The Effect of a Regimen of Antifungal Cream Use on Episodes of Acute Adenolymphangitis (ADL) among Lymphedema Patients: An Application Using Marginal Structural Models

Episodes of adenolymphangitis (ADL) are a recurrent clinical aspect of lymphatic filariasis (LF) and a risk factor for progression of lymphedema. Inter-digital entry lesions, often found on the web spaces between the toes of those suffering from lymphedema, have been shown to contribute to the occurrence of ADL episodes. Use of antifungal cream on lesions is often promoted as a critical component of lymphedema management. Our objective was to estimate the observed effect of antifungal cream use on ADL episodes according to treatment regimen among a cohort of lymphedema patients enrolled in a morbidity management program. We estimated this effect using marginal structural models for time varying confounding. In this longitudinal study, we estimate that for every one-unit increase in the number of times one was compliant to cream use through 12 months, there was a 23% (RR = 0.77 (0.62, 0.96)) decrease in the number of ADL episodes at 18 months, however the RR’s were not statistically significant at other study time points. Traditionally adjusted models produced a non-significant RR closer to the null at all time points. This is the first study to estimate the effect of a regimen of antifungal cream on the frequency of ADL episodes. This study also highlights the importance of the consideration and proper handling of time-varying confounders in longitudinal observational studies.

Cancer deaths and cases attributable to lifestyle factors and infections in China, 2013

Background

The burden of cancer in China is high, and it is expected to further increase. Information on cancers attributable to potentially modifiable risk factors is essential in planning preventive measures against cancer. We estimated the number and proportion of cancer deaths and cases attributable to ever-smoking, second-hand smoking, alcohol drinking, low fruit/vegetable intake, excess body weight, physical inactivity, and infections in China, using contemporary data from nationally representative surveys and cancer registries.

Methods

The number of cancer deaths and cases in 2013 were obtained from the National Central Cancer Registry of China and data on most exposures were obtained from the China National Nutrition and Health Survey 2002 or 2006 and Global Adult Tobacco Smoking 2010. We used a bootstrap simulation method to calculate the number and proportion of cancer deaths and cases attributable to risk factors and their corresponding 95% confidence intervals (CIs), allowing for uncertainty in data.

Results

Approximately 718 000 (95% CI 702 100-732 200) cancer deaths in men and 283 100 (278 800-288 800) cancer deaths in women were attributable to the studied risk factors, accounting for 52% of all cancer deaths in men and 35% in women. The numbers for incident cancer cases were 952 500 (95% CI 934 200-971 400) in men and 442 700 (437 200-447 900) in women, accounting for 47% of all incident cases in men and 28% in women. The greatest proportions of cancer deaths attributable to risk factors were for smoking (26%), HBV infection (12%), and low fruit/vegetable intake (7%) in men and HBV infection (7%), low fruit/vegetable intake (6%), and second-hand smoking (5%) in women.

Conclusions

Effective public health interventions to eliminate or reduce exposure from these risk factors, notably tobacco control and vaccinations against carcinogenic infections, can have considerable impact on reducing the cancer burden in China.

Test-Retest Reproducibility of Adult-Reported High School Diet Varies among Racially and Ethnically Diverse US Men and Women

Background

Adolescent diet is thought to play an important role in future chronic disease risk. However, few studies have examined the reproducibility of adult-reported adolescent diet, and evidence for possible differences in reproducibility by demographic characteristics is limited.

Objective

We assessed the ability of adults to consistently report past high school diet over a 1-y period and examined differences in reproducibility by selected demographic characteristics.

Methods

By using age-adjusted partial Spearman (ρ) or Pearson (r) correlations, we assessed 1-y reproducibility for 33 line items, 20 food groups, and 2 dietary patterns of high school diet reported in adulthood via a questionnaire completed by 742 participants in the Cancer Prevention Study 3 (CPS-3) Diet Substudy.

Results

Participants' median age was 53 y (range: 31-70 y), 65.2% were women, 59.8% were non-Hispanic white, 24.8% were non-Hispanic black, and 15.4% were Hispanic. The mean Spearman correlation assessing reproducibility across the 33 line items was 0.60 and ranged from 0.44 to 0.72, with no differences in mean correlations by age, sex, race/ethnicity, education, or body mass index (BMI). Reproducibility was similar across food groups (ρ = 0.62; range: 0.44-0.68), with differences by sex, ethnicity, age, or BMI observed for some food groups (e.g., sugar-sweetened beverages). Pearson correlations for the reproducibility of 2 major eating patterns, "fast food" and "whole food," were 0.73 and 0.72, respectively.

Conclusion

These results show good 1-y reproducibility of assessed high school diet, as reported from memory in adulthood, by line item, food group, and dietary pattern, with noted differences by demographic characteristics.

Norovirus in symptomatic and asymptomatic individuals: cytokines and viral shedding

Noroviruses (NoV) are the most common cause of epidemic gastroenteritis world-wide. NoV infections are often asymptomatic, although individuals still shed large amounts of NoV in their stool. Understanding the differences between asymptomatic and symptomatic individuals would help in elucidating mechanisms of NoV pathogenesis. Our goal was to compare the serum cytokine responses and faecal viral RNA titres of asymptomatic and symptomatic NoV-infected individuals. We tested serum samples from infected subjects (n = 26; 19 symptomatic, seven asymptomatic) from two human challenge studies of GI.1 NoV for 16 cytokines. Samples from prechallenge and days 1-4 post-challenge were tested for these cytokines. Cytokine levels were compared to stool NoV RNA titres quantified previously by reverse transcription-polymerase chain reaction (RT-qPCR). While both symptomatic and asymptomatic groups had similar patterns of cytokine responses, the symptomatic group generally exhibited a greater elevation of T helper type 1 (Th1) and Th2 cytokines and IL-8 post-challenge compared to the asymptomatic group (all P < 0·01). Daily viral RNA titre was associated positively with daily IL-6 concentration and negatively with daily IL-12p40 concentration (all P < 0·05). Symptoms were not associated significantly with daily viral RNA titre, duration of viral shedding or cumulative shedding. Symptomatic individuals, compared to asymptomatic, have greater immune system activation, as measured by serum cytokines, but they do not have greater viral burden, as measured by titre and shedding, suggesting that symptoms may be immune-mediated in NoV infection.

Human norovirus infection and the acute serum cytokine response

Noroviruses (NoV) are the most common cause of epidemic gastroenteritis worldwide. The acute immune response to NoV in humans is poorly understood, hindering research on prevention and treatment. To elucidate the acute immune response and test for cytokine predictors of susceptibility to infection, serum samples from two human NoV challenge studies were tested for 16 cytokines. Subjects who became infected (n = 26) were age-matched with subjects who remained uninfected following NoV challenge (n = 26). Samples were tested from prechallenge and days 1-4 post-challenge. Cytokine responses were compared between infected and uninfected groups. Overall, infected individuals exhibited an elevation in T helper type 1 (Th1) and Th2 cytokines, as well as chemokines interleukin (IL)-8 and monocyte chemoattractant protein (MCP-1), compared to uninfected individuals (all P < 0.05). Most cytokines peaked on day 2 post-challenge in infected subjects, and tumour necrosis factor (TNF)-α, IL-8, and IL-10 remained elevated to day 3. The only cytokine elevated significantly among infected subjects to day 4 post-challenge was IL-10 (P = 0.021). Prechallenge cytokine concentrations were not predictive of infection status post-challenge. There were no significant changes in serum cytokines among NoV-challenged subjects who remained uninfected. These results suggest that NoV infection elicits a Th1-type response, with some Th2 activation. Persistent elevation of IL-10 among infected subjects is consistent with activation of adaptive immune responses, such as B cell expansion, as well as down-regulation of Th1 cytokines. This study presents the first comprehensive description of the acute cytokine response to GI.1 NoV in humans.

Characterizing concentrations of diethylene glycol and suspected metabolites in human serum, urine, and cerebrospinal fluid samples from the Panama DEG mass poisoning

CONTEXT

Diethylene glycol (DEG) mass poisoning is a persistent public health problem. Unfortunately, there are no human biological data on DEG and its suspected metabolites in poisoning. If present and associated with poisoning, the evidence for use of traditional therapies such as fomepizole and/or hemodialysis would be much stronger.

OBJECTIVE

To characterize DEG and its metabolites in stored serum, urine, and cerebrospinal fluid (CSF) specimens obtained from human DEG poisoning victims enrolled in a 2006 case-control study.

METHODS

In the 2006 study, biological samples from persons enrolled in a case-control study (42 cases with new-onset, unexplained AKI and 140 age-, sex-, and admission date-matched controls without AKI) were collected and shipped to the Centers for Disease Control and Prevention (CDC) in Atlanta for various analyses and were then frozen in storage. For this study, when sufficient volume of the original specimen remained, the following analytes were quantitatively measured in serum, urine, and CSF: DEG, 2-hydroxyethoxyacetic acid (HEAA), diglycolic acid, ethylene glycol, glycolic acid, and oxalic acid. Analytes were measured using low resolution GC/MS, descriptive statistics calculated and case results compared with controls when appropriate. Specimens were de-identified so previously collected demographic, exposure, and health data were not available. The Wilcoxon Rank Sum test (with exact p-values) and bivariable exact logistic regression were used in SAS v9.2 for data analysis.

RESULTS

The following samples were analyzed: serum, 20 case, and 20 controls; urine, 11 case and 22 controls; and CSF, 11 samples from 10 cases and no controls. Diglycolic acid was detected in all case serum samples (median, 40.7 mcg/mL; range, 22.6-75.2) and no controls, and in all case urine samples (median, 28.7 mcg/mL; range, 14-118.4) and only five (23%) controls (median, < Lower Limit of Quantitation (LLQ); range, < LLQ-43.3 mcg/mL). Significant differences and associations were identified between case status and the following: 1) serum oxalic acid and serum HEAA (both OR = 14.6; 95% C I = 2.8-100.9); 2) serum diglycolic acid and urine diglycolic acid (both OR > 999; exact p < 0.0001); and 3) urinary glycolic acid (OR = 0.057; 95% C I = 0.001-0.55). Two CSF sample results were excluded and two from the same case were averaged, yielding eight samples from eight cases. Diglycolic acid was detected in seven (88%) of case CSF samples (median, 2.03 mcg/mL; range, < LLQ, 7.47).

DISCUSSION

Significantly elevated HEAA (serum) and diglycolic acid (serum and urine) concentrations were identified among cases, which is consistent with animal data. Low urinary glycolic acid concentrations in cases may have been due to concurrent AKI. Although serum glycolic concentrations among cases may have initially increased, further metabolism to oxalic acid may have occurred thereby explaining the similar glycolic acid concentrations in cases and controls. The increased serum oxalic acid concentration results in cases versus controls are consistent with this hypothesis.

CONCLUSION

Diglycolic acid is associated with human DEG poisoning and may be a biomarker for poisoning. These findings add to animal data suggesting a possible role for traditional antidotal therapies. The detection of HEAA and diglycolic acid in the CSF of cases suggests a possible association with signs and symptoms of DEG-associated neurotoxicity. Further work characterizing the pathophysiology of DEG-associated neurotoxicity and the role of traditional toxic alcohol therapies such as fomepizole and hemodialysis is needed.

Physical activity and cardiovascular risk factors at menopause: the Nord-Trøndelag health study

BACKGROUND

Lowered physical activity levels may partially explain changes in metabolic risk factors in women after menopause.

OBJECTIVES

To evaluate the association between physical activity and metabolic risk factors at baseline and after 11 years, as well as the change in that association over time in women who were premenopausal and ≥ 40 years at baseline.

METHODS

Subjects in a Norwegian population-based health survey answered questionnaires and had body and serum measurements during 1995-1997 (HUNT 2) and in a follow-up study during 2006-2008 (HUNT 3). Repeated-measures analyses were used to estimate the association between physical activity and metabolic factors, adjusting for age, smoking status, education, alcohol intake, and parity. Adjustment for hormonal treatment and medication was made, as appropriate.

RESULTS

In women remaining premenopausal, a higher physical activity score in HUNT 3 was associated with lower weight (p < 0.01) and waist-hip ratio (p < 0.01) and higher high density lipoprotein (HDL) cholesterol in HUNT 3 (p < 0.01). In women that were postmenopausal by the time of follow-up, a higher physical activity score in HUNT 3 was associated with lower weight (p < 0.01), waist-hip ratio (p < 0.01), triglycerides (p < 0.01), and higher total cholesterol (p < 0.05), HDL cholesterol (p < 0.01), and diastolic blood pressure (p < 0.05) in HUNT 3. The association of total physical activity score with weight and waist-hip ratio was stronger in HUNT 3 than in HUNT 2 (p < 0.01).

CONCLUSION

Increased physical activity may reduce the risk of adverse outcomes and use of pharmacological management in women of menopausal age.

Comparison of emergency department and hospital admissions data for air pollution time-series studies

BACKGROUND

Emergency department (ED) visit and hospital admissions (HA) data have been an indispensible resource for assessing acute morbidity impacts of air pollution. ED visits and HAs are types of health care visits with similarities, but also potentially important differences. Little previous information is available regarding the impact of health care visit type on observed acute air pollution-health associations from studies conducted for the same location, time period, outcome definitions and model specifications.

METHODS

As part of a broader study of air pollution and health in St. Louis, individual-level ED and HA data were obtained for a 6.5 year period for acute care hospitals in the eight Missouri counties of the St. Louis metropolitan area. Patient demographic characteristics and diagnostic code distributions were compared for four visit types including ED visits, HAs, HAs that came through the ED, and non-elective HAs. Time-series analyses of the relationship between daily ambient ozone and PM₂.₅ and selected cardiorespiratory outcomes were conducted for each visit type.

RESULTS

Our results indicate that, compared with ED patients, HA patients tended to be older, had evidence of greater severity for some outcomes, and had a different mix of specific outcomes. Consideration of 'HA through ED' appeared to more effectively select acute visits than consideration of 'non-elective HA'. While outcomes with the strongest observed temporal associations with air pollutants tended to show strong associations for all visit types, we found some differences in observed associations for ED visits and HAs. For example, risk ratios for the respiratory disease-ozone association were 1.020 for ED visits and 1.004 for 'HA through ED'; risk ratios for the asthma/wheeze-ozone association were 1.069 for ED visits and 1.106 for 'HA through ED'. Several factors (e.g. age) were identified that may be responsible, in part, for the differences in observed associations.

CONCLUSIONS

Demographic and diagnostic differences between visit types may lead to preference for one visit type over another for some questions and populations. The strengths of observed associations with air pollutants sometimes varied between different health care visit types, but the relative strengths of association generally were specific to the pollutant-outcome combination.

Physical activity and age at menopause: the Nord-Trøndelag population-based health study

BACKGROUND

Age at menopause may affect women's subsequent morbidity and mortality. In contrast to numerous other health outcomes, little is known about the possible effects of physical activity on age at menopause.

OBJECTIVES

To assess the relationship between leisure-time physical activity and age at menopause.

METHODS

Premenopausal women participating in a population-based health survey (HUNT 2) conducted in the county of Nord-Trøndelag, Norway reported their physical activity in the period of 1995-1997. Age at menopause was reported during 2006-2008 (HUNT 3). Cox proportional hazards models were used to estimate hazard ratios for menopause and logistic regression to estimate odds ratios for early menopause, with 95% confidence intervals, adjusting for age at menarche, parity, use of oral contraceptives prior to the 6 months preceding participation in HUNT 2, symptoms of depression, smoking status, and education.

RESULTS

Women aged 40-49 years at baseline had lower hazard ratios for menopause when participating in any light leisure-time physical activity compared with no activity (p < 0.05) and similar results were observed in 19-39-year-olds. In 50-59-year-old women, the results varied greatly and did not reach statistical significance.

CONCLUSIONS

The effects of leisure-time physical activity on age at menopause may be age-dependent. We found indications of earlier menopause for the least active women aged 19-49 years at baseline.

Race, neighbourhood characteristics and disparities in chemotherapy for colorectal cancer

BACKGROUND

Studies have found significant race/ethnic and age differences in receipt of adjuvant chemotherapy for stages III colon and II/III rectal cancers. Little is known about the role of neighbourhood factors in these disparities.

METHODS

The 4748 Black and White patients from the Georgia Comprehensive Cancer Registry were diagnosed with stages III colon and II/III rectal cancers between 2000 and 2004. Neighbourhood poverty, segregation (% Black residents) and rurality were linked to each patient using census tract identifiers. Multilevel analyses explored the role of neighbourhood characteristics and the nested association of patient race within categories of neighbourhoods in receipt of chemotherapy.

RESULTS

Odds of receiving chemotherapy for urban and suburban patients were 38% (95% CI 1.09 to 1.74) and 53% (95% CI 1.20 to 1.94) higher than for rural patients. However, odds of receiving chemotherapy for urban Black patients were 24% (95% CI 0.62 to 0.94) lower than for their White counterparts. Receipt of chemotherapy did not significantly differ between Blacks and Whites residing in suburban or rural areas.

CONCLUSION

Black-White disparities in receipt of chemotherapy among Georgia colorectal cancer patients were confined to urban patients. Disparities in receipt of this treatment for rural patients were found irrespective of patient race. Our findings highlight geographic areas where targeted interventions might be needed.

Physical activity and fertility in women: the North-Trøndelag Health Study

BACKGROUND

Changes in the state of energy balance owing to changes in physical activity may affect the reproductive system. We evaluated the association between physical activity (PA) and fertility and parity in healthy women.

METHODS

A population-based health survey (HUNT 1) was conducted during 1984-1986 in Nord-Trøndelag county, Norway, with follow-up from 1995 to 1997 (HUNT 2). The study included 3887 women, <45 years old in HUNT 2. PA was assessed by baseline questionnaire, and fertility and parity by questionnaire at follow-up. Data focused on overall occurrence of infertility in the population (without biological confirmation).

RESULTS

Increased frequency, duration and intensity of PA were associated with increased subfertility, and frequency of PA was associated with voluntary childlessness (P < 0.01). After adjusting for age, parity, smoking, and marital status, women who were active on most days were 3.2 times more likely to have fertility problems than inactive women. Exercising to exhaustion was associated with 2.3 times the odds of fertility problems versus low intensity. Women with highest intensity of PA at baseline had the lowest frequency of continuing nulliparity and highest frequency of having three or more children during follow-up (P < 0.05). Sensitivity analysis including body mass index as confounder did not alter the results. No associations were found between lower activity levels and fertility or parity.

CONCLUSION

Increased risk of infertility was only found for the small group of women reporting the highest levels of intensity and frequency of PA. Awareness of the possible risks of infertility should be highlighted among non-athletic women who exercise vigorously.

Hospital characteristics associated with surgery for non-small cell lung cancer

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Background: Previous research suggests that black patients are less likely to undergo curative-intent surgery for early stage non-small cell lung cancer (NSCLC) compared to whites, holding all else constant. Among Medicare beneficiaries 65 and older, the likelihood of patients undergoing surgery is significantly reduced in hospitals with racial compositions of > 30% black patients after controlling for hospital and patient characteristics. This study analyzes whether hospital racial composition is associated with curative-intent surgery among early stage NSCLC patients of all ages. Methods: All adult patients ages 19–104 diagnosed with an invasive initial primary early stage (TNM I-II) NSCLC during 2003–2005 were selected from the National Cancer Data Base (NCDB). Facility characteristics were extracted from the NCDB and American College of Surgeons (ACoS) Commission on Cancer (CoC) Facility Information Profile System (FIPS). Hospital racial composition of lung cancer patients, operationalized as percent black, was initially divided into tertiles; sensitivity analyses used dichotomous definitions. Generalized estimating equations with a logistic model were used to control for clustering by facility. Results: Of 52,853 evaluable patients seen at CoC-approved hospitals, blacks were primarily (74%) seen at hospitals with a racial composition of > 11% black patients. Hispanics (72%), non-Hispanic whites (69%), and Asians or other (72%) were primarily seen at hospitals with < 11% black patients. In sensitivity analyses, irrespective of the cutpoint used to classify hospitals by racial composition of black patients (10, 20, or 30%), black patients seen at hospitals with a high black racial composition were significantly less likely to undergo curative-intent surgery than black patients seen at hospitals with a lower black racial composition. After controlling for patient characteristics in multivariate models, however, high black racial composition at the facility level was no longer significant. Conclusions: Hospital racial composition (% black) was not predictive of reduced likelihood of curative-intent surgery among patients > 18 years of age with NSCLC. Patient-level predictors accounted for the majority of the variation in likelihood of curative-intent surgery.

No significant financial relationships to disclose.

The issue of confounding in epidemiological studies of ambient air pollution and pregnancy outcomes

BACKGROUND

Relationships between ambient air pollution levels during pregnancy and adverse pregnancy outcomes have been investigated using one of three analytic approaches: ambient pollution levels have been contrasted over space, time or both space and time. Although the three approaches share a common goal, to estimate the causal effects of pollution on pregnancy outcomes, they face different challenges with respect to confounding.

METHODS

A framework based on counterfactual effect definitions to examine issues related to confounding in spatial, temporal, and spatial-temporal analyses of air pollution and pregnancy outcomes is presented, and their implications for inference are discussed.

RESULTS

In spatial analyses, risk factors that are spatially correlated with pollution levels are confounders; the primary challenges relate to the availability and validity of risk factor measurements. In temporal analyses, where smooth functions of time are commonly used to control for confounding, concerns relate to the adequacy of control and the possibility that abrupt changes in risk might be systematically related to pollution levels. Spatial-temporal approaches are subject to challenges faced in both spatial and temporal analyses.

CONCLUSION

Each approach faces different challenges with respect to the likely sources of confounding and the ability to control for that confounding because of differences in the type, availability, and quality of information required. Thoughtful consideration of these differences should help investigators select the analytic approach that best promotes the validity of their research.

Maternal plasma cytokines in early- and mid-gestation of normal human pregnancy and their association with maternal factors

Few studies have assessed longitudinal changes in circulating cytokine levels during normal pregnancy. We have examined the natural history of maternal plasma cytokines from early- to mid-pregnancy in a large, longitudinal cohort. Multiplex flow cytometry was used to measure interleukin (IL)-2, IL-6, IL-12, tumor necrosis factor (TNF)-alpha, interferon (IFN)-gamma and granulocyte-macrophage colony-stimulating factor (GM-CSF) in early- (median [IQR]: 8.5 weeks [7.1, 10.0]) and mid-pregnancy (25.0 [24.1, 26.1]) from 1274 Danish women delivering singleton term infants. GM-CSF decreased from early- to mid-pregnancy (median percent change [95% CI]: -51.3% [-59.1%, -41.8%]), while increases were observed in IL-6 (24.3% [4.6%, 43.9%]), IL-12 (21.3% [8.9%, 35.7%]) and IFN-gamma (131.7% [100.2%, 171.6%]); IL-2 (-2.8% [-11.5%, 0.0%]) and TNF-alpha (0% [-5.9%, 25.6%]) remained stable. Positive correlations were found between all cytokines, both in early- and mid-pregnancy (all p<0.001). Early- and mid-pregnancy levels were rank-correlated for IL-2, IL-12, TNF-alpha and GM-CSF, but not IL-6 and IFN-gamma; these correlations were generally weaker than correlations between different cytokines at a single time point in pregnancy. Women with a pre-pregnancy BMI <18.5 had reduced levels of IFN-gamma and GM-CSF compared to women in other BMI categories, while women aged >or=35 years had elevated IL-2, IL-6, TNF-alpha and IFN-gamma. Early-pregnancy levels of TNF-alpha were higher in women with a prior preterm delivery. Cytokine levels were not associated with gravidity. In conclusion, cytokines were detected in plasma during early- and mid-pregnancy, with IL-6, IL-12, IFN-gamma and GM-CSF concentrations varying over pregnancy. Concentrations may depend on BMI, maternal age and prior preterm delivery.

Blood lead levels and risk factors for lead poisoning in children and caregivers in Chuuk State, Micronesia

Lead poisoning is a preventable environmental disease. Children and developing fetuses are especially vulnerable; even low blood lead levels (BLLs) are linked with learning and behavioral problems. We assessed children's and their caregivers' BLLs and risk factors for lead exposure in Chuuk State, Federated States of Micronesia. Children aged 2-6 years were randomly selected within 20 randomly selected villages. Children and caregivers provided venous blood, and caregivers offered information about possible risk factors for lead exposure. Mean BLLs were 39 microg/l for children and 16 microg/l for caregivers. Children with BLLs of > or = 100 microg/l (elevated) were 22.9 (95% CI: 4.5-116.0) times more likely to have a caregiver with an elevated BLL, 6.2 (95% CI: 1.4-27.3) times more likely to live on an outer island, and 3.4 (95% CI: 1.7-6.9) times more likely to have a family member who made lead fishing weights than did other children even after controlling for age and sex. For children, 61% of elevated BLLs could be attributed to making fishing weights. Caregivers with elevated BLLs were 5.9 (95% CI: 1.5-23.7) times more likely to live in a household that melted batteries than other caregivers even after controlling for age and education. For caregivers, 37% of the elevated BLLs could be attributed to melting batteries. The association of elevated BLLs in children and their caregiver suggests a common environmental exposure. Melting batteries to make fishing sinkers is a preventable source of lead exposure for children and their caregivers in Chuuk. Published by Elsevier GmbH.

Tests of trait—haplotype association when linkage phase is ambiguous, appropriate for matched case-control and cohort studies with competing risks

The impact of competing risks on tests of association between disease and haplotypes has been largely ignored. We consider situations in which linkage phase is ambiguous and show that tests for disease-haplotype association can lead to rejection of the null hypothesis, even when true, with more than the nominal 5 per cent frequency. This problem tends to occur if a haplotype is associated with overall mortality, even if the haplotype is not associated with disease risk. A small simulation study illustrates the magnitude of bias (high type I error rate) in the context of a cohort study in which a modest number of disease cases (about 350) occur over time. The bias remains even if the score test is based on a logistic model that includes age as a covariate. For cohort studies, we propose a new test based on a modification of the proportional hazards model and for case-control studies, a test based on a conditional likelihood that have the correct size under the null even in the presence of competing risks, and that can be used when haplotype is ambiguous.

Is readmission to hospital an indicator of poor process of care for patients with heart failure?

BACKGROUND

Controversy exists about the appropriateness of using readmission as an indicator of the quality of care. A study was undertaken to measure the validity and predictive ability of readmission in this context.

METHODS

An evaluation study was performed in patients discharged alive with heart failure from three Swiss academic medical centres. Process quality indicators were derived from evidence based guidelines for the management and treatment of heart failure. Readmissions were calculated from hospital administrative data. The predictive ability of readmissions was evaluated using bivariate and multivariate analyses, and validity by calculating sensitivity, specificity, positive and negative predictive value, using process indicators as the "gold standard".

RESULTS

Of 1055 eligible patients discharged alive, 139 (13.2%) were readmitted within 30 days. The adjusted odds ratio (OR) for absence of measurement of left ventricular function was 0.70 (95% CI 0.45 to 1.08) for readmissions. In patients with left ventricular systolic dysfunction, three dose categories of angiotensin converting enzyme inhibitor were examined using ordinal logistic regression. The adjusted OR for these categories was 1.07 (95% CI 0.56 to 2.06) for readmissions. When using process indicators as the gold standard to assess the validity of readmissions, sensitivity ranged from 0.08 to 0.17 and specificity from 0.86 to 0.93.

CONCLUSIONS

Readmission did not predict and was not a valid indicator of the quality of care for patients with heart failure admitted to three Swiss university hospitals.

Assessment of two self-reporting questionnaires for eating disorders in women

OBJECTIVE

The goals of this study were to evaluate how well the Eating Disorder Inventory (EDI) predicted specific eating disorders as identified by the Survey of Eating Disorders (SED), and to identify the most predictive EDI scales. An additional goal was to evaluate the EDI as a screening instrument for eating disorders among a large non-clinical group of women.

METHOD

The community-based study sample consisted of 1245 Norwegian women between age 18 and 50 years (mean 23). Subjects filled out the EDI and the SED.

RESULTS

The strongest predictors of SED-defined eating disorders were the EDI scales bulimia (BN) and drive of thinness (DT) and body mass index (BMI). When we classified women with an EDI sum score of 40 or higher as having an eating disorder (ED), the sensitivity was 38% and the specificity was 90%, compared to the SED diagnosis of ED.

DISCUSSION

Our findings suggest modest agreement between the EDI and the SED, and modest sensitivity and specificity of the EDI. While these instruments, perhaps with some modification, may be adequate for use in selected research applications, they should probably be supplemented with additional information in a clinical or treatment setting.

Eating disorder behavior in physically active Norwegian women

Competitive female athletes may have higher risk of eating disorders (ED) than recreational athletes, in part because low body fat may be advantageous in sports. However, women who participate in sports or physical activities might also do this for weight reduction, altering body shape, and for other food related reasons. This study was conducted to evaluate the association between hours of leisure time physical activity (PA) and prevalence of ED, and whether the association between the Eating Disorders Inventory (EDI) scales and ED, as classified by the Survey of Eating Disorders (SED), was the same among women with high vs. low physical activity levels. The community-based study sample consisted of 898 female students aged 18-50 years. Subjects filled out the EDI, the SED, and a questionnaire concerning physical activity and demographic data. Physical activity was not associated with increased risk of having a SED-defined diagnosis of an ED or of having an EDI score greater than 40, which is sometimes used to define women at risk for having an eating disorder. Women with a SED-defined ED had higher scores on all subscales of the EDI, but did not differ with respect to age, BMI or hours of weekly activity. The strongest predictors of having a SED-defined ED were body mass index (BMI), two EDI scales, drive of thinness and Bulimia Nervosa, with no differences between the two PA groups. Among women with a SED-defined ED, those with more than 5 h weekly PA did not differ from others with respect to scoring on the EDI or BMI. Results suggest that hours of physical activity may not increase risk of developing ED. Effective interventions are needed to help the growing numbers of persons with body-image and eating difficulties. For some, moderate physical training might be helpful.

New estimator of the genotype risk ratio for use in case-parental control studies

Estimation of the genotype risk ratio can be an important part of studying the role of genetics in disease causation. For example, one might estimate risk among persons with genotype DD compared with risk among those with genotype Dd, where the candidate locus has alleles D and d, with D representing the disease susceptibility allele. In this paper, the authors propose a modified method of analysis for case-parental control studies that can improve efficiency. They show how investigators can use information from families in which both parents are observed to improve the estimator created by Sun et al., which applies when only one parent and an affected offspring have been observed. Since this information is not used by the conditional approach of Schaid and Sommer, the authors' approach allows for more complete use of available information, leading to a smaller mean squared error of the genotype risk ratio estimators. The authors also suggest a way to combine estimates from families in which one parent and one offspring are observed and estimates from families in which both parents and one offspring are observed.

Statistical models to predict the need for postoperative intensive care and hospitalization in pediatric surgical patients

OBJECTIVE

To develop statistical models for predicting postoperative hospital and ICU stay in pediatric surgical patients based on preoperative clinical characteristics and operative factors related to the degree of surgical stress. We hypothesized that preoperative and operative factors will predict the need for ICU admission and may be used to forecast the length of ICU stay or postoperative hospital stay.

DESIGN

Prospective data collection from 1,763 patients.

SETTING

Tertiary care children's hospital.

PATIENTS AND PARTICIPANTS

All pediatric surgical patients, including those undergoing day surgery. Patients undergoing dental or ophthalmologic surgical procedures were excluded.

INTERVENTIONS

None.

MEASUREMENTS AND RESULTS

A logistic regression model predicting ICU admission was developed from all patients. Poissonregression models were developed from 1,161 randomly selected patients and validated from the remaining 602 patients. The logistic regression model for ICU admission was highlypredictive (area under the receiver operating characteristics (ROC) curve = 0.981). In the data set used for development of Poisson regression models, significant correlations occurred between the observed and predicted ICU stay (Pearson r = 0.468, p < 0.0001, n = 131) and between the observed and predicted hospital stay for patients undergoing general (r = 0.695, p < 0.0001), orthopedic (r = 0.717, p < 0.0001), cardiothoracic (r = 0.746, p < 0.0001), urologic (r = 0.458, p < 0.0001), otorhinolaryngologic (r = 0.962, p < 0.0001), neurosurgical (r = 0.7084, p < 0.0001) and plastic surgical (r = 0.854, p < 0.0001) procedures. In the validation data set, correlations between predicted and observed hospital stay were significant for general (p < 0.0001), orthopedic (p < 0.0001), cardiothoracic (p = 0.0321) and urologic surgery (p = 0.0383). The Poisson models for length of ICU stay, otorhinolaryngology, neurosurgery or plastic surgery could not be validated because of small numbers of patients.

CONCLUSIONS

Preoperative and operative factors may be used to develop statistical models predicting the need for ICU admission in pediatric surgical patients, and hospital stay following general surgical, orthopedic, cardiothoracic and urologic procedures. These statistical models need to be refined and validatedfurther, perhaps using data collection from multiple institutions.

Accounting for unmeasured population substructure in case-control studies of genetic association using a novel latent-class model

We propose a novel latent-class approach to detect and account for population stratification in a case-control study of association between a candidate gene and a disease. In our approach, population substructure is detected and accounted for using data on additional loci that are in linkage equilibrium within subpopulations but have alleles that vary in frequency between subpopulations. We have tested our approach using simulated data based on allele frequencies in 12 short tandem repeat (STR) loci in four populations in Argentina.