Evaluation of variation in special educational needs provision and its impact on health and education using administrative records for England: umbrella protocol for a mixed-methods research programme

INTRODUCTION

One-third of children in England have special educational needs (SEN) provision recorded during their school career. The proportion of children with SEN provision varies between schools and demographic groups, which may reflect variation in need, inequitable provision and/or systemic factors. There is scant evidence on whether SEN provision improves health and education outcomes.

METHODS

The Health Outcomes of young People in Education (HOPE) research programme uses administrative data from the Education and Child Health Insights from Linked Data-ECHILD-which contains data from all state schools, and contacts with National Health Service hospitals in England, to explore variation in SEN provision and its impact on health and education outcomes. This umbrella protocol sets out analyses across four work packages (WP). WP1 defined a range of 'health phenotypes', that is health conditions expected to need SEN provision in primary school. Next, we describe health and education outcomes (WP1) and individual, school-level and area-level factors affecting variation in SEN provision across different phenotypes (WP2). WP3 assesses the impact of SEN provision on health and education outcomes for specific health phenotypes using a range of causal inference methods to account for confounding factors and possible selection bias. In WP4 we review local policies and synthesise findings from surveys, interviews and focus groups of service users and providers to understand factors associated with variation in and experiences of identification, assessment and provision for SEN. Triangulation of findings on outcomes, variation and impact of SEN provision for different health phenotypes in ECHILD, with experiences of SEN provision will inform interpretation of findings for policy, practice and families and methods for future evaluation.

ETHICS AND DISSEMINATION

Research ethics committees have approved the use of the ECHILD database and, separately, the survey, interviews and focus groups of young people, parents and service providers. These stakeholders will contribute to the design, interpretation and communication of findings.

Exploring placement stability for children in out-of-home care in England: a sequence analysis of longitudinal administrative data

BACKGROUND

To monitor stability of care, the proportion of children in England who have experienced three or more placements in the preceding 12-month period is published in government statistics. However, these annual snapshots cannot capture the complexity and heterogeneity of children's longitudinal care histories.

OBJECTIVE

To describe the stability of care histories from birth to age 18 for children in England using a national administrative social care dataset, the Children Looked After return (CLA).

PARTICIPANTS AND SETTING

We analyzed CLA data for a large, representative sample of children born between 1992 and 1994 (N = 16,000).

METHODS

Using sequence analysis methods, we identified distinct patterns of stability, based on the number, duration, and timing of care placements throughout childhood.

RESULTS

Although care histories were varied, six distinct patterns of stability were evident including; adolescent 1^st entries (17.6%), long-term complex care (13.1%) and early intervention (6.9%). Overall, most children (58.4%) had a care history that we classified as shorter term care with an average of 276 days and 2.48 placements in care throughout childhood. Few children (4.0%) had a care history that could be described as long-term stable care.

CONCLUSIONS

Longitudinal analyses of administrative data can refine our understanding of how out-of-home care is used as a social care intervention. Sequence analysis is a particularly useful tool for exploring heterogeneous and complex care histories. Considering out-of-home care histories from a life course perspective over the entire childhood period could enable service providers to better understand and address the needs of looked after children.

Maternal obesity causes fetal hypothalamic insulin resistance and disrupts development of hypothalamic feeding pathways

Objective

Perinatal exposure to maternal obesity results in predisposition of offspring to develop obesity later in life. Increased weight gain in offspring exposed to maternal obesity is usually associated with hyperphagia, implicating altered central regulation of food intake as a cause. We aimed to define how maternal obesity impacts early development of the hypothalamus to program lasting dysfunction in feeding regulatory pathways.

Methods

Mice offspring of diet-induced obese mothers were compared to the offspring of lean control mothers. We analysed gene expression in the fetal hypothalamus, alongside neurosphere assays to investigate the effects of maternal obesity on neural progenitor cell proliferation in vitro. Western blotting was used to investigate the insulin signalling pathway in the fetal hypothalamus. Characterisation of cell type and neuropeptide profile in adulthood was linked with analyses of feeding behaviour.

Results

There was a reduction in the expression of proliferative genes in the fetal hypothalamus of offspring exposed to maternal obesity. This reduction in proliferation was maintained in vitro when hypothalamic neural progenitor cells were grown as neurospheres. Hypothalamic fetal gene expression and neurosphere growth correlated with maternal body weight and insulin levels. Foetuses of obese mothers showed hypothalamic insulin resistance, which may be causative of reduced proliferation. Furthermore, maternal obesity activated the Notch signalling pathway in neonatal offspring hypothalamus, resulting in decreased neurogenesis. Adult offspring of obese mothers displayed an altered ratio of anorexigenic and orexigenic signals in the arcuate nucleus, associated with an inability to maintain energy homeostasis when metabolically challenged.

Conclusions

These findings show that maternal obesity alters the molecular signature in the developing hypothalamus, which is associated with disrupted growth and development of hypothalamic precursor cells and defective feeding regulation in adulthood. This is the first report of fetal hypothalamic insulin resistance in an obese pregnancy and suggests a mechanism by which maternal obesity causes permanent changes to hypothalamic structure and function.

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Exposure to maternal obesity reduces hypothalamic neural progenitor cell growth.

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Maternal obesity activates hypothalamic Notch signalling and reduces neurogenesis.

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Maternal obesity causes fetal hypothalamic insulin resistance.

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Maternal obesity alters the ratio of anorexigenic/orexigenic signals in ARC.

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Changes in food intake precede increased adiposity in offspring of obese dams.

Impact of air pollution on educational attainment for respiratory health treated students: A cross sectional data linkage study

INTRODUCTION

There is some evidence that exam results are worse when students are acutely exposed to air pollution. Studies investigating the association between air pollution and academic attainment have been constrained by small sample sizes.

METHODS

Cross sectional educational attainment data (2009-2015) from students aged 15-16 years in Cardiff, Wales were linked to primary health care data, modelled air pollution and measured pollen data, and analysed using multilevel linear regression models. Annual cohort, school and individual level confounders were adjusted for in single and multi-pollutant/pollen models. We stratified by treatment of asthma and/or Seasonal Allergic Rhinitis (SAR).

RESULTS

A unit (10μg/m3) increase of short-term exposure to NO2 was associated with 0.044 (95% CI: -0.079, -0.008) reduction of standardised Capped Point Score (CPS) after adjusting for individual and household risk factors for 18,241 students. This association remained statistically significant after controlling for other pollutants and pollen. There was no association of PM2.5, O3, or Pollen with standardised CPS remaining after adjustment. We found no evidence that treatment for asthma or SAR modified the observed NO2 effect on educational attainment.

CONCLUSION

Our study showed that short-term exposure to traffic-related air pollution, specifically NO2, was associated with detrimental educational attainment for students aged 15-16. Longitudinal investigations in different settings are required to confirm this possible impact and further work may uncover the long-term economic implications, and degree to which impacts are cumulative and permanent.

Is educational attainment associated with acute exposure to air pollution and pollen, and is it worse for pupils with asthma and seasonal allergic rhinitis?

IntroductionThere is a lack of evidence of the adverse effects of air pollution and pollen on cognition for people with air quality related health conditions. This study explored the effects of air quality and respiratory health conditions on educational attainment for 18,241 pupils across the city of Cardiff, United Kingdom. Objectives and ApproachAnonymised, routinely collected health and education data were linked at the household and school level with modelled high spatial resolution pollution data, and daily pollen measurements using the Secure Anonymised Information Linkage (SAIL) databank. This created 7 repeated cross-sectional cohorts (2009-2015). Multilevel linear regression analysis examined whether exam performance was associated with health status and/or air quality levels averaged at school and home locations during revision and examination periods. We also investigated the combined effects of air quality and associations with educational attainment for pupils who were treated for asthma and/or Severe Allergic Rhinitis (SAR), and those who were not. ResultsThe cohort contained 9337 males and 8904 female pupils. There were 871 treated for asthma, 2091 for SAR, and 634 treated for both. Asthma was not associated with exam performance (p=0.700). However, SAR was positively associated with exam performance (p 2) was negatively associated with educational attainment (p = 0.002). Other indicators of air quality (pollutants: Ozone, Particulate Matter - PM2.5, and pollen) were not associated with educational attainment (p> 0.05). Exposure to NO2 was negatively associated with educational attainment irrespective of treatment for asthma or SAR. There was no combined effect of air quality on the variation in educational attainment between those who are treated for asthma and/or SAR and those who were not. Conclusion/ImplicationsIrrespective of health status, exposure to NO2 was negatively associated with educational attainment. Treatment seeking behaviour may be a possible explanation for the positive association between SAR and educational attainment. For a more accurate reflection of health status, health outcomes not subject to treatment seeking behaviour should be investigated.

Cognitive development Respiratory Tract Illness and Effects of eXposure (CORTEX) project: Combining high spatial resolution pollution measurements with individual level data, a methodological approach

IntroductionThe Secure Anonymised Information Linkage (SAIL) databank facilitated linkage of routinely collected health and education data, high spatial resolution pollution modelling and daily pollen measurements for 18,241 pupils in 7 cross-sectional cohorts across Cardiff city, UK, to investigate effects of air quality and respiratory health conditions on education attainment. Objectives and ApproachAn urban atmospheric dispersion and chemistry modelling system (ADMS-Urban) simulated modelled hourly concentrations of air pollutants: PM2.5, PM10, NO2 and ozone levels. These were summarised into minimum, average and maximum daily readings for 4 time periods (e.g. school hours 9am-3pm) for all home and school locations across Cardiff between 2009 and 2015. The combination of different pollutants, measurements and time-periods created a comprehensive multi-row dataset per location. We transformed the dimensionality of this high-resolution data to create one row of summarised data per pupil per cohort, in preparation for statistical analysis. Results157,361 school and home locations across Cardiff were anonymised and household linkage fields were appended to combine pollution estimates at the household/school to individual health data. The pollution dataset contained 369 columns, 472,083 rows per year with one column per location, pollutant type, pollutant measurement, daily time-period, and day of year. Dataset transformation reduced algorithm computation by creating a single date column, producing a five column, 3,446,205,900-row matrix per year dataset. The algorithm adjusted for weekends, school/bank holidays and allowed location to vary 3pm-5pm on school days when pupil location was uncertain. The algorithm calculated tailored pollution exposures per pupil for revision and examination periods, creating one row per pupil and reducing 7 years of data and 24 billion rows to 18,241. Conclusion/ImplicationsWe successfully linked 95% of the cohorts’ household/school pollution data to their corresponding health and education data. This demonstrates data linking retrospective exposures for total populations using multiple daily locations, and extends our analysis platform for natural experiments to include daily exposure. Future work includes adding modelled route exposures.

Creating individual level air pollution exposures in an anonymised data safe haven: a platform for evaluating impact on educational attainment

Introduction

There is a lack of evidence on the adverse effects of air pollution on cognition for people with air quality-related health conditions. We propose that educational attainment, as a proxy for cognition, may increase with improved air quality. This study will explore whether asthma and seasonal allergic rhinitis, when exacerbated by acute exposure to air pollution, is associated with educational attainment.

Objective

To describe the preparation of individual and household-level linked environmental and health data for analysis within an anonymised safe haven. Also to introduce our statistical analysis plan for our study: COgnition, Respiratory Tract illness and Effects of eXposure (CORTEX).

Methods

We imported daily air pollution and aeroallergen data, and individual level education data into the SAIL databank, an anonymised safe haven for person-based records. We linked individual-level education, socioeconomic and health data to air quality data for home and school locations, creating tailored exposures for individuals across a city. We developed daily exposure data for all pupils in repeated cross sectional exam cohorts (2009-2015).

Conclusion

We have used the SAIL databank, an innovative, data safe haven to create individual-level exposures to air pollution and pollen for multiple daily home and school locations. The analysis platform will allow us to evaluate retrospectively the impact of air quality on attainment for multiple cross-sectional cohorts of pupils. Our methods will allow us to distinguish between the pollution impacts on educational attainment for pupils with and without respiratory health conditions. The results from this study will further our understanding of the effects of air quality and respiratory-related health conditions on cognition.

Highlights

Cognitive development Respiratory Tract Illness and Effects of eXposure (CORTEX) project: Data processing challenges in combining high spatial resolution pollution level data with individual level health and education data

Background and ObjectivesThere is a lack of evidence of the adverse effects of air pollution and pollen on cognition for people with air quality-related health conditions. The CORTEX project combined routinely collected health and education data, high spatial resolution air pollution modelling, and daily pollen measurements for 18,241 pupils living in Cardiff, UK, between 2009 and 2015, to investigate the acute effects of air quality and respiratory conditions on education attainment. DatasetsAir pollutants PM2.5, PM10, NO2, and ozone levels were modelled for 157,361 home and school locations, anonymised into the Secure Anonymised Information Linkage (SAIL) Databank, and summarised into minimum, average and maximum readings for 4 daily time periods reflecting pupil home/school exposure. Adding a unique Residential Anonymised Linking Field (RALF) allowed linkage of pollution estimates to individual level data. Annual pollution datasets contained 369 columns and 472,083-rows, with one column per location, pollutant, daily time-period and day of year. Dataset transformation produced a 5 column, 3,446,205,900-row matrix per year. Methods and ConclusionsAn algorithm using Structured Query Language (SQL) to manage data held within a relational database management system, was designed to reduce dimensionality from 24 billion to 18,241 rows of data. The algorithm calculated average means for each pollutant (PM2.5, PM10, NO2, and ozone levels) over the revision and examination periods, and summarised data into one row per pupil. The algorithm adjusted for weekends, school, and bank holidays, it calculated daily pollutant exposure for each pupil, and successfully linked 95% of pupil pollution exposures to their health and education data.

Are children who are treated for asthma and seasonal allergic rhinitis disadvantaged in their educational attainment when acutely exposed to air pollution and pollen? A feasibility study

BackgroundThere is a lack of evidence of the adverse effects which air quality has on cognition for people with air quality-related health conditions, these are not widely documented in the literature. Educational attainment, as a proxy for cognition, may increase with improved air quality. ObjectivesPrepare individual and household level linked environmental and health data for analysis within an anonymised safe haven; analyse the linked dataset for our study investigating: Cognition, Respiratory Tract illness and Effects of eXposure (CORTEX). MethodsAnonymised, routinely collected health and education data were linked with high spatial resolution pollution measurements and daily pollen measurements to provide repeated cross-sectional cohorts (2009-2015) on 18,241 pupils across the city of Cardiff, using the SAIL databank. A fully adjusted multilevel linear regression analysis examined associations between health status and/or air quality. Cohort, school and individual level confounders were controlled for. We hope that using individual-level multi-location daily exposure assessment will help to clarify the role of traffic and prevent potential community-level confounding. Combined effects of air quality on variation in educational attainment between those treated for asthma and/or Severe Allergic Rhinitis (SAR), and those not treated, was also investigated. FindingsAsthma was not associated with exam performance (p=0.7). However, SAR was positively associated with exam performance (p<0.001). Exposure to air pollution was negatively associated with educational attainment regardless of health status. ConclusionsIrrespective of health status, air quality was negatively associated with educational attainment. Treatment seeking behaviour may explain the positive association between SAR and educational attainment. For a more accurate reflection of health status, health outcomes not subject to treatment seeking behaviours, such as emergency hospital admission, should be investigated.

Exploring longitudinal care histories for looked after children: a sequence analysis of administrative social care data

BackgroundOutcomes for children in care vary by the stability of their placements (for example, more placement changes have been associated with poorer educational attainment). Official statistics describing the stability of care histories for children in England are limited to placement changes within a 12-month period. These annual statistical ‘snapshots’ cannot capture the complexity of children’s experiences; however, as administrative data have been routinely collected since 1992, it is possible to reconstruct longitudinal care histories. ObjectiveTo identify distinct patterns of care history by applying sequence analysis methods to longitudinal, administrative data. MethodsWe extracted care histories from birth to age 18 for a large, representative sample of children born 1992-94 (N=16,000) from routinely-collected Children Looked After Return data. We explored the heterogeneity of  children’s care histories in terms of stability and identified sub-groups based on the number, duration and timing of placements using sequence analysis methods. ResultsChildren’s care histories were varied with the number of placements ranging from 1 to 184 (median: 2). However, six distinct sub-groups of care history were evident including; adolescent entries (17.6%), long-term instability (13.1%) and early intervention (6.9%). Overall, most children (58.4%) had a care history that could be classified as’short-term care’ with an average of 276 days in care and 2.48 placements throughout childhood. Few children (4.0%) had a care history that could be described as ‘long-term stable care’. ConclusionsSequence analyses of longitudinal data can refine our understanding of how out-of-home care is used as a social care intervention. Despite the policy focus on achieving long-term stability for children in care, the vast majority of children remain in care for a short period of time. Future work exploring how outcomes vary between the different sub-groups of care history could enable better evaluation of the effects of longitudinal care experiences.

Early academic achievement in children with isolated clefts: a population-based study in England

OBJECTIVES

We used national data to study differences in academic achievement between 5-year-old children with an isolated oral cleft and the general population. We also assessed differences by cleft type.

METHODS

Children born in England with an oral cleft were identified in a national cleft registry. Their records were linked to databases of hospital admissions (to identify additional anomalies) and educational outcomes. Z-scores (signed number of SD actual score is above national average) were calculated to make outcome scores comparable across school years and across six assessed areas (personal development, communication and language, maths, knowledge of world, physical development andcreative development).

RESULTS

2802 children without additional anomalies, 5 years old between 2006 and 2012, were included. Academic achievement was significantly below national average for all six assessed areas with z-scores ranging from -0.24 (95% CI -0.32 to -0.16) for knowledge of world to -0.31 (-0.38 to -0.23) for personal development. Differences were small with only a cleft lip but considerably larger with clefts involving the palate. 29.4% of children were documented as having special education needs (national rate 9.7%), which varied according to cleft type from 13.2% with cleft lip to 47.6% with bilateral cleft lip and palate.

CONCLUSIONS

Compared with national average, 5-year-old children with an isolated oral cleft, especially those involving the palate, have significantly poorer academic achievement across all areas of learning. These outcomes reflect results of modern surgical techniques and multidisciplinary approach. Children with a cleft may benefit from extra academic support when starting school.

Factors associated with re-entry to out-of-home care among children in England

Exiting and re-entering out-of-home care (OHC) is considered a disruption to permanence which may have long-lasting, negative consequences for children due to a lack of stability and continuity. Each year approximately one-third of children in OHC in England exit, but information is lacking on rates of re-entries and associated factors. Using national administrative data, we calculated rates of re-entry among children exiting OHC from 2007 to 2012, identified key child and care factors associated with re-entry using Cox proportional hazards modelling, and developed a simple probability calculator to estimate which groups of children are most likely to re-enter OHC within three months. Between 2007 and 2012 re-entries to OHC in England decreased (from 23.3% to 14.4% within one year of exit, p<0.001), possibly due to concurrent changes in the way children exited OHC. Overall, more than one-third of children exiting OHC in 2008 re-entered within five years (35.3%, N=4076), but rates of re-entry varied by child and care characteristics including age, ethnicity, mode of exit, and placement stability. Based on these associated factors, we developed a calculator that can estimate the likelihood of rapid re-entry to OHC for a group of children and could be used by social care practitioners or service planners. Our findings provide insight into which groups of children are most likely to re-enter OHC, who may benefit from additional support or ongoing monitoring.

Changes in first entry to out-of-home care from 1992 to 2012 among children in England

Placement in out-of-home care (OHC) indicates serious childhood adversity and is associated with multiple adverse outcomes. Each year 0.5% of children in England live in OHC but evidence is lacking on the cumulative proportion who enter during childhood and how this varies over time. We measured the proportion of children born between 1992 and 2011 who entered OHC, including variation in rates of entry over time, and explored the determinants of these changes using decomposition methods. We also described changes in placement type, duration and stability. By age 18, 3.3% of children born 1992-94 entered OHC. This proportion varied by ethnicity (1.6% of White vs. 4.5% of Black children born 2001-03 entered OHC by age 9, 95% CI [1.5-1.7] and [4.4-4.6], p<0.001) and increased over time (0.8% of children born 2009-11 entered OHC by age 1 vs. 0.5% born 1992-94, 95% CI [0.7-0.9] and [0.4-0.6], p<0.001). This overall increase was driven primarily by the increased rate of entry among White children and not by concurrent changes in the population's ethnic composition. The proportion of children entering OHC in England is increasing and characteristics of the care they receive are changing with earlier intervention and longer, more stable placements. Further research is required to understand the reasons for these changes in practice and whether they are cost-effective, sustainable, and improve outcomes for children and society.

The drivers of month-of-birth differences in children's cognitive and non-cognitive skills

Previous research has found that children who are born later in the academic year have lower educational attainment, on average, than children who are born earlier in the year, especially at younger ages; much less is known about the mechanisms that drive this inequality. The paper uses two complementary identification strategies to estimate an upper bound of the effect of age at test by using rich data from two UK birth cohorts. We find that differences in the age at which cognitive skills are tested accounts for the vast majority of the difference in these outcomes between children who are born at different times of the year, whereas the combined effect of the other factors (age of starting school, length of schooling and relative age) is close to zero. This suggests that applying an age adjustment to national achievement test scores may be an appropriate policy response to overcome the penalty that is associated with being born later in the academic year. Age at test does not, however, explain all of the difference in children's view of their own scholastic competence. Age adjusting national achievement test scores may help to overcome differences in ability beliefs between children who are born at different times of the year, but our results suggest that additional policy responses may be required.

The tolerability of dothiepin: a review of clinical studies between 1963 and 1990 in over 13,000 depressed patients

1. A total of 13,834 depressed patients were exposed to dothiepin most frequently at a dose of 150 mg/day and over 6 weeks, in 116 clinical studies between 1963 and 1990. 2. Overall, 2,066 (15%) patients were withdrawn prematurely from dothiepin for a variety of reasons, the most commonly specified reason being due to drug-related events in 500 (4%) patients. 3. In the remaining 11,768 patients, there were 9,312 reports of unwanted events most typically associated with the pharmacological effects of a tricyclic antidepressant although no serious sequelae were reported. 4. This review indicates that the incidence of serious adverse events associated with dothiepin at therapeutic doses is very low.

Effects of dietary fatty acid saturation on serum and tissue cholesterol concentrations and fecal sterol excretion: a chronic metabolic study in the rat

We studied the effect of the degree of fatty acid saturation on cholesterol metabolism in rats fed either a low cholesterol-low fat diet (control group), high cholesterol-low fat diet (Chol group), high cholesterol-high saturated fat diet (Chol-SF) or high cholesterol-high PUF diet (Chol-PUF). The highest serum cholesterol levels were found in the Chol-SF group. No significant difference in serum cholesterol was found between the Chol and Chol-PUF groups. The Chol-PUF group showed the greatest accumulation of cholesterol in the liver. There was no significant difference in fecal excretion of acidic sterols, cholesterol and coprostanol between the Chol-PUF and Chol-SF groups. We conclude that in chronic feeding experiments in rats: a) high dietary cholesterol intake results in hypercholesterolemia; b) the hypercholesterolemia is accentuated by high dietary SF but is unaffected by PUF; c) addition of PUF to high cholesterol diet leads to massive cholesterol accumulation in the liver which can partly account for the apparent hypocholesterolemic effect of PUF relative to SF; and d) differences in serum and tissue cholesterol levels between SF and PUF supplemented groups are unlikely to be due to their effects on fecal sterol excretion.

Syncytioskeletons in choriocarcinoma in culture

Indirect immunofluorescence microscopy using anti-actin serum has been used to investigate the distribution of actin-containing polymers in BeWo cells. This cell line, derived from a human choriocarcinoma, contains tissue that, like its tissue of origin, is partly syncytial. The syncytial nature has been inferred from study of Nomarski optical sections and from transmission electron microscopy. The multinucleated plaques of tissue possess a syncytioskeleton with a number of actin-containing features characteristic of cultured cells. These include stress fibres, cortical layers and ruffled membranes. Other actin-containing structures are more typical of the related non-pathological syncytiotrophoblast. These include a dense population of microvilli. The overall organization of the actin syncytioskeletons bears no obvious relationship to the number or position of nuclei in the syncytium. Indirect immunofluorescence microscopy has also been employed to localize the protein tubulin in BeWo cells. The microtubules do not appear to be spatially organized by a particular nucleus. Rather, there are numerous microtubule-organizing centres (MTOCs) that exist in the cytoplasm and do not have the expected numerical and positional relationship to nuclei. From these data it appears that polymeric cytoskeletal elements in these syncytia are organized in a manner not immediately subordinate to syncytial nuclei.

The role of leukocytes in ethchlorvynol-induced pulmonary edema

Intravenous administration of ethchlorvynol (Placidyl) is known to produce noncardiogenic pulmonary edema in animals and humans. Since intrapulmonary sequestration of leukocytes has been observed to occur following injection of ethchlorvynol, we evaluated the role of these elements of the blood in producing pulmonary edema. In vivo studies in dogs showed intrapulmonary trapping of leukocytes, as evidenced by increasing leukocyte differences between blood from the pulmonary artery and arterial blood. In both animals with normal leukocyte counts and those depleted of leukocytes (less than 500 cells per millimeter), pulmonary edema occurred, as evidenced by increased pulmonary water after injection of ethchlorvynol. Preparations of isolated lung perfused with either whole blood or leukocyte-poor plasma had similar gains in weight following injection of ethchlorvynol, in spite of marked differences in leukocyte counts. We conclude that intrapulmonary sequestered leukocytes do not play a role in ethchlorvynol-induced pulmonary edema.