Neighborhood walkability and active travel (walking and cycling) in New York City

Urban planners have suggested that built environment characteristics can support active travel (walking and cycling) and reduce sedentary behavior. This study assessed whether engagement in active travel is associated with neighborhood walkability measured for zip codes in New York City. Data were analyzed on engagement in active travel and the frequency of walking or biking ten blocks or more in the past month, from 8,064 respondents to the New York City 2003 Community Health Survey (CHS). A neighborhood walkability scale that measures: residential, intersection, and subway stop density; land use mix; and the ratio of retail building floor area to retail land area was calculated for each zip code. Data were analyzed using zero-inflated negative binomial regression incorporating survey sample weights and adjusting for respondents' sociodemographic characteristics. Overall, 44 % of respondents reported no episodes of active travel and among those who reported any episode, the mean number was 43.2 episodes per month. Comparing the 75th to the 25th percentile of zip code walkability, the odds ratio for reporting zero episodes of active travel was 0.71 (95 % CI 0.61, 0.83) and the exponentiated beta coefficient for the count of episodes of active travel was 1.13 (95 % CI 1.06, 1.21). Associations between lower walkability and reporting zero episodes of active travel were significantly stronger for non-Hispanic Whites as compared to non-Hispanic Blacks and to Hispanics and for those living in higher income zip codes. The results suggest that neighborhood walkability is associated with higher engagement in active travel.

More neighborhood retail associated with lower obesity among New York City public high school students

Policies target fast food outlets to curb adolescent obesity. We argue that researchers should examine the entire retail ecology of neighborhoods, not just fast food outlets. We examine the association between the neighborhood retail environment and obesity using Fitnessgram data collected from 94,348 New York City public high school students. In generalized hierarchical linear models, the number of fast food restaurants predicted lower odds of obesity for adolescents (OR:0.972 per establishment; CI:0.957-0.988). In a "placebo test" we found that banks--a measure of neighborhood retail ecology--also predicted lower obesity (OR:0.979 per bank; CI:0.962-0.994). Retail disinvestment might be associated with greater obesity; accordingly, public health research should study the influence of general retail disinvestment not just food-specific investment.

Urinary concentrations of bisphenol A in an urban minority birth cohort in New York City, prenatal through age 7 years

BACKGROUND

Despite growing concern over potential health effects associated with exposures to the endocrine disruptor, bisphenol A (BPA), insufficient information is available on determinants of BPA concentrations among minority populations in the US.

OBJECTIVES

To describe concentrations and predictors of BPA in an inner-city longitudinal birth cohort.

METHODS

We analyzed spot urines for total BPA collected during pregnancy and child ages 3, 5, and 7 years from African Americans and Dominicans (n=568) enrolled in the Columbia Center for Children's Environmental Health birth cohort and residing in Northern Manhattan and the South Bronx. Adjusting for specific gravity, generalized estimating equations were used to compare BPA concentrations across paired samples and linear regression analyses were used to determine relationships between BPA, season of sample collection, socio-demographic variables and urinary concentrations of phthalate metabolites.

RESULTS

BPA was detected in ≥ 94% of samples. Prenatal concentrations were significantly lower than postnatal concentrations. Geometric means were higher among African Americans compared to Dominicans in prenatal (p=0.008), 5 year (p<0.001) and 7 year (p=0.017) samples. Geometric means at 5 and 7 years were higher (p=0.021, p=0.041 respectively) for children of mothers never married compared to mothers ever married at enrollment. BPA concentrations were correlated with phthalate metabolite concentrations at prenatal, 3, 5 and 7 years (p-values <0.05). Postnatal BPA concentrations were higher in samples collected during the summer.

CONCLUSIONS

This study shows widespread BPA exposure in an inner-city minority population. BPA concentration variations were associated with socio-demographic characteristics and other xenobiotics.

Socioeconomic and Outdoor Meteorological Determinants of Indoor Temperature and Humidity in New York City Dwellings

BACKGROUND

Numerous mechanisms link outdoor weather and climate conditions to human health. It is likely that many health conditions are more directly affected by indoor rather than outdoor conditions. Yet, the relationship between indoor temperature and humidity conditions to outdoor variability, and the heterogeneity of the relationship among different indoor environments are largely unknown.

METHODS

We use 5-14 day measures of indoor temperature and relative humidity from 327 dwellings in New York City for the years 2008-2011 to investigate the relationship between indoor climate, outdoor meteorological conditions, socioeconomic conditions, and building descriptors. Study households were primarily middle-income and located across the boroughs of Brooklyn, Queens, Bronx, and Manhattan.

RESULTS

Indoor temperatures are positively associated with outdoor temperature during the warm season and study dwellings in higher socioeconomic status neighborhoods are significantly cooler. During the cool season, outdoor temperatures have little effect on indoor temperatures; however, indoor temperatures can range more than 10 °C between dwellings despite similar outdoor temperatures. Apartment buildings tend to be significantly warmer than houses and dwellings on higher floors are also significantly warmer than dwellings on lower floors. Outdoor specific humidity is positively associated with indoor specific and relative humidity, but there is no consistent relationship between outdoor and indoor relative humidity.

CONCLUSIONS

In New York City, the relationship between indoor and outdoor temperature and humidity conditions vary significantly between dwellings. These results can be used to inform studies of health outcomes for which temperature or humidity is an established factor affecting human health and highlights the need for more research on the determinants of indoor climate.

A pilot randomized controlled trial of a commercial diet and exercise weight loss program in minority breast cancer survivors

OBJECTIVE

Obesity is associated with poorer breast cancer outcomes and losing weight postdiagnosis may improve survival. As Hispanic and black women have poorer breast cancer prognosis than non-Hispanic whites diagnosed at similar age and stage, and have higher rates of obesity, effective weight loss strategies are needed. We piloted a randomized, waitlist-controlled, crossover study to examine the effects and feasibility of the commercial Curves weight loss program among Hispanic, African American and Afro-Caribbean breast cancer survivors.

DESIGN AND METHODS

Women with stage 0-IIIa breast cancer ≥ 6 months posttreatment, sedentary, and BMI ≥ 25 kg/m(2) were randomized to the immediate arm (IA): 6 months of the Curves program followed by 6 months of observation; or the waitlist control arm (WCA): 6 months of observation followed by 6 months of the Curves program. The Curves program uses a 30-min exercise circuit and a high-vegetable/low-fat/calorie-restricted diet.

RESULTS

A total of 42 women enrolled (79% Hispanic, 21% black), mean age 51 (range 32-69) and mean BMI 33.2(± 5.9) kg/m(2); 91% were retained at month 12. At month 6, women in the IA lost an average 3.3% (± 3.5%) of body weight (range: 1.7% gain to 10.6% loss), as compared with 1.8% (± 2.9%) weight loss in the WCA (P = 0.04). At month 12, on average women in the IA regained some but not all of the weight lost during the first 6 months (P = 0.02).

CONCLUSIONS

Minority breast cancer survivors were recruited and retained in a weight loss study. Six months of the Curves program resulted in moderate weight loss, but weight loss was not maintained postintervention. Future interventions should identify methods to increase uptake and maintenance of weight loss behaviors.

Exercise-induced wheeze, urgent medical visits, and neighborhood asthma prevalence

OBJECTIVE

Exercise-induced wheeze (EIW) may identify a distinct population among asthmatics and give insight into asthma morbidity etiology. The prevalence of pediatric asthma and associated urgent medical visits varies greatly by neighborhood in New York City and is highest in low-income neighborhoods. Although increased asthma severity might contribute to the disparities in urgent medical visits, when controlling for health insurance coverage, we previously observed no differences in clinical measures of severity between asthmatic children living in neighborhoods with lower (3%-9%) versus higher (11%-19%) asthma prevalence. Among these asthmatics, we hypothesized that EIW would be associated with urgent medical visits and a child's neighborhood asthma prevalence.

METHODS

Families of 7- to 8-year-old children were recruited into a case-control study of asthma through an employer-based health insurance provider. Among the asthmatics (n = 195), prevalence ratios (PRs) for EIW were estimated. Final models included children with valid measures of lung function, seroatopy, and waist circumference (n = 140).

RESULTS

EIW was associated with urgent medical visits for asthma (PR, 2.29; P = .021), independent of frequent wheeze symptoms. In contrast to frequent wheeze, EIW was not associated with seroatopy or exhaled NO, suggesting a distinct mechanism. EIW prevalence among asthmatics increased with increasing neighborhood asthma prevalence (PR, 1.09; P = .012), after adjustment for race, ethnicity, maternal asthma, environmental tobacco smoke, household income, and neighborhood income.

CONCLUSIONS

EIW may contribute to the disparities in urgent medical visits for asthma between high- and low-income neighborhoods. Physicians caring for asthmatics should consider EIW an indicator of risk for urgent medical visits.

Prenatal exposure to butylbenzyl phthalate and early eczema in an urban cohort

BACKGROUND

Recent cross-sectional studies suggest a link between butylbenzyl phthalate (BBzP) in house dust and childhood eczema.

OBJECTIVES

We aimed to evaluate whether concentrations of monobenzyl phthalate (MBzP), the main BBzP metabolite in urine, during pregnancy are associated prospectively with eczema in young children, and whether this association varies by the child's sensitization to indoor allergens or serological evidence of any allergies.

METHODS

MBzP was measured in spot urine samples during the third trimester of pregnancy from 407 African-American and Dominican women residing in New York City in 1999-2006. Repeated questionnaires asked mothers whether their doctor ever said their child had eczema. Child blood samples at 24, 36, and 60 months of age were analyzed for total, anti-cockroach, dust mite, and mouse IgE. Relative risks (RR) were estimated with multivariable modified Poisson regression. Analyses included a multinomial logistic regression model for early- and late-onset eczema versus no eczema through 60 months of age.

RESULTS

MBzP was detected in > 99% of samples (geometric mean = 13.6; interquartile range: 5.7-31.1 ng/mL). By 24 months, 30% of children developed eczema, with the proportion higher among African Americans (48%) than among Dominicans (21%) (p < 0.001). An interquartile range increase in log MBzP concentration was associated positively with early-onset eczema (RR = 1.52 for eczema by 24 months; 95% confidence interval: 1.21, 1.91, p = 0.0003, n = 113 reporting eczema/376 total sample), adjusting for urine specific gravity, sex, and race/ethnicity. MBzP was not associated with allergic sensitization, nor did seroatopy modify consistently the MBzP and eczema association.

CONCLUSIONS

Prenatal exposure to BBzP may influence the risk of developing eczema in early childhood.

Children's urinary phthalate metabolites and fractional exhaled nitric oxide in an urban cohort

RATIONALE

Phthalates are used widely in consumer products. Exposure to several phthalates has been associated with respiratory symptoms and decreased lung function. Associations between children's phthalate exposures and fractional exhaled nitric oxide (Fe(NO)), a biomarker of airway inflammation, have not been examined.

OBJECTIVES

We hypothesized that urinary concentrations of four phthalate metabolites would be positively associated with Fe(NO) and that these associations would be stronger among children with seroatopy or wheeze.

METHODS

In an urban ongoing birth cohort, 244 children had phthalate metabolites determined in urine collected on the same day as Fe(NO) measurement. Repeated sampling gathered 313 observations between ages 4.9 and 9.1 years. Seroatopy was assessed by specific IgE. Wheeze in the past year was assessed by validated questionnaire. Regression models used generalized estimating equations.

MEASUREMENTS AND MAIN RESULTS

Log-unit increases in urinary concentrations of metabolites of diethyl phthalate (DEP) and butylbenzyl phthalate (BBzP) were associated with a 6.6% (95% confidence interval [CI] 0.5-13.1%) and 8.7% (95% CI, 1.9-16.0%) increase in Fe(NO), respectively, adjusting for other phthalate metabolites and potential covariates/confounders. There was no association between concentrations of metabolites of di(2-ethylhexyl) phthalate or di-n-butyl phthalate and Fe(NO). There was no significant interaction by seroatopy. The BBzP metabolite association was significantly stronger among children who wheeze (P = 0.016).

CONCLUSIONS

Independent associations between exposures to DEP and BBzP and Fe(NO) in a cohort of inner-city children were observed. These results suggest that these two ubiquitous phthalates, previously shown to have substantial contributions from inhalation, are positively associated with airway inflammation in children.

Influence of sports, physical education, and active commuting to school on adolescent weight status

OBJECTIVE

To compare the associations between weight status and different forms of physical activity among adolescents.

METHODS

We conducted telephone surveys with 1718 New Hampshire and Vermont high school students and their parents as part of a longitudinal study of adolescent health. We surveyed adolescents about their team sports participation, other extracurricular physical activity, active commuting, physical education, recreational activity for fun, screen time, diet quality, and demographics. Overweight/obesity (BMI for age ≥ 85th percentile) and obesity (BMI for age ≥ 95 percentile) were based on self-reported height and weight.

RESULTS

Overall, 29.0% (n = 498) of the sample was overweight/obese and 13.0% (n = 223) were obese. After adjustments, sports team participation was inversely related to overweight/obesity (relative risk [RR] = 0.73 [95% confidence interval (CI): 0.61, 0.87] for >2 sports teams versus 0) and obesity (RR = 0.61 [95% CI: 0.45, 0.81] for >2 sports teams versus 0). Additionally, active commuting to school was inversely related to obesity (RR = 0.67 [95% CI: 0.45, 0.99] for >3.5 days per week versus 0). Attributable risk estimates suggest obesity prevalence would decrease by 26.1% (95% CI: 9.4%, 42.8%) if all adolescents played on 2 sports teams per year and by 22.1% (95% CI: 0.1%, 43.3%) if all adolescents walked/biked to school at least 4 days per week.

CONCLUSIONS

Team sport participation had the strongest and most consistent inverse association with weight status. Active commuting to school may reduce the risk of obesity, but not necessarily overweight, and should be studied further. Obesity prevention programs should consider strategies to increase team sport participation among all students.

Domestic airborne black carbon and exhaled nitric oxide in children in NYC

Differential exposure to combustion by-products and allergens may partially explain the marked disparity in asthma prevalence (3-18%) among New York City neighborhoods. Subclinical changes in airway inflammation can be measured by fractional exhaled nitric oxide (FeNO). FeNO could be used to test independent effects of these environmental exposures on airway inflammation. Seven- and eight-year-old children from neighborhoods with lower (range 3-9%, n=119) and higher (range 11-18%, n=121) asthma prevalence participated in an asthma case-control study. During home visits, FeNO was measured, and samples of bed dust (allergens) and air (black carbon; BC) were collected. Neighborhood built-environment characteristics were assessed for the 500 m surrounding participants' homes. Airborne BC concentrations in homes correlated with neighborhood asthma prevalence (P<0.001) and neighborhood densities of truck routes (P<0.001) and buildings burning residual oil (P<0.001). FeNO concentrations were higher among asthmatics with than in those without frequent wheeze (≥4 times/year) (P=0.002). FeNO concentrations correlated with domestic BC among children without seroatopy (P=0.012) and with dust mite allergen among children with seroatopy (P=0.020). The association between airborne BC in homes and both neighborhood asthma prevalence and FeNO suggest that further public health interventions on truck emissions standards and residual oil use are warranted.

Relationship between maternal demoralization, wheeze, and immunoglobulin E among inner-city children

BACKGROUND

Prior research has linked maternal prenatal and postnatal mental health with the subsequent development of asthma in children. However, this relationship has not been examined in inner-city African Americans and Hispanics, populations at high risk for asthma.

OBJECTIVE

To determine the relationship of maternal demoralization with wheeze, specific wheeze phenotypes, and seroatopy among children living in a low-income, urban community.

METHODS

African American and Dominican women aged 18 to 35 years residing in New York City (the Bronx and Northern Manhattan) were recruited during pregnancy (n = 279). Maternal demoralization (ie, psychological distress) was measured both prenatally and postnatally by validated questionnaire. Outcomes included wheeze, transient (birth to 2.5 years of age), late onset (3-5 years), and persistent (birth to 5 years of age), evaluated via questionnaire and total and indoor allergen specific IgE (at birth and ages 2, 3, and 5 years). Logistic regression with generalized estimating equations assessed the association of demoralization with wheeze and atopy. Multinomial regression explored associations between demoralization and specific wheeze phenotypes.

RESULTS

Prenatal demoralization significantly predicted overall wheeze (adjusted odds ratio OR, 1.66; 95% confidence interval [CI], 1.29-2.14), transient wheeze (OR, 2.25; 95% CI, 1.34-3.76), and persistent wheeze (OR, 2.69; 95% CI, 1.52-4.77). No association was found between demoralization and IgE after adjustment (total IgE: OR, 1.04; 95% CI, 0.74-1.45; any specific IgE: OR, 0.96; 95% CI, 0.57-1.60).

CONCLUSIONS

In this inner-city cohort, prenatal demoralization was associated with transient and persistent wheeze. Understanding how maternal demoralization influences children's respiratory health may be important for developing effective interventions among disadvantaged populations.

Neighborhood differences in exposure and sensitization to cockroach, mouse, dust mite, cat, and dog allergens in New York City

BACKGROUND

Asthma prevalence varies widely among neighborhoods within New York City. Exposure to mouse and cockroach allergens has been suggested as a cause.

OBJECTIVE

To test the hypotheses that children living in high asthma prevalence neighborhoods (HAPNs) would have higher concentrations of cockroach and mouse allergens in their homes than children in low asthma prevalence neighborhoods (LAPNs), and that these exposures would be related to sensitization and asthma.

METHODS

In the New York City Neighborhood Asthma and Allergy Study, a case-control study of asthma, children 7 to 8 years old from HAPNs (n = 120) and LAPNs (n = 119) were recruited through the same middle-income health insurance plan. Children were classified as asthma cases (n = 128) or controls without asthma (n = 111) on the basis of reported symptoms or medication use. Allergens were measured in bed dust.

RESULTS

HAPN homes had higher Bla g 2 (P = .001), Mus m 1 (P = .003), and Fel d 1 (P = .003) and lower Der f 1 (P = .001) than LAPN homes. Sensitization to indoor allergens was associated with asthma, but relevant allergens differed between LAPNs and HAPNs. Sensitization to cockroach was more common among HAPN than LAPN children (23.7% vs 10.8%; P = .011). Increasing allergen exposure was associated with increased probability of sensitization (IgE) to cockroach (P < .001), dust mite (P = .009), and cat (P = .001), but not mouse (P = .58) or dog (P = .85).

CONCLUSION

These findings further demonstrate the relevance of exposure and sensitization to cockroach and mouse in an urban community and suggest that cockroach allergen exposure could contribute to the higher asthma prevalence observed in some compared with other New York City neighborhoods.

Reconsidering access: park facilities and neighborhood disamenities in New York City

With increasing concern about rising rates of obesity, public health researchers have begun to examine the availability of parks and other spaces for physical activity, particularly in cities, to assess whether access to parks reduces the risk of obesity. Much of the research in this field has shown that proximity to parks may support increased physical activity in urban environments; however, as yet, there has been limited consideration of environmental impediments or disamenities that might influence individuals' perceptions or usage of public recreation opportunities. Prior research suggests that neighborhood disamenities, for instance crime, pedestrian safety, and noxious land uses, might dissuade people from using parks or recreational facilities and vary by neighborhood composition. Motivated by such research, this study estimates the relationship between neighborhood compositional characteristics and measures of park facilities, controlling for variation in neighborhood disamenities, using geographic information systems (GIS) data for New York City parks and employing both kernel density estimation and distance measures. The central finding is that attention to neighborhood disamenities can appreciably alter the relationship between neighborhood composition and spatial access to parks. Policy efforts to enhance the recreational opportunities in urban areas should expand beyond a focus on availability to consider also the hazards and disincentives that may influence park usage.

Urinary and air phthalate concentrations and self-reported use of personal care products among minority pregnant women in New York city

Diethyl phthalate (DEP) and di-n-butyl phthalate (DnBP) are used extensively in personal care products, including fragrances (DEP) and nail polish (DnBP). Between May 2003 and July 2006, we gathered questionnaire data on the use of seven product categories (deodorant, perfume, hair spray, hair gel, nail polish/polish remover, liquid soap/body wash, and lotion/mist) over 48 h during the third trimester of pregnancy from 186 inner-city women. A 48-h personal air sample was collected and analyzed for DEP and DnBP; a maternal spot urine sample was collected and analyzed for their monoester metabolites, monoethyl phthalate (MEP) and mono-n-butyl phthalate (MnBP), respectively. In all, 97% of air samples and 84% of urine samples were collected within ±2 days of the questionnaire. During the 48 h, 41% of women reported perfume use and 10% reported nail polish/polish remover use. In adjusted analyses, no association was seen between nail product use and air DnBP or urine MnBP concentrations. Women reporting perfume use had 2.3 times higher (95% CI 1.6, 3.3) urinary MEP concentrations. Personal air DEP increased by 7% for each 25% increase in a composite indicator of the six other product categories (P<0.05), but was not associated with perfume use. Air DEP was correlated with urine MEP concentrations only among non-perfume users (r=0.51, P<0.001). Results suggest that perfume use is a significant source of DEP exposure.

Modeling the effects of obesity and weight gain on PSA velocity

BACKGROUND

Hemodilution theory states that higher blood volume in obese men effectively dilutes circulating PSA levels resulting in lower PSA test results. Here we apply hemodilution theory to model the effect of weight gain on PSA velocity.

METHODS

Hemodilution formulas were used to model PSA velocity for a series of plausible scenarios in which initial weight and weight gain were varied. The formulas were also applied to published summary data on weight, weight change and PSA velocity from the Prostate Cancer Prevention Trial (PCPT).

RESULTS

Under hemodilution theory, PSA velocity is understood to be influenced by total circulating PSA mass (ng of PSA) and BMI at the initial test and total circulating PSA mass and BMI at the subsequent test. PSA velocity in a man with a stable BMI of 35 is estimated to be 13% lower than in a man with a stable BMI of 25. A gain of 4 BMI units is predicted to attenuate PSA velocity by as much as 25%. When applied to summary data from the PCPT, the formulas estimate that a 10 pound weight gain causes a -0.028 ng/ml change in PSA, which closely matches PCPT results where a 10 pound weight gain caused a -0.024 ng/ml change in PSA. We provide software to implement the hemodilution formulas to model PSA velocity for different weights and changes in weight through time (http://www.eheintl.com/psa.jsp).

CONCLUSION

Stable obesity and weight gain both independently attenuate PSA velocity, potentially obscuring clinically relevant changes in circulating PSA.

Preliminary studies on the effect of moderate physical activity on blood levels of glutathione

Molecular epidemiological approaches are being used to study how physical activity may protect against cancer. Prior epidemiological data suggest that physical activity protects against lung cancer; however, interpretation of these data is complicated by potential confounding by smoking. Glutathione (GSH) detoxifies cigarette smoke carcinogens and the paper tests whether physical activity levels are associated with blood GSH levels. Study subjects were enrolled in a chemoprevention trial testing whether antioxidant micronutrient supplementation reduces genetic damage from cigarette smoking. Physical activity data were collected by questionnaire from 178 subjects at 12 months of follow-up in the trial. Total GSH (tGSH), which is the sum of free and protein-bound GSH and glutathione disulfide levels, was measured using the 5,5'-dithiobis-(2-nitrobenzenoic acid) colormetric assay with red blood cell samples collected at the 12-month time point. In multivariate linear regression analyses that controlled for gender and cigarettes smoked per day, tGSH was positively associated with hours per week of moderate intensity activity (beta=0.005, p=0.02). Hours per week of vigorous intensity activity were unassociated with tGSH and the effect of moderate activity remained after control for vigorous activity. The results are consistent with prior research showing differential effects of moderate and vigorous activity and suggest a mechanism through which physical activity may influence lung cancer risk.

Sleep duration associated with mortality in elderly, but not middle-aged, adults in a large US sample

STUDY OBJECTIVES

To explore age differences in the relationship between sleep duration and mortality by conducting analyses stratified by age. Both short and long sleep durations have been found to be associated with mortality. Short sleep duration is associated with negative health outcomes, but there is little evidence that long sleep duration has adverse health effects. No epidemiologic studies have published multivariate analyses stratified by age, even though life expectancy is 75 years and the majority of deaths occur in the elderly.

DESIGN

Multivariate longitudinal analyses of the first National Health and Nutrition Examination Survey using Cox proportional hazards models.

SETTING

Probability sample (n = 9789) of the civilian noninstitutionalized population of the United States between 1982 and 1992.

PARTICIPANTS

Subjects aged 32 to 86 years.

MEASUREMENTS AND RESULTS

In multivariate analyses controlling for many covariates, no relationship was found in middle-aged subjects between short sleep of 5 hours or less and mortality (hazards ratio [HR] = 0.67, 95% confidence interval [CI] 0.43-1.05) or long sleep of 9 hours or more and mortality (HR = 1.04, 95% CI 0.66-1.65). A U-shaped relationship was found only in elderly subjects, with both short sleep duration (HR = 1.27, 95% CI 1.06-1.53) and long sleep duration (HR = 1.36, 95% CI 1.15-1.60) having significantly higher HRs.

CONCLUSIONS

The relationship between sleep duration and mortality is largely influenced by deaths in elderly subjects and by the measurement of sleep durations closely before death. Long sleep duration is unlikely to contribute toward mortality but, rather, is a consequence of medical conditions and age-related sleep changes.

Colonoscopic screening in average-risk individuals ages 40 to 49 vs 50 to 59 years

BACKGROUND & AIMS

Screening guidelines for colorectal cancer include colonoscopy starting at age 50 years based on the prevalence of adenomas and the incidence of colon cancer at that age. However, only one prior study has investigated the prevalence of colorectal neoplasia with colonoscopic screening in asymptomatic average-risk individuals ages 40-49 years in the United States.

METHODS

We analyzed the results of screening colonoscopies offered to patients of a health care provider that offers screening services as part of an employer-provided wellness program. The primary end points were prevalence of adenomas and cancers for those aged 40-49 years vs those 50-59 years.

RESULTS

We analyzed 553 screening colonoscopies for patients ages 40-49 years and 352 screening colonoscopies for patients ages 50-59 years. In the 40-49 years age group, 79 patients (14%) had 1 or more adenomas, of which 11 (2% of screened) had an advanced neoplasm (>1 cm). In the 50-59 years age group, 56 patients (16%) had 1 or more adenomas detected. Of those patients, 13 (3.7% of screened) had an advanced neoplasm, and 1 patient (0.3%) had an adenocarcinoma detected.

CONCLUSIONS

We found on colonoscopic screening that the prevalence of total adenomas was similar in individuals ages 40-49 and in those 50-59 years, although the prevalence of advanced neoplasia in the 50-59 years age group may be higher than that in the 40-49 years age group.

Sleep duration as a risk factor for diabetes incidence in a large U.S. sample

STUDY OBJECTIVES

To explore the relationship between sleep duration and diabetes incidence over an 8- to 10-year follow-up period in data from the First National Health and Nutrition Examination Survey (NHANES I). We hypothesized that prolonged short sleep duration is associated with diabetes and that obesity and hypertension act as partial mediators of this relationship. The increased load on the pancreas from insulin resistance induced by chronically short sleep durations can, over time, compromise beta-cell function and lead to type 2 diabetes. No plausible mechanism has been identified by which long sleep duration could lead to diabetes.

DESIGN

Multivariate longitudinal analyses of the NHANES I using logistic regression models.

SETTING

Probability sample (n=8992) of the noninstitutionalized population of the United States between 1982 and 1992.

PARTICIPANTS

Subjects between the ages of 32 and 86 years.

MEASUREMENTS AND RESULTS

Between 1982 and 1992, 4.8% of the sample (n=430) were determined by physician diagnosis, hospital record, or cause of death to be incident cases of diabetes. Subjects with sleep durations of 5 or fewer hours (odds ratio = 1.47, 95% confidence interval 1.03-2.09) and subjects with sleep durations of 9 or more hours (odds ratio = 1.52, 95% confidence interval 1.06-2.18) were significantly more likely to have incident diabetes over the follow-up period after controlling for covariates.

CONCLUSIONS

Short sleep duration could be a significant risk factor for diabetes. The association between long sleep duration and diabetes incidence is more likely to be due to some unmeasured confounder such as poor sleep quality.

Asthma, body mass, gender, and Hispanic national origin among 517 preschool children in New York City

BACKGROUND

Striking differences in asthma prevalence have been reported among Hispanic adults and children living in different cities of the USA. Prevalence is highest among those of Puerto Rican and lowest among those of Mexican origin. We hypothesized that body size would mediate this association.

METHODS

Parents of children in New York City Head Start programs completed a questionnaire including demographic factors, health history, a detailed history of respiratory conditions, lifestyle, and home environment. Children's height and weight were measured in home visits. Logistic regression was used to model the association of asthma with body mass index percentile (<85th percentile, gender/age specific vs>or=85th percentile, gender/age specific), national origin, and other factors.

RESULTS

Of 517 children at mean age of 4.0 +/- 0.6 years, 34% met the study criteria for asthma, and 43% were above the 85th percentile. Asthma was strongly associated with non-Mexican national origin, male gender, allergy symptoms, and maternal asthma, and marginally with body size. The odds of asthma among boys of non-Mexican origin was 5.9 times that among boys of Mexican origin [95% confidence interval (CI): 2.9-12.2]; the comparable odds ratio (OR) among girls was 1.8 (95% CI: 0.9-3.6). Body mass was associated with asthma among girls [OR = 2.0 (95% CI: 1.1-3.7)], but not boys [OR = 1.4 (95% CI: 0.8-2.6)].

CONCLUSIONS

The association of asthma with both body mass and national origin was gender-specific among the children in our study. Ours is one of the first studies to report on pediatric asthma in different Hispanic populations in the same city, by gender.

Short sleep duration as a risk factor for hypertension: analyses of the first National Health and Nutrition Examination Survey

Depriving healthy subjects of sleep has been shown to acutely increase blood pressure and sympathetic nervous system activity. Prolonged short sleep durations could lead to hypertension through extended exposure to raised 24-hour blood pressure and heart rate, elevated sympathetic nervous system activity, and increased salt retention. Such forces could lead to structural adaptations and the entrainment of the cardiovascular system to operate at an elevated pressure equilibrium. Sleep disorders are associated with cardiovascular disease, but we are not aware of any published prospective population studies that have shown a link between short sleep duration and the incidence of hypertension in subjects without apparent sleep disorders. We assessed whether short sleep duration would increase the risk for hypertension incidence by conducting longitudinal analyses of the first National Health and Nutrition Examination Survey (n=4810) using Cox proportional hazards models and controlling for covariates. Hypertension incidence (n=647) was determined by physician diagnosis, hospital record, or cause of death over the 8- to 10-year follow-up period between 1982 and 1992. Sleep durations of < or =5 hours per night were associated with a significantly increased risk of hypertension (hazard ratio, 2.10; 95% CI, 1.58 to 2.79) in subjects between the ages of 32 and 59 years, and controlling for the potential confounding variables only partially attenuated this relationship. The increased risk continued to be significant after controlling for obesity and diabetes, which was consistent with the hypothesis that these variables would act as partial mediators. Short sleep duration could, therefore, be a significant risk factor for hypertension.

Design options for molecular epidemiology research within cohort studies

Past discussions of the relative strengths of nested case-control and case-cohort designs have not fully considered cohorts with stored biological samples in which biomarker analyses are planned. Issues related to biomarker analyses can affect an investigator's choice of design and the conduct of these two designs. The key issues identified are effects of analytic batch, long-term storage, and freeze-thaw cycles on biomarkers. In comparison with the nested case-control design, the case-cohort design is less able to handle these challenges. Problems arise because most implementations of the case-cohort design do not allow for simultaneous evaluation of biomarkers in cases and reference group members, and there is no matching. By design, the nested case-control study controls for storage duration and the batching of biological samples from cases and controls is logistically simple. The allowance for matching also means that subjects can be matched on the number of freeze-thaw cycles experienced by the biological sample. However, the matching generates complex data sets that can be more difficult to analyze, and the costly biomarker data generated from the controls has few uses outside of testing the specific hypotheses of the study. In addition, because the same subject can serve as a control and a case, or multiple times as a control, biomarker analyses and sample batching can be more complex than initially anticipated. However, in total, of the two designs, the nested case-control study is better suited for studying biomarkers that can be influenced by analytic batch, long-term storage, and freeze-thaw cycles.

Further development of the case-only design for assessing gene-environment interaction: evaluation of and adjustment for bias

BACKGROUND

The case-only study for investigating gene-environment interactions provides increased statistical efficiency over case-control analyses. This design has been criticized for being susceptible to bias arising from non-independence between the genetic and environmental factors in the population. Given that independence is critical to the validity of case-only estimates of interaction, researchers frequently use controls to evaluate whether the independence assumption is tenable, as advised in the literature. Our work investigates to what extent this approach is appropriate and how non-independence can be accounted for in case-only analyses.

METHODS

We provide a formula in epidemiological terms that illustrates the relationship between the gene-environment association measured among controls and the gene-environment association in the source population. Using this formula, we conducted sensitivity analyses to describe the circumstances in which controls can be used as proxy for the source population when evaluating gene-environment independence. Lastly, we generated hypothetical cohort data to examine whether multivariable modelling approaches can be used to control for non-independence.

RESULTS

Our sensitivity analyses show that controls should not be used to evaluate gene-environment independence in the population, even when the baseline risk of disease is low (i.e. 1%), and the interaction and independent effects are moderate (i.e. risk ratio = 2). When the factors are associated, it is possible to remove bias arising from non-independence using standard statistical multivariable techniques in case-only analyses.

CONCLUSIONS

Even when the disease risk is low, evaluation of gene-environment independence in controls does not provide a consistent test for bias in the case-only study. Given that control for non-independence is possible when the source of the non-independence can be conceptualized, the case-only design may still be a useful epidemiological tool for examining gene-environment interactions.

Measures of genotype versus gene products: promise and pitfalls in cancer prevention

We present a critical assessment of the promise and pitfalls of genotype versus gene function measures in cancer epidemiology studies. While both measures have pros and cons and are complementary, in terms of potential for contributing knowledge that directly leads to prevention, we argue that attention should be given to research relating functional parameters (single protein expression, functional or phenotypic assays or patterns of gene/protein expression) to disease risk. We present the theoretical and conceptual basis of why studies focusing on polymorphisms in the low-penetrance genes may be logically less fruitful for making inroads to cancer prevention than appropriately designed studies using validated functional parameters. We then substantiate these arguments with some concrete examples based on the current literature. We also discuss the limitations of including functional parameters in epidemiological studies and technical improvements required before such studies can truly fulfil their promise. Finally, we offer some specific recommendations for future research directions in this area.