Body Mass Index Development and Asthma Throughout Childhood

Several studies have found an association between overweight and asthma, yet the temporal relationship between their onsets remains unclear. We investigated the development of body mass index (BMI) from birth to adolescence among 2,818 children with and without asthma from a Swedish birth cohort study, the BAMSE (a Swedish acronym for “children, allergy, milieu, Stockholm, epidemiology”) Project, during 1994–2013. Measured weight and height were available at 13 time points throughout childhood. Asthma phenotypes (transient, persistent, and late-onset) were defined by timing of onset and remission. Quantile regression was used to analyze percentiles of BMI, and generalized estimating equations were used to analyze the association between asthma phenotypes and the risk of high BMI. Among females, BMI development differed between children with and without asthma, with the highest BMI being seen among females with persistent asthma. The difference existed throughout childhood but increased with age. For example, females with persistent asthma had 2.33 times’ (95% confidence interval: 1.21, 4.49) greater odds of having a BMI above the 85th percentile at age ≥15 years than females without asthma. Among males, no clear associations between asthma and BMI were observed. In this study, persistent asthma was associated with high BMI throughout childhood among females, whereas no consistent association was observed among males.

Intervention to diminish dehydration and kidney damage among sugarcane workers

Objective The aim of this study was to assess the potential to reduce kidney function damage during the implementation of a water, rest, shade (WRS) and efficiency intervention program among sugarcane workers. Methods A WRS intervention program adapted from the US Occupational Safety and Health Administration (OSHA) coupled with an efficiency program began two months into the 5-month harvest. One of the two groups of workers studied was provided with portable water reservoirs, mobile shaded tents, and scheduled rest periods. Health data (anthropometric and questionnaires), blood, and urine were collected at baseline and at three subsequent times over the course of the harvest. Daily wet bulb globe temperatures (WBGT) were recorded. Results Across a working day there were changes in biomarkers indicating dehydration (urine osmolality) and serum albumin and reduced estimated glomerular filtration rate (eGFR). Cross-shift eGFR decrease was present in both groups; -10.5 mL/min/1.73m2 [95% confidence interval (95% CI) -11.8- -9.1], but smaller for the intervention group after receiving the program. Decreased eGFR over the 5-month harvest was seen in both groups: in the one receiving the intervention -3.4 mL/min/1.73m ²(95% CI -5.5- -1.3) and in the other -5.3 (95% CI -7.9- -2.7). The decrease appeared to halt after the introduction of the intervention in the group receiving the program. Conclusion A WRS and efficiency intervention program was successfully introduced for workers in sugarcane fields and appears to reduce the impact of heat stress on acute and over-harvest biomarkers of kidney function. Further research is needed to determine whether biomarker changes predict reduced risk of chronic kidney disease in this type of work.

Human hantavirus infection elicits pronounced redistribution of mononuclear phagocytes in peripheral blood and airways

Hantaviruses infect humans via inhalation of virus-contaminated rodent excreta. Infection can cause severe disease with up to 40% mortality depending on the viral strain. The virus primarily targets the vascular endothelium without direct cytopathic effects. Instead, exaggerated immune responses may inadvertently contribute to disease development. Mononuclear phagocytes (MNPs), including monocytes and dendritic cells (DCs), orchestrate the adaptive immune responses. Since hantaviruses are transmitted via inhalation, studying immunological events in the airways is of importance to understand the processes leading to immunopathogenesis. Here, we studied 17 patients infected with Puumala virus that causes a mild form of hemorrhagic fever with renal syndrome (HFRS). Bronchial biopsies as well as longitudinal blood draws were obtained from the patients. During the acute stage of disease, a significant influx of MNPs expressing HLA-DR, CD11c or CD123 was detected in the patients’ bronchial tissue. In parallel, absolute numbers of MNPs were dramatically reduced in peripheral blood, coinciding with viremia. Expression of CCR7 on the remaining MNPs in blood suggested migration to peripheral and/or lymphoid tissues. Numbers of MNPs in blood subsequently normalized during the convalescent phase of the disease when viral RNA was no longer detectable in plasma. Finally, we exposed blood MNPs in vitro to Puumala virus, and demonstrated an induction of CCR7 expression on MNPs. In conclusion, the present study shows a marked redistribution of blood MNPs to the airways during acute hantavirus disease, a process that may underlie the local immune activation and contribute to immunopathogenesis in hantavirus-infected patients.

Inhalation of hantavirus-infected rodent droppings can cause a wide range of disease ranging from mild symptoms to deaths in humans. Central to hantavirus disease is vascular leakage that can manifest in different organs, including the lungs. Although the virus can infect endothelial cells lining the blood vessels, it does not cause cell death. Instead, activation of the immune system in response to viral infection has been implicated in causing vascular leakage. In this study, we investigated how monocytes and dendritic cells (DCs) are involved in hantavirus disease, given their capacity to activate other immune cells. We obtained unique clinical material from 17 Puumala virus-infected patients including mucosal biopsies from the airways as well as multiple blood draws over the course of disease. In the airways of these patients, we observed an infiltration of monocytes and DCs. In parallel, there was a dramatic depletion in peripheral blood—more than ten-fold—of monocytes and DCs that was sustained throughout the first two weeks of disease. Taken together, this study provides novel insights into immune mediated processes underlying human hantavirus pathogenesis.

Fitness adjusted racial disparities in central adiposity among women in the USA using quantile regression

OBJECTIVE

This study comprehensively explores racial/ethnic disparities in waist circumference (WC) after adjusting for cardiorespiratory fitness (CRF), among both adult and adolescent women, across WC percentiles.

METHODS

Analysis was conducted using data from the 1999 to 2004 National Health and Nutrition Examination Survey. Female participants (n = 3,977) aged 12-49 years with complete data on CRF, height, weight and WC were included. Quantile regression models, stratified by age groups (12-15, 16-19 and 20-49 years), were used to assess the association between WC and race/ethnicity adjusting for CRF, height and age across WC percentiles (10th, 25th, 50th, 75th, 90th and 95th).

RESULTS

For non-Hispanic (NH) Black, in both the 16-19 and 20-49 years age groups, estimated WC was significantly greater than for NH White across percentiles above the median with estimates ranging from 5.2 to 11.5 cm. For Mexican Americans, in all age groups, estimated WC tended to be significantly greater than for NH White particularly for middle percentiles (50th and 75th) with point estimates ranging from 1.9 to 8.4 cm.

CONCLUSIONS

Significant disparities in WC between NH Black and Mexican women, as compared to NH White, remain even after adjustment for CRF. The magnitude of the disparities associated with race/ethnicity differs across WC percentiles and age groups.

Pregnancy outcome in more than 5000 births to women with viral hepatitis: a population-based cohort study in Sweden

Previous studies have shown inconsistent results with respect to hepatitis B (HBV), hepatitis C (HCV) and pregnancy outcome. The aim of this study was to investigate pregnancy outcome in women with HBV or HCV. In a nationwide cohort of births between 2001 and 2011 we investigated the risks of adverse pregnancy outcomes in 2990 births to women with HBV and 2056 births to women with HCV using data from Swedish healthcare registries. Births to women without HBV (n = 1090 979), and births without HCV (n = 1091 913) served as population controls. Crude and adjusted relative risks (aRR) were calculated using Poisson regression analysis. Women with HCV were more likely to smoke (46.7 vs. 8.0%) and to have alcohol dependence (18.9 vs. 1.3%) compared with population controls. Most women with HBV were born in non-Nordic countries (91.9%). Maternal HCV was associated with a decreased risk of preeclampsia (aRR: 0.39, 95% CI: 0.24–0.64), but an increased risk of preterm birth (aRR: 1.32, 95% CI: 1.08–1.60) and late neonatal death (7–27 days: aRR: 3.79, 95% CI: 1.07–13.39) Preterm birth were also more common in mothers with HBV, aRR: 1.21 (95% CI: 1.02–1.45). Both HBV and HCV are risk factors for preterm birth, while HCV seems to be associated with a decreased risk for preeclampsia. Future studies should corroborate these findings.

Phthalates, non-phthalate plasticizers and bisphenols in Swedish preschool dust in relation to children's exposure

Children are exposed to a wide range of chemicals in their everyday environments, including the preschool. In this study, we evaluated the levels of phthalates, non-phthalate plasticizers and bisphenols in dust from 100 Swedish preschools and identified important exposure factors in the indoor environment. In addition, children's total exposure to these chemicals was determined by urine analysis to investigate their relation with dust exposure, and to explore the time trends by comparing with children who provided urine fifteen years earlier. The most abundant plasticizers in preschool dust were the phthalates di-isononyl phthalate (DiNP) and di-(2-ethylhexyl) phthalate (DEHP) with geometric mean levels of 450 and 266μg/g dust, respectively, and the non-phthalate plasticizers bis(2-ethylhexyl) terephthalate (DEHT) and diisononylcyclohexane-1,2-dicarboxylate (DiNCH) found at 105 and 73μg/g dust, respectively. The levels of several substitute plasticizers were higher in newer preschools, whereas the levels of the strictly regulated phthalate di-n-butyl phthalate (DnBP) were higher in older preschools. The presence of foam mattresses and PVC flooring in the sampling room were associated with higher levels of DiNP in dust. Children's exposure from preschool dust ingestion was below established health based reference values and the estimated exposure to different phthalates and BPA via preschool dust ingestion accounted for 2-27% of the total exposure. We found significantly lower urinary levels of BPA and metabolites of strictly regulated phthalates, but higher levels of DiNP metabolites, in urine from the children in this study compared to the children who provided urine samples fifteen years earlier.

Parametric modeling of quantile regression coefficient functions with censored and truncated data

Quantile regression coefficient functions describe how the coefficients of a quantile regression model depend on the order of the quantile. A method for parametric modeling of quantile regression coefficient functions was discussed in a recent article. The aim of the present work is to extend the existing framework to censored and truncated data. We propose an estimator and derive its asymptotic properties. We discuss goodness-of-fit measures, present simulation results, and analyze the data that motivated this article. The described estimator has been implemented in the R package qrcm.

Age at adiposity rebound and body mass index trajectory from early childhood to adolescence; differences by breastfeeding and maternal immigration background

OBJECTIVE

This paper aims to assess association between breastfeeding and maternal immigration background and body mass index development trajectories from age 2 to 16 years.

METHODS

A cohort of children born in Stockholm during 1994 to 1996 was followed from age 2 to 16 years with repeated measurement of height and weight at eight time points (n = 2278). Children were categorized into groups by breastfeeding status during the first 6 months of life and maternal immigration background. Body mass index (BMI) trajectories and age at adiposity rebound were estimated using mixed-effects linear models.

RESULTS

Body mass index trajectories were different by breastfeeding and maternal immigration status (P-value < 0.0001). Compared with exclusively breastfed counterparts, never/short breastfed children of Swedish mothers had a higher BMI trajectory, whereas never/short breastfed children of immigrant mothers followed a lower BMI trajectory. Ages at adiposity rebound were earlier for higher BMI trajectories regardless of maternal immigration background.

CONCLUSION

Differences in BMI trajectories between offspring of immigrant and of Swedish mothers suggest a lack of beneficial association between breastfeeding and long-term BMI development among children of immigrant mothers. Given the relation between long-term BMI development and risk of overweight/obesity, these differences challenge the notion that exclusive breastfeeding is always beneficial for children's BMI development and subsequent risk of overweight/obesity.

The effect of central nervous system involvement and irradiation in childhood acute lymphoblastic leukemia: Lessons from the NOPHO ALL-92 and ALL-2000 protocols

BACKGROUND

Central nervous system irradiation (CNS-RT) has played a central role in the cure of acute lymphoblastic leukemia (ALL), but due to the risk of long-term toxicity, it is now considered a less-favorable method of CNS-directed therapy.

PROCEDURES

Retrospectively, we estimated the effect of CNS involvement and CNS-RT on events and overall survival (OS) in 835 children treated for high-risk ALL in the Nordic Society of Paediatric Haematology and Oncology (NOPHO) ALL-92 and ALL-2000 trials.

RESULTS

We did not observe a statistically significant difference in the OS or event-free survival (EFS) in patients with CNS involvement at diagnosis, but the risk of isolated CNS relapse was higher (hazard ratio [HR] 7.09, P < 0.001). CNS-RT was given to 169 of the 783 patients in first complete remission, of which 16 had CNS involvement at diagnosis. In general, CNS-RT improved EFS (HR 0.58, P < 0.05) but not OS (HR 0.69, P = n.s.). The adjusted HRs for all relapses, isolated bone marrow relapse, CNS-involving relapse, and isolated CNS relapse, were 0.47 (P < 0.01), 0.50 (P < 0.05), 0.34 (P < 0.01), and 0.12 (P < 0.01), respectively, in irradiated patients.

CONCLUSIONS

CNS-RT was associated with an advantage in EFS by decreasing the risk of relapse but without improving OS.

Optimal timing of vitamin K antagonist resumption after upper gastrointestinal bleeding. A risk modelling analysis

The optimal timing of vitamin K antagonists (VKAs) resumption after an upper gastrointestinal (GI) bleeding, in patients with continued indication for oral anticoagulation, is uncertain. We included consecutive cases of VKA-associated upper GI bleeding from three hospitals retrospectively. Data on the bleeding location, timing of VKA resumption, recurrent GI bleeding and thromboembolic events were collected. A model was constructed to evaluate the 'total risk', based on the sum of the cumulative rates of recurrent GI bleeding and thromboembolic events, depending on the timing of VKA resumption. A total of 121 (58 %) of 207 patients with VKA-associated upper GI bleeding were restarted on anticoagulation after a median (interquartile range) of one (0.2-3.4) week after the index bleeding. Restarting VKAs was associated with a reduced risk of thromboembolism (HR 0.19; 95 % CI, 0.07-0.55) and death (HR 0.61; 95 % CI, 0.39-0.94), but with an increased risk of recurrent GI bleeding (HR 2.5; 95 % CI, 1.4-4.5). The composite risk obtained from the combined statistical model of recurrent GI bleeding, and thromboembolism decreased if VKAs were resumed after three weeks and reached a nadir at six weeks after the index GI bleeding. On this background we will discuss how the disutility of the outcomes may influence the decision regarding timing of resumption. In conclusion, the optimal timing of VKA resumption after VKA-associated upper GI bleeding appears to be between 3-6 weeks after the index bleeding event but has to take into account the degree of thromboembolic risk, patient values and preferences.

Subthreshold and threshold attention deficit hyperactivity disorder symptoms in childhood: psychosocial outcomes in adolescence in boys and girls

OBJECTIVE

To examine the association between different levels of childhood attention deficit hyperactivity disorder (ADHD) symptoms and sex differences in psychosocial outcomes during adolescence.

METHOD

Swedish children (n = 4635) were screened for neuropsychiatric symptoms at age 9 or 12. ADHD symptoms were divided into three levels: screen-negative, screen-intermediate, and screen-positive. At follow-up (age 15), parents and teenagers filled out questionnaires regarding (i) hyperactivity/inattention, (ii) peer problems, (iii) school problems, (iv) internalizing problems, (v) antisocial behaviour, (vi) alcohol misuse, and (vii) drug misuse. All outcomes were controlled for symptoms of diagnostic categories other than ADHD.

RESULTS

Increasing levels of ADHD symptoms in childhood were associated with higher proportions of adolescents who displayed negative psychosocial outcomes. More girls than boys reported internalizing problems (all levels) and risky drug use (screen-intermediate and screen-positive only). More boys reported antisocial behaviour at the screen-negative and screen-intermediate levels, but at the screen-positive level, similar proportions of girls and boys displayed antisocial behaviour.

CONCLUSION

The findings support the view that ADHD symptoms, as well as their negative outcomes, are dimensionally distributed in the population and that adolescent girls and boys display different risk profiles. The findings confirm that ADHD symptoms are associated with higher risk of drug misuse in girls.

Body height as risk factor for emphysema in COPD

Pulmonary emphysema is a phenotypic component of chronic obstructive pulmonary disease (COPD) which carries substantial morbidity and mortality. We explored the association between emphysema and body height in 726 patients with COPD using computed tomography as the reference diagnostic standard for emphysema. We applied univariate analysis to look for differences between patients with emphysema and those without, and multivariate logistic regression to identify significant predictors of the risk of emphysema. As covariates we included age, sex, body height, body mass index, pack-years of smoking, and forced expiratory volume in one second (FEV₁) as percent predicted. The overall prevalence of emphysema was 52%. Emphysemic patients were significantly taller and thinner than non-emphysemic ones, and featured significantly higher pack-years of smoking and lower FEV₁ (P < 0.001). The prevalence of emphysema rose linearly by 10-cm increase in body height (r² = 0.96). In multivariate analysis, the odds of emphysema increased by 5% (95% confidence interval, 3 to 7%) along with one-centimeter increase in body height, and remained unchanged after adjusting for all the potential confounders considered (P < 0.001). The odds of emphysema were not statistically different between males and females. In conclusion, body height is a strong, independent risk factor for emphysema in COPD.

Short-term and long-term effects of childhood cancer on income from employment and employment status: A national cohort study in Sweden

BACKGROUND

There is insufficient knowledge regarding the economic impact of childhood cancer on parents. The objectives of the current study were to investigate the short-term and long-term effects of childhood cancer on mothers' and fathers' income from employment and employment status.

METHODS

The study sample consisted of the parents of children diagnosed with cancer from 2004 to 2009 in Sweden (3626 parents of 1899 children). Annual register data concerning income from employment and employment status (employed/not employed) were retrieved from the Longitudinal Integration Database for Health Insurance and Labor Market Studies. Using generalized linear models, the mean income from employment and employment status were compared with a matched control cohort of 34,874 parents sampled from the general population.

RESULTS

Parents' income was found to decrease significantly after the child's cancer diagnosis. The effect was most pronounced for mothers, whose income was reduced for 6 years after diagnosis, whereas fathers' income was similar to that of control fathers 3 years after the diagnosis. Mothers were more likely to stop working after a child's cancer diagnosis compared with controls. No association was found for fathers' employment status. Younger age of parents; lower level of education; and, among mothers, being born outside of Sweden were found to be associated with more adverse effects on income.

CONCLUSIONS

Parents' income from employment and employment status appear to be adversely affected by having a child with cancer. Socioeconomic consequences are not distributed equally: the income of fathers appears to catch up after a few years, whereas mothers tend to be disadvantaged in their professional life for several years after a child's cancer diagnosis. Cancer 2017;123:1238-1248. © 2016 American Cancer Society.

Cohort study of growth patterns by gestational age in preterm infants developing morbidity

OBJECTIVES

To examine differences in growth patterns in preterm infants developing major morbidities including retinopathy of prematurity (ROP), bronchopulmonary dysplasia (BPD), necrotising enterocolitis (NEC) and intraventricular haemorrhage (IVH).

STUDY DESIGN

Cohort study of 2521 infants born at a gestational age (GA) of 23-30 weeks from 11 level III neonatal intensive care units in USA and Canada, and 3 Swedish population-based cohorts.

OUTCOMES

Birth weight and postnatal weight gain were examined relative to birth GA and ROP, BPD, NEC and IVH development.

RESULTS

Among infants with a birth GA of 25-30 weeks, birth weight SD score and postnatal weight were lower in those developing ROP and BPD. Infants developing ROP showed lower growth rates during postnatal weeks 7-9 in the 23-24 weeks GA group, during weeks 4-6 in the 25-26 weeks GA group and during weeks 1-5 in the 27-30 weeks GA group. Infants with BPD born at 27-30 weeks GA showed lower growth rates during postnatal weeks 3-5. Infants with NEC had lower growth rates after postnatal week 6 in all GA groups, with no significant differences in birth weight SD score. IVH was not associated with prenatal or postnatal growth.

CONCLUSIONS

In this cohort study of extremely preterm infants, we found that the postnatal growth pattern was associated with morbidities such as ROP, BPD and NEC as well as with gestational age at birth.

Elevated serum ferritin is associated with increased mortality in non-alcoholic fatty liver disease after 16 years of follow-up

BACKGROUND & AIMS

High levels of ferritin in patients with non-alcoholic fatty liver disease (NAFLD) are associated with significant fibrosis and higher NAFLD activity score (NAS). It is unclear if this association has an impact on mortality. We investigated if high levels of ferritin, with or without iron overload, were associated with an increased mortality in NAFLD.

METHODS

We included 222 patients between 1979 and 2009 with biopsy-proven NAFLD and available serum ferritin concentrations. The cohort was divided into 'high' (n = 89) and 'normal' (n = 133) ferritin values, using a cut-point of 350 μg/L in males, and 150 μg/L in females, and stratified upon iron overload status. Data on mortality were obtained from a national, population-based register. Poisson regression was used to estimate hazard ratios for mortality. The estimates were adjusted for age at biopsy, sex, smoking, BMI, diabetes, hypertension, cardiovascular disease and fibrosis stage at the time of biopsy.

RESULTS

The median follow-up time was 15.6 years (range: 0.5-34.2). Patients with high ferritin had more advanced fibrosis and higher NAS than patients with normal ferritin (P < 0.05). Fifteen years after diagnosis, and after adjusting for confounders, the high-ferritin group showed an increasingly higher mortality that was statistically significant (Hazard ratio = 1.10 per year, 95% Confidence interval 1.01-1.21, P < 0.05). There was no difference in mortality between patients with different iron overload patterns.

CONCLUSIONS

High levels of ferritin are associated with a long-term increased risk of death.

The Fate of Reconstructive Surgery Following Colectomy for Inflammatory Bowel Disease in Sweden: A Population-based Cohort Study

BACKGROUND AND AIMS

Previous studies describing the cumulative failure rate after reconstructive surgery in patients with inflammatory bowel disease have been restricted to specific hospitals, and the generalizability of these results in a population-based setting is unknown. The aim of this study was to investigate the cumulative failure rate and risk factors for failure after reconstructive surgery in patients with inflammatory bowel disease.

METHODS

The study cohort includes all patients with inflammatory bowel disease in Sweden who underwent colectomy in 2000 through 2013 who were later treated with reconstructive surgery with ileal pouch-anal anastomosis or ileorectal anastomosis. Each patient was followed from admission for reconstructive surgery until admission for failure (a diverting stoma or permanent stoma), date of death, migration or December 31, 2013. Cumulative failure distributions were obtained with the Kaplan-Meier method, and multivariable Cox regression models were used to calculate the risk of failure.

RESULTS

Of the 1809 patients with inflammatory bowel disease treated with colectomy and reconstructive surgery, 83% had ulcerative colitis. During follow-up, 270 patients failed, and the cumulative failure rate was 4.1%, 13.2%, and 15.3% after 1, 3, and 5 years, respectively. The risk of failure was lower after treatment with ileal pouch-anal anastomosis than with ileorectal anastomosis [hazard ratio (95% confidence interval): 0.72 (0.56-0.93)]. Gender, hospital volume, and timing of reconstruction were not significantly associated with the risk of failure.

CONCLUSIONS

The 5-year cumulative failure rate in a nationwide setting was 15.3%, and hospital volume was not associated with the risk of failure.

Cross-Country Individual Participant Analysis of 4.1 Million Singleton Births in 5 Countries with Very High Human Development Index Confirms Known Associations but Provides No Biologic Explanation for 2/3 of All Preterm Births

BACKGROUND

Preterm birth is the most common single cause of perinatal and infant mortality, affecting 15 million infants worldwide each year with global rates increasing. Understanding of risk factors remains poor, and preventive interventions have only limited benefit. Large differences exist in preterm birth rates across high income countries. We hypothesized that understanding the basis for these wide variations could lead to interventions that reduce preterm birth incidence in countries with high rates. We thus sought to assess the contributions of known risk factors for both spontaneous and provider-initiated preterm birth in selected high income countries, estimating also the potential impact of successful interventions due to advances in research, policy and public health, or clinical practice.

METHODS

We analyzed individual patient-level data on 4.1 million singleton pregnancies from four countries with very high human development index (Czech Republic, New Zealand, Slovenia, Sweden) and one comparator U.S. state (California) to determine the specific contribution (adjusting for confounding effects) of 21 factors. Both individual and population-attributable preterm birth risks were determined, as were contributors to cross-country differences. We also assessed the ability to predict preterm birth given various sets of known risk factors.

FINDINGS

Previous preterm birth and preeclampsia were the strongest individual risk factors of preterm birth in all datasets, with odds ratios of 4.6-6.0 and 2.8-5.7, respectively, for individual women having those characteristics. In contrast, on a population basis, nulliparity and male sex were the two risk factors with the highest impact on preterm birth rates, accounting for 25-50% and 11-16% of excess population attributable risk, respectively (p<0.001). The importance of nulliparity and male sex on population attributable risk was driven by high prevalence despite low odds ratios for individual women. More than 65% of the total aggregated risk of preterm birth within each country lacks a plausible biologic explanation, and 63% of difference between countries cannot be explained with known factors; thus, research is necessary to elucidate the underlying mechanisms of preterm birth and, hence, therapeutic intervention. Surprisingly, variation in prevalence of known risk factors accounted for less than 35% of the difference in preterm birth rates between countries. Known risk factors had an area under the curve of less than 0.7 in ROC analysis of preterm birth prediction within countries. These data suggest that other influences, as yet unidentified, are involved in preterm birth. Further research into biological mechanisms is warranted.

CONCLUSIONS

We have quantified the causes of variation in preterm birth rates among countries with very high human development index. The paucity of explicit and currently identified factors amenable to intervention illustrates the limited impact of changes possible through current clinical practice and policy interventions. Our research highlights the urgent need for research into underlying biological causes of preterm birth, which alone are likely to lead to innovative and efficacious interventions.

Pain rather than induced emotions and ICU sound increases skin conductance variability in healthy volunteers

BACKGROUND

Assessing pain in critically ill patients is difficult. Skin conductance variability (SCV), induced by the sympathetic response to pain, has been suggested as a method to identify pain in poorly communicating patients. However, SCV, a derivate of conventional skin conductance, could potentially also be sensitive to emotional stress. The purpose of the study was to investigate if pain and emotional stress can be distinguished with SCV.

METHODS

In a series of twelve 1-min sessions with SCV recording, 18 healthy volunteers were exposed to standardized electric pain stimulation during blocks of positive, negative, or neutral emotion, induced with pictures from the International Affective Picture System (IAPS). Additionally, authentic intensive care unit (ICU) sound was included in half of the sessions. All possible combinations of pain and sound occurred in each block of emotion, and blocks were presented in randomized order.

RESULTS

Pain stimulation resulted in increases in the number of skin conductance fluctuations (NSCF) in all but one participant. During pain-free baseline sessions, the median NSCF was 0.068 (interquartile range 0.013-0.089) and during pain stimulation median NSCF increased to 0.225 (interquartile range 0.146-0.3175). Only small increases in NSCF were found during negative emotions. Pain, assessed with the numeric rating scale, during the sessions with pain stimulation was not altered significantly by other ongoing sensory input.

CONCLUSION

In healthy volunteers, NSCF appears to reflect ongoing autonomous reactions mainly to pain and to a lesser extent, reactions to emotion induced with IAPS pictures or ICU sound.

Physical activity outcomes in afterschool programs: A group randomized controlled trial

INTRODUCTION

Afterschool programs (ASPs) across the US are working towards achieving the standard of all children accumulating 30min of moderate-to-vigorous physical activity (MVPA) during program time. This study describes the two-year impact of an intervention designed to assist ASPs meeting the 30min/day MVPA standard.

METHODS

Using a two-year delayed treatment, group randomized controlled trial, 20 ASPs serving ~1700 children/year (6-12yrs) were randomized to either an immediate (n=10, baseline-2013 and 2yrs intervention fall-2013-to-spring-2015) or delayed group (n=10, baseline 2013-2014 and 1yr intervention fall-2014-to-spring-2015). The intervention, Strategies-To-Enhance-Practice (STEPs), focused on programming MVPA in the daily schedule, training of staff and leaders, and ongoing technical support/assistance. Accelerometry-derived proportion of children meeting the 30min/day MVPA standard was measured in the spring of each year. Mixed model logistic regressions were used to examine the change in the odds of achieving the MVPA standard. Analyses were conducted in 2015. Data were collected in one southeastern US state.

RESULTS

Immediate boys (n=677) and delayed girls (n=658) increased the percent achieving 30min MVPA/day from 35.9% to 47.0% (odds ratio [OR]=1.88, 95% CI 1.18-3.00) and 13.1% to 19.1% (OR=1.42, 95% CI 1.03-1.96). Immediate girls (n=613) and delayed boys (n=687) exhibited a nonsignificant increase from 19.1% to 21.6% (OR=1.20, 95% CI 0.84-1.72) and 29.0% to 31.3% (OR=1.13, 95%CI 0.80-1.58).

CONCLUSIONS

STEPs can have an impact on children's MVPA and time spent sedentary, yet was unable to fully achieve the goal of all children accumulating 30minMVPA/day. Additional efforts are need to identify strategies ASPs can use to meet this important public health standard.

Use of auxiliary data in semi-parametric spatial regression with nonignorable missing responses

We propose a method for reducing the error of the prediction of a quantity of interest when the outcome has missing values that are suspected to be nonignorable and the data are correlated in space. We develop a maximum likelihood approach for the parameter estimation of semi-parametric regressions in a mixed model framework. We apply the proposed method to phytoplankton data collected at fixed stations in the Chesapeake Bay, for which chlorophyll data coming from remote sensing are available. A simulation study is also performed. The availability of a variable correlated to the response allows us to achieve a substantial reduction of the prediction error of the expected value of the smoother, without having to specify a nonignorable model.

Bayesian model averaging method for evaluating associations between air pollution and respiratory mortality: a time-series study

OBJECTIVE

To demonstrate an application of Bayesian model averaging (BMA) with generalised additive mixed models (GAMM) and provide a novel modelling technique to assess the association between inhalable coarse particles (PM10) and respiratory mortality in time-series studies.

DESIGN

A time-series study using regional death registry between 2009 and 2010.

SETTING

8 districts in a large metropolitan area in Northern China.

PARTICIPANTS

9559 permanent residents of the 8 districts who died of respiratory diseases between 2009 and 2010.

MAIN OUTCOME MEASURES

Per cent increase in daily respiratory mortality rate (MR) per interquartile range (IQR) increase of PM10 concentration and corresponding 95% confidence interval (CI) in single-pollutant and multipollutant (including NOx, CO) models.

RESULTS

The Bayesian model averaged GAMM (GAMM+BMA) and the optimal GAMM of PM10, multipollutants and principal components (PCs) of multipollutants showed comparable results for the effect of PM10 on daily respiratory MR, that is, one IQR increase in PM10 concentration corresponded to 1.38% vs 1.39%, 1.81% vs 1.83% and 0.87% vs 0.88% increase, respectively, in daily respiratory MR. However, GAMM+BMA gave slightly but noticeable wider CIs for the single-pollutant model (-1.09 to 4.28 vs -1.08 to 3.93) and the PCs-based model (-2.23 to 4.07 vs -2.03 vs 3.88). The CIs of the multiple-pollutant model from two methods are similar, that is, -1.12 to 4.85 versus -1.11 versus 4.83.

CONCLUSIONS

The BMA method may represent a useful tool for modelling uncertainty in time-series studies when evaluating the effect of air pollution on fatal health outcomes.

Diagnosis and classification of idiopathic inflammatory myopathies

The idiopathic inflammatory myopathies (IIMs) are a heterogeneous group of diseases, collectively termed myositis, sharing symptoms of muscle weakness, fatigue and inflammation. Other organs are frequently involved, supporting the notion that these are systemic inflammatory diseases. The IIMs can be subgrouped into dermatomyositis, polymyositis and inclusion body myositis. The myositis-specific autoantibodies (MSAs) identify other and often more distinct clinical phenotypes, such as the antisynthetase syndrome with antisynthetase autoantibodies and frequent interstitial lung disease and anti-SRP and anti-HMGCR autoantibodies that identify necrotizing myopathy. The MSAs are important both to support myositis diagnosis and to identify subgroups with different patterns of extramuscular organ involvement such as interstitial lung disease. Another cornerstone in the diagnostic procedure is muscle biopsy to identify inflammation and to exclude noninflammatory myopathies. Treatment effect and prognosis vary by subgroup. To develop new and better therapies, validated classification criteria that identify distinct subgroups of myositis are critical. The lack of such criteria was the main rationale for the development of new classification criteria for IIMs, which are summarized in this review; the historical background regarding previous diagnostic and classification criteria is also reviewed. As the IIMs are rare diseases with a prevalence of 10 in 100 000 individuals, an international collaboration was essential, as was the interdisciplinary effort including experts in adult and paediatric rheumatology, neurology, dermatology and epidemiology. The new criteria have been developed based on data from more than 1500 patients from 47 centres worldwide and are based on clinically easily available variables.