Relative Risks of Adverse Perinatal Outcomes in Three Australian Communities Exposed to Per- and Polyfluoroalkyl Substances: Data Linkage Study

INTRODUCTION

Firefighting foams containing per- and polyfluoroalkyl substances (PFAS) have caused environmental contamination in several Australian residential areas, including Katherine in the Northern Territory (NT), Oakey in Queensland (Qld), and Williamtown in New South Wales (NSW). We examined whether the risks of adverse perinatal outcomes were higher in mothers living in these exposure areas than in selected comparison areas without known contamination.

METHODS

We linked residential addresses in exposure areas to addresses collected in the jurisdictional Perinatal Data Collections of the NT (1986-2017), Qld (2007-2018), and NSW (1994-2018) to select all pregnancies from mothers who gave birth while living in these areas. We also identified one comparison group for each exposure area by selecting pregnancies where the maternal address was in selected comparison areas. We examined 12 binary perinatal outcomes and three growth measurements. For each exposure area, we estimated relative risks (RRs) of adverse outcomes and differences in means of growth measures, adjusting for sociodemographic characteristics and other potential confounders.

RESULTS

We included 16,970 pregnancies from the NT, 4654 from Qld, and 7475 from NSW. We observed elevated risks of stillbirth in Oakey (RR = 2.59, 95% confidence interval (CI) 1.25 to 5.39) and of postpartum haemorrhage (RR = 1.94, 95% CI 1.13 to 3.33) and pregnancy-induced hypertension (RR = 1.88, 95% CI 1.30 to 2.73) in Williamtown. The risks of other perinatal outcomes were not materially different from those in the relevant comparison areas or were uncertain due to small numbers of events.

CONCLUSIONS

There was limited evidence for increased risks of adverse perinatal outcomes in mothers living in areas with PFAS contamination from firefighting foams. We found higher risks of some outcomes in individual areas, but these were not consistent across all areas under study and could have been due to chance, bias, or confounding.

Psychological distress in three Australian communities living with environmental per- and polyfluoroalkyl substances contamination

BACKGROUND

Environmental chemical contamination is a recognised risk factor for psychological distress, but has been seldom studied in the context of per- and polyfluoroalkyl substances (PFAS) contamination. We examined psychological distress in a cross-sectional study of three Australian communities exposed to PFAS from the historical use of aqueous film-forming foam in firefighting activities, and three comparison communities without environmental contamination.

METHODS

Participation was voluntary following recruitment from a PFAS blood-testing program (exposed) or random selection (comparison). Participants provided blood samples and completed a survey on their exposure history, sociodemographic characteristics, and four measures of psychological distress (Kessler-6, Distress Questionnaire-5, Patient Health Questionnaire-15, and Generalised Anxiety Disorder-7). We estimated prevalence ratios (PR) of clinically-significant psychological distress scores, and differences in mean scores: (1) between exposed and comparison communities; (2) per doubling in PFAS serum concentrations in exposed communities; (3) for factors that affect the perceived risk of living in a community exposed to PFAS; and (4) in relation to self-reported health concerns.

RESULTS

We recruited 881 adults in exposed communities and 801 in comparison communities. We observed higher levels of self-reported psychological distress in exposed communities than in comparison communities (e.g., Katherine compared to Alice Springs, Northern Territory: clinically-significant anxiety scores, adjusted PR = 2.82, 95 % CI 1.16-6.89). We found little evidence to suggest that psychological distress was associated with PFAS serum concentrations (e.g., Katherine, PFOS and anxiety, adjusted PR = 0.85, 95 % CI 0.65-1.10). Psychological distress was higher among exposed participants who were occupationally exposed to firefighting foam, used bore water on their properties, or were concerned about their health.

CONCLUSION

Psychological distress was substantially more prevalent in exposed communities than in comparison communities. Our findings suggest that the perception of risks to health, rather than PFAS exposure, contribute to psychological distress in communities with PFAS contamination.

Interventional radiology in obstetric patients: A population-based record linkage study of use and outcomes

INTRODUCTION

Interventional radiology (IR) is a technique for controlling hemorrhage and preserving fertility for women with serious obstetric conditions such as placenta accreta spectrum (PAS) or postpartum hemorrhage. This study examined maternal, pregnancy and hospital characteristics and outcomes for women receiving IR in pregnancy and postpartum.

MATERIAL AND METHODS

A population-based record linkage study was conducted, including all women who gave birth in hospital in New South Wales or the major tertiary hospital in the neighboring Australian Capital Territory, Australia, between 2003 and 2019. Data were obtained from birth and hospital records. Characteristics and outcomes of women who underwent IR in pregnancy or postpartum are described. Outcomes following IR were compared in a high-risk cohort of women: those with PAS who had a planned cesarean with hysterectomy. Women were grouped by those who did and those who did did not have IR and were matched using propensity score and other factors.

RESULTS

We identified IR in 236 pregnancies of 1 584 708 (15.0 per 100 000), including 208 in the delivery and 26 in a postpartum admission. Two-thirds of women receiving IR in the birth admission received a transfusion of red cells or blood products, 28% underwent hysterectomy and 12.5% were readmitted within 6 weeks. Other complications included: severe maternal morbidity (29.8%), genitourinary tract trauma/repair (17.3%) and deep vein thrombosis/pulmonary embolism (4.3%). Outcomes for women with PAS who underwent planned cesarean with hysterectomy were similar for those who did and did not receive IR, with a small reduction in transfusion requirement for those who received IR.

CONCLUSIONS

Interventional radiology is infrequently used in pregnant women. In our study it was performed at a limited number of hospitals, largely tertiary centers, with the level of adverse outcomes reflecting use in a high-risk population. For women with PAS undergoing planned cesarean with hysterectomy, most outcomes were similar for those receiving IR and those not receiving IR, but IR may reduce bleeding.

Interaction effects of multimorbidity and frailty on adverse health outcomes in elderly hospitalised patients

We quantified the interaction of multimorbidity and frailty and their impact on adverse health outcomes in the hospital setting. Using aretrospective cohort study of persons aged ≥ 75 years, admitted to hospital during 2010–2012 in New South Wales, Australia, and linked with mortality data, we constructed multimorbidity, frailty risk and outcomes: prolonged length of stay (LOS), 30-day mortality and 30-day unplanned readmissions. Relative risks (RR) of outcomes were obtained using Poisson models with random intercept for hospital. Among 257,535 elderly inpatients, 33.6% had multimorbidity and elevated frailty risk, 14.7% had multimorbidity only, 19.9% had elevated frailty risk only and 31.8% had neither. Additive interactions were present for all outcomes, with a further multiplicative interaction for mortality and LOS. Mortality risk was 4.2 (95% CI 4.1–4.4), prolonged LOS 3.3 (95% CI 3.3–3.4) and readmission 1.8 (95% CI 1.7–1.9) times higher in patients with both factors present compared with patients with neither. In conclusion, multimorbidity and frailty coexist in older hospitalized patients and interact to increase the risk of adverse outcomes beyond the sum of their individual effects. Their joint effect should be considered in health outcomes research and when administering hospital resources.

Differences in the pre-hospital management of women and men with stroke by emergency medical services in New South Wales

OBJECTIVES

To examine whether pre-hospital emergency medical service care differs for women and men subsequently admitted to hospital with stroke.

DESIGN, SETTING, PARTICIPANTS

Population-based cohort study; analysis of linked Admitted Patient Data Collection and NSW Ambulance data for people admitted to New South Wales hospitals with a principal diagnosis of stroke at separation, 1 July 2005 - 31 December 2018.

MAIN OUTCOME MEASURES

Emergency medical service assessments, protocols, and management for patients subsequently diagnosed with stroke, by sex.

RESULTS

Of 202 231 people hospitalised with stroke (mean age, 73 [SD, 14] years; 98 599 women [51.0%]), 101 357 were conveyed to hospital by ambulance (50.1%). A larger proportion of women than men travelled by ambulance (52.4% v 47.9%; odds ratio [OR], 1.09; 95% CI, 1.07-1.11), but time between the emergency call and emergency department admission was similar for both sexes. The likelihood of being assessed as having a stroke (adjusted OR [aOR], 0.97; 95% CI, 0.93-1.01) or subarachnoid haemorrhage (aOR, 1.22; 95% CI, 0.73-2.03) was similar for women and men, but women under 70 years of age were less likely than men to be assessed as having a stroke (aOR, 0.89; 95% CI, 0.82-0.97). Women were more likely than men to be assessed by paramedics as having migraine, other headache, anxiety, unconsciousness, hypertension, or nausea. Women were less likely than men to be managed according to the NSW Ambulance pre-hospital stroke care protocol (aOR, 0.95; 95% CI, 0.92-0.97), but the likelihood of basic pre-hospital care was similar for both sexes (aOR, 1.01; 95% CI, 0.99-1.04).

CONCLUSION

Our large population-based study identified sex differences in pre-hospital management by emergency medical services of women and men admitted to hospital with stroke. Paramedics should receive training that improves the recognition of stroke symptoms in women.

Maternal factors and risk of spontaneous preterm birth due to high ambient temperatures in New South Wales, Australia

BACKGROUND

Exposure to high ambient temperatures has been shown to increase the risk of spontaneous preterm birth. Determining which maternal factors increase or decrease this risk will inform climate adaptation strategies.

OBJECTIVES

This study aims to assess the risk of spontaneous preterm birth associated with exposure to ambient temperature and differences in this relationship between mothers with different health and demographic characteristics.

METHODS

We used quasi-Poisson distributed lag non-linear models to estimate the effect of high temperature-measured as the 95th percentile of daily minimum, mean and maximum compared with the median-on risk of spontaneous preterm birth (23-36 weeks of gestation) in pregnant women in New South Wales, Australia. We estimated the cumulative lagged effects of daily temperature and analyses on population subgroups to assess increased or decreased vulnerability to this effect.

RESULTS

Pregnant women (n = 916,678) exposed at the 95th percentile of daily mean temperatures (25ºC) had an increased risk of preterm birth (relative risk 1.14, 95% confidence interval 1.07, 1.21) compared with the median daily mean temperature (17℃). Similar effect sizes were seen for the 95th percentile of minimum and maximum daily temperatures compared with the median. This risk was slightly higher among women with diabetes, hypertension, chronic illness and women who smoked during pregnancy.

CONCLUSIONS

Higher temperatures increase the risk of preterm birth and women with pre-existing health conditions and who smoke during pregnancy are potentially more vulnerable to these effects.

Sex differences in emergency medical services management of patients with myocardial infarction: analysis of routinely collected data for over 110,000 patients

Emergency medical services (EMS) activation is an integral component in managing individuals with myocardial infarction (MI). EMS play a crucial role in early MI symptom recognition, prompt transport to percutaneous coronary intervention centres and timely administration of management. The objective of this study was to examine sex differences in prehospital EMS care of patients hospitalized with Ml using data from a retrospective population-based cohort study of linked health administrative data for people with a hospital diagnosis of MI in Australia (2001-18).

Predicting outcomes in older patients undergoing vascular surgery using the Hospital Frailty Risk Score

BACKGROUND

Frailty may explain why some older patients having vascular surgery are at high risk of adverse outcomes. The Hospital Frailty Risk Score (HFRS) has been designed specifically for use with administrative data and has three categories of frailty risk (low, intermediate and high). The aim of this study was to evaluate the HFRS in predicting mortality, and hospital use in older patients undergoing vascular surgery.

METHODS

Routinely collected hospital data linked to death records were analysed for all patients aged 75 years or older who had undergone either endovascular or open vascular surgery between 2010 and 2012 in New South Wales, Australia. Multilevel logistic regression models were used to compare outcomes adjusted for patient and procedural factors, with and without frailty.

RESULTS

Some 9752 patients were identified, of whom 1719 (17·6 per cent) had a high-risk HFRS. Patients in the high-risk frailty category had an adjusted odds ratio for death by 30 days after surgery of 4·15 (95 per cent c.i. 2·99 to 5·76) compared with those in the low-risk frailty category, and a similarly increased odds of death by 2 years (odds ratio 4·27, 3·69 to 4·95). Adding the HFRS to a model adjusted for age, sex, co-morbidity score, socioeconomic status, previous hospitalization and vascular procedure type improved the prediction of 2-year mortality and prolonged hospital stay, but there was minimal improvement for 30-day mortality and readmission.

CONCLUSION

Adjusting for the HFRS in addition to other patient and procedural risk factors provided greater discrimination of outcomes in this cohort of older patients undergoing vascular surgery.

Are newly introduced criteria for the diagnosis of gestational diabetes mellitus associated with improved pregnancy outcomes and/or increased interventions in New South Wales, Australia? A population-based data linkage study

INTRODUCTION

The incidence of gestational diabetes mellitus (GDM) is increasing in Australia, influenced by changed diagnostic criteria. We aimed to identify whether the diagnostic change was associated with improved outcomes and/or increased obstetric interventions using state-wide data in New South Wales (NSW), Australia.

RESEARCH DESIGN AND METHODS

Perinatal and hospital data were linked for singleton births, 33-41 weeks' gestation, 2006-2015, NSW. An adjusted Poisson model was used to split pregnancies from 2011 onwards into those that would have been diagnosed under the old criteria ('previous GDM') and newly diagnosed cases ('additional GDM'). We compared actual rates of total and early (<39 weeks) planned births, cesareans, and maternal and neonatal adverse outcomes for GDM-diagnosed pregnancies using three predicted scenarios, where the 'additional GDM' group was assumed to have the same rates as: the 'previous GDM' group <2011 (scenario A); the 'non-GDM' group <2011 (scenario B); or the 'non-GDM' group ≥2011 (scenario C).

RESULTS

GDM incidence more than doubled over the study period, with an inflection point observed at 2011. For those diagnosed with GDM since 2011, the actual incidence of interventions (planned births and cesareans) and macrosomia was consistent with scenario A, which meant higher intervention rates, but lower rates of macrosomia, than those with no GDM. Incidence of neonatal hypoglycemia was lower than scenario A and closer to the other scenarios. There was a reduction in perinatal deaths among those with GDM, lower than that predicted by all scenarios, indicating an improvement for all with GDM, not only women newly diagnosed. Incidence of maternal and neonatal morbidity indicators was within the confidence bounds for all three predicted scenarios.

CONCLUSIONS

Our study suggests that the widely adopted new diagnostic criteria for GDM are associated with increased obstetric intervention rates and lower rates of macrosomic babies, but with no clear impacts on maternal or neonatal morbidity.

Gestational age, morbidity and mortality among twin births in New South Wales, Australia 2003-2014: A cohort study

BACKGROUND

Evidence suggests that the trend toward early planned births observed among singletons may be evident among twin pregnancies.

AIMS

To describe trends in gestational age at birth, pregnancy characteristics, neonatal morbidity and mortality among twin pregnancies.

MATERIALS AND METHODS

Population-based data linkage study of twin births of ≥30 weeks of gestation without a major congenital anomaly born in 2003-2014 in New South Wales (NSW), Australia. Linked pregnancy and birth, hospital and mortality data were used. Generalised linear regression was used to assess linear trends. Risk difference (RD) and 95% confidence intervals were estimated.

RESULTS

Among 28 076 eligible twin births (14 038 pregnancies), 49% of births occurred prior to 37 weeks and 69% of births were planned (pre-labour caesarean or induction of labour). There were increases over time in the proportion of twin births at preterm gestations (30-34 weeks (RD 2.1, 95% CI 0.1, 4.0), 35-36 weeks (RD 7.5, 95% CI 5.4, 9.7)) and in the rates of planned births (pre-labour caesarean (RD 6.4, 95% CI 4.0, 8.8), induction (RD 4.6, 95% CI 2.6, 6.6)). There was no significant change in stillbirth or neonatal death rates, but there was an increase in neonatal morbidity over the study period. Concurrently, there were increases in the prevalence of gestational diabetes; and decreases in pregnancy hypertension, assisted reproductive technology use, small-for-gestational age and birthweight discordance.

CONCLUSIONS

Gestational age at birth among twin births is decreasing and birth intervention is increasing. There are increasing rates of neonatal morbidity, but no overall change in perinatal mortality.

The association between haemoglobin levels in the first 20 weeks of pregnancy and pregnancy outcomes

BACKGROUND

Low haemoglobin has been linked to adverse pregnancy outcomes. Our study aimed to assess the association of haemoglobin (Hb) in the first 20 weeks of pregnancy, and restoration of low Hb levels, with pregnancy outcomes in Australia.

METHODS

Clinical data for singleton pregnancies from two tertiary public hospitals in New South Wales were extracted for 2011-2015. The relationship between the lowest Hb result in the first 20 weeks of pregnancy and adverse outcomes was determined using adjusted Poisson regression. Those with Hb <110 g/L were classified into 'restored' and 'not restored' based on Hb results from 21 weeks onwards, and risk of adverse outcomes explored with adjusted Poisson regression.

RESULTS

Of 31,906 singleton pregnancies, 4.0% had Hb <110 and 10.2% had ≥140 g/L at ≤20 weeks. Women with low Hb had significantly higher risks of postpartum haemorrhage, transfusion, preterm birth, very low birthweight, and having a baby transferred to higher care or stillbirth. High Hb was also associated with higher risks of preterm, very low birthweight, and transfer to higher care/stillbirth. Transfusion was the only outcome where risk decreased with increasing Hb. Risk of transfusion was significantly lower in the 'restored' group compared with the 'not restored' group (OR 0.39, 95% CI 0.22-0.70), but restoration of Hb did not significantly affect the other outcomes measured.

CONCLUSIONS

Women with both low and high Hb in the first 20 weeks of pregnancy had higher risks of adverse outcomes than those with normal Hb. Restoring Hb after 20 weeks did not improve most adverse outcome rates but did reduce risk of transfusion.

Mortality and hospital readmissions in the first year of life after intra-uterine and neonatal blood product transfusions: A population data linkage study

AIM

Blood product transfusions are a potentially life-saving therapy for fetal and neonatal anaemia, but there is limited population-based research on outcomes. We aimed to describe mortality, readmission and average hospital stay in the first year of life for infants with or without intra-uterine or neonatal blood product transfusions.

METHODS

Linked birth, hospital and deaths data from New South Wales, Australia (January 2002-June 2014) were used to identify singleton infants (≥23 weeks' gestation, surviving to 29 days; n = 1 089 750) with intra-uterine or neonatal transfusion or no transfusion. Rates of mortality and readmission in the first year (29-365 days) and days in hospital were calculated.

RESULTS

Overall, 68 (0.06/1000) infants had experienced intra-uterine transfusion and 4332 (3.98/1000) neonatal transfusion. Transfusion was more common among those born at earlier gestational ages requiring invasive ventilation. Mortality, readmissions and average days in hospital were higher among transfused than non-transfused infants. Over half of infants with intra-uterine and neonatal transfusion had ≥1 readmission in the first 29-365 days (55.9 and 51.8%, respectively), and around a quarter had ≥2 (20.6 and 28.5%, respectively) compared with 15.3% with ≥1 and 3.5% with ≥2 in the non-transfused group.

CONCLUSION

Infants with a history of blood product transfusion, particularly those needing a neonatal transfusion, had higher mortality and more frequent contact with the hospital system in the first year of life than those infants with no history of transfusion.

Multimorbidity among Aboriginal people in New South Wales contributes significantly to their higher mortality

OBJECTIVES

To compare the prevalence of multimorbidity and its impact on mortality among Aboriginal and non-Aboriginal Australians who had been hospitalised in New South Wales in the previous 10 years.

DESIGN, SETTING AND PARTICIPANTS

Cohort study analysis of linked NSW hospital (Admitted Patient Data Collection) and mortality data for 5 437 018 New South Wales residents with an admission to a NSW hospital between 1 March 2003 and 1 March 2013, and alive at 1 March 2013.

MAIN OUTCOME MEASURES

Admissions for 30 morbidities during the 10-year study period were identified. The primary outcome was the presence or absence of multimorbidity during the 10-year lookback period; the secondary outcome was mortality in the 12 months from 1 March 2013 to 1 March 2014.

RESULTS

31.5% of Aboriginal patients had at least one morbidity and 16.1% had two or more, compared with 25.0% and 12.1% of non-Aboriginal patients. After adjusting for age, sex, and socio-economic status, the prevalence of multimorbidity among Aboriginal people was 2.59 times that for non-Aboriginal people (95% CI, 2.55-2.62). The prevalence of multimorbidity was higher among Aboriginal people in all age groups, in younger age groups because of the higher prevalence of mental morbidities, and from age 60 because of physical morbidities. The age-, sex- and socio-economic status-adjusted hazard of one-year mortality (Aboriginal v non-Aboriginal Australians) was 2.43 (95% CI, 2.24-2.62), and 1.51 (95% CI, 1.39-1.63) after also adjusting for morbidity count.

CONCLUSIONS

The prevalence of multimorbidity was higher among Aboriginal than non-Aboriginal patients, and this difference accounted for much of the difference in mortality between the two groups. Evidence-based interventions for reducing multimorbidity among Aboriginal and Torres Strait Islander Australians must be a priority.

Variation in the recording of common health conditions in routine hospital data: study using linked survey and administrative data in New South Wales, Australia

OBJECTIVES

To investigate the nature and potential implications of under-reporting of morbidity information in administrative hospital data.

SETTING AND PARTICIPANTS

Retrospective analysis of linked self-report and administrative hospital data for 32,832 participants in the large-scale cohort study (45 and Up Study), who joined the study from 2006 to 2009 and who were admitted to 313 hospitals in New South Wales, Australia, for at least an overnight stay, up to a year prior to study entry.

OUTCOME MEASURES

Agreement between self-report and recording of six morbidities in administrative hospital data, and between-hospital variation and predictors of positive agreement between the two data sources.

RESULTS

Agreement between data sources was good for diabetes (κ=0.79); moderate for smoking (κ=0.59); fair for heart disease, stroke and hypertension (κ=0.40, κ=0.30 and κ =0.24, respectively); and poor for obesity (κ=0.09), indicating that a large number of individuals with self-reported morbidities did not have a corresponding diagnosis coded in their hospital records. Significant between-hospital variation was found (ranging from 8% of unexplained variation for diabetes to 22% for heart disease), with higher agreement in public and large hospitals, and hospitals with greater depth of coding.

CONCLUSIONS

The recording of six common health conditions in administrative hospital data is highly variable, and for some conditions, very poor. To support more valid performance comparisons, it is important to stratify or control for factors that predict the completeness of recording, including hospital depth of coding and hospital type (public/private), and to increase efforts to standardise recording across hospitals. Studies using these conditions for risk adjustment should also be cautious of their use in smaller hospitals.

The contribution of geography to disparities in preventable hospitalisations between indigenous and non-indigenous Australians

OBJECTIVES

To quantify the independent roles of geography and Indigenous status in explaining disparities in Potentially Preventable Hospital (PPH) admissions between Indigenous and non-Indigenous Australians.

DESIGN, SETTING AND PARTICIPANTS

Analysis of linked hospital admission data for New South Wales (NSW), Australia, for the period July 1 2003 to June 30 2008.

MAIN OUTCOME MEASURES

Age-standardised admission rates, and rate ratios adjusted for age, sex and Statistical Local Area (SLA) of residence using multilevel models.

RESULTS

PPH diagnoses accounted for 987,604 admissions in NSW over the study period, of which 3.7% were for Indigenous people. The age-standardised PPH admission rate was 76.5 and 27.3 per 1,000 for Indigenous and non-Indigenous people respectively. PPH admission rates in Indigenous people were 2.16 times higher than in non-Indigenous people of the same age group and sex who lived in the same SLA. The largest disparities in PPH admission rates were seen for diabetes complications, chronic obstructive pulmonary disease and rheumatic heart disease. Both rates of PPH admission in Indigenous people, and the disparity in rates between Indigenous than non-Indigenous people, varied significantly by SLA, with greater disparities seen in regional and remote areas than in major cities.

CONCLUSIONS

Higher rates of PPH admission among Indigenous people are not simply a function of their greater likelihood of living in rural and remote areas. The very considerable geographic variation in the disparity in rates of PPH admission between Indigenous and non-Indigenous people indicates that there is potential to reduce unwarranted variation by characterising outlying areas which contribute the most to this disparity.

Statistical methods to enhance reporting of Aboriginal Australians in routine hospital records using data linkage affect estimates of health disparities

OBJECTIVE

To investigate under-recording of Aboriginal people in hospital data from New South Wales (NSW), Australia, define algorithms for enhanced reporting, and examine the impact of these algorithms on estimated disparities in cardiovascular and injury outcomes.

METHODS

NSW Admitted Patient Data were linked with NSW mortality data (2001-2007). Associations with recording of Aboriginal status were investigated using multilevel logistic regression. The number of admissions reported as Aboriginal according to six algorithms was compared with the original (unenhanced) Aboriginal status variable. Age-standardised admission, and 30- and 365-day mortality ratios were estimated for cardiovascular disease and injury.

RESULTS

Sixty per cent of the variation in recording of Aboriginal status was due to the hospital of admission, with poorer recording in private and major city hospitals. All enhancement algorithms increased the number of admissions reported as Aboriginal, from between 4.1% and 37.8%. Admission and mortality ratios varied markedly between algorithms, with less strict algorithms resulting in higher admission rate ratios, but generally lower mortality rate ratios, particularly for cardiovascular disease.

CONCLUSIONS

The choice of enhancement algorithm has an impact on the number of people reported as Aboriginal and on estimated outcome ratios. The influence of the hospital on recording of Aboriginal status highlights the importance of continued efforts to improve data collection.

IMPLICATIONS

Estimates of Aboriginal health disparity can change depending on how Aboriginal status is reported. Sensitivity analyses using a number of algorithms are recommended.

Disparities in cataract surgery between Aboriginal and non-Aboriginal people in New South Wales, Australia

Background

To investigate variation in rates of cataract surgery in New South Wales, Australia by area of residence for Aboriginal and non-Aboriginal adults.

Design

Observational data linkage study of hospital admissions.

Participants

Two hundred eighty-nine thousand six hundred forty-six New South Wales residents aged 30 years and over admitted to New South Wales hospitals for 444 551 cataract surgery procedures between 2001 and 2008.

Methods

Analysis of linked routinely collected hospital data using direct standardization and multilevel negative binomial regression models accounting for clustering of individuals within Statistical Local Areas.

Main Outcome Measures

Age-standardized cataract surgery rates and adjusted rate ratios.

Results

Aboriginal people had lower rates of cataract procedures than non-Aboriginal people of the same age and sex, living in the same Statistical Local Area (adjusted rate ratio 0.71, 95% confidence interval 0.68–0.75). There was significant variation in cataract surgery rates across Statistical Local Areas for both Aboriginal and non-Aboriginal people, with the disparity greater in major cities and less disadvantaged areas. Rates of surgery were lower for Aboriginal than non-Aboriginal people in most Statistical Local Areas, but in a few, the rates were similar or higher for Aboriginal people.

Conclusions

Aboriginal people in New South Wales received less cataract surgery than non-Aboriginal people, despite evidence of higher cataract rates. This disparity was greatest in urban and wealthier areas. Higher rates of surgery for Aboriginal people observed in some specific locations are likely to reflect the availability of public ophthalmology services, targeted services for Aboriginal people and higher demand for surgery in these populations.

Disentangling the impacts of geography and Aboriginality on serious road transport injuries in New South Wales

Aboriginal people in Australia have higher rates of transport injury than non-Aboriginal people, but a greater proportion of Aboriginal people live in rural or remote areas where risk of these injuries is higher. This paper investigated the contributing effect of geography on the relationship between Aboriginality and road transport injury rates in the state of New South Wales. Linked hospital admission and mortality records for individuals for the years 2001-2007 were grouped into distinct injury events. Multilevel Poisson regression was used to examine disparities in injury rates between Aboriginal and non-Aboriginal people clustered within geographic areas of residence. Overall, Aboriginal people had higher rates of road transport injuries (IRR: 1.18, 95% CIs: 1.09-1.28). However, there was no significant difference when geographic clustering was taken into account (IRR: 1.00, 95% CIs: 0.96-1.04). This effect was further influenced by mode of transport for the injury, with Aboriginal people having higher rates of pedestrian (IRR: 1.96, 95% CIs: 1.75-2.19) and lower rates of motorcycle (IRR: 0.64, 95% CIs: 0.59-0.70) injuries in all almost all local areas, while there was no systematic pattern across geographic areas for small vehicle injuries (IRR: 1.01, 95% CIs: 0.94-1.08). Geography plays an important role in the population disparity of road transport injuries between Aboriginal and non-Aboriginal people, and has a differential impact for different types of road transport injury. Exploring how individual and geographic factors influence patterns of disparity allows for clearer targeting of future intervention strategies.

Disparities in revascularization rates after acute myocardial infarction between aboriginal and non-aboriginal people in Australia

BACKGROUND

This study examined revascularization rates after acute myocardial infarction (AMI) for Aboriginal and non-Aboriginal patients sequentially controlling for admitting hospital and risk factors.

METHODS AND RESULTS

Hospital data from the state of New South Wales, Australia (July 2000 through December 2008) were linked to mortality data (July 2000 through December 2009). The study sample were all people aged 25 to 84 years admitted to public hospitals with a diagnosis of AMI (n=59 282). Single level and multilevel Cox regression was used to estimate rates of revascularization within 30 days of admission. A third (32.9%) of Aboriginal AMI patients had a revascularization within 30 days compared with 39.7% non-Aboriginal patients. Aboriginal patients had a revascularization rate 37% lower than non-Aboriginal patients of the same age, sex, year of admission, and AMI type (adjusted hazard ratio, 0.63; 95% confidence interval, 0.57-0.70). Within the same hospital, however, Aboriginal patients had a revascularization rate 18% lower (adjusted hazard ratio, 0.82; 95% confidence interval, 0.74-0.91). Accounting for comorbidities, substance use and private health insurance further explained the disparity (adjusted hazard ratio, 0.96; 95% confidence interval, 0.87-1.07). Hospitals varied markedly in procedure rates, and this variation was associated with hospital size, remoteness, and catheterization laboratory facilities.

CONCLUSIONS

Aboriginal Australians were less likely to have revascularization procedures after AMI than non-Aboriginal Australians, and this was largely explained by lower revascularization rates at the hospital of first admission for all patients admitted to smaller regional and rural hospitals, a higher comorbidity burden for Aboriginal people, and to a lesser extent a lower rate of private health insurance among Aboriginal patients.

Mortality after admission for acute myocardial infarction in Aboriginal and non-Aboriginal people in New South Wales, Australia: a multilevel data linkage study

Background

Heart disease is a leading cause of the gap in burden of disease between Aboriginal and non-Aboriginal Australians. Our study investigated short- and long-term mortality after admission for Aboriginal and non-Aboriginal people admitted with acute myocardial infarction (AMI) to public hospitals in New South Wales, Australia, and examined the impact of the hospital of admission on outcomes.

Methods

Admission records were linked to mortality records for 60047 patients aged 25–84 years admitted with a diagnosis of AMI between July 2001 and December 2008. Multilevel logistic regression was used to estimate adjusted odds ratios (AOR) for 30- and 365-day all-cause mortality.

Results

Aboriginal patients admitted with an AMI were younger than non-Aboriginal patients, and more likely to be admitted to lower volume, remote hospitals without on-site angiography. Adjusting for age, sex, year and hospital, Aboriginal patients had a similar 30-day mortality risk to non-Aboriginal patients (AOR: 1.07; 95% CI 0.83-1.37) but a higher risk of dying within 365 days (AOR: 1.34; 95% CI 1.10-1.63). The latter difference did not persist after adjustment for comorbid conditions (AOR: 1.12; 95% CI 0.91-1.38). Patients admitted to more remote hospitals, those with lower patient volume and those without on-site angiography had increased risk of short and long-term mortality regardless of Aboriginal status.

Conclusions

Improving access to larger hospitals and those with specialist cardiac facilities could improve outcomes following AMI for all patients. However, major efforts to boost primary and secondary prevention of AMI are required to reduce the mortality gap between Aboriginal and non-Aboriginal people.

The importance of blood-borne viruses in elevated cancer risk among opioid-dependent people: a population-based cohort study

OBJECTIVE

To quantify cancer risk in opioid dependence and the association with infection by the oncogenic blood-borne viruses (BBVs) hepatitis C (HCV), hepatitis B (HBV) and HIV.

DESIGN

Cohort study.

SETTING

New South Wales, Australia.

PARTICIPANTS

All 45 412 adults aged 16 years or over registered for opioid substitution therapy (OST) between 1985 and 2007. Notifications of cancer, death and infection with HCV, HBV and HIV were ascertained by record linkage with registries.

MAIN OUTCOME MEASURES

The ratios of observed to expected number of cancers, standardised incidence ratios (SIRs), and the average annual per cent change (AAPC) in overall age and sex-standardised cancer incidence.

RESULTS

Overall cancer risk was modestly increased compared to the general population (SIR 1.15, 95% CI 1.07 to 1.23). Excess risk was observed for 11 cancers, particularly lung (4.02, 95% CI 3.32 to 4.82), non-Hodgkin's lymphoma (1.51, 95% CI 1.20 to 1.88) and liver (8.04, 95% CI 6.18 to 10.3). Reduced risk was observed for six cancers, including prostate (0.16, 95% CI 0.06 to 0.32) and breast (0.48, 95% CI 0.35 to 0.62). Individuals notified with HCV or HBV had a markedly increased risk of liver cancer; lung cancer risk was also increased in those with HCV. HIV was associated with an elevated risk of liver, anus and kidney cancer, non-Hodgkin lymphoma and Kaposi sarcoma. Cancer risk was not increased in individuals without a BBV notification, apart from pancreatic cancer (3.92, 95% CI 1.07 to 10.0). Cancer incidence increased significantly over time (AAPC 9.4%, 4.2% to 15%, p=0.001).

CONCLUSIONS

BBVs play a major role in the cancer risk profile of opioid-dependent individuals registered for OST. To address the dramatic increasing trend in cancer incidence, the OST setting could be utilised for cancer prevention strategies.

Major histocompatibility complex diversity in the endangered Ethiopian wolf (Canis simensis)

The major histocompatibility complex (MHC) influences immune response to infection and vaccination. In most species, MHC genes are highly polymorphic, but few wild canid populations have been investigated. In Ethiopian wolves, we identified four DLA (dog leucocyte antigen)-DRB1, two DLA-DQA1 and five DQB1 alleles. Ethiopian wolves, the world's rarest canids with fewer than 500 animals worldwide, are further endangered and threatened by rabies. Major rabies outbreaks in the Bale Mountains of southern Ethiopia (where over half of the Ethiopian wolf population is located) have killed over 75% of wolves in the affected sub-populations. In 2004, following a rabies outbreak, 77 wolves were vaccinated, and 19 were subsequently recaptured to monitor the effectiveness of the intervention. Pre- and post-vaccination rabies antibody titres were available for 18 animals, and all of the animals sero-converted after vaccination. We compared the haplotype frequencies of this group of 18 with the post-vaccination antibody titre, and showed that one haplotype was associated with a lower response (uncorrected P < 0.03). In general, Ethiopian wolves probably have an adequate amount of MHC variation to ensure the survival of the species. However, we sampled only the largest Ethiopian wolf population in Bale, and did not take the smaller populations further north into consideration.

Interpretation of cloud-climate feedback as produced by 14 atmospheric general circulation models

Understanding the cause of differences among general circulation model projections of carbon dioxide-induced climatic change is a necessary step toward improving the models. An intercomparison of 14 atmospheric general circulation models, for which sea surface temperature perturbations were used as a surrogate climate change, showed that there was a roughly threefold variation in global climate sensitivity. Most of this variation is attributable to differences in the models' depictions of cloud-climate feedback, a result that emphasizes the need for improvements in the treatment of clouds in these models if they are ultimately to be used as climatic predictors.

Low-coverage vaccination strategies for the conservation of endangered species

The conventional objective of vaccination programmes is to eliminate infection by reducing the reproduction number of an infectious agent to less than one, which generally requires vaccination of the majority of individuals. In populations of endangered wildlife, the intervention required to deliver such coverage can be undesirable and impractical; however, endangered populations are increasingly threatened by outbreaks of infectious disease for which effective vaccines exist. As an alternative, wildlife epidemiologists could adopt a vaccination strategy that protects a population from the consequences of only the largest outbreaks of disease. Here we provide a successful example of this strategy in the Ethiopian wolf, the world's rarest canid, which persists in small subpopulations threatened by repeated outbreaks of rabies introduced by domestic dogs. On the basis of data from past outbreaks, we propose an approach that controls the spread of disease through habitat corridors between subpopulations and that requires only low vaccination coverage. This approach reduces the extent of rabies outbreaks and should significantly enhance the long-term persistence of the population. Our study shows that vaccination used to enhance metapopulation persistence through elimination of the largest outbreaks of disease requires lower coverage than the conventional objective of reducing the reproduction number of an infectious agent to less than one.

Rabies in endangered Ethiopian wolves

With rabies emerging as a particular threat to wild canids, we report on a rabies outbreak in a subpopulation of endangered Ethiopian wolves in the Bale Mountains, Ethiopia, in 2003 and 2004. Parenteral vaccination of wolves was used to manage the outbreak.

Tonsillectomy in diagnosis of the unknown primary tumor of the head and neck

OBJECTIVES

The purpose of this study was to discuss the experience of one tumor registry with performing tonsillectomy in the diagnostic approach to unknown head and neck primary tumors. It also describes the importance of including tonsillectomy in this evaluation algorithm.

STUDY DESIGN

A retrospective chart review was done of 68 patients with either tonsillar or unknown primary squamous cell carcinoma culled from 829 patients seen from 1956 to 1996 at the head and neck tumor registry at the Naval Medical Center San Diego.

METHODS

Records from the head and neck tumor registry, radiation oncology service, and pathology department were reviewed with attention to presenting symptom, initial examination, diagnostic studies performed, and type and result of biopsies performed.

RESULTS

Thirty-four patients sought treatment for a neck lymph node metastasis of squamous cell carcinoma without an identifiable primary tumor site. Six of these (18%) had the primary site diagnosed by performing tonsillectomy ipsilateral to the presenting neck mass. Six of 14 T1 tonsillar carcinomas in this series had the primary site identified by tonsillectomy.

CONCLUSIONS

Despite a diligent search, a primary tumor site may not be found in the head and neck cancer patient. The tonsil may harbor an occult squamous cell carcinoma. The patient benefits from identification of the initial tumor site because postoperative irradiation ports may be reduced and because surveillance for recurrence may be improved. For these reasons, tonsillectomy should be performed ipsilateral to the presenting cervical metastasis if no other primary tumor site is identified.

Assessment of the respiratory actions of intramuscular morphine in conscious dogs

The actions on the respiratory system of 0.25, 0.5 and 1.0 mg kg(-1) morphine given intramuscularly were studied in conscious dogs. Dogs breathed oxygen with 0, 2 and 4 per cent CO(2), in that order, through a mask attached to a flow sensor and connected to a respiratory mechanics monitor. When a steady state period of respiration was reached breathing pure oxygen, respiratory rate, tidal volume, respiratory minute volume, peak expiratory flow rate and end tidal CO(2)(PetCO(2)) were measured. The respiratory minute volume and PetCO(2) were measured when the dogs breathed 2 and 4 per cent CO(2) in oxygen, the points plotted onto a graph and the gradient of the line, describing the PCO(2)/ventilation response, plus the intercept with the y-axis were determined. Measurements for each morphine dose were taken before injection and at 30 minutes, 1, 2, 3, 4, 6 and 8 hours post injection. The incidence of panting after morphine was dose related and it occurred in all dogs given the high dose. Morphine reduced the gradients of the PCO(2)/ventilation response lines and raised the intercept. Other changes were increased respiratory minute volume and peak expiratory flow and decreased PetCO(2) and tidal volume.

Complications of tonsillectomy and adenoidectomy

Adenotonsillectomy is generally safe surgery, but surgeons should be cognizant of potential complications and be prepared to manage them. Postoperative hemorrhage usually responds to local measures or cautery but can be life-threatening. Preoperative screening of coagulation profiles appears unnecessary. Anesthetic risks have declined with modern techniques, but airway risks, aspiration, and pulmonary edema are possible. Nasopharyngeal valving may be altered by velopharyngeal incompetence or nasopharyngeal stenosis. Sore throat, otalgia, fever, dehydration, and uvular edema are more common postoperative complaints. Less common complications include atlantoaxial subluxation, mandible condyle fracture, infection, eustachian tube injury, and psychological trauma. The prevalence, management, and strategies for avoidance of these are discussed.

Reliability of disposable intraoperative facial nerve stimulators

Facial nerve injury is one major morbidity of surgery performed along the course of this nerve. Surgeons frequently employ stimulators to identify and protect the nerve. Both disposable devices as well as larger, reusable stimulators are available. Despite their common use, relatively little documentation exists regarding the safety and reliability of these devices. We tested the electrical output of the four disposable, single-use motor nerve stimulators that are marketed in the United States. We found that each produced consistent stimulus output over time. One stimulator slightly exceeded the manufacturer's listed output while three devices produced significantly less voltage and current than specified by the manufacturer.

Modeling the Exchanges of Energy, Water, and Carbon Between Continents and the Atmosphere

Atmospheric general circulation models used for climate simulation and weather forecasting require the fluxes of radiation, heat, water vapor, and momentum across the land-atmosphere interface to be specified. These fluxes are calculated by submodels called land surface parameterizations. Over the last 20 years, these parameterizations have evolved from simple, unrealistic schemes into credible representations of the global soil-vegetation-atmosphere transfer system as advances in plant physiological and hydrological research, advances in satellite data interpretation, and the results of large-scale field experiments have been exploited. Some modern schemes incorporate biogeochemical and ecological knowledge and, when coupled with advanced climate and ocean models, will be capable of modeling the biological and physical responses of the Earth system to global change, for example, increasing atmospheric carbon dioxide.

Epidural administration of bupivacaine, morphine, or their combination for postoperative analgesia in dogs

OBJECTIVE

To compare the analgesic effects of epidural administration of morphine (MOR), bupivacaine hydrochloride (BUP), their combination (COM), and 0.9% sterile NaCl solution (SAL) in dogs undergoing hind limb orthopedic surgeries.

DESIGN

Blinded, randomized clinical trial.

ANIMALS

41 healthy dogs admitted for elective orthopedic surgeries involving the pelvis or hind limbs.

PROCEDURE

Analgesic and control agents were administered postoperatively prior to recovery from isoflurane anesthesia. Ten dogs received MOR, 0.1 mg/kg of body weight; 10 received BUP, 0.5%, 1 ml/10-cm distance from the occipital protuberance to the lumbosacral space; 11 received COM; and 10 received SAL epidurally. Dogs were monitored for 24 hours after epidural injection for pain score, heart and respiratory rates, blood pressure, time to required administration of supplemental analgesic agent, total number of supplemental doses of analgesic agent required, and plasma concentrations of cortisol, MOR, and BUP.

RESULTS

Pain scores were significantly lower in dogs in the COM and BUP groups than in dogs in the SAL group. Pain scores also were significantly lower in dogs in the COM group than in dogs in the MOR group. Time to required administration of supplemental analgesic agent was longer for dogs in the COM group than for dogs in the MOR and SAL groups. Total number of supplemental doses of analgesic agent required was lower for dogs in the BUP and COM groups than for dogs in the SAL group.

CLINICAL IMPLICATIONS

Postoperative epidural administration of COM or BUP alone provides longer-lasting analgesia, compared with MOR or SAL.

Epistaxis balloon catheter stabilization of zygomatic arch fractures

Isolated zygomatic arch fractures represent about 10% of facial fractures. Most are easily reduced, but about 7% require fixation. Stabilization with plates, transcutaneous wiring, and various packing materials may involve additional morbidity and other drawbacks. A double balloon epistaxis catheter may be inserted beneath the arch fracture site and inflated for 5 to 7 days as a relatively simple, reliable alternative that involves minimal morbidity.

Evaluation of pulmonary function and analgesia in dogs after intercostal thoracotomy and use of morphine administered intramuscularly or intrapleurally and bupivacaine administered intrapleurally

Eighteen dogs undergoing lateral thoracotomy at the left fifth intercostal space were randomly assigned to 1 of 3 postoperative analgesic treatment groups of 6 dogs each as follows: group A, morphine, 1.0 mg/kg of body weight, IM; group B, 0.5% bupivacaine, 1.5 mg/kg given interpleurally; and group C, morphine, 1.0 mg/kg given interpleurally. Heart rate, respiratory rate, arterial blood pressure, arterial blood gas tensions, alveolar-arterial oxygen differences, rectal temperature, pain score, and pulmonary mechanics were recorded hourly for the first 8 hours after surgery, and at postoperative hours 12, 24, and 48. These values were compared with preoperative (control) values for each dog. Serum morphine and cortisol concentrations were measured at 10, 20, and 30 minutes, hours 1 to 8, and 12 hours after treatment administration. All dogs had significant decreases in pHa, PaO2, and oxygen saturation of hemoglobin, and significant increases in PaCO2 and alveolar-arterial oxygen differences in the postoperative period, but these changes were less severe in group-B dogs. Decreases of 50% in lung compliance, and increases of 100 to 200% in work of breathing and of 185 to 383% in pulmonary resistance were observed in all dogs after surgery. Increases in work of breathing were lower, and returned to preoperative values earlier in group-B dogs. The inspiratory time-to-total respiratory time ratio was significantly higher in group-B dogs during postoperative hours 5 to 8, suggesting improved analgesia. Blood pressure was significantly lower in group-A dogs for the postoperative hour. Significant decreases in rectal temperature were observed in all dogs after surgery, and hypothermia was prolonged in dogs of groups A and C. Significant differences in pain score were not observed between treatment groups. Cortisol concentration was high in all dogs after anesthesia and surgery, and was significantly increased in group-B dogs at hours 4 and 8. Significant differences in serum morphine concentration between groups A and C were only observed 10 minutes after treatment administration. In general, significant differences in physiologic variables between groups A and C were not observed. Results of the study indicate that the anesthesia and thoracotomy are associated with significant alterations in pulmonary function and lung mechanics. Interpleurally administered bupivacaine appears to be associated with fewer blood gas alterations and earlier return to normal of certain pulmonary function values. Interpleural administration of morphine does not appear to provide any advantages, in terms of analgesia or pulmonary function, compared with its IM administration.

Uncertainties in Carbon Dioxide Radiative Forcing in Atmospheric General Circulation Models

Global warming caused by an increase in the concentrations of greenhouse gases, is the direct result of greenhouse gas-induced radiative forcing. When a doubling of atmospheric carbon dioxide is considered, this forcing differed substantially among 15 atmospheric general circulation models. Although there are several potential causes, the largest contributor was the carbon dioxide radiation parameterizations of the models.

The role of the Medicare fiscal intermediary and the regional home health intermediary, Part 2

The Medicare fiscal intermediaries (FIs) are private insurance companies that serve as the federal government's agents in the administration of the Medicare program, including the payment of claims. There are two primary functions of the FI--reimbursement review and medical coverage review. Hospital-based home health agencies relate to the hospital's FI for reimbursement purposes. All home health agencies are assigned to a special FI, the Regional Home Health Intermediary (RHHI), for medical review issues. This may be the same FI or a different one than that audits the hospital's cost report. Freestanding home health agencies deal with separate reimbursement and medical review divisions within a single RHHI's office. The author reviews the role of the Medicare FI and the RHHI and their relationship to home health agencies. Part 1 was featured in the June issue.

The role of the Medicare fiscal intermediary and the Regional Home Health Intermediary, Part 1

The Medicare fiscal intermediaries (FIs) are private insurance companies that serve as the federal government's agents in the administration of the Medicare program, including the payment of claims. There are two primary functions for the FI--reimbursement review and medical coverage review. Hospital-based home health agencies relate to the hospital's FI for reimbursement purposes. All home health agencies are assigned to a special FI, the Regional Home Health Intermediary (RHHI), for medical review issues. The same or a different FI may audit the hospital's cost report. Freestanding home health agencies deal with separate reimbursement and medical review divisions within a single RHHI's office. The author reviews the role of the Medicare FI and the RHHI and their relationship to home health agencies. Part 2 will appear in the July/August issue.

Management of recurrent otitis media

Recurrent otitis media is defined as three or more episodes of acute otitis media in six months or four or more episodes in one year, with the bouts of acute infection separated by intervals of full resolution. The disorder is common in children and is different from otitis media with effusion, the other frequently encountered chronic ear disease. Daily low-dose antibiotic therapy is recommended as initial prophylaxis against recurrent otitis media. Pressure-equalizing tubes may be used in patients who have more than one episode of breakthrough otitis media while receiving antibiotics. Adenoidectomy should be reserved for use when pressure-equalizing tubes fail or when insertion of a second set of tubes is required.

Indications for tonsillectomy and adenoidectomy

Tonsillectomy and adenoidectomy are separate procedures that should be performed for distinct reasons. Studies now indicate that severe, recurrent pharyngitis responds well to tonsillectomy. According to separate recommendations from the American Medical Association and the American Academy of Pediatrics, patients are candidates for tonsillectomy if they have four or more episodes of pharyngitis a year. Recurrent otitis media and chronic otitis media are improved by adenoidectomy, although placement of pressure-equalizing tubes remains the preferred initial treatment for these conditions. Adenotonsillectomy improves severe upper airway obstruction (cor pulmonale and obstructive sleep apnea), as well as milder forms of airway obstruction (loud snoring). The effectiveness of these procedures in proposed indications, such as sinusitis and adenoiditis, is less well substantiated.