Validation studies from the Western Australian Congenital Malformations Registry

School performance for children with cleft lip and palate: a population-based study

BACKGROUND

Educational attainment is important in shaping young people's life prospects. To investigate whether being born with orofacial cleft (OFC) affects school performance, we compared school test results between children born with and without OFC.

METHODS

Using record-linked datasets, we conducted a population-based cohort study of children liveborn in Western Australia 1980-2010 with a diagnosis of OFC on the Register of Developmental Anomalies, and a random sample of 6603 children born without OFC. We compared odds ratios for meeting national minimum standards in five domains (reading, numeracy, writing, spelling, grammar and punctuation), and adjusted OR (aOR) for children with cleft lip only (CLO), cleft lip and palate (CL + P) and cleft palate only (CPO) for each domain.

RESULTS

Results from two testing programs (WALNA and NAPLAN) were available for 3238 (89%) children expected to participate. Most met the national minimum standards. Compared with children without OFC, children with CPO were less likely to meet minimum standards for NAPLAN reading (aOR 0.57 [95%CI 0.34, 0.96]) grammar and punctuation (aOR 0.49 [95%CI 0.32, 0.76]), WALNA writing (aOR 0.66 [95%CI 0.47, 0.92]), and WALNA and NAPLAN numeracy (aOR 0.64 [95%CI 0.43, 0.95] and aOR 0.47 [95%CI 0.28, 0.82]), respectively. Children with CL + P had significantly lower odds for reaching the spelling standard in NAPLAN tests (aOR 0.52 [95%CI 0.29, 0.94]). Children with CLO had similar odds for reaching all minimum standards.

CONCLUSION

Children born with OFC, particularly children with CPO, should be monitored to identify learning difficulties early, to enable intervention to maximize school attainment.

Hospitalisations up to adulthood for children born with orofacial clefts

AIM

The aim of this study was to compare hospital admissions from infancy to adulthood, between children born with orofacial clefts (OFC) and those without OFC.

METHODS

The method used was a cohort study using record-linked administrative datasets. Participants included all children liveborn in Western Australia (WA) between 1980 and 2010 diagnosed with OFC, who were frequency matched by year of birth to randomly selected liveborn children without OFC. We calculated rate ratios (RR) of hospital admission, number and reason of admissions, cumulative length of stay, for each cleft type (cleft lip only (CLO), cleft lip and palate (CL+P), cleft palate only (CPO), no OFC) and by age period (infancy, pre-school, primary and high school ages, and early adulthood).

RESULTS

Overall, 1396 children were diagnosed with an OFC and compared with 6566 children without OFC. Individuals born with OFC were up to three times more likely to be admitted to hospital, had more admissions and longer cumulative length of stay in all age periods. Children with OFC were also more likely to be admitted for ear and digestive system conditions (RR up to 30 and six times higher, respectively). Children with CL+P and CPO were more likely to be admitted for respiratory conditions (RR 1.3-2.0) and children with CPO were six times more likely to be admitted for care for other congenital anomalies.

CONCLUSIONS

Throughout childhood, individuals born with OFC were more likely to be admitted, and had more hospitalisations than those without OFC. Children born with CL+P or CPO had a higher hospitalisation burden than children born with CLO.

Long-term survival for infants born with orofacial clefts in Western Australia

BACKGROUND

Only two population-based studies have reported survival beyond 15 years for individuals with orofacial clefts (OFC), and only for individuals with isolated OFC. Compared with the general population, long-term survival was similar for individuals with cleft lip only, and lower for individuals with cleft palate only. Results for those born with isolated cleft lip and cleft palate were inconsistent.

METHODS

Using linked population-based health data, including a congenital anomaly register with active surveillance and diagnoses up to 6 years, we compared survival at 1, 5, and 20 years for infants born 1980 to 2010 with, and without OFC.

RESULTS

Of the 8112 live born infants in the cohort, 186 died before 20 years; most (81%) died during infancy. Compared with infants without OFC, infants born with all types of isolated OFC ± additional minor anomalies had similar infant survival (around 99%), but we found lower survival for infants with all cleft types and an additional major anomaly (66-84%). From 1 to 5 years, only infants with cleft palate only and an additional major anomaly had lower survival (97%) compared with children without OFC (99.9%). From 5 to 20 years, children with all cleft types, with or without additional major anomalies had similar survival to children without OFC (98-100%).

CONCLUSION

Parents with a child diagnosed with an OFC ± additional minor anomalies only can be reassured that the OFC does not influence survival rates in infancy, or long-term. Infant survival was lower only for children with OFC and additional major anomalies.

Birth defects in children with autism spectrum disorders: a population-based, nested case-control study

The causes of autism spectrum disorders (ASDs) are unknown, although genetic and environmental influences have been implicated. Previous studies have suggested an association with birth defects, but most investigators have not addressed associations with specific diagnostic categories of ASD. In this study, the authors investigated the associations between birth defects and autism, Asperger syndrome, and pervasive developmental disorder not otherwise specified. Using Western Australian population-based linked data, the authors compared all children with ASD born in Western Australia during 1980-1995 (n = 465) with their siblings (n = 481) and population controls (n = 1,313) in a nested case-control study. The prevalence of birth defects was significantly higher in ASD cases than in population controls; this difference remained significant after adjustment for confounding factors. Odds ratios for birth defects were similar for autism (odds ratio (OR) = 2.0, 95% confidence interval (CI): 1.3, 3.0) and pervasive developmental disorder not otherwise specified (OR = 2.2, 95% CI: 1.1, 4.3) but not for Asperger syndrome (OR = 0.5, 95% CI: 0.1, 1.9). Birth defects in case siblings were not significantly different from those in cases and population controls. The association between birth defects and ASD may be due to underlying genetic and/or environmental factors common to both ASD and birth defects, or birth defects may predispose a child to ASD.

Is cerebral palsy associated with birth defects other than cerebral defects?

The objective of the study was to identify the origin (s) of the association between cerebral palsy (CP) and birth defects in the absence of cerebral birth defects. Data from the 1980 to 1994 Western Australian birth cohorts (355 659 neonatal survivors) were linked to the Cerebral Palsy Register (941 links) and the Birth Defects Registry (17070 links). Associations between CP (congenital or acquired) and birth defects (cerebral or exclusively non-cerebral) were estimated. The origin of the association between non-cerebral defects and acquired CP was investigated with an observational study, and the origin of the association between non-cerebral defects and congenital CP was investigated with a blinded case-control study of births with non-cerebral defects with or without CP. With non-cerebral defects, the odds ratio for CP was 4.8 (95% CI 3.1-7.4) if acquired and 4.7 (3.9-5.7) if congenital. For acquired CP, the association arose primarily as a result of cardiac defects. For congenital CP, the association arose partly from ascertainment bias and partly from defects known to be associated with cerebral defects (but not identified in these data). However, a significant portion remained unexplained. The presence of non-cerebral defects should heighten clinical alertness to the possibility of CP and of cerebral birth defects.

Primary prevention of neural tube defects with folate in Western Australia: the value of the Western Australian Birth Defects Registry

This paper reviews the role of the Western Australian Birth Defects Registry in the primary prevention of neural tube defects. The Registry provides complete and up-to-date information on all neural tube defects (NTD), including terminations of pregnancy. These data have been used to determine a baseline rate of NTD and to monitor trends in NTD over time, when health promotion of folic acid supplement use and voluntary fortification of food with folate were introduced. The register has also been used to investigate NTD in special populations (Indigenous infants in Australia) and as a sampling frame for case control studies. The data derived from these studies have been used to assist in assessing whether mandatory food fortification in Australia is indicated to prevent NTD.

Risk factors for isolated talipes equinovarus in Western Australia, 1980-1994

A case-control study based on routinely collected data for a West Australian (WA) cohort of births born 1980-94 inclusive was used to identify potential risk factors for the foot deformity isolated talipes equinovarus. Race and sex were identified as risk factors and risk modifiers of the condition in WA infants. In comparison with their female counterparts, Aboriginal males were at greater risk of the deformity than Caucasian males (odd ratio [OR] 7.15, 95% confidence interval [CI] 2.68, 21.12 vs. OR 1.63, 95% CI 1.24, 2.15 respectively). Sex-specific risk estimates of the deformity showed that Aboriginal males were at more than four times the risk of Caucasian males (OR 4.27, 95% CI 2.30, 8.25 respectively), but the risk amongst Aboriginal females was not dissimilar to the risk amongst Caucasian females (OR 1.12, 95% CI 0.49, 2.45). Intrauterine constraint of the fetus was not found to be an important contributing factor to the deformity after accounting for the effect of all risk factors modelled in multivariable analyses. Indicators of intrauterine constraint including prolonged gestation, high infant birthweight, young maternal age (< 20 years) and breech presentation were not associated with excess numbers of isolated talipes equinovarus cases. Limited numbers of cases associated with other indicators of intrauterine constraint, including the specific categories of short maternal stature and a twin pregnancy prevented definitive conclusions regarding their association with the deformity. Improved data quality for gestational age estimates and oligohydramnios status are required before determining the prenatal risk impact of season of conception and of reduced amniotic fluid levels, respectively, on the occurrence of the deformity.

Validation study of the Victorian Birth Defects Register

OBJECTIVE

To determine whether there has been an improvement in ascertainment of birth defects cases ('case validity') by the Victorian Birth Defects Register (BDR) since an earlier study (conducted in 1993), to ascertain the accuracy of registered data ('item validity') and to investigate another possible source of notification.

METHODS

The medical records were reviewed of 500 children born after 1 January 1993 who were consecutively admitted after 1 January 1999 to two paediatric teaching hospitals in Victoria. In addition, records of 200 children referred to a clinical genetics service were reviewed for children born after 1 January 1993 and who were seen in two periods: 2 months after 1 January 2001 and 2 months after 1 January 2002. The records from the hospitals and clinical genetics service were reviewed separately to determine whether children recorded as having a birth defect had previously been notified to the BDR.

RESULTS

Twenty percent of the hospital records related to a child with a birth defect, as did 70% of the clinical genetics service records. Overall case validity for birth defect cases from the hospitals was 88%. There was 100% ascertainment for three of five categories. Sixty per cent of birth defects cases from the clinical genetics service had been notified to the BDR. When all diagnoses in matched cases were considered, item validity was 54%, however, if only primary diagnoses were included then 92% of cases had the same diagnosis.

CONCLUSIONS

Overall case validity from the two paediatric teaching hospitals has significantly improved since our previous study. The addition of an extra data source from a clinical genetics service would identify new cases, particularly genetic disorders and developmental delay, as well as adding new diagnoses to existing ones. This study has highlighted the need to improve item validity, perhaps through routine education for all coders and notifiers on the inclusion and exclusion of specific associated conditions when notifying major birth defects.

Talipes equinovarus in Western Australia

In Western Australia (WA), talipes equinovarus is a notifiable birth defect and, since 1980, has been ascertained by the population-based Birth Defects Registry (BDR). Talipes equinovarus deformities were classified as two distinct and distinguishable types, viz. isolated talipes equinovarus (no other birth defects present) and associated talipes equinovarus (other birth defects present). The birth prevalence of associated talipes in WA between 1980 and 1994 was 0.90 per 1000 births, and of isolated talipes was 1.25 per 1000 births. The rate of the isolated deformity was higher in Aboriginal infants (3.49 per 1000 births) than in Caucasian infants (1.11 per 1000 births) and non-Aboriginal non-Caucasian infants (0.73 per 1000 births). The sex differential in the rate of the isolated deformity was greatest among Aboriginal infants, with the rate in males being almost four times that in females. The birth prevalence of both types of the deformity remained stable over the 15-year study period. The rate of caesarean and breech deliveries and the proportion of bilaterally affected feet was greater among infants with associated talipes equinovarus deformity. An accurate and complete identification of cases of isolated talipes equinovarus in the 1980-94 WA birth cohort provides a basis for furthering the understanding of the epidemiology and hence the aetiology of the deformity.