Survival of children and adolescents with intellectual disability following gastrostomy insertion.

BACKGROUND: Positive health outcomes have been observed following gastrostomy insertion in children with intellectual disability, which is being increasingly used at younger ages to improve nutritional intake. This study investigated the effect of gastrostomy insertion on survival of children with severe intellectual disability. METHODS: We used linked disability and health data of children and adolescents who were born in Western Australia between 1983 and 2009 to compare survival of individuals with severe intellectual disability by exposure to gastrostomy status. For those born in 2000-2009, we employed propensity score matching to adjust for confounding by indication. Effect of gastrostomy insertion on survival was compared by pertinent health and sociodemographic risk factors. RESULTS: Compared with children born in the 1980s-1990s, probability of survival following first gastrostomy insertion for those born in 2000-2009 was higher (2 years: 94% vs. 83%). Mortality risk was higher in cases than that in their matched controls (hazard ratio 2.9, 95% confidence interval 1.1, 7.3). The relative risk of mortality (gastrostomy vs. non-gastrostomy) may have differed by sex, birthweight and time at first gastrostomy insertion. Respiratory conditions were a common immediate or underlying cause of death among all children, particularly among those undergoing gastrostomy insertion. CONCLUSIONS: Whilst gastrostomy insertion was associated with lower survival rates than children without gastrostomy, survival improved with time, and gastrostomy afforded some protection for the more vulnerable groups, and earlier use appears beneficial to survival. Specific clinical data that may be used to prioritise the need for gastrostomy insertion may be responsible for the survival differences observed.

The aggregation of early-onset melanoma in young Western Australian families.

BACKGROUND: Few studies have examined the familial aggregation of melanoma or its co-aggregation with other cancers using whole-population based designs. This study aimed to investigate aggregation patterns in young Western Australian families, using population-based linked health data to identify individuals born in Western Australia between 1974 and 2007, their known relatives, and all incident cancer diagnoses within the resulting 1,506,961 individuals. METHODS: Cox proportional hazards regression models were used to compare the risk of melanoma for first-degree relatives of melanoma cases to that for first-degree relatives of controls, with bootstrapping used to account for correlations within families. The risk of (i) developing melanoma based on the number of first-degree relatives with other cancers, and (ii) developing non-melanoma cancers based on the number of first-degree relatives diagnosed with melanoma was also investigated. RESULTS: First-degree relatives of melanoma cases had a significantly greater incidence of melanoma than first-degree relatives of individuals not affected with melanoma (Hazard Ratio (HR)=3.58, 95% bootstrap confidence interval (CI): 2.43-5.43). Sensitivity analyses produced a higher hazard ratio estimate when restricted to melanoma cases diagnosed before 40 years of age (HR=3.77, bootstrap 95% CI: 2.49-6.39) and a lower estimate when only later-onset cases (>40 years) were considered (HR=2.45, bootstrap 95% CI: 1.23-4.82). No significant evidence was found for co-aggregation between melanoma and any other cancers. CONCLUSIONS: Results indicated a strong familial basis of melanoma, with the higher than expected hazard ratio observed likely to reflect early-age at onset cases in this young cohort, supported by the results of the sensitivity analyses. Exploratory analyses suggested that the determinants of melanoma causing the observed aggregation within families may be independent of other malignancies, although these analyses were limited by the young age of the sample. Determining familial aggregation patterns will provide valuable knowledge regarding improved clinical risk prediction and the underlying biological mechanisms of melanoma and other cancers.

The triple challenges associated with age-related comorbidities in Down syndrome.

BACKGROUND: Major increases in the survival of people with Down syndrome during the last two generations have resulted in extended periods of adulthood requiring specialist care, which in turn necessitates greater understanding of the nature, timing and impact of comorbidities associated with the disorder. METHOD: The prevalence of five comorbidities reported as common in adults with Down syndrome, visual impairment, hearing impairment, epilepsy, thyroid disorders and dementia was assessed by decade of life. RESULTS: From early adulthood, people with Down syndrome are at enhanced risk of developing new comorbidities and they may present with multiple conditions. Three specific challenges are identified and discussed: are comorbidities detected in a timely manner, is the clinical progress of the disorder adequately understood, and who is responsible for the provision of care? CONCLUSIONS: Further detailed investigations into the development and treatment of comorbidities across the lifespan are needed for a successful longitudinal approach to healthcare in people with Down syndrome. Implementation of this approach will better inform healthcare providers to ensure continuity of care with advancing age.

The impact of single gene and chromosomal disorders on hospital admissions of children and adolescents: a population-based study.

BACKGROUND: It is well recognized that genetic disease makes a significant contribution to childhood illness. Here, we present recent population data describing the impact of single gene and chromosomal disorders on hospital admissions of children and adolescents. METHODS: Hospital admissions for patients aged 0-19 years between 2000 and 2006, with a single gene or chromosomal disorder, were extracted from the Western Australian Hospital Morbidity Data System using 296 diagnosis codes identified from the International Statistical Classification of Diseases, Tenth Revision, Australian Modification. Data extracted for each patient included the number, length and cost of all admissions. RESULTS: Between 2000 and 2006, 14,197 admissions were identified for 3,271 patients aged 0-19 years with single gene and chromosomal disorders, representing 2.6% of admissions and 4.3% of total hospital costs in this age group. Patients with genetic disorders had more admissions and stayed longer in hospital than patients admitted for any reason. Specific disorders associated with a high demand on hospital services included cystic fibrosis, Down syndrome, osteogenesis imperfecta, thalassemia, and von Willebrand's disease. CONCLUSIONS: Children and adolescents with single gene and chromosomal disorders placed higher demands on hospital services than other patients in their age group, but were responsible for a relatively small proportion of hospital admissions and costs. These data will enable informed planning of health care services for patients with single gene and chromosomal disorders in Western Australia.

The profile and incidence of cancer in Down syndrome.

BACKGROUND: Down syndrome is one of the commonest causes of intellectual disability. As life expectancy improves with early and more intensive surgical and medical treatments, people with the disorder are more likely to exhibit classic morbidity and mortality patterns and be diagnosed with diseases such as cancer. METHODS: A profile of cancer cases among people with Down syndrome has been compiled, based on the analysis of a linked data set that included information from the Disability Services Commission of Western Australian and the State Cancer Registry. RESULTS AND CONCLUSIONS: Although the total age- and sex-standardized incidence ratios (SIRs) for people with Down syndrome were similar to that for the general population, SIRs for leukaemia were significantly higher while the incidence of certain other types of cancers was reduced. Overall, there was a lower incidence of solid tumours in Down syndrome, possibly reflecting the age profile of the study cohort.

A long-term population-based clinical and morbidity profile of Angelman syndrome in Western Australia: 1953-2003.

PURPOSE: To investigate the incidence, clinical presentation and associated comorbidities of Angelman syndrome (AS) in Western Australia, with establishment of an information database for the disorder. METHODS: Data were collected from Disability Services Commission files, supplemented by datasets provided by the Western Australian Data Linkage Unit. The analysis was retrospective and quantitative. RESULTS: Thirty-four individuals (two deceased) were identified (19 F, 15 M), with a mean age of 21.6 years; 52.9% had an IQ < 40, with the remainder of IQ 40-69. The incidence was one in 40,000 births and mean age at diagnosis was 5.8 years. The mean age of the 23 home residents was 20.2 years compared to 27.9 years in the nine individuals in sheltered accommodation. In general, the patients exhibited a typical AS clinical presentation. A median of 5.5 (range 0-20) hospital admissions was recorded per person, with epilepsy, gastrointestinal disorders, and dental work all common reasons for admission. CONCLUSIONS: The estimated incidence was low compared to other reports, as was the proportion of IQ < 40. AS cases required substantial levels of medical care, especially those who were epileptic. An increase in the future numbers of AS patients needing sheltered accommodation is predicted.

A long-term population-based clinical and morbidity review of Prader-Willi syndrome in Western Australia.

BACKGROUND: An investigation of the clinical morbidity and genetic profiles of individuals with Prader-Willi syndrome (PWS) in Western Australia (WA) was undertaken as part of a wider study into the effects of intellectual disability (ID) on the life course of individuals. METHODS: All persons with a diagnosis of PWS were identified from the records of the Disability Services Commission of WA (DSC). The DSC client files formed the main data source, and were supplemented by information from other state health data sets. The analysis was retrospective and quantitative in nature. RESULTS: A total of 56 individuals were identified, 10 of whom exhibited normal methylation patterns and so were analysed separately (PWS-like). The ages of the PWS group ranged from 0.9 to 48.3 years, with six persons deceased. Most people with PWS (76%) had mild or moderate ID, and 70% lived in their family home. The birth prevalence of the disorder was 1 in 29 500 births. Respiratory disorders, dentistry and gastrointestinal disorders were common reasons for hospital admission, with epilepsy or convulsions also reported at moderate frequency. The PWS-like group shared many clinical features in common with PWS patients, the principal exceptions being hypotonia and feeding difficulties in infancy. CONCLUSIONS: The estimated birth prevalence of PWS was lower than expected; however, the case ascertainment method may have excluded some individuals. Older people with PWS were generally living in sheltered accommodation. As the cohort ages, demand for places in similar accommodation will increase, adding to the existing burden on service providers. Substantial future increases in the use of medical services and hospital-based care also are predicted with the onset of age-associated disorders.

An assessment of intellectual disability among Aboriginal Australians.

BACKGROUND: The health and well-being of Indigenous people is a significant global problem, and Aboriginal Australians suffer from a considerably higher burden of disease and lower life expectancy than the non-Indigenous population. Intellectual disability (ID) can further compromise health, but there is little information that documents the prevalence of ID among indigenous populations. This study provides information on ID among the Aboriginal population of Western Australia. METHODS: The Disability Services Commission (DSC) of Western Australia has maintained a statewide database of people with ID since 1953. Data on people of Aboriginal descent were extracted from the DSC database and linked to two other state-based databases, the Hospital Morbidity Data System and the Deaths Registry, with additional linkage to the National Death Index. The linked data were used to assess the prevalence, survival patterns and causes of death in Aboriginal people with ID. RESULTS: Although comprising 3.5% of the population, Aboriginal Australians represented 7.4% of all people registered for ID services. The level of ID was assessed as borderline or mild in 40.7% of cases, moderate in 19.9%, severe or profound in 12.1%, but had not been specified in 27.2% cases. Median survival was 55.1 years for men and 64.0 years for women, with a mean age at death (n = 102) of 19.6 years. The leading causes of death were respiratory diseases, diseases of the circulatory system, and accidents. CONCLUSIONS: The study presents unique population summary data for ID in the Aboriginal community of Western Australia. To provide appropriate prevention and intervention strategies, there is an urgent need for more detailed information on the prevalence and patterns of ID.

Breast cancer and the uptake of mammography screening services by women with intellectual disabilities.

BACKGROUND: It is estimated that approximately 50% of women in Australia with intellectual disability will live to 70 years of age and as a result many will fall within the age group at highest risk for breast cancer (50-69 years). METHODS: Subjects were identified through the Western Australia Disability Services database. To determine the number of women diagnosed with breast cancer during the period 1982-2000, individual records (n = 2,370) were linked to the Western Australia Cancer Registry and the Mammography Screening Registry. RESULTS: The incidence of breast cancer among women with intellectual disability was 64.0 per 100,000 person-years, by comparison with 146.7 per 100,000 person-years in the general population. The uptake of breast cancer screening was examined in a subgroup of 380 women, 34.7% of whom had used mammographic screening, as opposed to 54.6% screening uptake in the general population. Failure to use screening services was highest in women who were unmarried, and was positively associated with severity of intellectual disability, presence of physical disabilities, and urban residence. CONCLUSIONS: The lower incidence of breast cancer in women with intellectual disability may in part be attributable to decreased life expectancy, but it also appears to reflect significant under utilization of the readily available screening services.

Comparative survival advantage of males with Down syndrome.

In virtually all countries life expectancy is longer in females than in males. A multigeneration, population-based dataset was used to investigate whether a gender-specific difference in life expectancy could be determined in a large cohort (n = 1,332) of people with Down syndrome resident in Western Australia. Contrary to the established pattern of longevity in the general population, and in most people with intellectual disability, males with Down syndrome had a significantly greater life expectancy than females with the same disorder. The reasons for this atypical finding are discussed in terms of the patterns of morbidity experienced by people with Down syndrome, especially at early and late stages of their lifespan.

The changing survival profile of people with Down's syndrome: implications for genetic counselling.

Cohort studies have indicated that the survival of individuals with Down's syndrome has dramatically increased over the past 50 years. Early childhood survival in particular has shown major improvement, due largely to advances in cardiac surgery and in general health management. The present study was based on a continuous cohort of 1332 people with Down's syndrome in Western Australia, registered for intellectual disability services between 1953 and 2000. Their life expectancy was 58.6 years, 25% lived to 62.9 years, and the oldest living person is 73 years of age. Life expectancy for males was greater than females by 3.3 years. The substantial increase in survival across the study period means that the life expectancy of people with Down's syndrome is approaching that of the general population, but accompanied by a range of significant mid-life health problems. The findings are of relevance to all developed countries and have considerable implications in terms of the counselling information provided to families at risk of having a child with Down's syndrome.

The influence of intellectual disability on life expectancy.

BACKGROUND: To date, relatively few representative data have been available to health planners and advocacy groups on the life expectancy of people with intellectual disability. A study of trends in the survival profiles of people with intellectual disability was undertaken to assist in the planning of appropriate medical and support services. METHODS: Since 1953, the Disability Services Commission of Western Australia has maintained a database of persons diagnosed with intellectual disability. The database was used to calculate survival probabilities on a total of 8724 individuals, 7562 of whom were still alive at the time of sampling in December 2000. RESULTS: Kaplan-Meier survival plots showed a strong negative association between severity of intellectual disability and survival, with median life expectancies of 74.0, 67.6, and 58.6 years for people with mild, moderate, and severe levels of handicap. Significant negative associations also were observed with male gender, Indigenous Australian parentage, and individuals diagnosed with a specific genetic disorder. CONCLUSIONS: The findings indicate a major and expanding increase in the service requirements of this aging, intellectually disabled population during the past two generations.

A population-based approach to the investigation of osteopenia in Rett syndrome.

This study compares bone mass in a national sample of girls with Rett syndrome (RS) with a sample of control children. The Australian RS Database was the source of cases for this population-based study. Hand radiographs were available from 101 of 137 subjects (74% of the known Australian population of girls with RS aged < or = 20 years). Control radiographs matched for age, sex, and laterality were obtained from hospital radiology departments. A measure of cortical thickness was made from the difference between the outer diameter and the medullary space in the second metacarpal bone. A mean z-score value for cortical thickness and percentage cortical area for each individual was calculated. The mean cortical thickness (z score) for girls with RS was -1.94 compared with -0.38 for control children (P<0.001). In girls with RS, the mean cortical thickness decreased with age (P<0.001). In girls who were taking epilepsy medication it was -2.21 compared with -1.23 in those not taking epilepsy medication (P<0.001). There was no evidence of a beneficial effect of increased calcium intake on cortical thickness. A similar pattern was obtained when percentage cortical area was estimated. In multivariate analysis, increasing age and use of anticonvulsant medication were associated with decreased cortical thickness and only use of anticonvulsant medication with decreased percentage cortical area. Fractures had occurred in one-third of cases and it was estimated that just over 40% of girls would sustain a fracture by the age of 15 years. Girls with RS may be at increased risk of fractures and their bone quality compromised as determined by cortical thickness and percentage cortical area measurements from the second metacarpal.

Diagnosis of Rett syndrome: can a radiograph help?

Rett syndrome (RS), a neurodevelopmental disorder almost exclusively affecting girls, is associated with severe intellectual and motor disability. In the absence of biological markers, diagnosis is determined by a set of clinical criteria. In a previous study in Scotland, shortening of the fourth metatarsal was reported clinically in 20% of classical RS cases aged 5 years or older. The Australian Rett Syndrome Study database has facilitated a population-based radiological study of the hands and feet of girls with RS. Straight radiographs of hands and feet were available from 94 cases, representing 70.1% of the known RS population in Australia. Control radiographs were matched for age, sex, and laterality. Relative shortening of the fourth metacarpal/metatarsal was assessed using the sign method. A short ulna (negative ulna variance) was defined as the distal articular surface of the ulna being at least 5mm proximal to the distal articular surface of the radius. A positive metacarpal sign was twice as common in verified cases of RS than in controls in the right but not the left hand. A short ulna was more common in subjects with RS than in controls. A short fourth metatarsal was also more common among subjects with RS. More than half (56.6%) the girls with RS over the age of 4 years had a negative ulnar variance in either wrist or a metatarsal sign in either foot. These findings will assist with the diagnosis of RS and may help direct research towards the location of the molecular defect.