Circulating biomarkers of airflow limitation across the life span

BACKGROUND

Airflow limitation is a hallmark of chronic obstructive pulmonary disease, which can develop through different lung function trajectories across the life span. There is a need for longitudinal studies aimed at identifying circulating biomarkers of airflow limitation across different stages of life.

OBJECTIVES

This study sought to identify a signature of serum proteins associated with airflow limitation and evaluate their relation to lung function longitudinally in adults and children.

METHODS

This study used data from 3 adult cohorts (TESAOD [Tucson Epidemiological Study of Airway Obstructive Disease], SAPALDIA [Swiss Cohort Study on Air Pollution and Lung and Heart Diseases in Adults], LSC [Lovelace Smoker Cohort]) and 1 birth cohort (TCRS [Tucson Children's Respiratory Study]) (N = 1940). In TESAOD, among 46 circulating proteins, we identified those associated with FEV1/forced vital capacity (FVC) percent (%) predicted levels and generated a score based on the sum of their z-scores. Cross-sectional analyses were used to test the score for association with concomitant lung function. Longitudinal analyses were used to test the score for association with subsequent lung function growth in childhood and decline in adult life.

RESULTS

After false discovery rate adjustment, serum levels of 5 proteins (HP, carcinoembryonic antigen, ICAM1, CRP, TIMP1) were associated with percent predicted levels of FEV1/FVC and FEV1 in TESAOD. In cross-sectional multivariate analyses the 5-biomarker score was associated with FEV1 % predicted in all adult cohorts (meta-analyzed FEV1 decrease for 1-SD score increase: -2.9%; 95% CI: -3.9%, -1.9%; P = 2.4 × 10-16). In multivariate longitudinal analyses, the biomarker score at 6 years of age was inversely associated with FEV1 and FEV1/FVC levels attained by young adult life (P = .02 and .005, respectively). In adults, persistently high levels of the biomarker score were associated with subsequent accelerated decline of FEV1 and FEV1/FVC (P = .01 and .001).

CONCLUSIONS

A signature of 5 circulating biomarkers of airflow limitation was associated with both impaired lung function growth in childhood and accelerated lung function decline in adult life, indicating that these proteins may be involved in multiple lung function trajectories leading to chronic obstructive pulmonary disease.

Circulating CC16 and Asthma: A Population-based, Multicohort Study from Early Childhood through Adult Life

Rationale: Club cell secretory protein (CC16) is an antiinflammatory protein highly expressed in the airways. CC16 deficiency has been associated with lung function deficits, but its role in asthma has not been established conclusively. Objectives: To determine 1) the longitudinal association of circulating CC16 with the presence of active asthma from early childhood through adult life and 2) whether CC16 in early childhood predicts the clinical course of childhood asthma into adult life. Methods: We assessed the association of circulating CC16 and asthma in three population-based birth cohorts: the Tucson Children's Respiratory Study (years 6-36; total participants, 814; total observations, 3,042), the Swedish Barn/Children, Allergy, Milieu, Stockholm, Epidemiological survey (years 8-24; total participants, 2,547; total observations, 3,438), and the UK Manchester Asthma and Allergy Study (years 5-18; total participants, 745; total observations, 1,626). Among 233 children who had asthma at the first survey in any of the cohorts, baseline CC16 was also tested for association with persistence of symptoms. Measurements and Main Results: After adjusting for covariates, CC16 deficits were associated with increased risk for the presence of asthma in all cohorts (meta-analyzed adjusted odds ratio per 1-SD CC16 decrease, 1.20; 95% confidence interval [CI], 1.12-1.28; P < 0.0001). The association was particularly strong for asthma with frequent symptoms (meta-analyzed adjusted relative risk ratio, 1.40; 95% CI, 1.24-1.57; P < 0.0001), was confirmed for both atopic and nonatopic asthma, and was independent of lung function impairment. After adjustment for known predictors of persistent asthma, children with asthma in the lowest CC16 tertile had a nearly fourfold increased risk for having frequent symptoms persisting into adult life compared with children with asthma in the other two CC16 tertiles (meta-analyzed adjusted odds ratio, 3.72; 95% CI, 1.78-7.76; P < 0.0001). Conclusions: Circulating CC16 deficits are associated with the presence of asthma with frequent symptoms from childhood through midadult life and predict the persistence of asthma symptoms into adulthood. These findings support a possible protective role of CC16 in asthma and its potential use for risk stratification.

Cytomegalovirus serology in young to mid-adult life and decline of lung function

INTRODUCTION

Cytomegalovirus (CMV) seropositivity has been recently linked to severity and progression of asthma, cystic fibrosis, and chronic obstructive pulmonary disease (COPD). To date, no longitudinal study has addressed the relation of CMV serology to levels and decline of lung function in the general adult population.

METHODS

We evaluated 403 participants from the Tucson Epidemiological Study of Airway Obstructive Disease (TESAOD) who at enrollment were aged 28-55 years and completed lung function tests. During follow-up, the 403 participants completed on average 7.2 lung function tests per subject for a total of 2908 observations over a mean period of 14.7 years. We tested CMV serology in serum samples from enrollment and categorized participants into low, medium, and high CMV serology based on tertiles. The relation of CMV serology at enrollment to lung function levels and decline during follow-up was tested in multivariate random coefficients models.

RESULTS

After full adjustment, participants in the highest CMV serology tertile had faster declines of forced expiratory volume in 1 s (FEV1 ) and FEV1 /forced vital capacity (FVC) compared with subjects in the lowest tertile (by -7.9 ml/year 95% confidence interval [-13.9 ml/year, -1.93 ml/year], and by -0.13%/year [-0.23%/year, -0.026%/year], respectively). These CMV effects were additive with those of cigarette smoking. No associations were found between CMV serology and FVC, indicating specific effects of CMV seropositivity on airflow limitation.

CONCLUSION

High CMV serology in young to mid-adult life may be linked to increased COPD risk through an accelerated decline of lung function.

Single breath nitrogen test as predictor of lung function decline and COPD over an 8-year follow-up

BACKGROUND

The single breath nitrogen (SBN2) test was proposed for early detection of "small airways disease" in the seventies. Few longitudinal studies have subsequently evaluated the relationships between SBN2 test measurements and lung function decline or COPD incidence.

AIM

This study evaluates whether SBN2 test abnormalities may be significant predictors of lung function decline and COPD incidence over an 8-year follow-up.

STUDY DESIGN AND METHODS

In this longitudinal study, 907 adults (20+ years old; 56% males) from the prospective Po River Delta epidemiological study underwent SBN2 test at baseline and spirometry testing at both baseline and follow-up 8-year apart. Multinomial and multiple regression models were used to assess associations of SBN2 indexes and rates of FEV1 decline or risk of COPD incidence over time, after adjusting for sex, height and baseline age, FEV1 and smoking status. COPD was defined according to either GOLD or ATS-ERS criteria.

RESULTS

Among SBN2 indexes, only the slope of alveolar plateau (N2-slope) was significantly associated with rates of FEV1 decline (7.93 mL/year for a one-unit change in N2-slope, p<0.0001), and with an increased risk of developing COPD as defined by GOLD (RR 1.81, 95%CI 1.29-2.52, mild; RR 2.78, 95%CI 1.70-4.53, moderate or severe obstruction) and ATS-ERS criteria (RR 1.62, 95%CI 1.14-2.29, mild; RR 3.40, 95%CI 1.72-6.73, moderate or severe obstruction).

CONCLUSION

In this population-based study, N2-slope from SBN2 test is a significant predictor of lung function decline and COPD incidence over an 8-year follow-up, confirming the role of the "small airways disease" in the natural history of COPD.

Club cell secretory protein and lung function in children with cystic fibrosis

BACKGROUND

Club cell secretory protein (CC16) exerts anti-inflammatory functions in lung disease. We sought to determine the relation of serum CC16 deficits and genetic variants that control serum CC16 to lung function among children with cystic fibrosis (CF).

METHODS

We used longitudinal data from CF children (EPIC Study) with no positive cultures for Pseudomonas aeruginosa prior to enrollment. Circulating levels of CC16 and an inflammatory score (generated from CRP, SAA, calprotectin, G-CSF) were compared between participants with the lowest and highest FEV1 levels in adolescence (LLF and HLF groups, respectively; N = 130-per-group). Single nucleotide variants (SNVs) in the SCGB1A1, EHF-APIP loci were tested for association with circulating CC16 and with decline of FEV1 and FEV1/FVC% predicted levels between ages 7-16 using mixed models.

RESULTS

Compared with the HLF group, the LLF group had lower levels of CC16 (geometric means: 8.2 vs 6.5 ng/ml, respectively; p = 0.0002) and higher levels of the normalized inflammatory score (-0.21 vs 0.21, p = 0.0007). Participants in the lowest CC16 and highest inflammation tertile had the highest odds for having LLF (p<0.0001 for comparison with participants in the highest CC16 and lowest inflammation tertile). Among seven SNVs associated with circulating CC16, the top SNV rs3741240 was associated with decline of FEV1/FVC and, marginally, FEV1 (p = 0.003 and 0.025, respectively; N = 611 participants, 20,801 lung function observations).

CONCLUSIONS

Serum CC16 deficits are strongly associated with severity of CF lung disease and their effects are additive with systemic inflammation. The rs3741240 A allele is associated with low circulating CC16 and, possibly, accelerated lung function decline in CF.

The role of growth and nutrition in the early origins of spirometric restriction in adult life: a longitudinal, multicohort, population-based study

BACKGROUND

Spirometric restriction, defined as a reduced forced vital capacity (FVC) with a preserved FEV1/FVC ratio, is associated with increased respiratory and non-respiratory comorbidities and all-cause mortality in adulthood. Little is known about the early origins of this condition. We sought to identify early-life risk factors for spirometric restriction in adult life.

METHODS

In this longitudinal, multicohort, population-based study, we used data from the Tucson Children's Respiratory Study (TCRS), which recruited 1246 healthy infants at birth between April 1980, and October 1984, in Tucson, AZ, USA. Questionnaires were answered by the primary caregiver at enrolment, immediately after the child's birth, and multiple follow-up questionnaires were completed through childhood and adulthood. At the age of 22, 26, 32, and 36 years, lung function was measured with spirometry. At each survey, three mutually exclusive spirometric patterns were defined: (1) normal (FEV1/FVC ≥10th percentile and FVC ≥10th percentile); (2) restrictive (FEV1/FVC ≥10th percentile and FVC <10th percentile); and (3) obstructive (FEV1/FVC <10th percentile, independent of FVC). Data on demographic features and parental health factors were collected from questionnaires; pregnancy and perinatal data (including nutritional problems) and birth measurements were obtained from medical records; and weight, height, and body-mass index (BMI) during childhood (age 6-16 years) were measured by study nurses. The associations between early-life risk factors and spirometric patterns were assessed by multivariate multinomial logistic regression analysis, adjusted for survey year, sex, and race-ethnicity. Significant risk factors were further tested for replication in the Swedish Child (Barn), Allergy, Milieu, Stockholm, Epidemiological (BAMSE; n=1817; spirometry surveys were done at age 24 years) survey and the UK Manchester Asthma and Allergy Study (MAAS; n=411; spirometry surveys were done at age 18 years) birth cohorts, and fixed-effect meta-analyses of relative risk ratios (RRRs) from multinomial logistic regression models were done to generate a pooled estimate of the effect across the three cohorts. Measurements of body composition (MAAS; n=365) and total lung capacity (TCRS; n=173 and MAAS; n=407) were also available for a subset of participants.

FINDINGS

Of 1246 healthy infants included in TCRS, for the present study we included data for 652 participants who had at least one set of spirometry data, contributing up to 1668 observations. In the TCRS cohort, results from the multivariate models showed that maternal nutritional problems during pregnancy (RRR 2·48 [95% CI 1·30-4·76]; p=0·0062), being born small for gestational age (birthweight <10th percentile; 3·26 [1·34-7·93]; p=0·0093), and being underweight in childhood (BMI-for-age <5th percentile; 3·54 [1·35-9·26]; p=0·010) were independent predictors of spirometric restriction in adult life. Associations between being small for gestational age (p=0·0028) and underweight in childhood (p<0·0001) with adult spirometric restriction were supported by the results of meta-analysis of data from all three cohorts. In the MAAS cohort, having a low lean BMI (ie, <10th percentile) at age 11 years predicted adult (age 18 years) spirometric restriction (RRR 3·66 [1·48-9·02]; p=0·0048). These associations of spirometric restriction with small for gestational age, childhood underweight, and low lean BMI in childhood were verified in participants with spirometric restriction who had diminished total lung capacity, indicating that these factors specifically increase the risk of lung restriction.

INTERPRETATION

Poor growth and nutritional deficits in utero and throughout childhood precede and predict the development of spirometric restriction in adult life. Strategies to improve prenatal and childhood growth trajectories could help to prevent spirometric restriction and its associated morbidity and mortality burden.

FUNDING

National Institutes of Health.

Fetal Origins of Asthma: A Longitudinal Study from Birth to Age 36 Years

Rationale: Deficits in infant lung function-including the ratio of the time to reach peak tidal expiratory flow to the total expiratory time (tptef/te) and maximal expiratory flow at FRC (V̇maxFRC)-have been linked to increased risk for childhood asthma.Objectives: To examine the individual and combined effects of tptef/te and V̇maxFRC in infancy on risk for asthma and abnormalities of airway structure into mid-adult life.Methods: One hundred eighty participants in the Tucson Children's Respiratory Study birth cohort had lung function measured by the chest-compression technique in infancy (mean age ± SD: 2.0 ± 1.2 mo). Active asthma was assessed in up to 12 questionnaires between ages 6 and 36 years. Spirometry and chest high-resolution computed tomographic (HRCT) imaging were completed in a subset of participants at age 26. The relations of infant tptef/te and V̇maxFRC to active asthma and airway structural abnormalities into adult life were tested in multivariable mixed models.Measurements and Main Results: After adjustment for covariates, a 1-SD decrease in infant tptef/te and V̇maxFRC was associated with a 70% (P = 0.001) and 55% (P = 0.005) increased risk of active asthma, respectively. These effects were partly independent, and two out of three infants who were in the lowest tertile for both tptef/te and V̇maxFRC developed active asthma by mid-adult life. Infant V̇maxFRC predicted reduced airflow and infant tptef/te reduced HRCT airway caliber at age 26.Conclusions: These findings underscore the long-lasting effects of the fetal origins of asthma, support independent contributions by infant tptef/te and V̇maxFRC to development of asthma, and link deficits at birth in tptef/te with HRCT-assessed structural airway abnormalities in adult life.

High cytomegalovirus serology and subsequent COPD-related mortality: a longitudinal study

Background

Positive serology for cytomegalovirus (CMV) has been associated with all-cause mortality risk but its role in COPD mortality is unknown. The objective of the present study was to assess the relationship between CMV serology and COPD mortality.

Methods

We analysed data from 806 participants in the Tucson Epidemiological Study of Airway Obstructive Disease who, at enrolment, were aged 28–70 years and had completed lung function tests. We tested CMV serology in sera from enrolment and defined “high CMV serology” as being in the highest tertile. Vital status, date and cause of death were assessed through death certificates and/or linkage with the National Death Index up to January 2017. The association of CMV serology with all-cause and cause-specific mortality risk was tested in Cox models adjusted for age, sex, level of education, body mass index, smoking status and pack-years.

Results

High CMV serology was marginally associated with all-cause mortality (p=0.071) but the effect was inversely dependent on age, with the association being much stronger among participants <55 years than among participants ≥55 years at enrolment (p-value for CMV-by-age interaction <0.001). Compared with low CMV serology, high CMV serology was associated with mortality from COPD among all subjects (adjusted hazard ratio (HR) 2.38, 95% CI 1.11–5.08; p=0.025) and particularly in subjects <55 years old at enrolment (HR 5.40, 95% CI 1.73–16.9; p=0.004). Consistent with these results, high CMV serology also predicted mortality risk among subjects who already had airflow limitation at enrolment (HR 2.10, 95% CI 1.20–3.68; p=0.009).

Conclusions

We report a strong relationship between CMV serology and the risk of dying from COPD, and thus identify a novel risk factor for COPD mortality.

Using a 45-year longitudinal population-based cohort, it was demonstrated for the first time that high CMV serology predicts COPD mortality risk, particularly in younger subjects, identifying a novel and early risk factor for COPD mortalityhttp://bit.ly/32odP0Q

Serum levels of L1-ORF1p and airflow limitation

LINE-1 (long interspersed nuclear element-1) is a group of polymorphic DNA sequences in the human genome that mobilise via RNA binding proteins, reverse transcriptase and endonuclease to alter the host genome via mutational insertions, chromosomal rearrangements and reprogramming of gene expression (reviewed by Ramoset al. [1]). Full-length LINE-1 sequences encode two proteins: L1-ORF1p, a 40-kDa protein with nucleic acid binding activity; and L1-ORF2p, a 150-kDa protein with endonuclease and reverse transcriptase activities. The activity of LINE-1 is repressed in somatic tissues via DNA methylation and covalent protein modifications, and reactivated by displacement of retinoblastoma-associated proteins from the regulatory region [2]. Recent studies in our laboratory have implicated LINE-1 as a master regulator of human bronchial epithelial cell phenotypes in experimental in vitro and in vivo models [3].

In a population-based study, higher circulating levels of L1-ORF1p were associated with lower lung function levels and increased risk for airflow limitation among former smokershttp://bit.ly/2ZEIjNv

Club Cell Secretory Protein Deficiency Leads to Altered Lung Function

RATIONALE

CC16 (club cell secretory protein-16), a member of the secretoglobin family, is one of the most abundant proteins in normal airway secretions and has been described as a serum biomarker for obstructive lung diseases.

OBJECTIVES

To determine whether low CC16 is a marker for airway pathology or is implicated in the pathophysiology of progressive airway damage in these conditions.

METHODS

Using human data from the birth cohort of the Tucson Children's Respiratory Study, we examined the relation of circulating CC16 levels with pulmonary function and responses to bronchial methacholine challenge from childhood up to age 32 years. In wild-type and CC16-/- mice, we set out to comprehensively examine pulmonary physiology, inflammation, and remodeling in the naive airway.

MEASUREMENTS AND MAIN RESULTS

We observed that Tucson Children's Respiratory Study participants in the lowest tertile of serum CC16 had significant deficits in their lung function and enhanced airway hyperresponsiveness to methacholine challenge from 11 years throughout young adult life. Similarly, CC16-/- mice had significant deficits in lung function and enhanced airway hyperresponsiveness to methacholine as compared with wild-type mice, which were independent of inflammation and mucin production. As compared with wild-type mice, CC16-/- mice had significantly elevated gene expression of procollagen type I, procollagen type III, and α-smooth muscle actin, areas of pronounced collagen deposition and significantly enhanced smooth muscle thickness.

CONCLUSIONS

Our findings support clinical observations by providing evidence that lack of CC16 in the lung results in dramatically altered pulmonary function and structural alterations consistent with enhanced remodeling.

Persistent light to moderate alcohol intake and lung function: A longitudinal study

Alcohol intake has been inconsistently associated with lung function levels in cross-sectional studies. The goal of our study was to determine whether longitudinally assessed light-to-moderate alcohol intake is associated with levels and decline of lung function. We examined data from 1333 adult participants in the population-based Tucson Epidemiological Study of Airway Obstructive Disease. Alcohol intake was assessed with four surveys between 1972 and 1992. Subjects who completed at least two surveys were classified into longitudinal drinking categories ("never", "inconsistent", or "persistent drinker"). Spirometric lung function was measured in up to 11 surveys between 1972 and 1992. Random coefficient models were used to test for differences in lung function by drinking categories. After adjustment for sex, age, height, education, BMI categories, smoking status, and pack-years, as compared to never-drinkers, persistent drinkers had higher FVC (coefficient: 157 mL, p < 0.001), but lower FEV₁/FVC ratio (-2.3%, p < 0.001). Differences were due to a slower decline of FVC among persistent than among never-drinkers (p = 0.003), and these trends were present independent of smoking status. Inconsistent drinking showed similar, but weaker associations. After adjustment for potential confounders, light-to-moderate alcohol consumption was associated with a significantly decreased rate of FVC decline over adult life.

Positive Airway Pressure Therapies and Hospitalization in Chronic Obstructive Pulmonary Disease

BACKGROUND

Hospitalization of patients with chronic obstructive pulmonary disease creates a huge healthcare burden. Positive airway pressure therapy is sometimes used in patients with chronic obstructive pulmonary disease, but the possible impact on hospitalization risk remains controversial. We studied the hospitalization risk of patients with chronic obstructive pulmonary disease before and after initiation of various positive airway pressure therapies in a "real-world" bioinformatics study.

METHODS

We performed a retrospective analysis of administrative claims data of hospitalizations in patients with chronic obstructive pulmonary disease who received or did not receive positive airway pressure therapy: continuous positive airway pressure, bilevel positive airway pressure, and noninvasive positive pressure ventilation using a home ventilator.

RESULTS

The majority of 1,881,652 patients with chronic obstructive pulmonary disease (92.5%) were not receiving any form of positive airway pressure therapy. Prescription of bilevel positive airway pressure (1.5%), continuous positive airway pressure (5.6%), and noninvasive positive pressure ventilation (<1%) in patients with chronic obstructive pulmonary disease demonstrated geographic-, sex-, and age-related variability. After adjusting for confounders and propensity score, noninvasive positive pressure ventilation (odds ratio [OR], 0.19; 95% confidence interval [CI], 0.13-0.27), bilevel positive airway pressure (OR, 0.42; 95% CI, 0.39-0.45), and continuous positive airway pressure (OR, 0.70; 95% CI, 0.67-0.72) were individually associated with lower hospitalization risk in the 6 months post-treatment when compared with the 6 months pretreatment but not when compared with the baseline period between 12 and 6 months before treatment initiation. Stratified analysis suggests that comorbid sleep-disordered breathing, chronic respiratory failure, heart failure, and age less than 65 years were associated with greater benefits from positive airway pressure therapy.

CONCLUSION

Initiation of positive airway pressure therapy was associated with reduction in hospitalization among patients with chronic obstructive pulmonary disease, but the causality needs to be determined by randomized controlled trials.

Longitudinal change and stability of refractive, keratometric, and internal astigmatism in childhood

PURPOSE

To assess longitudinal change in refractive, keratometric, and internal astigmatism in a sample of students from a population with a high prevalence of with-the-rule (WTR) astigmatism and to determine the optical origins of changes in refractive astigmatism.

METHODS

A retrospective analysis of longitudinal measurements of right eye refractive and keratometric astigmatism in Tohono O'odham Native American children was conducted. Changes in refractive and keratometric astigmatism per year were compared in a younger cohort (n = 1594, 3 to <11 years old) and an older cohort (n = 648, 11 to <19 years old). Data were analyzed in clinical notation (Cyl) and vector notation (J0, J45).

RESULTS

On average, refractive astigmatism (means: 1.19 diopters [D] Cyl, +0.54 J0, +0.03 J45) resulted primarily from WTR corneal astigmatism (means: +0.85 J0, -0.02 J45) and against-the-rule (ATR) internal astigmatism (means: -0.31 J0, +0.05 J45). Mean longitudinal changes in astigmatism were statistically significant (younger cohort -0.02 D/y Cyl; older cohort +0.06 D/y Cyl). In the younger cohort, astigmatism decreased with age in low and moderate astigmats (<3.00 D) and increased with age in high astigmats (≥3.00 D). In the older cohort, astigmatism increased with age across all levels of astigmatism. Longitudinal changes in keratometric and internal astigmatism were negatively correlated in both cohorts.

CONCLUSIONS

Cross-sectional data suggest the presence of a constant ATR contribution from internal astigmatism (0.60 D Cyl) that is close to the 0.50 D ATR constant reported by Javal and others. Highly astigmatic 3- to <11-year-old children and children older than age 11 years show a small (not clinically significant) increase in astigmatism with age. A negative correlation between changes in keratometric astigmatism and internal astigmatism suggests an active compensation that may contribute to the stability of astigmatism in Tohono O'odham children.

Accommodation in astigmatic children during visual task performance

PURPOSE

To determine the accuracy and stability of accommodation in uncorrected children during visual task performance.

METHODS

Subjects were second- to seventh-grade children from a highly astigmatic population. Measurements of noncycloplegic right eye spherical equivalent (Mnc) were obtained while uncorrected subjects performed three visual tasks at near (40 cm) and distance (2 m). Tasks included reading sentences with stimulus letter size near acuity threshold and an age-appropriate letter size (high task demands) and viewing a video (low task demand). Repeated measures ANOVA assessed the influence of astigmatism, task demand, and accommodative demand on accuracy (mean Mnc) and variability (mean SD of Mnc) of accommodation.

RESULTS

For near and distance analyses, respectively, sample size was 321 and 247, mean age was 10.37 (SD 1.77) and 10.30 (SD 1.74) years, mean cycloplegic M was 0.48 (SD 1.10) and 0.79 diopters (D) (SD 1.00), and mean astigmatism was 0.99 (SD 1.15) and 0.75 D (SD 0.96). Poor accommodative accuracy was associated with high astigmatism, low task demand (video viewing), and high accommodative demand. The negative effect of accommodative demand on accuracy increased with increasing astigmatism, with the poorest accommodative accuracy observed in high astigmats (≥3.00 D) with high accommodative demand/high hyperopia (1.53 D and 2.05 D of underaccommodation for near and distant stimuli, respectively). Accommodative variability was greatest in high astigmats and was uniformly high across task condition. No/low and moderate astigmats showed higher variability for the video task than the reading tasks.

CONCLUSIONS

Accuracy of accommodation is reduced in uncorrected children with high astigmatism and high accommodative demand/high hyperopia, but improves with increased visual task demand (reading). High astigmats showed the greatest variability in accommodation.

Astigmatism and myopia in Tohono O'odham Native American children

PURPOSE

To describe change in spherical equivalent (M) in a longitudinal sample of Tohono O'odham students ages 3 to 18 years and to test the hypothesis that astigmatism creates complex cues to emmetropization, resulting in increased change in M in the direction of increasing myopia and increased occurrence of myopia.

METHODS

Subjects were 777 Tohono O'odham Native American children on whom cycloplegic right eye autorefraction was measured on at least two study encounters between ages 3 and 18 years (first encounter prior to age 5.5 years, final encounter ≥3 years later). Regression lines were fit to individual subjects' longitudinal M data to estimate rate of change in M (regression slope, D/yr). Regression was also used to predict if a subject would be myopic (≤-0.75 D M) by age 18 years. Analysis of covariance was used to assess the relation between M slope and magnitude of baseline M and astigmatism. Chi-square analyses were used to assess the relation between predicted myopia onset and magnitude of baseline M and astigmatism.

RESULTS

Mean M slope was significantly more negative for hyperopes (M ≥ +2.00) than for myopes (M ≤ -0.75) or for subjects neither hyperopic nor myopic (NHM, M > -0.75 and < +2.00), but there was no significant difference between the myopic and NHM groups. Chi-square analysis indicated that final myopia status varied across level of baseline astigmatism. Subjects with high astigmatism were more likely to be predicted to have significant myopia by age 18 years.

CONCLUSIONS

The association between greater shift in M towards myopia with age in subjects who were hyperopic at baseline is consistent with continued emmetropization in the school years. Results regarding predicted myopia development imply that degradation of image quality due to refractive astigmatism creates complex cues to emmetropization, resulting in increased occurrence of myopia.

The relation of circulating YKL-40 to levels and decline of lung function in adult life

BACKGROUND

YKL-40 is a chitinase-like protein that, in cross-sectional clinical studies, has been associated with severe asthma and COPD in smokers.

AIM

To determine the longitudinal relation of circulating YKL-40 to levels and decline of lung function in the general population.

METHODS

We used longitudinal data from up to 13 surveys from the population-based TESAOD study which was conducted in Tucson, Arizona between 1972 and 1996. In cross-sectional analyses, we also used data from 3 Spanish centers of the multicenter ECRHS study (ECRHS-Sp). Serum YKL-40 was measured at baseline in TESAOD and in survey 2 in ECRHS-Sp using ELISAs. Multivariate linear regression was used to test associations of serum YKL-40 to concomitant lung function. In TESAOD, random coefficients models were used to test associations of serum YKL-40 to subsequent decline of lung function.

RESULTS

Data on YKL-40 and lung function were available from 1088 TESAOD and 854 ECRHS-Sp adult participants (59% and 51% females; respectively). In adjusted multivariate meta-analyses, being in the highest YKL-40 quartile was associated cross-sectionally with significant deficits in FEV1 and FVC %predicted. In adjusted longitudinal analyses, TESAOD participants in the top YKL-40 quartile had an FEV1 decline that was 5 ml/yr (p = 0.05) faster than subjects in the third quartile, 5 ml/yr (p = 0.02) faster than subjects in the second quartile, and 10 ml/yr (p < 0.001) faster than subjects in the lowest YKL-40 quartile. These longitudinal effects were particularly strong in smokers and absent in never smokers. After adjusting for covariates, as compared with the other three quartiles combined, the top YKL-40 quartile was associated with a 9 ml/yr (p = 0.001) faster FEV1 decline among smokers, while no significant effects were found among never smokers (2 ml/yr, p = 0.35).

CONCLUSIONS

Circulating YKL-40 is associated with levels and decline of lung function in the general population and may be a biomarker of susceptibility to the long-term effects of cigarette smoking.

Combined effects of parental and active smoking on early lung function deficits: a prospective study from birth to age 26 years

BACKGROUND

Cross-sectional reports have suggested that, among active smokers, previous exposure to parental smoking may increase susceptibility to development of chronic obstructive pulmonary disease. We assessed prospectively whether parental smoking enhances the effects of active smoking on early deficits of lung function in young adults.

METHODS

We used data from the prospective birth cohort, the Tucson Children's Respiratory Study. Maternal and paternal smoking was assessed via questionnaires completed by the parents at the time of the participant's birth. Active smoking by participants was assessed via personal questionnaires completed at ages 16 (YR16), 22 and 26 years. Four groups were generated based on the combination of parental and active smoking. Lung function parameters, including forced expiratory volume in 1 s (FEV1)/forced vital capacity (FVC) ratio, were assessed by spirometry before and after inhalation of 180 μg of albuterol at YR11, YR16, YR22 and YR26.

RESULTS

Complete data were available for 519 participants. Pre-bronchodilator FEV1/FVC values did not differ at YR11, YR16 or YR22 by parental or active smoking. However, at YR26 participants with exposure to parental and active smoking had pre-bronchodilator FEV1/FVC levels that were, on average, 2.8% (0.9% to 4.8%; p=0.003) lower than participants who were not exposed to parental or active smoking. In contrast, subjects who were only exposed to active smoking or only exposed to parental smoking did not differ from those who were not exposed to either. Between YR11 and YR26, participants with exposure to parental and active smoking had the steepest decline in sex, age and height adjusted residuals of FEV1/FVC, FEV1, forced expiratory flow between 25% and 75% of the FVC (FEF25-75) and FEF25-75/FVC (all p values between 0.03 and <0.001).

CONCLUSIONS

Parental and active smoking act synergistically to affect early lung function deficits in young adulthood.

Acute exacerbations of COPD in the United States: inpatient burden and predictors of costs and mortality

Acute exacerbations of chronic obstructive pulmonary disease (AECOPD) are a leading cause of hospitalizations in the United States and the major cost driver of COPD. This study determined the national inpatient burden of AECOPD and assessed the association of co-morbidities and hospital characteristics with inpatient costs and mortality. Discharge records from the Agency for Healthcare Research and Quality (AHRQ) Healthcare Cost and Utilization Project (HCUP) Nationwide Inpatient Sample for 2006 was utilized. Outcomes of costs and mortality were assessed for AECOPD hospitalizations in cases ≥40 years of age. Multivariate regression analyses using a generalized linear model framework were conducted to determine predictors of inpatient costs and mortality controlling for patient demographics, primary payer, co-morbidity index, length of stay, hospital region, mechanical ventilation, and admission period. Overall, 1,254,703 hospitalizations for AECOPD were observed with mean costs of $9545(±12,700) and total costs of $11.9 billion. In-hospital mortality was 4.3% (N = 53,748). Discharges averaged 70.6 (±11.9) years of age. The majority were female (52.8%) and of white race (83.6% of reported race). Several co-morbidities were significantly associated with both costs and mortality (p < 0.001): acute myocardial infarction; congestive heart failure; cerebrovascular disease; lung cancer; cardiac arrhythmias; pulmonary circulation disorders; and weight loss. Significantly higher costs (p < 0.001) were associated with large and urban hospitals. The importance of co-morbidities in AECOPD is indicated in their association with prognosis and inpatient costs. Future research should determine if better management of these conditions can favorably impact the COPD disease burden.

Identification of patients with sleep disordered breathing: comparing the four-variable screening tool, STOP, STOP-Bang, and Epworth Sleepiness Scales

STUDY OBJECTIVE

The Epworth Sleepiness Scale (ESS) has been used to detect patients with potential sleep disordered breathing (SDB). Recently, a 4-Variable screening tool was proposed to identify patients with SDB, in addition to the STOP and STOP-Bang questionnaires. This study evaluated the abilities of the 4-Variable screening tool, STOP, STOP-Bang, and ESS questionnaires in identifying subjects at risk for SDB.

METHODS

A total of 4,770 participants who completed polysomnograms in the baseline evaluation of the Sleep Heart Health Study (SHHS) were included. Subjects with RDIs ≥ 15 and ≥ 30 were considered to have moderate-to-severe or severe SDB, respectively. Variables were constructed to approximate those in the questionnaires. The risk of SDB was calculated by the 4-Variable screening tool according to Takegami et al. The STOP and STOP-Bang questionnaires were evaluated including variables for snoring, tiredness/sleepiness, observed apnea, blood pressure, body mass index, age, neck circumference, and gender. Sleepiness was evaluated using the ESS questionnaire and scores were dichotomized into < 11 and ≥ 11.

RESULTS

The STOP-Bang questionnaire had higher sensitivity to predict moderate-to-severe (87.0%) and severe (70.4%) SDB, while the 4-Variable screening tool had higher specificity to predict moderate-to-severe and severe SDB (93.2% for both).

CONCLUSIONS

In community populations such as the SHHS, high specificities may be more useful in excluding low-risk patients, while avoiding false positives. However, sleep clinicians may prefer to use screening tools with high sensitivities, like the STOP-Bang, in order to avoid missing cases that may lead to adverse health consequences and increased healthcare costs.

Familial aggregation of allergen-specific sensitization and asthma

BACKGROUND

Familial aggregation of specific response to allergens and asthma adjusted for age and sensitization to multiple allergens was assessed in two large population cohorts.

METHODS

Allergen skin prick tests (SPTs) were administered to 1151 families in the Tucson Children's Respiratory Study (CRS) and 435 families in the Tucson Epidemiological Study of Airway Obstructive Disease (TESAOD). Sensitization was defined by wheal size ≥3 mm; physician-diagnosed asthma at age ≥8 yr was based on questionnaires. Using S.A.G.E. 6.1 software ASSOC and FCOR, familial correlations of crude and adjusted phenotypes were evaluated.

RESULTS

Crude estimates of parent-offspring (P-O) and sibling correlations were statistically significant for most allergens, ranging from 0.03 to 0.29. After adjusting for age of assessment and 'other atopy' (SPT-positive response to additional allergens), correlations were reduced by 14-71%. Sibling correlations for specific response to allergens were consistently higher than P-O correlations, but this difference was significant only for dust mite and weed mix in the TESAOD population. Familial correlation for atopic status (any positive SPTs vs. none) tended to be higher than for specific allergens. Asthma, with and without adjustment, showed greater familial correlation than either specific or general SPT response and significantly higher sibling correlation in TESAOD than in CRS, probably due to the older age of the siblings and the longer period of ascertainment.

CONCLUSIONS

Significant familial aggregation of specific response to allergen after adjustment for other atopy appears to reflect a genetic propensity toward atopy, dependent on shared familial exposures. Results also suggest that inheritance of asthma is independent of atopic sensitization.

The European Respiratory Society spirometry tent: a unique form of screening for airway obstruction

In order to raise public awareness of the importance of early detection of airway obstruction and to enable many people who had not been tested previously to have their lung function measured, the European Lung Foundation and the European Respiratory Society (ERS) organised a spirometry testing tent during the annual ERS Congresses in 2004-2009. Spirometry was performed during the ERS Congresses in volunteers; all participants answered a simple, brief questionnaire on their descriptive characteristics, smoking and asthma. Portable spirometers were freely provided by the manufacturer. Nurses and doctors from pulmonary departments of local hospitals/universities gave their service for free. Lower limit of normal (LLN) and Global Initiative for Chronic Obstructive Lung Disease (GOLD) criteria for diagnosing and grading airway obstruction were used. Of 12,448 participants in six congress cities, 10,395 (83.5%) performed acceptable spirometry (mean age 51.0 ± 18.4 yrs; 25.5% smokers; 5.5% asthmatic). Airway obstruction was present in 12.4% of investigated subjects according to LLN criteria and 20.3% according to GOLD criteria. Through multinomial logistic regression analysis, age, smoking habits and asthma were significant risk factors for airway obstruction. Relative risk ratio and 95% confidence interval for LLN stage I, for example, was 2.9 (2.0-4.1) for the youngest age (≤ 19 yrs), 1.9 (1.2-3.0) for the oldest age (≥ 80 yrs), 2.4 (2.0-2.9) for current smokers and 2.8 (2.2-3.6) for reported asthma diagnosis. In addition to being a useful advocacy tool, the spirometry tent represents an unusual occasion for early detection of airway obstruction in large numbers of city residents with an important public health perspective.

Rheumatoid arthritis is associated with less optimal hip structural geometry

The overall goal of this study was to assess the longitudinal changes in bone strength in women reporting rheumatoid arthritis (RA; n=78) compared with nonarthritic control participants (n=4779) of the Women's Health Initiative bone mineral density (WHI-BMD) subcohort. Hip structural analysis program was applied to archived dual-energy X-ray absorptiometry scans (baseline, years 3, 6, and 9) to estimate bone mineral density (BMD) and hip structural geometry parameters in 3 femoral regions: narrow neck (NN), intertrochanteric (IT), and shaft (S). The association between RA and hip structural geometry was tested using linear regression and random coefficient models. Compared with the nonarthritic control, the RA group had a lower BMD (p=0.061) and significantly lower outer diameter (p=0.017), cross-sectional area (p=0.004), and section modulus (p=0.035) at the NN region in the longitudinal models. No significant associations were seen at the IT regions or S regions, and the association was not modified by age, ethnicity, glucocorticoid use, or time. Within the WHI-BMD, women with RA group had reduced BMD and structural geometry at baseline, and this reduction was seen at a fixed rate throughout the 9 yr of study.

Relation of early childhood growth and wheezing phenotypes to adult lung function

RATIONALE

Several studies have reported associations between indicators of birth size and postnatal growth rates with levels of pulmonary function achieved as adults. The objective of this study was to determine if levels and/or rates of weight gain, measured in early life (birth-6 years), are associated with FVC or FEV1 levels achieved in young adulthood and if these associations differ by early childhood wheezing phenotypes.

METHODS

We used data from participants in the Tucson Children's Respiratory Study (CRS), a prospective birth cohort study. Weight was measured quarterly up to age 3 years and again at age 6 years. Pulmonary function was assessed at ages 16 and 22. Mean weight and slope of weight growth between 3 and 6 years were estimated using standardized residuals. Longitudinal models were used to determine predictors of FVC and FEV1 at ages 16 and 22 years.

RESULTS

There were 127 non-Hispanic white subjects that had at least four weight measures and one or more pulmonary function measures as young adults. After adjusting for sex, height, and age, the standardized slope of weight growth (between 3 and 6 years) was positively associated with higher levels of FVC at age 16 and 22 years (P = 0.0001) among subjects who did not have preschool wheezing. However, this association was completely absent among subjects who had wheezing lower respiratory tract illnesses in the first 3 years of life. Similar trends were found for FEV1.

CONCLUSION

The rate of weight gain between 3 and 6 years is significantly positively related to adult FVC and FEV1 and this association is modified by early wheezy phenotypes.

Longitudinal association between short sleep, body weight, and emotional and learning problems in Hispanic and Caucasian children

STUDY OBJECTIVE

To determine the impact of lower amounts of childhood sleep assessed by polysomnogram on development of obesity, being anxious or depressed, or having learning problems 5 years later.

DESIGN

Prospective cohort.

PARTICIPANTS

Subjects were 304 community participants from the Tucson Children's Assessment of Sleep Apnea study, aged 6-12 years old at baseline.

MEASUREMENTS AND RESULTS

Children were classified according to baseline sleep as those who slept ≥ 9 h/night, those who slept > 7.5 to < 9 h/night, and those who slept ≤ 7.5 h/night. Odds of overweight/obese (≥ 85(th) BMI percentile), obese (≥ 95(th) BMI percentile), anxious or depressed, and learning problems at follow-up were assessed according to baseline sleep categories. Children who slept ≤ 7.5 h/night had higher odds of being obese (OR = 3.3, P < 0.05) at follow-up than children who slept ≥ 9 h/night. Borderline significance for overweight/obese (OR = 2.2, P < 0.1), anxious or depressed (OR = 3.3, P < 0.1), and having learning problems (OR = 11.1, P < 0.1) were seen for children who slept ≤ 7.5 h/night as compared to those who slept ≥ 9 h/night. A mean increase in BMI of 1.7 kg/m(2) (P = 0.01) over the 5 years of follow-up was seen for children who slept ≤ 7.5 h/night compared to those who slept ≥ 9 h/night. These relationships did not differ between Hispanic and Caucasian children.

CONCLUSIONS

Children with reduced amounts of sleep (≤ 7.5 h/night) had an increased risk for higher body weight in early adolescence. Similarly, children who slept ≤ 7.5 h/night had higher risk of being anxious or depressed or having learning problems in early adolescence.

Role of neprilysin in airway inflammation induced by diesel exhaust emissions

In this study, we examined the role of neprilysin (NEP), a key membrane-bound endopeptidase, in the inflammatory response induced by diesel exhaust emissions (DEE) in the airways through a number of approaches: in vitro, animal, and controlled human exposure. Our specific aims were (1) to examine the role of NEP in inflammatory injury induced by diesel exhaust particles (DEP) using Nep-intact (wild-type) and Nep-null mice; (2) to examine which components of DEP are associated with NEP downregulation in vitro; (3) to determine the molecular impact of DEP exposure and decreased NEP expression on airway epithelial cells' gene expression in vitro, using a combination of RNA interference (RNAi) and microarray approaches; and (4) to evaluate the effects on NEP activity of human exposure to DEE. We report four main results: First, we found that exposure of normal mice to DEP consisting of standard reference material (SRM) 2975 via intratracheal installation can downregulate NEP expression in a concentration-dependent manner. The changes were accompanied by increases in the number of macrophages and epithelial cells, as well as proinflammatory cytokines, examined in bronchoalveolar lavage (BAL) fluid and cells. Nep-null mice displayed increased and/or additional inflammatory responses when compared with wild-type mice, especially in response to exposure to the higher dose of DEP that we used. These in vivo findings suggest that loss of NEP in mice could cause increased susceptibility to injury or exacerbate inflammatory responses after DEP exposure via release of specific cytokines from the lungs. Second, we found evidence, using in vitro studies, that downregulation of NEP by DEP in cultured human epithelial BEAS-2B cells was mostly attributable to DEP-adsorbed organic compounds, whereas the carbonaceous core and transition metal components of DEP had little or no effect on NEP messenger RNA (mRNA) expression. This NEP downregulation was not a specific response to DEP or its contents because the change also occurred after exposure to urban dust (SRM 1649a), which differs in physical and chemical composition from DEP. Third, we also collected the transcriptome profiles of the concentration-effects of SRM 2975 in cultured BEAS-2B cells through a 2 X 3 factorial design. DEP exposure upregulated 151 genes and downregulated 59 genes. Cells with decreased NEP expression (accomplished by transfecting an NEP-specific small interfering RNA [siRNA]) substantially altered the expression of genes (upregulating 17 and downregulating 14) associated with DNA/protein binding, calcium channel activities, and the cascade of intracellular signaling by cytokines. Data generated from the combined RNAi and microarray approaches revealed that there is a complex molecular cascade mediated by NEP in different subcellular compartments, possibly influencing the inflammatory response. Fourth, in a controlled human exposure study, we observed significant increases in soluble NEP in sputum after acute exposure to DEE, with an average net increase of 31%. We speculate that the change in NEP activity in sputum, if confirmed in larger epidemiologic investigations at ambient exposure levels to DEE, may provide a useful endpoint and promote insight into the mechanism of DEE-induced airway alterations.

Morbidity and mortality associated with the restrictive spirometric pattern: a longitudinal study

BACKGROUND

Recent studies have suggested that a restrictive pattern assessed with a single spirometric test is associated with increased morbidity and mortality. This study was undertaken to determine demographic, clinical and mortality profiles of subjects with either a recurrent or an inconsistent restrictive spirometric pattern assessed prospectively.

METHODS

Data from 2048 adult participants in the population-based TESAOD study were analysed. Normal (forced expiratory volume in 1 s/forced vital capacity (FEV(1)/FVC) ratio >or=70% and FVC >or=80% predicted), restrictive (FEV(1)/FVC >or=70% and FVC <80% predicted) and obstructive (FEV(1)/FVC <70%) patterns were assessed at the enrollment survey in 1972 and in 11 subsequent follow-up surveys up to 1996. Demographic and clinical characteristics were measured at enrollment and vital status and cause of death were assessed at January 2005.

RESULTS

Overall, 12% of participants had a restrictive spirometric pattern at enrollment. They were less likely to be male, to smoke and to have asthma, and had lower IgE levels than subjects in the obstructive group. Among subjects with a restrictive pattern at enrollment, 38% developed an obstructive pattern during follow-up. The remaining 62% had either a recurrent (restrictive pattern >or=50% of follow-up surveys) or inconsistent (restrictive pattern <50% of follow-up surveys) longitudinal restrictive pattern. The recurrent and inconsistent restrictive groups had increased mortality risk for all-cause (adjusted HR 1.7 (95% CI 1.3 to 2.3) and 1.9 (95% CI 1.4 to 2.6), respectively), heart disease (2.0 (95% CI 1.3 to 3.1) and 2.7 (95% CI 1.7 to 4.3)), stroke (2.4 (95% CI 0.9 to 6.3) and 3.5 (95% CI 1.2 to 9.8)) and diabetes (8.0 (95% CI 2.9 to 21.8) and 6.0 (95% CI 1.9 to 19.2)).

CONCLUSIONS

The restrictive spirometric pattern identifies a pulmonary condition that is distinguishable from obstructive lung disease and is associated with an increased risk of life-threatening comorbidities.

Chronic bronchitis before age 50 years predicts incident airflow limitation and mortality risk

BACKGROUND

Previous studies on the relationship of chronic bronchitis to incident airflow limitation and all-cause mortality have provided conflicting results, with positive findings reported mainly by studies that included populations of young adults. This study sought to determine whether having chronic cough and sputum production in the absence of airflow limitation is associated with onset of airflow limitation, all-cause mortality and serum levels of C-reactive protein (CRP) and interleukin-8 (IL-8), and whether subjects' age influences these relationships.

METHODS

1412 participants in the long-term Tucson Epidemiological Study of Airway Obstructive Disease who at enrolment (1972-1973) were 21-80 years old and had FEV(1)/FVC (forced expiratory volume in 1 s/forced vital capacity) > or = 70% and no asthma were identified. Chronic bronchitis was defined as cough and phlegm production on most days for > or = 3 months in two or more consecutive years. Incidence of airflow limitation was defined as the first follow-up survey with FEV(1)/FVC <70%. Serum IL-8 and CRP levels were measured in cryopreserved samples from the enrolment survey.

RESULTS

After adjusting for covariates, chronic bronchitis at enrolment significantly increased the risk for incident airflow limitation and all-cause mortality among subjects <50 years old (HR 2.2, 95% CI 1.3 to 3.8; and HR 2.2, 95% CI 1.3 to 3.8; respectively), but not among subjects > or = 50 years old (HR 0.9, 95% CI 0.6 to 1.4; and HR 1.0, 95% CI 0.7 to 1.3). Chronic bronchitis was associated with increased IL-8 and CRP serum levels only among subjects <50 years old.

CONCLUSIONS

Among adults <50 years old, chronic bronchitis unaccompanied by airflow limitation may represent an early marker of susceptibility to the effects of cigarette smoking on systemic inflammation and long-term risk for chronic obstructive pulmonary disease and all-cause mortality.

Association Between Sleep Disordered Breathing and Behavior in School-Aged Children: The Tucson Children's Assessment of Sleep Apnea Study

STUDY OBJECTIVES: This study analyzed the association between the Respiratory Disturbance Index (RDI) and two behavior measures, the Conners' Parent Rating Scale (CPRS-R) and the Child Behavior Checklist (CBCL) in school-aged children to determine whether there is an optimal threshold of Sleep-disordered Breathing (SDB) associated with increased risk of behavior problems. METHODS: The Tucson Children's Assessment of Sleep Apnea Study (TuCASA) is an observational cohort study of 6-11 year old Caucasian and Hispanic children designed to assess the anatomic, physiologic and neurocognitive correlates of SDB. 403 children with both polysomnography (PSG) and behavioral data were included in this analysis. Three definitions of SDB were used: RDI independent of oxygen desaturation (RDI0), RDI with 2% oxygen desaturation (RDI2) and RDI with 3% oxygen desaturation (RDI3). T-scored behavioral data were dichotomized at a cutoff point of 65, a score indicative of moderate to severe clinical impairment. Logistic regression was used to access the risk associated with SDB. RESULTS: The analyses conducted using three different definitions of RDI suggest that the likelihood of having a clinically significant CPRS-R or CBCL subscale score was not necessarily progressive or linear across RDI categories. Cutoff points and prevalences for each definition of RDI proposed to be indicators of clinically significant SDB were RDI0 ≥ 7 (19.38%), RDI2 ≥ 2 (29.38%) and RDI3 ≥ 0.5 (23.96%) events per hour of sleep. Behaviors such as CPRS oppositional, social problems, psychosomatic and CBCL somatic complaints, social problems and aggressive behaviors were found to be significantly associated with SDB. CONCLUSIONS: This analysis found an increased risk of behavior problems such as somatic complaints, oppositional or aggressive behaviors and social problems associated with sleep-disordered breathing in school-aged children. RDI cut points for three definitions of SDB are proposed: 7 for RDI0, 2 for RDI2, and 0.5 for RDI3 respectively.

Effects of parental smoking on interferon gamma production in children

OBJECTIVES

Environmental tobacco smoke is associated with several negative health outcomes in children, including an increased susceptibility to infections. One of the postulated mechanisms for these effects is the impairment of the immune system function and/or development. Yet, it remains unknown whether cumulative exposure to parental smoking is associated with altered immune responses in childhood and whether these effects are independent of in utero exposure to maternal smoking. In a population-based birth cohort, we sought to determine the relation of parental smoking, as assessed prospectively since pregnancy, to the child's interferon gamma and interleukin 4 production at 11 years of age.

PATIENTS AND METHODS

We used data on 512 children and their parents from the Tucson Children's Respiratory Study cohort. Information on maternal and paternal smoking was collected prospectively by questionnaire, and pack-years for mother, father, and both parents combined were assessed prospectively between the prenatal period and year 11. At age 11 years, children's interferon gamma and interleukin 4 production from mitogen-stimulated peripheral blood mononuclear cells was measured.

RESULTS

Children of parents who smoked between the prenatal period and year 11 were more likely to be in lower quartiles of interferon gamma production than children of nonsmoking parents. In addition, maternal, paternal, and parental pack-years showed significant inverse dose-response relationships with interferon gamma production in the child. These dose-response relationships with interferon gamma remained significant for both paternal and parental pack-years among children of mothers who did not smoke during pregnancy, suggesting the existence of specific postnatal effects of environmental tobacco smoke exposure. In contrast, no significant effects of parental smoking were found on interleukin 4 production.

CONCLUSIONS

Interferon gamma responses of school-aged children are impacted by parental smoking.

Use of salmeterol with and without concurrent use of inhaled corticosteroids and the risk of asthma-related hospitalization among patients with asthma

RATIONALE

Studies evaluating the safety of salmeterol are inconclusive, which might be the result from not taking into account the impact of concomitant inhaled corticosteroids (ICS).

OBJECTIVE

To study whether salmeterol use with and without concomitant ICS, respectively, was associated with an increased risk of asthma-related hospitalizations among patients with asthma.

METHODS

A case-control study nested within a cohort of patients with asthma, identified in the year 2000, over a 2-year period was conducted. Cases were subjects who had a first-time hospitalization for asthma in the year 2001, and were matched with up to five controls by age (+/- 5 years), sex, and number of asthma-related outpatient visits.

MEASUREMENTS

Hospitalizations and medication use were extracted from the MEDSTAT's MarketScan database.

MAIN RESULTS

There were 333 cases of asthma-related hospitalizations and 1607 matched control subjects. Any use of salmeterol with concomitant ICS use during the prior year was associated with a 32% risk reduction for being hospitalized due to asthma (OR = 0.68; 95% CI = 0.48, 0.96). In the presence of concomitant ICS use, patients who either used salmeterol currently or used seven or more canisters of salmeterol during the prior year had 46% (OR = 0.54, 95% CI = 0.32, 0.92), and 59% (OR = 0.41, 95% CI = 0.21, 0.79) reductions in the risk of hospital admissions for asthma, respectively.

LIMITATIONS

Though indirect measure of asthma severity was adjusted during the analyses, the lack of information on lung function might result in a selection bias. Additionally, only a small sample size of patients was found to use salmeterol without concomitant ICS use, and this introduced the issue of lack of power.

CONCLUSIONS

Use of salmeterol in conjunction with ICS is associated with a decreased risk of hospital admission for asthma.

Longitudinal decline of diffusing capacity of the lung for carbon monoxide in community subjects with the PiMZ alpha1-antitrypsin phenotype

BACKGROUND

It is well known that homozygous deficiency of alpha(1)-antitrypsin, PiZZ, is associated with an increased risk of emphysema. However, studies evaluating associations between the heterozygous form PiMZ with emphysema and impaired lung function have provided conflicting results.

STUDY OBJECTIVE

The goal of this study was to determine if the phenotype PiMZ is associated with an accelerated decline in diffusing capacity of the lung for carbon monoxide (Dlco).

DESIGN AND METHODS

The Tucson Epidemiologic Study of Airway Obstructive Disease is a prospective, population-based cohort study initiated in 1972. Participants completed standardized questionnaires in up to 12 periodic surveys and Dlco assessments in up to 4 surveys. Random-effects models were used to determine the effects of alpha(1)-antitrypsin phenotypes on percentage of predicted (% predicted) Dlco levels among 1,075 subjects > or = 18 years old.

RESULTS

% predicted Dlco declined more rapidly in subjects who smoked compared to nonsmoking subjects. Additionally, in smokers, the PiMZ phenotype was associated with borderline % predicted Dlco deficits at age 40 years (8.6%; p = 0.075) and significant % predicted Dlco deficits at age 60 years (15.2%; p = 0.001) and 80 years (21.9%; p = 0.003), as compared with the PiMM phenotype.

CONCLUSIONS

Dlco may be a more sensitive indicator of the long-term effects of intermediate levels of alpha(1)-antitrypsin on lung function especially in subjects who smoke.

Association of physical activity with sleep-disordered breathing

This study was performed to determine whether there is a protective association between participation in vigorous or vigorous/moderately vigorous physical activity and the prevalence of sleep-disordered breathing (SDB). Polysomnographic and questionnaire data from the baseline examination of 4,275 participants in the Sleep Heart Health Study (SHHS) were analyzed in relation to information on amount of physical activity and other potentially relevant factors collected from five SHHS parent cohorts (Atherosclerosis Risk in Communities Study, Cardiovascular Health Study, Framingham Heart Study, Strong Heart Study, and Tucson Epidemiologic Study of Airways Obstructive Diseases). Logistic regression models were fitted to determine if amount and strenuousness of physical activity was associated with the presence of SDB. At least 3 h per week of vigorous physical activity reduced the odds of SDB, defined as a respiratory disturbance index (RDI) of at least 15 apneas/hypopneas per hour (Adjusted OR, 0.68; 95%CI, 0.51-0.91). A qualitatively similar but slightly weaker association was observed when SDB was defined as a RDI > or = 10 per hour (Adjusted OR, 0.81; 95%CI, 0.64-1.02). These findings remained after adjustment for sleepiness and restricting analyses to participants with good health. Three or more hours of moderately vigorous or vigorous physical activity also appeared to confer some protection against SDB, but these associations were weaker. Gender- and obesity-stratified analyses suggested that the protective association between physical activity and SDB occurred primarily in men and those who were obese. A program of regular vigorous physical activity of at least 3 h per week may be a useful adjunctive treatment modality for SDB, but this association needs confirmation with a prospective clinical trial.

Comparison between reported and recorded total sleep time and sleep latency in 6- to 11-year-old children: the Tucson Children's Assessment of Sleep Apnea Study (TuCASA)

Research comparing parental report of sleep times to objectively obtained polysomnographic evidence of sleep times in schoolchildren is lacking. This report compares habitual sleep time and objectively recorded sleep time and sleep latency with parental reports of sleep time immediately after a night of polysomnography in elementary schoolchildren. Unattended home polysomnograms (PSG) were obtained from 480 children. On the night of the PSG, a parent was asked to complete a Sleep Habits Questionnaire, which inquired about the habitual total sleep time (HABTST) and habitual sleep onset latency (HABSOL) of his/her child on both school days and nonschool days. On the morning after the PSG, the parent was asked to estimate the total sleep time (ESTTST) and sleep onset latency (ESTSOL) of his/her child on the night of the recording. Comparisons were made to actual total sleep time (PSGTST) and sleep latency (PSGSOL) on the PSG. The sample was comprised of 50% girls, 42.3% Hispanic, and 53% aged 6-8 years. The mean HABTST, ESTTST, and PSGTST were 578, 547, and 480 min, respectively. HABTST was greater than both ESTST and PSGTST (p < 0.001). Moreover, ESTTST was greater than PSGTST (p < 0.001). The mean HABSOL, ESTSOL, and PSGSOL were 15, 17, and 11 min. ESTSOL was longer than PSGSOL (p < 0.001). There were no gender differences. However, Hispanic parents reported significantly less HABTST in their children than Caucasian parents (566 vs 587 min, p < 0.001). Parents of schoolchildren in this population-based sample substantially overestimated their children's actual total sleep time and sleep onset latency.

Relationship between reported and measured sleep times: the sleep heart health study (SHHS)

STUDY OBJECTIVE

Subjective and objective assessments of sleep may be discrepant due to sleep misperception and measurement effects, the latter of which may change the quality and quantity of a person's usual sleep. This study compared sleep times from polysomnography (PSG) with self-reports of habitual sleep and sleep estimated on the morning after a PSG in adults.

DESIGN

Total sleep time and sleep onset latency obtained from unattended home PSGs were compared to sleep times obtained from a questionnaire completed before the PSG and a Morning Survey completed the morning after the PSG.

PARTICIPANTS

A total of 2,113 subjects who were > or = 40 years of age were included in this analysis.

MEASURES AND RESULTS

Subjects were 53% female, 75% Caucasian, and 38% obese. The mean habitual sleep time (HABTST), morning estimated sleep time (AMTST), and PSG total sleep times (PSGTST) were 422 min, 379 min, and 363 min, respectively. The mean habitual sleep onset latency, morning estimated sleep onset latency, and PSG sleep onset latency were 17.0 min, 21.8 min, and 16.9 min, respectively. Models adjusting for related demographic factors showed that HABTST and AMTST differ significantly from PSGTST by 61 and 18 minutes, respectively. Obese and higher educated people reported less sleep time than their counterparts. Similarly, small but significant differences were seen for sleep latency.

CONCLUSIONS

In a community population, self-reported total sleep times and sleep latencies are overestimated even on the morning following overnight PSG.

The relation of rhinitis to recurrent cough and wheezing: a longitudinal study

BACKGROUND

Recurrent cough can be a clinical manifestation of rhinitis. However, it remains unclear if the association between rhinitis and recurrent cough among children is independent of asthma.

OBJECTIVE

The aim of the present study was to determine, in a large longitudinal cohort, whether rhinitis is significantly associated with recurrent cough alone, wheezing alone, or the combination of both symptoms during childhood.

METHODS

We investigated determinants of recurrent cough, with or without wheezing, using longitudinal data from the Tucson Children's Respiratory Study. Among the 1246 subjects originally enrolled, 1024 children completed at least one questionnaire between the ages of 6 and 18 years and were included in the present study. In any survey, wheezing was defined as at least one wheezing episode during the past year and recurrent cough as two or more coughing episodes lasting at least 1 week without a cold during the past year. Generalized estimating equations were used to determine significant risk factors.

RESULTS

After adjusting for sex, skin test reactivity and parental asthma, both rhinitis (OR = 2.47 CI = 1.84, 3.30) and sinusitis (OR = 1.54 CI = 1.11, 2.14) were associated with an increased risk of recurrent cough plus wheezing. The OR associated with rhinitis were significantly reduced for subjects reporting only recurrent cough or only wheezing (OR = 1.43, CI = 1.03, 1.99; and OR = 1.30, CI = 1.07, 1.58, respectively). Recurrent cough and wheezing, when examined independently, showed different patterns of risk factors.

CONCLUSION

We found rhinitis to be an independent risk factor for both recurrent cough and wheezing during childhood. Different pathways may be involved in the association of rhinitis with recurrent cough and wheezing.

Relation of beta2-adrenoceptor polymorphisms at codons 16 and 27 to persistence of asthma symptoms after the onset of puberty

BACKGROUND

It has long been recognized that many children with asthma outgrow the disease after the onset of puberty, but little is known about genetic factors influencing this outcome.

OBJECTIVES

The aim of the present study was to determine whether the polymorphisms at codons 16 and 27 of the beta2-adrenoceptor are significant predictors of the persistence of asthma during adolescence.

DESIGN AND PARTICIPANTS

We used data from the prospective Tucson Children's Respiratory Study. Children were genotyped for the polymorphisms at codons 16 and 27. The presence of wheezing/asthma was assessed by questionnaire from age 6 years up to the reported onset of puberty (prepubertal period) and after the onset of puberty up to age 16 years (adolescence).

RESULTS

Among children who wheezed in the prepubertal period (n = 168), subjects homozygous for Gly at codon 16 were at significantly increased risk for persistent wheezing after puberty, as compared with carriers of the other genotypes (relative risk [RR], 1.43; 95% confidence interval [CI], 1.06 to 1.92; p = 0.019). This relation was present among boys (RR, 2.17; 95% CI, 1.41 to 3.36) but not girls (RR, 0.85; 95% CI, 0.55 to 1.30), and increased linearly according to the frequency of wheezing episodes after the onset of puberty. These findings persisted after adjusting for ethnicity and other potential confounders and after selecting only white children. The polymorphism at codon 27 showed no relation with risk for persistent wheezing.

CONCLUSIONS

This study provides evidence for a strong gender-specific effect of the Gly16 polymorphism on the persistence of asthma after the onset of puberty.

Outcome of asthma and wheezing in the first 6 years of life: follow-up through adolescence

RATIONALE

The effect of early life wheezing on respiratory function and continued symptoms through adolescence has not been fully described. Using data from a population-based birth cohort in Tucson, Arizona, we previously described four phenotypes based on the occurrence of wheezing lower respiratory illnesses before age 3 yr and active wheeze at age 6 yr: never wheezers (n = 425), transient early wheezers (n = 164), persistent wheezers (n = 113), and late-onset wheezers (n = 124).

OBJECTIVE

We sought to determine the prognosis for these phenotypes, with reference to lung function and symptoms, through adolescence.

METHODS

Current wheeze was assessed by questionnaire, lung function was measured by conventional spirometry, and atopy was determined by skin prick tests.

RESULTS

The prevalence of atopy and wheeze by age 16 yr was similar for never and transient wheezers and for persistent and late-onset wheezers. Both transient early, and persistent wheezers had significantly lower FEF(25-75) (-259 ml/s, p < 0.001, and -260 ml/s, p = 0.001, respectively), FEV1 (-75 ml, p = 0.02, and -87 ml, p = 0.03, respectively), and FEV1:FVC ratio (-1.9%, p = 0.002, and -2.5%, p = 0.001, respectively) through age 16 yr compared with never wheezers. Late-onset wheezers had levels of lung function similar to those of never wheezers through age 16 yr. There was no significant change in lung function among subjects with any of the four phenotypes, relative to their peers, from age 6 to 16 yr.

CONCLUSION

Patterns of wheezing prevalence and levels of lung function are established by age 6 yr and do not appear to change significantly by age 16 yr in children who start having asthma-like symptoms during the preschool years.

Rhinitis is an independent risk factor for developing cough apart from colds among adults

BACKGROUND

In cross-sectional clinical studies, rhinitis has been shown to be strongly associated with co-existing chronic cough. However, to date, this association has been poorly delineated from a prospective and epidemiological standpoint.

METHODS

We used data from the 'Pisa Prospective Study', a population-based longitudinal cohort study composed of a baseline and a follow-up survey taken approximately 5 years apart from each other. Information on cough, rhinitis, and other risk factors was collected by standardized questionnaire. Cough apart from colds was defined as either 'chronic' (most days for at least 3 months for at least two consecutive years) or 'occasional' (if the three above temporal conditions were not met). 'Any' cough was defined as the presence of either occasional or chronic cough.

RESULTS

Complete information was available for 1670 subjects who were > or =15 years old and had no positive history of cough apart from colds at the baseline survey. Among them, 299 (18%) had rhinitis at baseline. By the follow-up survey, 16% of the subjects with rhinitis had developed any cough apart from colds, as compared with only 10% of the subjects without rhinitis (OR 1.7, 95% CI 1.2-2.5, P < 0.005). After adjustment for age, gender, asthma status, smoking, and occupational exposure, rhinitis remained significantly associated with an increased risk both for any cough (OR 1.8, 95% CI 1.2-2.6) and for occasional and chronic cough separately (OR 2.2, 95% CI 1.1-4.5, and OR 1.7, 95% CI 1.1-2.6, respectively).

CONCLUSIONS

Rhinitis is a significant and independent risk factor for developing cough among adults. Further research is needed to assess potential implications in terms of prevention.

Neurogenic responses in rat lungs after nose-only exposure to diesel exhaust

Using an in-line, real-time, in vivo exposure system, we investigated whether acute adverse effects of diesel exhaust (DE*) exposure involve neurogenic inflammation in the lungs via sensory nerve C fibers. A total of 168 female F344 rats (175 g, 8 weeks old) were randomly assigned to pretreatment with capsaicin or saline to deplete C-fiber neurotransmitters. In a 2 x 3 factorial design, groups of animals were then exposed nose-only to a low level of DE (LDE, 35.3 microg/m3), a high level of DE (HDE, 632.9 microg/m3), or side-stream cigarette smoke (CS, 0.4 mg/m3). Two control groups were exposed whole body to filtered air in the animal room (fRA) or unfiltered air in the diesel engine room (eRA), respectively. DE was taken directly from a heavy-duty Cummins N14 research engine operated at 75% throttle (California Air Resources Board [CARB] 8, mode 6). Exposure to DE or air was 4 hours/day, 5 days/week, for 3 weeks. Exposure to CS was for 4 hours/day for 7 days. Involvement of neurogenic inflammation in the response to DE or CS was assessed via comparison of plasma extravasation, a sensitive endpoint of neurogenic inflammation, between rats with and without capsaicin pretreatment. Lung injury was assessed via analysis of proinflammatory cytokines, respiratory permeability, and histopathology. Moreover, whether DE exposure affected the molecular mechanisms of neurogenic inflammation was analyzed through quantification of substance P (SP) and its primary neurokinin-1 (NK1) receptor at the gene and protein levels and through neutral endopeptidase (NEP) activity. DE and CS exposure induced dose-dependent plasma extravasation, which may play an important role in initiating the associated lung inflammation and injury. Exposure of rats to DE affected the SP signaling pathway as indicated by overexpression of the NK1 receptor or reduction of SP in the lung tissue. DE exposure consistently inactivated tissue NEP, a key factor that switches neurogenic inflammation from its physiological and protective functions to a role that increases and perpetuates lung injury. The roles of these overlapping neurokininergic mechanisms in the initiation of DE-associated lung injury are plausible, and these changes may contribute to DE-associated respiratory disorders. Capsaicin rats followed the same trends as those of saline animals when exposed to DE or CS: capsaicin rats did not have significantly different plasma extravasation in the airways or lung parenchyma compared to their corresponding controls. Histopathology evaluation likewise demonstrated the same degree of tissue changes, such as edema and alveolar macrophage collection, in capsaicin and saline rats after the same level of DE exposure. In summary, our data suggest that neurokininergic mechanisms may have been involved in DE-induced inflammatory conditions in rat lung but that C fibers did not appear to be involved under these exposure conditions. We believe that time-course or protein knockdown/knockout animal studies are required to characterize further the role of neurokininergic mechanisms in DE-induced lung injury.

Segregation analysis of bronchial hyperresponsiveness in a general population in north Italy

Bronchial hyperresponsiveness (BHR) is an intermediate phenotype of asthma, with a heritability component of 30-67% and possible linkage to regions on chromosome arms 5q, 11q, and 20p. Familial correlation analysis and segregation analysis for BHR, using the FCOR and REGC programs of the S.A.G.E package, were performed to examine inheritance patterns of BHR in a general population of 1167 subjects in 550 families from the Po River Delta. BHR was assessed using the log(10) of the slope of the methacholine dose-response curve (log slope) for each subject who met inclusion criteria. Using multiple linear regression analysis, the log slope values were adjusted for age, age(2), sex, and height, and used in the familial correlation and segregation analyses. Father-offspring correlations are statistically significant, due specifically to high father-son correlations (r = 0.296, P < 0.001, adjusted values). Segregation analysis of BHR in the overall population, with and without a smoking covariate (number of packyears smoked), indicates an apparent absence of genetic transmission within families. However, in a segregation analysis of BHR in smoking families only, after adjusting for number of packyears smoked, the Mendelian transmission models could not be rejected. This may be evidence of a gene by smoking effect, and suggests that in families of smokers, a single locus gene may in part explain the inheritance of a compound phenotype (BHR x packyears).

Asthma as a risk factor for COPD in a longitudinal study

BACKGROUND

For several years, asthma and COPD have been regarded as distinct entities, with distinct clinical courses. However, despite distinctive physiologic features at the time of diagnosis, and different risk factors, the two diseases over time may develop features that are quite similar.

STUDY OBJECTIVE

To evaluate the association between physician-diagnosed asthma and the subsequent development of COPD in a cohort of 3,099 adult subjects from Tucson, AZ.

DESIGN AND METHODS

A prospective observational study. Participants completed up to 12 standard respiratory questionnaires and 11 spirometry lung function measurements over a period of 20 years. Survival curves (with time to development of COPD as the dependent variable) were compared between subjects with asthma and subjects without asthma at the initial survey.

RESULTS

Subjects with active asthma (n = 192) had significantly higher hazard ratios than inactive (n = 156) or nonasthmatic subjects (n = 2751) for acquiring COPD. As compared with nonasthmatics, active asthmatics had a 10-times-higher risk for acquiring symptoms of chronic bronchitis (95% confidence interval [CI], 4.94 to 20.25), 17-times-higher risk of receiving a diagnosis of emphysema (95% CI, 8.31 to 34.83), and 12.5-times-higher risk of fulfilling COPD criteria (95% CI, 6.84 to 22.84), even after adjusting for smoking history and other potential confounders.

CONCLUSIONS

Physician-diagnosed asthma is significantly associated with an increased risk for CB, emphysema, and COPD.

Treatment of astigmatism-related amblyopia in 3- to 5-year-old children

Best-corrected acuity was measured for vertical and horizontal gratings and for Lea Symbols recognition acuity in 3- to 5-year-old children with high astigmatism and in non-astigmatic children. There was significant amblyopia among astigmatic children at baseline. There was no evidence that eyeglass correction of astigmatism resulted in a reduction in amblyopia over a 4-month average treatment duration (although vision in astigmatic children was significantly improved immediately upon eyeglass correction, indicating that eyeglass correction did provide a visual benefit). Treatment outcome results are discussed in terms of both methodological issues and theoretical implications.

Persistence of asthma symptoms during adolescence: role of obesity and age at the onset of puberty

Little is known about rates and predictors of remission of childhood asthma after the onset of puberty. We used data collected at ages 6, 8, 11, 13, and 16 years from the Tucson Children's Respiratory Study, a population-based birth cohort. The onset of puberty was defined as the age of appearance of the first pubertal signs as reported by parents. Information on wheezing both before and after onset of puberty (mean +/- SD follow-up from onset of puberty, 4.2 +/- 1 year) was available for 781 children. Of these, 166 had asthma (either frequent wheezing or a physician-confirmed diagnosis plus any wheezing) in at least one survey before puberty. In this group, 58% of the children (97 of 166) reported the presence of wheezing after the onset of puberty (unremitting asthma). In contrast, only 30% (39 of 131) of the children with infrequent wheezing before puberty experienced wheezing episodes after the onset of puberty (unremitting wheezing). In addition to frequent wheezing before puberty, obesity, early onset of puberty, active sinusitis, and skin test sensitization were significant and independent predictors of unremitting asthma after the onset of puberty. Our findings from a population-based longitudinal cohort challenge the commonly held view that asthma usually remits during adolescence.

Repeatability of spirometry in 18,000 adult patients

The objective of this study was to determine the limits for repeatability of FEV1, FVC, and PEF during spirometry test sessions in adult outpatients. A retrospective chart review of 18,000 consecutive patients, aged 20 to 90 years, referred to a large outpatient pulmonary function laboratory for testing was performed. Measurements included the differences between the highest and second-highest FVC (dFVC), FEV1 (dFEV1), and PEF (dPEF), from prebronchodilator spirometry, and anthropometric factors. Ninety percent of the patients were able to reproduce FEV1 within 120 ml (6.1%), FVC within 150 ml (5.3%), and PEF within 0.80 L (12%). Patient characteristics, such as sex, age, height, smoking status, and FEV1 (% predicted), had very little effect on repeatability, explaining only 2 to 4% of the variation in repeatability (expressed in milliliters). We conclude that the ability of patients to meet or exceed spirometry repeatability goals does not depend on patient characteristics when testing is performed by experienced personnel. The current American Thoracic Society repeatability goal of 200 ml for FEV1 and FVC may be too lenient.

Blood pressure elevation associated with sleep-related breathing disorder in a community sample of white and Hispanic children: the Tucson Children's Assessment of Sleep Apnea study

BACKGROUND

The Tucson Children's Assessment of Sleep Apnea study (TuCASA) was designed to investigate the prevalence and correlates of objectively measured sleep-related breathing disorder (SBD) in preadolescent Hispanic and white children.

OBJECTIVE

To describe the associations of SBD and elevation in resting blood pressure in the first 239 children enrolled in TuCASA.

DESIGN

Children between the ages of 6 and 11 years (45% girls and 51% Hispanic) from elementary schools of the Tucson Unified School District were enrolled in this prospective cohort study. Resting systolic and diastolic blood pressure, sleep symptoms, and parental smoking status were obtained during evening home visits, followed by overnight unattended home polysomnography.

RESULTS

The mean (SD) systolic and diastolic blood pressures were 98.4 (10.6) mm Hg and 62.0 (8.9) mm Hg, respectively. Fifteen children had hypertension. The mean (SD) respiratory disturbance index (2%), defined as the number of apneas and hypopneas per hour of sleep associated with a 2% oxygen desaturation, was 2.3 (3.8) events per hour. Factors independently associated with systolic and diastolic blood pressure elevation were obesity, sleep efficiency, and respiratory disturbance index (2%).

CONCLUSIONS

In preadolescent children, elevated blood pressure is associated with SBD and obesity, as previously noted in adults. The control of obesity in childhood may be important to reduce the daytime consequences of SBD and to reduce the risks of life-long hypertension.