Contemporary Incidence and Prevalence of Rheumatic Fever and Rheumatic Heart Disease in Australia Using Linked Data: The Case for Policy Change.

Background In 2018, the World Health Organization prioritized control of acute rheumatic fever (ARF) and rheumatic heart disease (RHD), including disease surveillance. We developed strategies for estimating contemporary ARF/RHD incidence and prevalence in Australia (2015-2017) by age group, sex, and region for Indigenous and non-Indigenous Australians based on innovative, direct methods. Methods and Results This population-based study used linked administrative data from 5 Australian jurisdictions. A cohort of ARF (age <45 years) and RHD cases (<55 years) were sourced from jurisdictional ARF/RHD registers, surgical registries, and inpatient data. We developed robust methods for epidemiologic case ascertainment for ARF/RHD. We calculated age-specific and age-standardized incidence and prevalence. Age-standardized rate and prevalence ratios compared disease burden between demographic subgroups. Of 1425 ARF episodes, 72.1% were first-ever, 88.8% in Indigenous people and 78.6% were aged <25 years. The age-standardized ARF first-ever rates were 71.9 and 0.60/100 000 for Indigenous and non-Indigenous populations, respectively (age-standardized rate ratio=124.1; 95% CI, 105.2-146.3). The 2017 Global Burden of Disease RHD prevalent counts for Australia (<55 years) underestimate the burden (1518 versus 6156 Australia-wide extrapolated from our study). The Indigenous age-standardized RHD prevalence (666.3/100 000) was 61.4 times higher (95% CI, 59.3-63.5) than non-Indigenous (10.9/100 000). Female RHD prevalence was double that in males. Regions in northern Australia had the highest rates. Conclusions This study provides the most accurate estimates to date of Australian ARF and RHD rates. The high Indigenous burden necessitates urgent government action. Findings suggest RHD may be underestimated in many high-resource settings. The linked data methods outlined here have potential for global applicability.

Geographical disparities in emergency department presentations for acute respiratory infections and risk factors for presenting: a population-based cohort study of Western Australian children.

INTRODUCTION: Studies examining acute respiratory infections (ARIs) in emergency department (EDs), particularly in rural and remote areas, are rare. This study aimed to examine the burden of ARIs among Aboriginal and non-Aboriginal children presenting to Western Australian (WA) EDs from 2002 to 2012. METHOD: Using a retrospective population-based cohort study linking ED records to birth and perinatal records, we examined presentation rates for metropolitan, rural and remote Aboriginal and non-Aboriginal children from 469 589 births. We used ED diagnosis information to categorise presentations into ARI groups and calculated age-specific rates. Negative binomial regression was used to investigate association between risk factors and frequency of ARI presentation. RESULTS: Overall, 26% of presentations were for ARIs. For Aboriginal children, the highest rates were for those aged <12 months in the Great Southern (1233 per 1000 child-years) and Pilbara regions (1088 per 1000 child-years). Rates for non-Aboriginal children were highest in children <12 months in the Southwest and Kimberley (400 and 375 per 1000 child-years, respectively). Presentation rates for ARI in children from rural and remote WA significantly increased over time in all age groups <5 years. Risk factors for children presenting to ED with ARI were: male, prematurity, caesarean delivery and residence in the Kimberley region and lower socio-economic areas. CONCLUSION: One in four ED presentations in WA children are for ARIs, representing a significant out-of-hospital burden with some evidence of geographical disparity. Planned linkages with hospital discharge and laboratory detection data will aid in assessing the sensitivity and specificity of ARI diagnoses in ED.

A Population-Based Matched-Sibling Analysis Estimating the Associations Between First Interpregnancy Interval and Birth Outcomes.

The association between a single interpregnancy interval (IPI) and birth outcomes has not yet been explored using matched methods. We modeled the odds of preterm birth, being small for gestational age, and having low birth weight in a second, live-born infant in a cohort of 192,041 sibling pairs born in Western Australia between 1980 and 2010. The association between IPI and birth outcomes was estimated from the interaction between birth order and IPI (with 18-23 months as the reference category), using conditional logistic regression. Matched analysis showed the odds of preterm birth were higher for siblings born following an IPI of <6 months (adjusted interaction odds ratio = 1.22, 95% confidence interval: 1.06, 1.38) compared with those born after an IPI of 18-23 months. There were no significant differences for IPIs of <6 months for other outcomes (small for gestational age or low birth weight). This is the first study to use matched analyses to investigate the association between a single IPI on birth outcomes. IPIs of <6 months were associated with increased odds of preterm birth in second-born infants, although the association is likely smaller than previously estimated by unmatched studies.

Assessment of on-time vaccination coverage in population subgroups: A record linkage cohort study.

Reported infant vaccination coverage at age 12 months in Australia is >90%. On-time coverage of the 2-4-6 month schedule and coverage in specific populations is rarely reported. We conducted a population-based cohort study of 1.9 million Australian births, 1996-2012, combining individual birth and perinatal records with immunisation records through probabilistic linkage. We assessed on-time coverage across 13 demographic and perinatal characteristics of diphtheria-tetanus-pertussis vaccines (DTP) defined as vaccination 14 days prior to the scheduled due date, to 30 days afterwards. On-time DTP vaccination coverage in non-Aboriginal infants was 88.1% for the 2-month dose, 82.0% for 4-month dose, and 76.7% for 6-month dose; 3-dose coverage was 91.3% when assessed at 12 months. On-time DTP coverage for Aboriginal infants was 77.0%, 66.5%, and 61.0% for the 2-4-6 month dose; 3-dose coverage at 12 months was 79.3%. Appreciable differences in on-time coverage were observed across population subgroups. On-time coverage in non-Aboriginal infants born to mothers with ≥3 previous pregnancies was 62.5% for the 6-month dose (47.9% for Aboriginal infants); up to 23.5 percentage points lower than for first-borns. Infants born to mothers who smoked during pregnancy had coverage 8.7-10.3 percentage points lower than infants born to non-smoking mothers for the 4- and 6-month dose. A linear relationship was apparent between increasing socio-economic disadvantage and decreasing on-time coverage. On-time coverage of the 2-4-6 month schedule is only 50-60% across specific population subgroups representing a significant avoidable public health risk. Aboriginal infants, multiparous mothers, and those who are socio-economically disadvantaged are key groups most likely to benefit from targeted programs addressing vaccine timeliness.

Mesothelioma in Australia: a review.

The incidence of malignant mesothelioma in Australia is among the highest in the world as a result of widespread use of asbestos by industry and in construction throughout the 20th century. The risk of developing malignant mesothelioma after asbestos exposure is dose-related; a transient, low dose exposure confers a correspondingly very low risk of disease. Malignant mesothelioma is a heterogeneous disease, partly explaining the limited role of biomarkers in screening and diagnosis. The prognosis remains poor, and early advice on medico-legal compensation and a collaborative team approach to managing malignant mesothelioma are both essential. Chemotherapy can have a modest treatment effect in some people. New therapies, such as immunotherapy, do not yet have a defined role in the treatment of malignant mesothelioma. As treatment options for malignant mesothelioma are limited and no cure is available, there is no established role for early detection or screening of at risk populations. A multidisciplinary approach to caring for patients with malignant mesothelioma and their carers is vital.

Record linkage study of the pathogen-specific burden of respiratory viruses in children.

BACKGROUND: Reliance on hospital discharge diagnosis codes alone will likely underestimate the burden of respiratory viruses. OBJECTIVES: To describe the epidemiology of respiratory viruses more accurately, we used record linkage to examine data relating to all children hospitalized in Western Australia between 2000 and 2012. PATIENTS/METHODS: We extracted hospital, infectious disease notification and laboratory data of a cohort of children born in Western Australia between 1996 and 2012. Laboratory records of respiratory specimens collected within 48 hours of admission were linked to hospitalization records. We calculated the frequency and rates of virus detection. To identify groups where under-ascertainment for respiratory viruses was greatest, we used logistic regression to determine factors associated with failure to test. RESULTS AND CONCLUSIONS: Nine percentage of 484 992 admissions linked to a laboratory record for respiratory virus testing. While 62% (n = 26 893) of laboratory-confirmed admissions received respiratory infection diagnosis codes, 38% (n = 16 734) had other diagnoses, notably viral infection of unspecified sites. Of those tested, incidence rates were highest for respiratory syncytial virus (247 per 100 000 child-years) followed by parainfluenza (63 per 100 000 child-years). Admissions among older children and those without a respiratory diagnosis were associated with failure to test for respiratory viruses. Linked data can significantly enhance diagnostic codes when estimating the true burden of disease. In contrast to current emphasis on influenza, respiratory syncytial virus and parainfluenza were the most common viral pathogens among hospitalized children. By characterizing those failing to be tested, we can begin to quantify the under-ascertainment of respiratory viruses.

Using record linkage to validate notification and laboratory data for a more accurate assessment of notifiable infectious diseases.

BACKGROUND: Infectious disease burden is commonly assessed using notification data. Using retrospective record linkage in Western Australia, we described how well notification data captures laboratory detections of influenza, pertussis and invasive pneumococcal disease (IPD). METHODS: We linked data from the Western Australian Notifiable Infectious Diseases Database (WANIDD) and the PathWest Laboratory Database (PathWest) pertaining to the Triple I birth cohort, born in Western Australia in 1996-2012. These were combined to calculate the number of unique cases captured in each dataset alone or in both datasets. To assess the impact of under-ascertainment, we compared incidence rates calculated using WANIDD data alone and using combined data. RESULTS: Overall, there were 5550 influenza, 513 IPD (2001-2012) and 4434 pertussis cases (2000-2012). Approximately 2% of pertussis and IPD cases and 7% of influenza cases were solely recorded in PathWest. Notification of influenza and pertussis cases to WANIDD improved over time. Overall incidence rates of influenza in children aged <5 years using both datasets was 10% higher than using WANIDD data alone (IRR = 1.1, 95% CI = 1.1-1.2). CONCLUSIONS: This is the first time WANIDD data have been validated against routinely collected laboratory data. We anticipated all cases would be captured in WANIDD but found additional laboratory-confirmed cases that were not notified. Studies investigating pathogen-specific infectious disease would benefit from using multiple data sources.

Establishing a process for conducting cross-jurisdictional record linkage in Australia.

OBJECTIVE: To describe the realities of conducting a cross-jurisdictional data linkage project involving state and Australian Government-based data collections to inform future national data linkage programs of work. METHODS: We outline the processes involved in conducting a Proof of Concept data linkage project including the implementation of national data integration principles, data custodian and ethical approval requirements, and establishment of data flows. RESULTS: The approval process involved nine approval and regulatory bodies and took more than two years. Data will be linked across 12 datasets involving three data linkage centres. A framework was established to allow data to flow between these centres while maintaining the separation principle that serves to protect the privacy of the individual. CONCLUSIONS: This will be the first project to link child immunisation records from an Australian Government dataset to other administrative health datasets for a population cohort covering 2 million births in two Australian states. IMPLICATIONS: Although the project experienced some delays, positive outcomes were realised, primarily the development of strong collaborations across key stakeholder groups including community engagement. We have identified several recommendations and enhancements to this now established framework to further streamline the process for data linkage studies involving Australian Government data.

Plasma micronutrient levels and telomere length in children.

OBJECTIVE: Telomeres are long hexamer (TTAGGG) repeats at the ends of chromosomes, and contribute to maintenance of chromosomal stability. Telomere shortening has been linked to cancers and other chronic diseases in adults, although evidence for causal associations is limited. The aim of this study was to determine whether nutritional factors are associated with telomere length (TL) in children. METHODS: We conducted a cross-sectional study of nutritional factors and TL in 437 children between 2009 and 2011. Healthy children ages 3, 6, and 9 y provided blood samples, and their parents completed a food frequency questionnaire and a telephone interview about relevant environmental exposures. TL and blood micronutrient levels were measured, and genotyping at 10 loci was undertaken. Associations between the micronutrients and other variables were assessed using linear regression. RESULTS: No significant main or interactive effects of age or sex were seen. After adjustment for age, sex, parental education, and month of blood collection, TL was inversely associated with plasma zinc, and shorter in children with the homozygous mutant genotype of the RFC G80A (rs1051266) polymorphism. CONCLUSIONS: To the best of our knowledge, this is the first investigation of the association between telomere length and micronutrients in healthy children. The reason for the inverse relationship of TL with zinc is unknown but could be the result of an increase in telomere sequence deletions caused by labile zinc induction of oxidative stress. These findings should be corroborated in other studies before nutritional recommendations might be considered.

Assessment of early bronchiectasis in young children with cystic fibrosis is dependent on lung volume.

OBJECTIVE: The aim of this study was to determine whether assessment of early CT scan-detected bronchiectasis in young children with cystic fibrosis (CF) depends on lung volume. METHODS: This study, approved by the hospital ethics committee, included 40 young children with CF from a newborn screened population contributing paired volume-controlled inspiratory and expiratory volumetric chest CT scans acquired under general anesthesia while clinically stable. Bronchiectasis was assessed with a semiquantitative CT scan score in inspiration and expiration, and the sensitivity of the expiratory CT scan to detect bronchiectasis was compared with the inspiratory CT scan by sensitivity and intraclass correlation coefficient analysis and Bland-Altman plots. Matched inspiratory and expiratory airway-vessel measurements were obtained in a subset of 10 children, and the relationship between lung volume and airway:vessel ratio after adjusting for age and vessel size was examined with the use of a linear regression model with generalized estimating equations. The number of visible airways in inspiration and expiration was compared in all 40 children by Wilcoxon signed rank test. RESULTS: Expiratory scans had poor sensitivity (0.46) to detect bronchiectasis, underestimating disease extent (P < .001). Airway:vessel ratios were consistently higher in inspiration, independent of age and vessel size (P < .001), with significantly more airways visible in inspiration than in expiration, independent of age (median, 71 vs 28, respectively; P < .001). CONCLUSIONS: In young children with CF, radiologic assessment of early bronchiectasis with chest CT scan depends on lung volume; thus, expiratory scans may not be appropriate for evaluating bronchiectasis in this population. Lung volume during CT image acquisition should be standardized to evaluate airway dimensions in young children.

Can linked emergency department data help assess the out-of-hospital burden of acute lower respiratory infections? A population-based cohort study.

BACKGROUND: There is a lack of data on the out-of-hospital burden of acute lower respiratory infections (ALRI) in developed countries. Administrative datasets from emergency departments (ED) may assist in addressing this. METHODS: We undertook a retrospective population-based study of ED presentations for respiratory-related reasons linked to birth data from 245,249 singleton live births in Western Australia. ED presentation rates <9 years of age were calculated for different diagnoses and predictors of ED presentation <5 years were assessed by multiple logistic regression. RESULTS: ED data from metropolitan WA, representing 178,810 births were available for analysis. From 35,136 presentations, 18,582 (52.9%) had an International Classification of Diseases (ICD) code for ALRI and 434 had a symptom code directly relating to an ALRI ICD code. A further 9600 presentations had a non-specific diagnosis. From the combined 19,016 ALRI presentations, the highest rates were in non-Aboriginal children aged 6-11 months (81.1/1000 child-years) and Aboriginal children aged 1-5 months (314.8/1000). Croup and bronchiolitis accounted for the majority of ALRI ED presentations. Of Aboriginal births, 14.2% presented at least once to ED before age 5 years compared to 6.5% of non-Aboriginal births. Male sex and maternal age <20 years for Aboriginal children and 20-29 years for non-Aboriginal children were the strongest predictors of presentation to ED with ALRI. CONCLUSIONS: ED data can give an insight into the out-of-hospital burden of ALRI. Presentation rates to ED for ALRI were high, but are minimum estimates due to current limitations of the ED datasets. Recommendations for improvement of these data are provided. Despite these limitations, ALRI, in particular bronchiolitis and croup are important causes of presentation to paediatric EDs.

Participation in population-based case-control studies: does the observed decline vary by socio-economic status?

An Australian study of childhood leukaemia (Aus-ALL) previously reported that control participation was positively associated with socio-economic status (SES). A similar study of childhood brain tumours (Aus-CBT) was carried out 4 years later, and this paper compares control participation and its relationship with SES in the two studies. To assess the representativeness of controls in terms of SES, the addresses of controls were linked to Australian Bureau of Statistics Census 2006 Collection Districts (CDs), and hence to area-based indices of SES. Independent sample t-tests and chi-squared tests were used to compare the SES indices of CDs where Aus-CBT controls lived with those where Aus-ALL controls lived and with those of all CDs where Australian families lived. The overall percentage of eligible families who agreed to participate was lower in Aus-CBT (53.9%) than in Aus-ALL (70.3%). Control families in both studies were of higher SES than the general population, while the distribution of SES among recruited controls was similar in both studies. These findings provide some reassurance that the observed decline in research participation over time may not be associated with an increasingly unrepresentative participant population.

Increasing incidence of malignant mesothelioma after exposure to asbestos during home maintenance and renovation.

OBJECTIVE: To determine trends in incidence of malignant mesothelioma (MM) caused by exposure to asbestos during home maintenance and renovation. DESIGN, SETTING AND PARTICIPANTS: Using the Western Australian Mesothelioma Register, we reviewed all cases of MM diagnosed in WA from 1960 to the end of 2008, and determined the primary source of exposure to asbestos. Categories of exposure were collapsed into seven groups: asbestos miners and millers from Wittenoom; all other asbestos workers; residents from Wittenoom; home maintenance/renovators; other people exposed but not through their occupation; and people with unknown asbestos exposure; or no known asbestos exposure. Latency periods and age at diagnosis for each group were calculated and compared. RESULTS: In WA, 1631 people (1408 men, 223 women) were diagnosed with MM between 1960 and 2008. Since 1981, there have been 87 cases (55 in men) of MM attributed to asbestos exposure during home maintenance and renovation, and an increasing trend in such cases, in both men and women. In the last 4 years of the study (2005-2008), home renovators accounted for 8.4% of all men and 35.7% of all women diagnosed with MM. After controlling for sex and both year and age at diagnosis, the latency period for people exposed to asbestos during home renovation was significantly shorter than that for all other exposure groups, but the shorter follow-up and difficulty recalling when exposure first occurred in this group may partly explain this. CONCLUSIONS: MM after exposure to asbestos during home renovation is an increasing problem in WA, and these cases seem to have a shorter latency period than other types of exposure. MM cases related to renovation will probably continue to increase because of the many homes that have contained, and still contain, asbestos building products.

Trends in infant/child mortality and life expectancy in Indigenous populations in Yunnan Province, China.

OBJECTIVE: The 2000 Census in China registered 55 groups of Indigenous population, including 104.49 million people, making up 8.1% of China's total population. Yunnan Province, located in Southwest China, is the only province where all 55 Indigenous nationalities are represented (14.15 million), making up 33.4% of Yunnan's total population. This study aimed to examine trends in infant and child mortality and life expectancy at birth of the 22 largest Indigenous nationalities and compared these trends with those of the majority Han Chinese in Yunnan and China as a whole. METHODS: Data sources of mortality and socioeconomic status came from the population censuses of China (1953, 1964, 1982, 1990, and 2000) and Yunnan (1990-2000) and from the Provincial Health Department (1990, 1995, 1996 and 2000). Weighted linear regression analysis was used to examine the associations between infant/child mortality and life expectancy at birth, socioeconomic indicators and the use of preventive health services. RESULTS: In 2000, the infant mortality rate was 26.90 for China and 53.64 for Han Chinese in Yunnan per 1,000 live birth versus 77.75 for the 22 largest minority nationalities in Yunnan, despite improvements in health status indicators since 1990. The inequalities in life expectancy at birth between China as a whole and some minority nationalities remained striking in 2000 (57.18 versus 71.40). Literacy, prenatal examination, hospital deliveries, economic development were important predictors of these health indicators. IMPLICATIONS: Efforts to continue to improve these intermediate proximate determinants and to target the most disadvantaged Indigenous groups are likely to further reduce health disparities between the Chinese and Indigenous populations.

Occurrence and management of acute respiratory illnesses in early childhood.

AIM: Acute respiratory illnesses (ARI) impose massive economic burden on health services. The growing costs, limited benefits of pharmacotherapeutic agents, and alarming rise in antibiotic resistance poses a major health challenge. Analysis of the nature and burden of ARI through well-designed epidemiologic studies will help in the development of a uniform public health approach to identify methods to reduce disease transmission and maximise prevention strategies. The aim of this study was to analyse the nature and magnitude of the burden of ARI encountered by a cohort of children in the first 5 years of life. METHODS: This community-based prospective study of ARI followed a cohort of children from birth until 5 years of age. Information on all episodes of ARI encountered, and their management, was collected through daily symptom diary and fortnightly telephone calls. RESULTS: Four episodes of ARI/year were reported in the first 2 years and 2-3 episodes/year between 2 and 5 years. The majority were upper respiratory infections. 53% had at least one lower respiratory infection in the first year. For the majority, symptoms lasted 1-2 weeks. 53% were treated with antitussives or cough mixtures, 44% with paracetamol and 23% with antibiotics. A total of 46% of the episodes presented to a family physician, with younger children and those with lower respiratory infection more likely to seek attention. CONCLUSION: ARI are common in childhood and although symptoms may last for 4 weeks, the majority resolve spontaneously. Use of medication does not appear to significantly alter the course or duration of symptoms of ARI.

Assessment of the potential effect of incremental increases in folic acid intake on neural tube defects in Australia and New Zealand.

OBJECTIVE: To estimate the number of neural tube defects that could be prevented in Australia and New Zealand by increasing levels of folic acid intake. METHODS: Available data on prevalence of neural tube defects in Australia and New Zealand, folic acid supplement use and serum folate were used in a published model to estimate the number of neural tube defects that could be prevented in Australia and New Zealand for increments of folic acid intake from 0.1 mg daily to 1 mg daily. RESULTS: An increase of 0.2 mg folic acid per day was estimated to result in the prevention of 49 (95% CI 27-84) neural tube defects per year in Australia and 11 (95% CI 6-18) in New Zealand. A separate estimation for Indigenous Australians found that 0.2 mg of folic acid daily could prevent 7 (95% CI 4-11) neural tube defects in Indigenous infants per year. CONCLUSIONS: These data should be useful in considering primary preventive strategies for neural tube defects, including the possible introduction of mandatory fortification of food with folic acid. The estimates are imprecise because of limitations in the data used in the model. IMPLICATIONS: More representative and precise data on neural tube defects, serum folate levels and use of folic acid supplements from all Australian States and New Zealand are needed to refine the output from the model and to provide a baseline assessment of folate status against which to measure the effects of any future interventions to prevent neural tube defects.

Patterns, trends, and increasing disparities in mortality for Aboriginal and non-Aboriginal infants born in Western Australia, 1980-2001: population database study.

BACKGROUND: Since there are known disparities between Aboriginal and non-Aboriginal populations in Australia, trends in infant mortality rates can be used to assess the effectiveness of programmes designed to improve the health of Aboriginal populations. We have examined mortality rates in these populations in Western Australia. METHODS: We used the most comprehensive and valid total population data available for an Australian state to determine all-cause and cause-specific mortality for Aboriginal and non-Aboriginal infants born in Western Australia from 1980 to 2001. FINDINGS: Overall, infant mortality rates fell in both populations, but less so in Aboriginal (from 25.0 in 1980-84 to 16.1 in 1998-2001) than in non-Aboriginal infants (from 8.4 in 1980-84 to 3.7 in 1998-2001) such that disparities between the two groups increased for all major causes of infant death. The relative risk for Aboriginal compared with non-Aboriginal infants rose from 3.0 (95% CI 2.5-3.6) to 4.4 (3.5-5.5), and there were significantly more potentially preventable deaths, such as those caused by infections (5.9 per 1000 livebirths vs 0.7 per 1000 livebirths, RR 8.5, 95% CI 7.1-10.2). Additionally, for Aboriginal infants, postneonatal mortality rates were higher than neonatal mortality rates (11.2 per 1000 livebirths vs 9.7 per 1000 livebirths), trend analyses showed that previous reductions in deaths due to preterm birth (4.3 per 1000 livebirths--1.4 per 1000 livebirths from 1980-97) were not sustained in the most recent years studied (3.5 per 1000 livebirths), and rates of sudden infant death syndrome did not fall significantly (4.9 per 1000 livebirths vs 4.7 per 1000 livebirths). INTERPRETATION: These increasing disparities between Aboriginal and non-Aboriginal infants, especially in remote areas, demand immediate action in partnership with Aboriginal communities, focusing on both access to primary health care and better living conditions. Implementation and assessment of policies to reduce the continuing social and economic disadvantage faced by Aboriginal families are vital.

Australian Twin Registry: a nationally funded resource for medical and scientific research, incorporating match and WATCH.

The Australian Twin Registry (ATR) has, since the late 1970s, enrolled more than 30,000 pairs of all zygosity types and ages willing to consider participation in approved research studies. Its core functions are the recruitment to, and maintenance of, an up-to-date database containing contact details and baseline information, and the management of fair and equitable access so as to enhance medical and scientific research. The ATR has facilitated more than 430 studies producing 525 peer-reviewed publications using a variety of designs including classic biometrical twin and twin family studies, co-twin control studies, intervention studies, longitudinal studies, and studies of issues relevant specifically to twins. The ATR is supported for 2004 to 2009 by an Australian National Health and Medical Research Council (NHMRC) Enabling Grant, a new form of funding which recognizes the importance of long-term support for shared national resources. New initiatives include: integration with the Western Australian Twin Child Health (WATCH) cohort and the new Western Australian Twin Registry (WATR); foundation of a cohort of mothers and their twin children recruited from the time of diagnosis of the multiple gestation (match); a national Twins Festival run in collaboration with the Australian Multiple Birth Association (AMBA); promotion of the ATR at medical conferences; and fostering an active network of researchers from a range of disciplines and providing financial support for new researchers to attend international twin research workshops. Consistent with its mission statement, the long-term goal of the ATR is to make twin studies a standard component of medical and scientific research.

Optimal fetal growth for the Caucasian singleton and assessment of appropriateness of fetal growth: an analysis of a total population perinatal database.

BACKGROUND: The appropriateness of an individual's intra uterine growth is now considered an important determinant of both short and long term outcomes, yet currently used measures have several shortcomings. This study demonstrates a method of assessing appropriateness of intrauterine growth based on the estimation of each individual's optimal newborn dimensions from routinely available perinatal data. Appropriateness of growth can then be inferred from the ratio of the value of the observed dimension to that of the optimal dimension. METHODS: Fractional polynomial regression models including terms for non-pathological determinants of fetal size (gestational duration, fetal gender and maternal height, age and parity) were used to predict birth weight, birth length and head circumference from a population without any major risk factors for sub-optimal intra-uterine growth. This population was selected from a total population of all singleton, Caucasian births in Western Australia 1998-2002. Births were excluded if the pregnancy was exposed to factors known to influence fetal growth pathologically. The values predicted by these models were treated as the optimal values, given infant gender, gestational age, maternal height, parity, and age. RESULTS: The selected sample (N = 62,746) comprised 60.5% of the total Caucasian singleton birth cohort. Equations are presented that predict optimal birth weight, birth length and head circumference given gestational duration, fetal gender, maternal height, age and parity. The best fitting models explained 40.5% of variance for birth weight, 32.2% for birth length, and 25.2% for head circumference at birth. CONCLUSION: Proportion of optimal birth weight (length or head circumference) provides a method of assessing appropriateness of intrauterine growth that is less dependent on the health of the reference population or the quality of their morphometric data than is percentile position on a birth weight distribution.