Search results

ABSTRACT
ObjectivesAcute lower respiratory infections (ALRI) such as bronchiolitis, pneumonia and influenza are a common cause of childhood morbidity. The relative importance of individual respiratory viruses associated with these infections may fluctuate in different populations. Knowledge of the aetiology of ALRI is important so that preventive strategies, such as vaccination, may be targeted appropriately. We sought to describe the virus-specific burden of ALRI in children born in Western Australia (WA).
ApproachWe identified a birth cohort of children born in WA from 1996 to 2012. ALRI-coded hospital admissions and routine laboratory data regarding the detection of respiratory viruses pertaining to these children were extracted and linked through the WA Data Linkage Unit. Hospitalisation and laboratory data were restricted to Jan 2000 to Jun 2013 as laboratory data were only available for this period.
Repeat hospital admissions for ALRI within 14 days of each other were collapsed into the same episode of infection. Virus detection was defined as detection via culture, immunofluorescence or molecular methods from a respiratory sample 48 hours pre- or post-hospitalisation. We estimated the proportion of ALRI episodes in children aged up to 17 years with a laboratory test recorded and identified the viruses detected. Using person-time-at-risk as the denominator, we calculated the virus-specific rates of ALRI in 2000-2012 in the birth cohort.
ResultsOf 469,589 children born 1996-2012, 7.0% were admitted to hospital at least once for ALRI between Jan 2000 and Jun 2013. Bronchiolitis and pneumonia were the most common diagnoses, collectively accounting for 73.3% (n=32,815) of all ALRI episodes.
45.4% of ALRI episodes (n=20,323) in children aged 0-17 years linked to a laboratory test record. Of those with a laboratory record, 60.0% tested positive for one or more viruses, most commonly respiratory syncytial virus (RSV; n=7671). Of those with at least 1 virus detected, 4.7% had 2 or more viruses detected, with RSV-adenovirus being the most common viral pair.
Among children aged under 5 years, rates of virus-related ALRI hospitalisation were highest in children aged 1-2 months (37.2 per 1000 child-years), corresponding to the peak in RSV-related hospitalisations (30.6 per 1000 child-years). By contrast, rates of adenovirus-related hospitalisations were highest in children aged 6-11 months (1.7 per 1000 child-years).
ConclusionThis study demonstrates the power of using linked data to assess the virus-specific burden of ALRI in a population of children. Future work will focus on viral-viral coinfection and its impact on clinical outcomes.

IntroductionSeveral countries have developed national immunisation registers, but only the Nordic countrieshave linked their registers to other health data in order to comprehensively evaluate the 'real world'effectiveness of vaccines. Nordic countries can link datasets deterministically using the nationalperson identifier, but most countries, including Australia, don't have such an identifier to enablethis type of linkage.
ObjectivesTo describe the process for assembling a linked study cohort that will enable the conduct ofpopulation-based studies related to immunisation and immunisation policy.
MethodsNational death and immunisation databases along with state health data (notifications of vaccinepreventable diseases, perinatal data, hospital admissions and emergency department presentations)up until December 2013 were probabilistically linked (using demographic details) for children bornbetween 1996 and 2012 in two states: Western Australia and New South Wales (42% of Australia'spopulation, combined).
ResultsAfter exclusions there were 1.95 million children in the study cohort (live born children withboth a birth and perinatal record which represents 97.5% of all live births in the state perinataldata collections - our source population) and 18.0 million person years of follow up (mean: 9.2years per child). The characteristics of children in the cohort were generally similar to those onlyincluded in state perinatal databases and outcome measures were in keeping with expected figuresfrom unlinked data sources. However, the lack of a dynamic national population register meantimmigrants could not be included.
ConclusionsWe have been able to develop a similarly comprehensive system to the Nordic countries based onprobabilistic linkage methods. Our experience should provide encouragement to other countrieswith national immunisation registers looking to establish similar systems.

BACKGROUND: Hospitalisation with skin infection in Western Australian (WA) Aboriginal children is common, with the highest rates in infants and children from remote WA. We aimed to quantify infant, maternal, and sociodemographic risk factors for skin infection hospitalization in WA children, focusing on Aboriginal children aged <17 years. METHODS: We conducted a retrospective population-based cohort study with linked perinatal and hospitalization data on WA-born children (1996–2012), of whom 31,348 (6.7%) were Aboriginal. We used Cox regression to calculate adjusted hazard ratios and associated population attributable fractions (PAFs) for perinatal factors attributed to the first hospitalization with skin infection. To identify specific risk factors for early-onset infection, we further restricted the cohort to infants aged <1 year. RESULTS: Overall, 5,439 (17.4%) Aboriginal and 6,750 (1.5%) non-Aboriginal children were hospitalized at least once with a skin infection. Aboriginal infants aged <1 year had the highest skin infection hospitalization rate (63.2/1,000 child-years). The strongest risk factors in Aboriginal children aged <17 years were socio-economic disadvantage, very remote location at birth and multi-parity (≥3 previous pregnancies) accounting for 24%, 23% and 15% of skin infection hospitalizations, respectively. Other risk factors included maternal age <20 years, maternal smoking during pregnancy and low birthweight. CONCLUSION: We have quantified the relative influence of perinatal risk factors associated with skin infection hospitalizations in WA children, providing measures indicating which factors have the potential to reduce the most hospitalizations. Our evidence supports existing calls for substantial government investment in addressing underlying social and environmental barriers to healthy skin in WA Aboriginal children but also identifies potential areas to target health promotion messaging at individuals/families on maternal smoking during pregnancy and skin hygiene for ...