical outcome.

DESIGN

A double blind, randomised controlled trial.

SETTING

Neonatal intensive care unit at Christchurch Women's Hospital.

PATIENTS

Infants with birth weight <1500 g or gestation <32 weeks, admitted to the unit within 48 hours of birth.

INTERVENTION

Infants were randomised to one of three protocols with regard to AA supplementation for the first 28 days of life: group LL received low supplementation throughout; group LH received low until day 10 and then high: group HH received high throughout.

MAIN OUTCOME MEASURES

Primary outcome measures were oxygen requirement at 28 days and 36 weeks postmenstrual age, total days supplemental oxygen, and retinopathy of prematurity. AA concentrations were measured at study entry (day 2), and days 10, 21, and 28.

RESULTS

A total of 119 infants were enrolled over 24 months (mean gestation 28.4 weeks; birth weight 1161 g). Six infants died, and these had significantly higher AA concentrations before randomisation than surviving infants (116 micromol/l (95% confidence interval 90 to 142) v 51 micromol/l (45 to 58), p<0.0001). There were no significant differences in primary outcomes between the groups. However, the proportion of surviving infants with an oxygen requirement at 36 weeks postmenstrual age in group HH (19%) was half that in group LL (41%) (p=0.06).

CONCLUSIONS

In a randomised controlled trial, no significant benefits or harmful effects were associated with treatment allocation to higher or lower AA supplementation throughout the first 28 days of life.

Outcomes for high risk New Zealand newborn infants in 1998-1999: a population based, national study

OBJECTIVE

To determine short term morbidity and mortality outcomes, provision of care, and treatments for a national cohort of high risk infants born in 1998-1999 and admitted to New Zealand neonatal intensive care units (NICUs).

SETTING

All level III (six) and level II (13) NICUs in New Zealand.

METHODS

Prospective audit by the Australian and New Zealand Neonatal Network (ANZNN) of all infants defined as "high risk" (born at < 32 weeks gestation or < 1500 g birth weight, or received assisted ventilation for four hours or more, or had major surgery). Data were collected from birth until discharge home or death.

RESULTS

There were 3368 high risk infants (3.0% of all live births), comprising 1241 (37%) < 32 weeks gestation, 1084 (32%) < 1500 g, 3156 (94%) who received assisted ventilation, and 243 (7%) who received major surgery (categories overlap). Most infants (87%) received some care in tertiary hospitals, and 13% were cared for entirely in non-tertiary hospitals. Survival was 91% for infants < 32 weeks gestation, 97% for infants > or = 32 weeks gestation who received assisted ventilation, and 92% for infants > or = 32 weeks gestation who had major surgery. The proportion of very preterm infants who survived free of early major morbidity was 11%, 28%, 53%, 81%, and 90% for infants born at < 24, 24-25, 26-27, 28-29, and 30-31 weeks gestation respectively.

CONCLUSIONS

These unique population based national data provide contemporary information on the care and early morbidity and mortality outcomes for all high risk infants, whether cared for in hospitals with level III or level II NICUs.

Improved outcomes for very low birthweight infants: evidence from New Zealand national population based data

OBJECTIVE

To compare the survival and short term morbidity of all New Zealand very low birthweight (VLBW) infants born in two epochs, 1986 and 1998-1999.

SETTING

All level III and level II neonatal intensive care units (NICUs) in New Zealand.

METHODS

In 1986, data were prospectively collected for a study of retinopathy of prematurity (ROP). In 1998-1999, prospective data were collected by the Australian and New Zealand Neonatal Network (ANZNN). Both cohorts included all VLBW infants born during the calendar year and admitted to a NICU. Data were collected from birth until discharge home or death.

RESULTS

More VLBW infants were admitted for care in 1998-1999 (n = 1084, 0.96% of livebirths) than in 1986 (n = 413, 0.78% of livebirths; p < 0.001), including a higher proportion of VLBW infants of < 1000 g birth weight (38% v 32% respectively; p < 0.05). Survival to discharge home increased from 81.8% in 1986 to 90.3% in 1998-1999 (p < 0.001). The 1998-1999 cohort had a higher proportion of infants born in a hospital with a level III NICU (87% v 72% in 1986; p < 0.001) and receiving antenatal corticosteroids (80% v 58% in 1986; p < 0.001). In 1998-1999, the incidence of several morbidities had decreased compared with 1986, including oxygen dependency at 28 days (29% v 39% respectively; p = 0.001) and at 36 weeks postmenstrual age (16% v 23%; p = 0.002), grade 1 intraventricular haemorrhage (IVH) (8% v 24%; p < 0.001), grade 2/3 IVH (5% v 11%; p < 0.001), and stage 3/4 ROP for infants < 1000 g (6% v 13%; p < 0.001).

CONCLUSIONS

The outlook for VLBW infants in New Zealand has improved since 1986.

Early-onset neonatal group B streptococcal infections in New Zealand 1998-1999

OBJECTIVE

To determine in New Zealand infants the attack rates, risk factors, preventive policies, strain serotype and antibiotic susceptibilities of early-onset neonatal group B streptococcus (GBS) infection.

METHOD

A 2-year prospective active surveillance study was conducted in New Zealand's 19 neonatal units. Cases had to present within 48 h of delivery, be unwell, possess abnormal haematological indices and have GBS isolated from sterile sites.

RESULTS

Of the 112 402 infants born in New Zealand during 1998-1999, 56 had early-onset GBS infection, an attack rate of 0.5 per 1000 live births (95% confidence interval [CI] 0.38, 0.65). Seven had meningitis and there was one death (case fatality rate of 1.8%; upper 95% CI 9.5%). Univariate analysis identified young maternal age, parity, preterm labour, prolonged membrane rupture, maternal fever and assisted delivery as risk factors. Preventive policies for GBS were reported by 14 (74%) obstetric centres associated with neonatal units. Of the 56 cases, five (9%) were born to mothers receiving intrapartum antibiotics, 32 (57%) had mothers with risk factors but were not treated with antibiotics, and 19 (34%) were born to mothers without identifiable risk factors for GBS prevention. Serotypes Ia and III predominated, while two isolates were resistant to erythromycin and/or clindamycin.

CONCLUSIONS

Rates of early-onset GBS infection are similar to other countries following the introduction of prevention policies. Further reductions are possible with full implementation of these guidelines. Meanwhile, emergence of antibiotic resistance complicates the management of women with penicillin allergy. Vaccine development therefore remains a priority.

An extended interval dosing method for gentamicin in neonates

Traditional gentamicin dosing every 8-24 h depending on age and weight in neonates does not provide the ideal concentration-time profile to both optimize the concentration-dependent killing by aminoglycosides and minimize toxicity. Fifty-three neonates were audited prospectively while receiving gentamicin 2.5 mg/kg every 8-24 h, aiming for peak concentrations (Cmax) of 6-10 mg/L and trough concentrations (Cmin) <2 mg/L. After the first dose, the mean (+/- s.d.) Cmax was 5.5 +/- 0.7 mg/L with sub-therapeutic concentrations (<6 mg/L) in 62% of patients, while the mean Cmin was >2 mg/L in 15% of the neonates. After the third dose the Cmax was 7.5 +/- 1.5 mg/L, with 17% <6 mg/L, whereas the mean Cmin was 2.2 +/- 1.1 mg/L with 49% of values >2 mg/L. An extended interval dosing method (24, 36 and 48 h) for infant weights of 0.75-5 kg was developed by simulation, and audited prospectively in 51 neonates. Prospective analysis of the extended interval dosing method showed a mean Cmax after the first dose of 13.1 +/- 3.6 mg/L, while the mean Cmin was 0.7 +/- 0.6 mg/L. Seventy-eight per cent had Cmax of >10 mg/L after the first dose. The mean area under the concentration versus time curve AUC0-24 was 93 mg*h/L (target = 100 mg*h/L). The extended interval dosing achieved higher Cmax values while ensuring that overall exposure per 24 h was acceptable. Prospective testing of the method demonstrated good predictive ability.

Vitamin C is reduced in human milk after storage

In order to establish how cold storage of human milk affects levels of bioavailable vitamin C, 11 samples were stored for 24 h in the refrigerator or up to 2 mo in the freezer. Total vitamin C levels decreased on average by one-third in the refrigerator or after I mo of freezing, with wide variations between individuals (6 to 76% and 3 to 100%, respectively). After 2 mo of freezing, the average decrease was two-thirds (7-100%).

CONCLUSION

We recommend a change in human milk storage practices, to under 24 h in a refrigerator or under 1 mo in a freezer. Alternatively, vitamin C supplementation may be considered.

Limiting light-induced lipid peroxidation and vitamin loss in infant parenteral nutrition by adding multivitamin preparations to Intralipid

Parenteral lipids are susceptible to light-induced peroxidation, particularly under phototherapy. Ascorbic acid is protective. The aim of this study was to investigate whether dark delivery tubing and/or coadministration of multivitamin preparations could prevent peroxidation of Intralipid without undue vitamin loss. In experiments carried out on the benchtop, lipid peroxidation occurred in ambient light and was more extensive under phototherapy. Dark tubing decreased peroxide formation, but only by about 65%. In simulated clinical conditions in which solutions were pumped through standard clear or dark minibore plastic tubing. Intralipid accumulated lipid peroxides as measured by the FOX assay (280 microM) or as triglyceride hydroperoxides (52 microM). Multivitamin preparations (MVIP or Soluvit/Vitlipid) inhibited peroxide formation almost completely, and were fully protective when used with dark tubing. There was loss of riboflavin (65% from Soluvit and 35% from MVIP) in clear tubing but this was decreased to 18% and 11%, respectively, in dark tubing. Ascorbate loss was 20% (MVIP) and 50% (Soluvit) and only slightly less in dark tubing. Ascorbate loss was also seen in the absence of Intralipid and is due to riboflavin-induced photo-oxidation.

CONCLUSION

Multivitamin preparations protect Intralipid against light-induced formation of lipid hydroperoxides, and administering multivitamins with Intralipid via dark delivery tubing provides a practical way of preventing peroxidation of the lipid while limiting vitamin loss. This procedure should be considered for routine use as well as with phototherapy.

Breast milk feeding and cognitive ability at 7-8 years

OBJECTIVE

To examine the association between duration of breast milk feeding and cognitive ability at 7-8 years in a birth cohort of very low birthweight infants.

DESIGN

280 survivors from a national birth cohort of 413 New Zealand very low birthweight infants born in 1986 were assessed at age 7-8 years on measures of verbal and performance intelligence quotient (IQ) using the WISC-R. At the same time mothers were questioned as to whether they had elected to provide expressed breast milk at birth and the total duration of breast milk feeding.

RESULTS

Some 73% of mothers provided expressed breast milk and 37% breast fed for four months or longer. Increasing duration of breast milk feeding was associated with increases in both verbal IQ (p < 0.001) and performance IQ (p < 0.05): children breast fed for eight months or longer had mean (SD) verbal IQ scores that were 10.2 (0.56) points higher and performance IQ scores that were 6.2 (0.35) points higher than children who did not receive breast milk. These differences were substantially reduced after control for selection factors associated with receipt of breast milk. Nevertheless, even after control for confounding, there remained a significant (p < 0.05) association between duration of breast milk feeding and verbal IQ: children breast fed for eight months or longer had adjusted mean (SD) verbal IQ scores that were 6 (0.36) points higher than the scores of those who did not receive breast milk.

CONCLUSIONS

These findings add to a growing body of evidence to suggest that breast milk feeding may have small long term benefits for child cognitive development.

Lipid peroxide and hydrogen peroxide formation in parenteral nutrition solutions containing multivitamins

BACKGROUND

Infusion of parenteral solutions containing peroxides may be detrimental to premature infants. Intralipid frequently contains lipid peroxides and undergoes further peroxidation when exposed to light. Peroxidation is inhibited by ascorbate, and we have proposed that administration of peroxides could be minimized by mixing multivitamins with the Intralipid. In contrast, others have reported that multivitamins generate peroxides and have advised against mixing them with lipid. Our objective was to assess whether light-dependent reactions in parenteral solutions containing MVI Pediatric (MVIP) generate hydrogen peroxide and establish whether addition of multivitamins to Intralipid is beneficial or detrimental.

RESULTS

We were unable to make accurate peroxide measurements in MVIP using the ferrous oxidation of xylenol orange (FOX) assay, even though others have used it for this purpose, because of interference by ascorbate. Therefore oxygen release on adding catalase was measured to assay for hydrogen peroxide. Freshly reconstituted solutions contained 250 to 500 micromol/L hydrogen peroxide, and this increased dramatically in ambient light. This is presumably due to light-dependent, riboflavin-catalyzed reduction of oxygen by ascorbic acid. The rate of peroxide generation was less for MVIP diluted in Intralipid than in dextrose solution.

CONCLUSIONS

Taken together with our previous findings, we conclude that multivitamins protect Intralipid against lipid peroxidation, but light-dependent hydrogen peroxide production and ascorbate loss occur. These latter changes are less than for multivitamins in other total parenteral nutrition solutions, so there is an advantage in mixing multivitamins with Intralipid. However, prevention of ascorbate loss and hydrogen peroxide formation in any multivitamin solution requires protection of the delivery system from light.

Regional differences in outcome for very low-birthweight infants: do they persist at 7-8 years of age?

OBJECTIVE

To determine whether regional differences in early neonatal morbidity in a national cohort of very low-birthweight (VLBW) infants persisted at 7-8 years of age.

METHODS

Perinatal data collected prospectively from birth on all VLBW infants born in New Zealand in 1986 and admitted to a neonatal unit included the hospital principally caring for the infant: hospitals A-D being level III hospitals and 'Other' including the smallest level III and all level II hospitals. At 7-8 years of age, 298 surviving children (96% survivors living in New Zealand) were assessed at a home visit. Parents were given a comprehensive questionnaire to complete, the children underwent a visual examination and were tested with the Revised Wechsler Intelligence Scale for Children and the child's teacher was sent a questionnaire to complete.

RESULTS

Neonatal survival was significantly greater in the two largest hospitals (A and B) and this difference in survival remained at 7-8 years of age after adjustment for perinatal factors (P < 0.05). There were no differences between hospitals in risks of long-term sensorineural disability and behavioural or educational outcomes. There were interhospital differences in rates of visual problems and, after adjustment for confounding factors, there remained a marginally significant (P = 0.06) increased risk of myopia in hospital D.

CONCLUSIONS

Despite differences in early morbidity favouring larger hospitals, there were no substantive differences in long-term (7-8 years) outcomes across a range of measures in this national cohort of VLBW infants.

Very low birthweight and asthma by age seven years in a national cohort

Several studies have suggested that very low birthweight (VLBW < 1500 g) is associated with increased rates of respiratory problems in childhood and that the presence of chronic lung disease further increases the risk. We aimed to assess rates of asthma at 7-8 years of age in a national cohort of VLBW infants born in 1986 and for whom perinatal data were available. Two hundred ninety-nine former VLBW children (96% of surviving children living in New Zealand) were assessed at a home visit. Parents were asked a comprehensive questionnaire, including three questions aimed at assessing morbidity from asthma: 1) was the child diagnosed as having asthma before age 7 years; 2) was the child still experiencing asthma at the age of 7 years; and 3) was the child prescribed daily medication for asthma at the age of 7 years. Overall, 50% of the cohort had been diagnosed with asthma before age 7, compared with 27% of a sample of New Zealand children assessed contemporaneously in an international study; 32% had asthma at age 7, and 11% were taking daily medication. All three categories of asthma were associated with a family history of asthma, but there was no association with any perinatal factors. A diagnosis of asthma before age 7 was more likely when the mother smoked in pregnancy (P < 0.005) and currently smoked (P < 0.01), and trended so when parents lacked high school qualifications and in Maori or Pacific Island families (P < 0.10). In contrast, daily medication was more frequent when parents had educational qualifications and in non-Maori or Pacific Island families (P < 0.05). On multiple logistic regression, a family history of asthma was a significant predictor for any and current asthma (P < 0.001) and daily medication (P < 0.05); maternal smoking in pregnancy was a significant predictor for any asthma (P < 0.05); and non-Maori or Pacific Island ethnicity was a significant predictor for asthma treatment (P < 0.05). We conclude that rates of childhood asthma are high in this VLBW cohort, but the high prevalence appears to be unrelated to perinatal factors, including respiratory morbidity. There are suggestions that social factors contribute to both asthma risk and treatment.

Protein carbonyls and lipid peroxidation products as oxidation markers in preterm infant plasma: associations with chronic lung disease and retinopathy and effects of selenium supplementation

The purpose of this study was to determine whether protein carbonyls and the lipid peroxidation product malondialdehyde (MDA) are elevated in plasma from very low birth weight (<1500 g) infants, whether they are affected by selenium supplementation, and whether they are associated with poor respiratory outcome or retinopathy. The study group comprised 173 infants enrolled in a randomized controlled trial of selenium supplementation. Plasma samples, collected before randomization, at 7 and 28 d after birth, and at 36 wk postmenstrual age, were analyzed for protein carbonyls and total MDA. Respiratory outcome was assessed as oxygen requirement at 28 d of age or 36 wk postmenstrual age and as number of days on oxygen. Protein carbonyl concentrations in very low birth weight infants were significantly higher than for adults but lower than for cord blood from term infants. Median values decreased significantly by 28 d, and there was no relationship with birth weight. MDA concentrations in very low birth weight infants overlapped the ranges for healthy adults and cord blood from term infants. They correlated positively with birth weight at 28 d but not at other times. Supplementation almost doubled plasma selenium concentrations, but carbonyls and MDA did not differ between the supplemented and unsupplemented groups. There were no significant differences in oxidant marker levels in infants who did or did not develop chronic lung disease or retinopathy. Protein carbonyls and MDA measurements in plasma do not show evidence of systemic oxidative stress in <1500-g infants and are not affected by selenium supplementation. Oxidative injury at sites such as the lung may be important in prematurity, but markers from such sites must be measured to relate to outcome and antioxidant supplementation.

Elevated protein carbonyls and lipid peroxidation products correlating with myeloperoxidase in tracheal aspirates from premature infants

The purpose of this study is to determine whether the oxidative injury markers, protein carbonyls and malondialdehyde (MDA), are elevated in tracheal aspirates from very low birth weight (< 1500 g) infants; to determine whether levels correlate with myeloperoxidase as a marker of neutrophil inflammation; and to assess whether high levels are associated with poor respiratory outcome. Tracheal aspirates (144 samples) were collected from 86 infants < 1500 g at times of routine suctioning. Aspirates (82 samples) from 54 infants > or = 1500 g who required intubation for a variety of diagnoses were analyzed for comparison. Analyses were performed for protein carbonyls by ELISA, total malondialdehyde by HPLC, and myeloperoxidase activity. Respiratory outcome was assessed as oxygen requirement at 28-d or 36-wk postmenstrual age, and as the number of days of oxygen requirement. Protein carbonyls were significantly higher in infants < 1500 g than larger infants, and were highest close to birth. MDA concentrations were also higher in the earlier samples. There was a strong positive correlation between protein carbonyls and myeloperoxidase, suggesting a link between protein oxidation and neutrophil activation. A similar but weaker correlation was seen for MDA. Carbonyls in samples taken after steroid administration were less than for controls with a similar age distribution. We did not see significant associations between oxidant marker levels and development of chronic lung disease. Our findings of higher amounts of protein and lipid oxidation products in tracheal aspirates with high myeloperoxidase activity, taken together with other studies showing a link between neutrophil accumulation and chronic lung disease, suggest a possible contribution by neutrophil-derived reactive oxygen species to the injury.

The effect of selenium supplementation on outcome in very low birth weight infants: a randomized controlled trial. The New Zealand Neonatal Study Group

BACKGROUND

Low selenium (SE) status has been documented in preterm infants and has been suggested to be a risk factor for chronic lung disease.

METHODS

A total of 534 infants with birth weight <1500 g were enrolled in 8 New Zealand centers in a double-blind placebo-controlled randomized trial of SE supplementation from week 1 of life until 36 weeks' postmenstrual age or discharge home. Supplemented infants received 7 microg/kg/d of SE when fed parenterally and 5 microg/kg/d when fed orally. Plasma SE and glutathione peroxidase concentrations were measured in mothers after delivery and in infants before randomization and at 28 days and 36 weeks' postmenstrual age. Primary outcome measures were oxygen dependency at 28 days and total days oxygen dependency.

RESULTS

No significant differences were seen between the groups with respect to primary or secondary outcome measures, with the exception that fewer supplemented infants had an episode of sepsis after the first week of life (P <.038). Mean plasma SE concentrations were 0.33 micromol/L before randomization in both groups and at 28 days had risen in the supplemented group (0.56 micromol/L) but fallen in the control group (0.29 micromol/L) (P <.0001). There was no association between outcome measures and SE concentrations at 28 days or 36 weeks' postmenstrual age. However, lower maternal and infant prerandomization SE concentrations were associated with increased respiratory morbidity.

CONCLUSIONS

Postnatal SE supplementation in very low birth weight infants did not improve neonatal outcome. Further investigation of SE supplementation of mothers from the second half of pregnancy is warranted.

Vitamin A supplementation for preventing morbidity and mortality in very low birthweight infants

BACKGROUND

Vitamin A is necessary for normal lung growth and the ongoing integrity of respiratory tract epithelial cells. Preterm infants have low vitamin A status at birth and this has been associated with increased risk of developing chronic lung disease. Several studies have been undertaken to assess whether vitamin A supplementation beyond that routinely given in multivitamin preparations can reduce the incidence of this outcome.

OBJECTIVES

To assess the benefit of supplementation with vitamin A in very low birthweight infants.

SEARCH STRATEGY

Searches were made of the Oxford Database of Perinatal Trials, MEDLINE, Cochrane Controlled Trials Register, and Science Citation Index. The reference lists of relevant trials, recent issues of paediatric and nutrition journals, abstracts and proceedings from relevant conferences in the English language were hand searched.

SELECTION CRITERIA

Randomised controlled trials which compared the effects of supplemental vitamin A with standard vitamin A regimes in infants with birthweight </=1500g, and which reported clinical outcomes (death, chronic lung disease or bronchopulmonary dysplasia) and/or vitamin A concentrations were considered for the review.

DATA COLLECTION AND ANALYSIS

Data on mortality, requirement for supplemental oxygen at one month of age and at 36 weeks post-menstrual age, retinopathy of prematurity and nosocomial sepsis were excerpted by both reviewers independently. Data analysis was conducted according to the standards of the Cochrane Neonatal Review Group.

MAIN RESULTS

Six eligible trials were identified, one having a much larger sample size than the others combined. The meta-analysis suggests supplementation with vitamin A results in benefit in terms of reducing oxygen requirement at 36 weeks post-menstrual age [summary RR 0.85 (0.73, 0.98), RD -8.5% (-15.9, -1.1), NNT 11.8 (6.3, 90.9)] and trends towards reduction in death or oxygen requirement at 36 weeks post-menstrual age [summary RR 0.89 (0.79, 1.00)], oxygen use in survivors at one month of age [summary RR 0.93 (0.86, 1.01)], and death or oxygen requirement at one month of age [summary RR 0.93 (0. 86, 1.00)]. Meta-analysis of the two studies which reported on retinopathy of prematurity suggests a trend towards reduced incidence in vitamin A supplemented infants.

REVIEWER'S CONCLUSIONS

Supplementing very low birthweight infants with vitamin A is associated with a reduction in oxygen requirement amongst survivors at 36 weeks post-menstrual age. Whether clinicians decide to utilise repeat intramuscular doses of vitamin A to prevent chronic lung disease may depend upon the local incidence of this outcome and the value attached to achieving a modest reduction in this outcome, balanced against the lack of other proven benefits and the acceptability of treatment. The benefits, in terms of vitamin A status, safety and acceptability of delivering vitamin A in an intravenous emulsion compared with repeat intramuscular injections should be assessed in a further trial.

Cerebellar vermis diameter at cranial sonography for assessing gestational age in low-birth-weight infants

BACKGROUND

Clinical assessment of gestational age for very-low-birth-weight infants is often inaccurate. Survival rates are more dependent on gestational age than on the birth weight.

OBJECTIVE

To assess whether cerebellar vermis diameter might predict gestational age in infants under 2,000 g and/or under 32 weeks' gestation.

MATERIALS AND METHODS

We carried out a retrospective review of the hard-copy images of midline sagittal views of the cerebellum obtained at cranial sonography, performed via the anterior or posterior fontanelle, in 518 infants admitted to a regional neonatal intensive care unit between June 1991 and November 1996. The vermis diameter was measured from the base of the fourth ventricle to the junction of folium and tuber vermis. We generated regression equations for estimating gestational age from vermis diameter, and from vermis diameter and birth weight, for the 86 infants of known gestational age (less than 32 weeks), with birth weight under 2,000 g and who had scans carried out within 1 week of birth.

RESULTS

Measurement of cerebellar vermis diameter alone allowed prediction of gestational age to +/- 1.53 weeks using a 68 % prediction interval, or +/- 3.0 weeks using a 95 % prediction interval. Gender was not significant in the regression analysis.

CONCLUSION

Cerebellar vermis diameter predicts gestational age with slightly more precision than the new Ballard score.

Neonatal abstinence syndrome following abrupt cessation of breastfeeding

Neonatal abstinence syndrome is seen commonly in infants born to women on methadone maintenance. Many of these infants are breast-fed but few data are available on the distribution of methadone in breast milk, particularly for women receiving doses greater than 60 mg daily. We report two infants who appeared to develop neonatal abstinence syndrome, after abrupt discontinuation of breast-feeding by women receiving 70 mg and 130 mg of methadone. Women on methadone maintenance on high doses should be counselled to wean breast-feeding gradually.

Plasma vitamin A levels in the very low birthweight infant--relationship to respiratory outcome

OBJECTIVE

To examine the association between plasma vitamin A levels and outcome measures in very low birthweight (VLBW) infants, including meta-analysis of all observational studies.

DESIGN

A prospective observational longitudinal study of plasma vitamin A levels measured in the cord blood; maternal blood in the first 48 h after delivery; and the infants' blood at 48 h, 7 days and 28 days of age and correlated with antenatal and postnatal events. A meta-analysis of all published observational studies on the association of vitamin A with respiratory outcome in the VLBW infant was undertaken.

PATIENTS

Fifty-seven infants (88% of all eligible) VLBW infants (< 1500 g) admitted from January through October 1993 to one of two regional neonatal intensive care units in the South Island of New Zealand.

RESULTS

Exposure to antenatal steroids led to a significant increase in infant cord plasma vitamin A levels (P = 0.003), but no influence on infant plasma vitamin A levels at any other time. Exposure to postnatal steroids produced a significant rise in infant plasma vitamin A levels between 7 and 28 days (P = 0.008). After controlling for gestational age, antenatal and postnatal steroid exposure, low vitamin A levels at 48 h increased the risk of developing chronic lung disease (odds ratio for 50 microg/l decrease: 2.04, 95% CI 1.19-5.77) and bronchopulmonary dysplasia (odds ratio 1.96, 95% CI 1.14-6.87). On combining our results in meta-analysis with those of other published prospective observational studies, infants with chronic lung disease had lower plasma vitamin A levels at all times.

CONCLUSIONS

Our results support an association between low plasma vitamin A levels and adverse outcome in the VLBW infant.

Pharmacologic levels of heparin do not destabilize neonatal parenteral nutrition

BACKGROUND

Calcium and heparin are known to destabilize the lipid emulsion of total parenteral nutrition (TPN). However, these observations were made over long periods of time, using 5 to 10 times the amount of heparin used in a neonatal intensive care unit. We investigated the effects of lower heparin concentrations with lipid-to-nutrient ratios normally administered to premature infants.

METHODS

Lipid emulsion stability was assessed over 30 minutes by measuring viscosity at 10 mmol/L calcium after the addition of 0, 0.5, 1, and 5 IU heparin/mL. This was done at a range of lipid-to-nutrient ratios in clinical use. The effect of varying calcium concentration and different multivitamin preparations on emulsion stability also was observed.

RESULTS

Heparin caused an immediate increase in viscosity of pure Intralipid 20% (Intralipid; Kabi Pharmacia AB, Stockholm, Sweden), which eventually separated into two phases. Although changes in viscosity were observed at 1:1 lipid-to-nutrient ratios, no effect was seen at a 1:9 ratio. With the 1:1 ratio, the multivitamin preparations, MVI Pediatric (Rhone-Poulec Rorer, Montreal, Canada) and Vitlipid (Kabi Pharmacia AB), reduced the increase in viscosity.

CONCLUSIONS

Heparin and calcium destabilize Intralipid. This is unlikely to cause problems for most infants receiving TPN, provided low heparin concentrations are used. In all cases, especially where the lipid ratio is high, the risk of the lipid phase separating out can be further minimized by (1) the addition of multivitamin preparations containing detergent or an emulsifying agent and (2) by having the shortest possible delivery tube between the point of mixing the lipid and amino acid solutions of TPN and entry into the infant.

Survival and disability at 7-8 years of age in New Zealand infants less than 28 weeks gestation

AIMS

To determine the survival and disability rates at 7-8 years in infants of less than 28 weeks gestation born in New Zealand in 1986 and admitted to a neonatal unit.

METHODS

In 1986, all infants with birthweight less than 1500 g and admitted to neonatal units were enrolled in a prospective audit of retinopathy of prematurity. Surviving infants, including the subset born at less than 28 weeks gestation, have been assessed at a home visit. Parents completed a comprehensive questionnaire and children underwent a visual assessment and were tested on the Wechsler Intelligence Scale for Children.

RESULTS

Of 126 liveborn infants less than 28 weeks gestation, 80 (64%) survived to 7-8 years. Sixty eight children (97% survivors resident in New Zealand) were assessed: 72% had no, and 86% no or only mild disability, 77% had some visual problem, with close to one-third having myopia, strabismus or requiring spectacles and 32% received Ministry of Education funded special needs assistance.

CONCLUSIONS

There have been few long-term follow-up studies of infants of less than 28 weeks gestation born in a defined geographical area. The outcome for New Zealand infants is comparable with that in other published data.

Cognitive, educational, and behavioural outcomes at 7 to 8 years in a national very low birthweight cohort

AIMS

To examine cognitive, behavioural, and educational outcomes in middle childhood among a birth cohort of very low birthweight children.

METHODS

Two hundred and ninety eight survivors from a national birth cohort of 413 New Zealand very low birthweight (VLBW) children born in 1986 were assessed at 7 to 8 years of age on measures of behaviour, cognitive ability, school performance and the need for special education. These outcomes were compared with the same measures in a general population sample of over 1000 children studied at a similar age.

RESULTS

The VLBW children had significantly higher rates of problems and poorer levels of functioning across all outcome measures than the general child sample. These differences persisted even after control for variability in social, family, and other characteristics of the two samples and for the degree of sensorineural disability. There was evidence of a gradient of risk with birthweight, with extremely low birthweight children having generally higher rates of problems and difficulties than other VLBW children after covariate control.

CONCLUSIONS

The findings are consistent with a growing body of research evidence which suggests that premature and VLBW infants are at increased risk of longer term morbidity and functional impairment in middle childhood.

Prospective study of New Zealand infants with birth weight less than 1500 g and screened for retinopathy of prematurity: visual outcome at age 7-8 years

AIM

To determine the visual outcome at 7-8 years in very low birth weight (VLBW: birth weight < 1500 g) infants screened for retinopathy of prematurity (ROP).

METHODS

In 1986 all 413 VLBW infants admitted to neonatal units in New Zealand were enrolled in a prospective study of acute ROP. Surviving infants were traced and assessed at a home visit. Visual assessment comprised examination for abnormal and range of eye movements, visual fields, distance and near visual acuity, stereopsis, and photorefraction.

RESULTS

Of 338 infants surviving to discharge, 313 (93%) had been examined for acute ROP. ROP was present in 66 (21%: ROP+), absent in 247 (ROP-), with 25 not examined (NA). 298 children (96% survivors resident in New Zealand: 91% all survivors) were assessed. Any visual problem occurred in 79% ROP+ and 60% ROP-/NA (p < 0.01). Distance visual acuity less than 4/10 in the worse eye occurred in 29% ROP+ and 15% ROP-/NA (p < 0.05); and in the better eye in 19% ROP+ and 5% ROP-/NA (p < 0.001). Any myopia in the worse eye occurred in 36% ROP+ and 18% ROP-/NA (p < 0.01); and in the better eye in 25% ROP+ and 11% ROP-/NA (p < 0.01). Strabismus, including treated, occurred in 33% ROP+ and 19% ROP-/NA (p < 0.05). Overall, 11% had astigmatism and 18% hypermetropia with no difference between the groups.

CONCLUSION

In a population based study it was confirmed that VLBW is associated with an increased risk of visual problems at school age. A history of ROP is associated with an additional risk of poor outcome, including a near doubling of poor distance acuity, myopia, and strabismus.

High iron status in very low birth weight infants is associated with an increased risk of retinopathy of prematurity

To explore the hypothesis that excessive iron loads may increase the formation of free radicals and the development of retinopathy of prematurity in preterm infants, we carried out a prospective observational study of the association between transfusion volume, iron status, and retinopathy.

How safe is antenatal transfer between level 3 units?

The effect of antenatal transport of women between level 3 units in New Zealand on maternal and infant well-being was examined in a retrospective case-controlled study. The outcomes of women transferred to other level 3 centres because of lack of neonatal unit space were compared with women who were able to be delivered at Christchurch Women's Hospital (CWH). Of 34 women transferred out of CWH from 1991-194, 20 (59%) were delivered at the receiving centre, the remained returning undelivered. Women transferred from Christchurch were more likely to be of lower parity (p < 0.05), and were less likely to be in premature labour than those who remained in Christchurch (p < 0.05). There was a trend for the initial risk of mortality as assessed by the Clinical Risk Index for Babies (CRIB) score to be lower for those infants born out of Christchurch but this was not statistically significant. Mortality, oxygen requirement at 36 week, periventricular haemorrhage, retinopathy of prematurity, and the time to regain birth-weight were not statistically different between the 2 groups, despite significantly more outborn children being male (p < 0.05). Antenatal transfer therefore seems to be a safe procedure, although this study did not consider the potentially serious side effect of social factors on transferred families.

Endotracheal suctioning of the neonate: comparison of two methods as a source of mucus material for research

Endotracheal suctioning in the neonatal intensive care setting is a routine procedure performed to maintain patency of the airway in ventilated infants. Harvested material can also be a source of mucus for research into neonatal respiratory disorders. We aimed to investigate whether the composition of material obtained by our clinically preferred technique of dry shallow suctioning differed significantly from that obtained with saline lavage and deep suctioning. Eleven pairs of dry and saline lavage aspiration samples were compared for neutrophil enzyme myeloperoxidase, total and active alpha(1)-antitrypsin, alpha(1)-antitrypsin complexed with elastase, and secretory leukoprotease inhibitor. Even though individual values of each analyte, expressed per gram of albumin, varied over at least a fivefold range, there was no difference between mean values of dry and lavage samples for any of the constituents. We conclude that the yield of material for research obtained by dry shallow suctioning is adequate and the quality at least as satisfactory as that provided by saline lavage.

Prospective study of New Zealand very low birthweight infants: outcome at 7-8 years

OBJECTIVE

To determine the survival and sensorineural outcome at 7-8 years in very low birthweight (VLBW) infants born in New Zealand in 1986.

METHODOLOGY

In 1986 all VLBW New Zealand infants admitted to neonatal units were enrolled in a prospective study of acute retinopathy of prematurity. Surviving infants were traced and were assessed at a home visit. Parents were asked a comprehensive questionnaire, and children underwent a visual assessment including photorefraction and were tested with the Revised Wechsler Intelligence Scale for Children (WISC-R).

RESULTS

Four hundred and thirteen VLBW infants were admitted to neonatal units in 1986, 338 (81.8%) surviving to discharge, 12 children died after discharge, 17 were traced to overseas, seven declined to participate and four were untraced, leaving 298 (96% survivors resident in New Zealand) who were assessed at a mean age of 7.6 (+/- 0.4 years, 15 children (5.0%) had severe disability, 14 (4.7%) moderate disability, and 46 (15.4%) mild disability. Blindness (vision worse than 6/60) occurred in eight children (2.7%), deafness requiring aids in four (1.3%), any form of cerebral palsy in 17 (5.7%), and an JQ score on the WISC-R > 1 SD below the mean in 62 (20.8%). There was no significant difference in outcome for children with birthweight < 1000 g and 1000-1499 g.

CONCLUSIONS

Long-term (7-8 year) survival and disability rates in this national cohort of VLBW infants is comparable with that reported from other populations. Although a majority of children have no disability a sizeable proportion do perform poorly on the WISC-R. This may relate in part to problems such as a short attention span and poor visual-motor integration.

The correlation of elevated levels of an index of lipid peroxidation (MDA-TBA) with adverse outcome in the very low birthweight infant

The objective of this study was to examine the relationship between malondialdehyde-thiobarbituric acid (MDA-TBA) levels, as a measure of lipid peroxidation, in very low birthweight (VLBW) infants and outcome measures. A prospective observational longitudinal study was carried out in two level III neonatal units in the South Island of New Zealand measuring MDA-TBA levels in 61 VLBW infants in 1993. MDA-TBA levels were measured in (i) maternal plasma within 48 h of parturition, (ii) cord plasma, and (iii) infants' plasma at 2, 7, 14 and 28 days of age and correlated with antenatal and postnatal factors. Elevated levels of plasma MDA-TBA at 7 days were associated with adverse respiratory and ophthalmological outcome in the VLBW infants. Elevated MDA-TBA levels were measured at sample times close to the time of death in the infants who died. These results substantiate previously reported preliminary observations and support the hypothesis that oxidative injury, particularly within the first 7 days of life, is associated with the development of the long-term complications of the pre-term infant. MDA-TBA levels appear to be a useful measure to continue to explore the role of free radical mediated disease in the VLBW infant.

Immunogenetic, clinical, and demographic characterization of childhood type I diabetes in New Zealand

OBJECTIVE

To examine the relationship between genetic susceptibility alleles and islet cell antibodies (ICAs) in type I diabetes.

RESEARCH DESIGN AND METHODS

The human leukocyte antigen (HLA)-DQB1 alleles and ICA levels of all incident type I diabetic cases in patients < 20 years of age diagnosed in 1990 and 1991 in Canterbury, New Zealand, were determined.

RESULTS

The mean annual incidence rate for type I diabetes over the 24 months was 19.0/100,000 patient-years (95% confidence interval [CI] 13.5-26.0/100,000), which was considerably higher than rates observed between 1982 and 1989 (11.7/100,000; 95% CI 9.6-14.3/100,000). ICAs > or = 10 Juvenile Diabetes Foundation units (JDF U) were present in 84.6% of the subjects, but there was a higher prevalence of ICA-negative (ICA-) subjects among those diagnosed during the winter months. The frequencies of the susceptibility allele DQB1*0302 and susceptibility genotype 0302/0201 were 71.8% and 43.5%, respectively. Subjects with 0302 tended to be younger (mean age 8.3 +/- 5.1 years) than those with nonsusceptibility types (mean age 11.8 +/- 4.7 years, P = 0.056). The probability of being ICA positive (ICA+) was not significantly different between subjects with allele 0302 (85.7%) and those without it (81.8%). All seven patients negative for ICA were homozygous for DQB1 nonaspartate-57. There was no clustering of the immunogenetic markers with demographic and clinical characteristics apart from age at diagnosis.

CONCLUSIONS

No direct relationship was observed between DQB1-defined genetic susceptibility and ICA at diagnosis, suggesting that variations at the DQB1 locus are not linked to the expression of this autoimmune marker of beta-cell destruction.

Selenium status of New Zealand infants fed either a selenium supplemented or a standard formula

OBJECTIVE

New Zealand soils are deficient in the essential micronutrient, selenium. New Zealand infants have low selenium levels at birth and experience a further decline if fed cows milk based formula. This study examined the selenium status of infants fed with a new commercially available selenium supplemented formula.

METHODOLOGY

Forty-four newborn infants, whose mothers wished to formula feed, were randomized in an open controlled trial to be fed a commercially available selenium supplemented cows milk formula (containing 17 micrograms Se/L) or an unsupplemented formula (containing 4.6 micrograms Se/L). Cord, 1 and 3 month blood samples were obtained for selenium status (plasma and red cell selenium and glutathione peroxidase) and thyroid function.

RESULTS

Mean plasma selenium and glutathione peroxidase values were significantly higher in supplemented than unsupplemented infants at 1 month (unpaired t-tests; P < 0.0001 and P = 0.001 respectively) and 3 months (P < 0.0001 and P = 0.0005). Analysis within treatment groups between time points (paired t-tests) showed that selenium supplementation prevented the fall in plasma selenium from birth to 1 month seen in unsupplemented infants and was associated with a rise in levels between 1 and 3 months (P = 0.002).

CONCLUSIONS

Supplementing cows milk formula with selenium to replicate the levels found in breast milk is nutritionally sound. Feeding from a few days of age with a formula containing 17 micrograms Se/L in infants with low selenium status at birth is sufficient to cause a rise to 80% of adult levels at 3 months of age.

The relationship of selenium status to respiratory outcome in the very low birth weight infant

OBJECTIVE

To examine the relationship between plasma and erythrocyte selenium and glutathione peroxidase (GPx) levels in premature infants and outcome measures.

DESIGN

Prospective observational longitudinal study.

SETTING

Two regional neonatal intensive care units in the South Island of New Zealand, an area with low soil selenium.

PATIENTS

Seventy-nine infants with birth weights less than 1500 g or gestation less than 32 weeks admitted within 48 hours of birth from November 1992 through November 1993.

MAIN OUTCOME MEASURES

Oxygen requirement at 28 days (chronic lung disease), or 36 weeks postmenstrual age and for all or most of the time from birth (bronchopulmonary dysplasia), total days in oxygen, retinopathy of prematurity, periventricular hemorrhage, or ventricular dilatation.

RESULTS

Initial infant plasma selenium and GPx levels were about two thirds of maternal levels and fell a further 30% in 28 days. In contrast to adults, there was a poor correlation in infant plasma between selenium and GPx at birth and 28 days. Plasma selenium at 28 days was significantly lower in infants with chronic lung disease and bronchopulmonary dysplasia. After controlling for gestational age and age when fully fed orally, 28-day plasma selenium was significantly associated with the log of total days of oxygen requirement, each drop of 0.1 mumol/L in 28-day selenium being associated with a 58% increase in days of oxygen dependency. No significant associations of other parameters of selenium status and respiratory outcome were found, and there were no significant associations of any parameters of selenium status with other outcome measures.

CONCLUSIONS

This study demonstrates for the first time in human infants that low plasma selenium levels are significantly associated with an increased respiratory morbidity. Whether selenium deficiency is etiologically important in determining the respiratory outcome or the result of sickness in the infant should be investigated in a randomized, controlled trial.

Maternal methadone dosage and neonatal withdrawal

The aim of this study was to assess the influence of maternal methadone dosage on the severity of neonatal withdrawal. The charts of 67 drug-abusing mothers and their 70 infants were examined to determine documented patterns of drug usage and the severity of neonatal withdrawal. Of these, 40 women were on a methadone programme. There was a strong relationship between maternal methadone dose at delivery and severity of neonatal withdrawal as assessed by the Neonatal Abstinence Score, length of stay and duration of treatment. Children whose mothers received methadone had mean peak symptom scores greater than 10 whereas the group receiving no methadone had mean scores of less than 4 (p < 0.001). These effects tended to increase with increasing doses of methadone. Length of stay and duration of neonatal treatment showed highly statistically significant increases (p < 0.001) with increasing methadone dose. Maternal methadone dose appears to be strongly related to the severity of neonatal withdrawal.

Oxidation of parenteral lipid emulsion by ambient and phototherapy lights: potential toxicity of routine parenteral feeding

Vitamin E can be a prooxidant in isolated lipoprotein suspensions. Because lipid emulsions used in parenteral nutrition are lipoprotein-like suspensions rich in polyunsaturated fatty acids and vitamin E, we hypothesized that vitamin E may act as a prooxidant in lipid emulsions, as it is in lipoprotein suspensions. We therefore exposed an intravenously administered lipid emulsion (Intralipid) to a single spotlight commonly used in the treatment of neonatal jaundice, and measured the formation of triglyceride hydroperoxides by using high-performance liquid chromatography with postcolumn chemiluminescence detection. Concentrations of these hydroperoxides in different batches of fresh intralipid were usually approximately 10 mumol/L but increased up to 60 times after exposure to phototherapy light for a period of 24 hours, even though significant amounts of vitamin E were present at the end of the exposure. Triglyceride hydroperoxides were formed during phototherapy light exposure whether the intralipid was in plastic tubing used routinely for infusion or in glass containers. Ambient light also caused significant peroxidation of the formula lipids, although to a much lesser extent than observed with phototherapy light. For infants in the neonatal intensive care unit who were receiving intralipid but not phototherapy, solutions being infused at the end of 24 hours contained a mean of 40 mumol/L hydroperoxides. For infants receiving phototherapy, the mean was 97 mumol/L. Phototherapy light-induced formation of triglyceride hydroperoxides was prevented by covering the intralipid with aluminum foil or supplementation with sodium ascorbate before light exposure. We conclude that intralipid is highly susceptible to oxidation and that elevated levels of oxidized lipids can be formed during its clinical use, especially when intralipid infusion is combined with phototherapy. Because lipid hydroperoxides are cytotoxic and can cause adverse effects, inadvertent infusion of rancid intralipid may add to the numerous problems encountered by premature neonates.

Vitamin A and E status in very low birth weight infants: development of an improved parenteral delivery system

Plasma vitamin A and E levels were inadequate in very low birth weight infants receiving a continuous infusion of a parenteral multivitamin preparation, 1.5 ml/kg per day, in dextrose-amino acid solution. A new delivery system using 2 ml/kg per day, infused for 6 hours from the first day of life, avoided loss during infusion and significantly improved plasma vitamin A and E levels during the first 28 days of life in very low birth weight infants.

Insulin loss at the injection site in children with type 1 diabetes mellitus

A simple filter paper technique is described for demonstrating and measuring insulin loss at the injection site in children with type 1 diabetes mellitus. Using this technique in a cohort of 19 children during a 7-day period, measurable fluid was demonstrated at the injection site in 68% of children at least once and was present following 23% of all injections. In nearly 80% of cases the insulin loss probably represented less than 1 unit but could on occasions be 2 units or more or up to 18% of the injected dose. Insulin losses were observed following injections given by children themselves and by parents. There was no significant relationship between insulin dose and insulin loss. Insulin losses at the injection site are frequent and, although usually small in amount, are a potential source of blood glucose variability.

Proteinase-antiproteinase balance in tracheal aspirates from neonates

We wanted to identify the inhibitors of neutrophil elastase, quantify their activities in the upper airways of neonates, and relate these to the presence of active elastase and the likelihood of elastolytic injury occurring due to inhibitory capacity being overwhelmed. Activities of neutrophil elastase and its inhibitors were measured in tracheal aspirates from 17 infants, 10 of whom subsequently developed bronchopulmonary dysplasia. All aspirates contained immunologically detectable alpha 1-proteinase inhibitor (alpha 1-PI), but their inhibitory capacity against neutrophil elastase ranged from being undetectable to being in excess of the amount of alpha 1-PI detected immunologically. When the alpha 1-PI was removed from each of the aspirates, using a specific antibody, from 0-50% of the original activity remained, indicating the presence of another elastase inhibitor. Its properties were consistent with it being the low molecular mass, secretory leucoproteinase inhibitor (SLPI), also known as bronchial antileucoproteinase. The alpha 1-PI was from 0-100% active. Most of the inactive inhibitor was shown by western blotting to be complexed with elastase, with a small amount of cleaved material. There was no evidence of major oxidative inactivation. Free elastase was detected in only three of the aspirates; these had little or no detectable elastase inhibitory capacity, and most of their alpha 1-PI was complexed. Elastase load, comprising the sum of free and complexed elastase, correlated closely with myeloperoxidase activity, a recognized marker of inflammatory activity. Active SLPI levels showed a positive correlation with gestational age (r = 0.66). We conclude that most neutrophil elastase in the upper airways of ventilated infants is complexed.(ABSTRACT TRUNCATED AT 250 WORDS)

Selenium and glutathione peroxidase levels in premature infants in a low selenium community (Christchurch, New Zealand)

By world standards, the selenium status of the adult population of Christchurch, New Zealand is low. To determine the status of infants undergoing neonatal intensive care, plasma and red cell selenium and glutathione peroxidase levels were measured in infants admitted to the regional neonatal unit. Plasma levels in all newborn infants were one third to one half those in adults. Premature infants had levels significantly lower than those in cord blood from term infants, but their levels were not different from those of term infants admitted to the unit. There were no differences between adult and infant red cell levels. The premature infants remaining in the neonatal unit showed dramatic decreases in plasma selenium and glutathione peroxidase with age, with many infants having selenium levels of less than 0.13 mumol/L (10 micrograms/L). Low levels were seen in infants fed orally as well as those on parenteral nutrition. Thus, the low selenium status of New Zealanders is associated with particularly low selenium levels in premature infants. Because these infants have a high risk for oxidative diseases such as bronchopulmonary dysplasia (chronic lung disease) and retinopathy of prematurity, the possibility that these conditions are more serious in the New Zealand population needs to be assessed and consideration given to dietary supplementation.

Chronic lung disease in very low birthweight infants: a prospective population-based study

A prospective population-based study of chronic lung disease among all very low birthweight infants (birthweight 500-1499 g) born in New Zealand in 1986 is reported. Of 413 of these infants admitted to neonatal units, 355 (86%) survived to 28 days. An additional 50 infants were recorded as liveborn but died in the labour ward or other place of birth. Both observed survival and survival adjusted for birthweight, gestation and gender were significantly (P less than 0.05) better in larger centres. Oxygen requirement was assessed at 28 days of age, 36 weeks equivalent gestation and 84 days of age, when 38.6, 23.1 and 13.8% of infants, respectively, were being treated with oxygen. To examine the joint effects of predictor variables on oxygen requirement at each age, the data were analysed using multiple logistic regression methods. At 28 days, lower birthweight, shorter gestation, respiratory distress syndrome (all P less than 0.0001), and gender and hospital principally caring for the infant (both P less than 0.05) were significantly associated with treatment with oxygen. In comparison with other studies, New Zealand appears to have a relatively high rate of chronic lung disease. We speculate that a contributing factor may be the small size of some regional neonatal units.

Temporal variation in incidence of IDDM in Canterbury, New Zealand

OBJECTIVES

To establish the statistical significance of observed variations over the last decade in the incidence of insulin-dependent diabetes mellitus (IDDM) in the 0- to 19-yr-old age-group and to determine whether incidence has increased in Canterbury, New Zealand.

RESEARCH DESIGN AND METHODS

The Canterbury, New Zealand, Diabetes Registry has recorded all incidence cases of diabetes mellitus prospectively since 1982. All IDDM subjects aged 0-19 yr at diagnosis and using insulin are included in the study. Ascertainment is believed to be 100%. Prevalence was recorded at 1 January 1982 and 1 January 1990. Annual incidence for 1982-1990 was determined using age and sex cross-sectional census population denominators. The statistical significance of temporal, age, sex, and seasonal variations in incidence rates was ascertained by Poisson regression models (GLIM statistical software).

RESULTS

Prevalence on 1 January 1990 was 115/100,000. Incidence rates during the 9 yr were periodic, with two major peaks--one in the early 1980s, the other in 1989 continuing into 1990. The temporal variation (P less than 0.02) was not age or sex specific. Incidence rates for boys were three- to fourfold higher during peak versus trough years, with a peak level of 20.7/100,000 in 1990. For girls, there was less variation, with a peak rate of 21.6/100,000 in 1990. There has been no significant increase in IDDM incidence over time. The mean rate of incidence across all age-groups for 1982-1990 was 12.7/100,000 person-yr. A significant seasonal association to the onset of IDDM was found only in boys, with incidence rates being significantly higher in winter than in summer (P less than 0.01).

CONCLUSIONS

IDDM in Canterbury, New Zealand, presents in cycles of incidence peaks and troughs, each spanning 2-3 yr.

Selenium status of Christchurch infants and the effect of diet

OBJECT

New Zealanders, because of a soil deficiency, have a low intake of selenium. To determine the impact of this on the infant population in Christchurch.

METHODS

we have measured red cell and plasma selenium and the selenoenzyme, glutathione peroxidase, in 70 infants less than 12 months old and related these to age and diet.

RESULTS

the infant population as a whole had mean plasma levels of selenium and glutathione peroxidase of 33 micrograms/L and 97 U/L compared with adult values of 74 micrograms/L and 150 U/L. Infant red cell levels of 0.30 mu g selenium and 9.0 U glutathione peroxidase per g haemoglobin were similar to those in adults. The selenium status of most breast fed infants after birth remained similar to that of cord blood. Mean plasma selenium and glutathione peroxidase levels in formula fed infants were about half those of breast fed infants, and their red cell selenium was also significantly lower. These did not increase until solids were introduced into the diet. The status of the infants reflected their diet, with the concentration of selenium in formulae being 3.9-5.2 micrograms/mL compared with a mean of 13.4 micrograms/mL in breast milk.

CONCLUSIONS

since infants in more replete selenium areas show a gradual rise in blood selenium parameters after birth, this study suggests that formula fed and some breast fed infants in Christchurch receive an inadequate selenium intake. Consideration should be given to supplementing infant formulae and perhaps also the diet of pregnant and/or breast feeding mothers.

Retinopathy of prematurity: risk factors in a prospective population-based study

A prospective study of risk factors for retinopathy of prematurity (ROP) in all very low birthweight (less than 1500 g) infants born in New Zealand in 1986 is reported. Of 413 liveborn infants admitted to neonatal units, 338 (81.2%) survived to be discharged home. Of surviving infants, 313 (93%) were examined by indirect ophthalmoscopy, as were eight infants who died before discharge. Sixty-nine infants (21.5% of 321) had acute retinopathy. On multiple logistic regression analysis, three variables made statistically significant independent contributions to the risk of any acute retinopathy; gestational age (P less than 0.0001), principal hospital caring for the infant (P less than 0.01) and treatment with indomethacin (P less than 0.01). Only two variables, gestational age (P less than 0.0001) and hospital (P less than 0.01), made significant contributions to the risk of stage 2 or more ROP. For both categories of ROP, timing of the examination also had a statistically significant effect (P less than 0.001). After adjustment for other significant predictor variables, it was estimated that approximately 70% of infants of less than 26 weeks' gestation were at risk of ROP and nearly 50% of stage 2 or more ROP, in comparison with less than 2% of infants of 32 weeks' gestation or more; infants treated with indomethacin were over 1.5 times more likely to have ROP than infants not so treated. Failure to enforce uniform timing of examination was the most serious defect in the study; only 205 (64%) of the 321 infants were examined at the recommended time. However, reanalysis of the model with information limited to these 205 infants yielded similar risk factors. The incidence of ROP, both observed (P less than 0.05) and adjusted for other significant variables in the regression model (P less than 0.01) was lowest in the two largest level III hospitals. These hospitals also had the best survival rates after adjustment for birthweight, gestation and gender (P less than 0.01). We speculate that the larger level III units obtained better results because their size and experience enabled them to provide a better overall quality of care.