Background Allergic sensitization is an important risk factor for the development of atopic disease. The National Health and Nutrition Examination Survey (NHANES) 2005-2006 provides the most ...comprehensive information on IgE-mediated sensitization in the general US population. Objective We investigated clustering, sociodemographic, and regional patterns of allergic sensitization and examined risk factors associated with IgE-mediated sensitization. Methods Data for this cross-sectional analysis were obtained from NHANES 2005-2006. Participants aged 1 year or older (n = 9440) were tested for serum specific IgEs (sIgEs) to inhalant and food allergens; participants 6 years or older were tested for 19 sIgEs, and children aged 1 to 5 years were tested for 9 sIgEs. Serum samples were analyzed by using the ImmunoCAP System. Information on demographics and participants' characteristics was collected by means of questionnaire. Results Of the study population aged 6 years and older, 44.6% had detectable sIgEs, whereas 36.2% of children aged 1 to 5 years were sensitized to 1 or more allergens. Allergen-specific IgEs clustered into 7 groups that might have largely reflected biological cross-reactivity. Although sensitization to individual allergens and allergen types showed regional variation, the overall prevalence of sensitization did not differ across census regions, except in early childhood. In multivariate modeling young age, male sex, non-Hispanic black race/ethnicity, geographic location (census region), and reported pet avoidance measures were most consistently associated with IgE-mediated sensitization. Conclusions The overall prevalence of allergic sensitization does not vary across US census regions, except in early life, although allergen-specific sensitization differs based on sociodemographic and regional factors. Biological cross-reactivity might be an important but not the sole contributor to the clustering of allergen-specific IgEs.
Background The national prevalence and patterns of food allergy (FA) in the United States are not well understood. Objective We developed nationally representative estimates of the prevalence of and ...demographic risk factors for FA and investigated associations of FA with asthma, hay fever, and eczema. Methods A total of 8203 participants in the National Health and Nutrition Examination Survey 2005-2006 had food-specific serum IgE measured to peanut, cow's milk, egg white, and shrimp. Food-specific IgE and age-based criteria were used to define likely FA (LFA), possible FA, and unlikely FA and to develop estimates of clinical FA. Self-reported data were used to evaluate demographic risk factors and associations with asthma and related conditions. Results In the United States, the estimated prevalence of clinical FA was 2.5% (peanut, 1.3%; milk, 0.4%; egg, 0.2%; shrimp, 1.0%; not mutually exclusive). Risk of possible FA/LFA was increased in non-Hispanic blacks (odds ratio, 3.06; 95% CI, 2.14-4.36), males (1.87; 1.32-2.66), and children (2.04; 1.42-2.93). Study participants with doctor-diagnosed asthma (vs no asthma) exhibited increased risk of all measures of food sensitization. Moreover, in those with LFA, the adjusted odds ratio for current asthma (3.8; 1.5-10.7) and an emergency department visit for asthma in the past year (6.9; 2.4-19.7) were both notably increased. Conclusion Population-based serologic data on 4 foods indicate an estimated 2.5% of the US population has FA, and increased risk was found for black subjects, male subjects, and children. In addition, FA could be an under-recognized risk factor for problematic asthma.
Background The National Health and Nutrition Examination Survey (NHANES) 2005-2006 was the first population-based study to investigate levels of serum total and allergen-specific IgE in the general ...US population. Objective We estimated the prevalence of allergy-related outcomes and examined relationships between serum IgE levels and these outcomes in a representative sample of the US population. Methods Data for this cross-sectional analysis were obtained from NHANES 2005-2006. Study subjects aged 6 years and older (n = 8086) had blood taken for measurement of total IgE and 19 specific IgE levels against common aeroallergens, including Alternaria alternata , Aspergillus fumigatus , Bermuda grass, birch, oak, ragweed, Russian thistle, rye grass, cat dander, cockroach, dog dander, dust mite ( Dermatophagoides farinae and Dermatophagoides pteronyssinus) , mouse and rat urine proteins, and selected foods (egg white, cow’s milk, peanut, and shrimp). Serum samples were analyzed for total and allergen-specific IgE by using the Pharmacia CAP System. Information on allergy-related outcomes and demographics was collected by questionnaire. Results In NHANES 2005-2006, 6.6% reported current hay fever, and 23.5% had current allergies. Allergy-related outcomes increased with increasing total IgE levels (adjusted odds ratios for a 10-fold increase in total IgE level of 1.86 95% CI, 1.44-2.41 for hay fever and 1.64 95% CI, 1.41-1.91 for allergies). Increased levels of plant-, pet-, and mold-specific IgE contributed independently to allergy-related symptoms. The greatest increase in odds was observed for hay fever and plant-specific IgE (adjusted odds ratio, 4.75; 95% CI, 3.83-5.88). Conclusion In the US population self-reported allergy symptoms are most consistently associated with increased levels of plant-, pet-, and mold-specific IgE.
Fatty liver disease is an emerging public health problem without effective therapies, and chronic hepatic inflammation is a key pathologic mediator in its progression. Cytochrome P450 (CYP) ...epoxygenases metabolize arachidonic acid to biologically active epoxyeicosatrienoic acids (EETs), which have potent anti-inflammatory effects. Although promoting the effects of EETs elicits anti-inflammatory and protective effects in the cardiovascular system, the contribution of CYP-derived EETs to the regulation of fatty liver disease-associated inflammation and injury is unknown. Using the atherogenic diet model of non-alcoholic fatty liver disease/non-alcoholic steatohepatitis (NAFLD/NASH), our studies demonstrated that induction of fatty liver disease significantly and preferentially suppresses hepatic CYP epoxygenase expression and activity, and both hepatic and circulating levels of EETs in mice. Furthermore, mice with targeted disruption of Ephx2 (the gene encoding soluble epoxide hydrolase) exhibited restored hepatic and circulating EET levels and a significantly attenuated induction of hepatic inflammation and injury. Collectively, these data suggest that suppression of hepatic CYP-mediated EET biosynthesis is an important pathological consequence of fatty liver disease-associated inflammation, and that the CYP epoxygenase pathway is a central regulator of the hepatic inflammatory response in NAFLD/NASH. Future studies investigating the utility of therapeutic strategies that promote the effects of CYP-derived EETs in NAFLD/NASH are warranted.
Inhaled endotoxin induces airway inflammation and is an established risk factor for asthma. The 2005-2006 National Health and Nutrition Examination Survey included measures of endotoxin and allergens ...in homes as well as specific IgE to inhalant allergens.
To understand the relationships between endotoxin exposure, asthma outcomes, and sensitization status for 15 aeroallergens in a nationally representative sample.
Participants were administered questionnaires in their homes. Reservoir dust was vacuum sampled to generate composite bedding and bedroom floor samples. We analyzed 7,450 National Health and Nutrition Examination Survey dust and quality assurance samples for their endotoxin content using extreme quality assurance measures. Data for 6,963 subjects were available, making this the largest study of endotoxin exposure to date. Log-transformed endotoxin concentrations were analyzed using logistic models and forward stepwise linear regression. Analyses were weighted to provide national prevalence estimates and unbiased variances.
Endotoxin exposure was significantly associated with wheeze in the past 12 months, wheeze during exercise, doctor and/or emergency room visits for wheeze, and use of prescription medications for wheeze. Models adjusted for age, sex, race and/or ethnicity, and poverty-to-income ratio and stratified by allergy status showed that these relationships were not dependent upon sensitization status but were worsened among those living in poverty. Significant predictors of higher endotoxin exposures were lower family income; Hispanic ethnicity; participant age; dog(s), cat(s), cockroaches, and/or smoker(s) in the home; and carpeted floors.
In this U.S. nationwide representative sample, higher endotoxin exposure was significantly associated with measures of wheeze, with no observed protective effect regardless of sensitization status.
Despite the prominent use of complex survey data and the growing popularity of machine learning methods in epidemiologic research, few machine learning software implementations offer options for ...handling complex samples. A major challenge impeding the broader incorporation of machine learning into epidemiologic research is incomplete guidance for analyzing complex survey data, including the importance of sampling weights for valid prediction in target populations. Using data from 15, 820 participants in the 1988-1994 National Health and Nutrition Examination Survey cohort, we determined whether ignoring weights in gradient boosting models of all-cause mortality affected prediction, as measured by the F1 score and corresponding 95% confidence intervals. In simulations, we additionally assessed the impact of sample size, weight variability, predictor strength, and model dimensionality. In the National Health and Nutrition Examination Survey data, unweighted model performance was inflated compared to the weighted model (F1 score 81.9% 95% confidence interval: 81.2%, 82.7% vs 77.4% 95% confidence interval: 76.1%, 78.6%). However, the error was mitigated if the F1 score was subsequently recalculated with observed outcomes from the weighted dataset (F1: 77.0%; 95% confidence interval: 75.7%, 78.4%). In simulations, this finding held in the largest sample size (N = 10,000) under all analytic conditions assessed. For sample sizes <5,000, sampling weights had little impact in simulations that more closely resembled a simple random sample (low weight variability) or in models with strong predictors, but findings were inconsistent under other analytic scenarios. Failing to account for sampling weights in gradient boosting models may limit generalizability for data from complex surveys, dependent on sample size and other analytic properties. In the absence of software for configuring weighted algorithms, post-hoc re-calculations of unweighted model performance using weighted observed outcomes may more accurately reflect model prediction in target populations than ignoring weights entirely.
Objective
Growing evidence suggests increasing frequencies of autoimmunity and certain autoimmune diseases, but findings are limited by the lack of systematic data and evolving approaches and ...definitions. This study was undertaken to investigate whether the prevalence of antinuclear antibodies (ANA), the most common biomarker of autoimmunity, changed over a recent 25‐year span in the US.
Methods
Serum ANA were measured by standard indirect immunofluorescence assays on HEp‐2 cells in 14,211 participants age ≥12 years from the National Health and Nutrition Examination Survey, with approximately one‐third from each of 3 time periods: 1988–1991, 1999–2004, and 2011–2012. We used logistic regression adjusted for sex, age, race/ethnicity, and survey design variables to estimate changes in ANA prevalence across the time periods.
Results
The prevalence of ANA was 11.0% (95% confidence interval 95% CI 9.7–12.6%) in 1988–1991, 11.5% (95% CI 10.3–12.8%) in 1999–2004, and 15.9% (95% CI 14.3–17.6%) in 2011–2012 (P for trend < 0.0001), which corresponds to ~22 million, ~27 million, and ~41 million affected individuals, respectively. Among adolescents age 12–19 years, ANA prevalence increased substantially, with odds ratios (ORs) of 2.02 (95% CI 1.16–3.53) and 2.88 (95% CI 1.64–5.04) in the second and third time periods relative to the first (P for trend < 0.0001). ANA prevalence increased in both sexes (especially in men), older adults (age ≥50 years), and non‐Hispanic whites. These increases in ANA prevalence were not explained by concurrent trends in weight (obesity/overweight), smoking exposure, or alcohol consumption.
Conclusion
The prevalence of ANA in the US has increased considerably in recent years. Additional studies to determine factors underlying these increases in ANA prevalence could elucidate causes of autoimmunity and enable the development of preventative measures.
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