It is estimated that up to half of the world’s population burns biomass fuel (wood, crop residues, animal dung and coal) for indoor uses such as cooking, lighting and heating. As a result, a large proportion of women and children are exposed to high levels of household air pollution (HAP). The short and long term effects of these exposures on the respiratory health of this population are not clearly understood. On May 9–11, 2011 NIH held an international workshop on the "Health Burden of Indoor Air Pollution on Women and Children," in Arlington, VA. To gather information on the knowledge base on this topic and identify research gaps, ahead of the meeting we conducted a literature search using PubMed to identify publications that related to HAP, asthma, and chronic obstructive pulmonary disease (COPD). Abstracts were all analyzed and we report on those considered by the respiratory sub study group at the meeting to be most relevant to the field. Many of the studies published are symptom-based studies (as opposed to objective measures of lung function or clinical examination etc.) and measurement of HAP was not done. Many found some association between indoor exposures to biomass smoke as assessed by stove type (e.g., open fire vs. liquid propane gas) and respiratory symptoms such as wheeze and cough. Among the studies that examined objective measures (e.g. spirometry) as a health outcome, the data supporting an association between biomass smoke exposure and COPD in adult women are fairly robust, but the findings for asthma are mixed. If an association was observed between the exposures and lung function, most data seemed to demonstrate mild to moderate reductions in lung function, the pathophysiological mechanisms of which need to be investigated. In the end, the group identified a series of scientific gaps and opportunities for research that need to be addressed to better understand the respiratory effects of exposure to indoor burning of the different forms of biomass fuels.
Biomass smoke; cooking fuel smoke; Indoor air pollution; COPD; asthma
Management of asthma requires attention to environmental exposures both indoors and outdoors. Americans spend most of their time indoors, where they have a greater ability to modify their environment. The indoor environment contains both pollutants (eg, particulate matter, nitrogen dioxide, secondhand smoke, and ozone) and allergens from furred pets, dust mites, cockroaches, rodents, and molds. Indoor particulate matter consists of particles generated from indoor sources such as cooking and cleaning activities, and particles that penetrate from the outdoors. Nitrogen dioxide sources include gas stoves, furnaces, and fireplaces. Indoor particulate matter and nitrogen dioxide are linked to asthma morbidity. The indoor ozone concentration is mainly influenced by the outdoor ozone concentration. The health effects of indoor ozone exposure have not been well studied. In contrast, there is substantial evidence of detrimental health effects from secondhand smoke. Guideline recommendations are not specific for optimizing indoor air quality. The 2007 National Asthma Education and Prevention Program asthma guidelines recommend eliminating indoor smoking and improving the ventilation. Though the guidelines state that there is insufficient evidence to recommend air cleaners, air cleaners and reducing activities that generate indoor pollutants may be sound practical approaches for improving the health of individuals with asthma. The guidelines are more specific about allergen avoidance; they recommend identifying allergens to which the individual is immunoglobin E sensitized and employing a multifaceted, comprehensive strategy to reduce exposure. Outdoor air pollutants that impact asthma include particulate matter, ozone, nitrogen dioxide, and sulfur dioxide, and guidelines recommend that individuals with asthma avoid exertion outdoors when these pollutants are elevated. Outdoor allergens include tree, grass, and weed pollens, which vary in concentration by season. Recommendations to reduce exposure include staying indoors, keeping windows and doors closed, using air conditioning and perhaps high-efficiency particulate arrestor (HEPA) air filters, and thorough daily washing to remove allergens from one’s person.
asthma; pollutants; particulate matter; nitrogen dioxide; sulfur dioxide; secondhand smoke; ozone; allergens
Although population differences in gene expression have been established, the impact on differential gene expression studies in large populations is not well understood. We describe the effect of self-reported race on a gene expression study of lung function in asthma. We generated gene expression profiles for 254 young adults (205 non-Hispanic whites and 49 African Americans) with asthma on whom concurrent total RNA derived from peripheral blood CD4+ lymphocytes and lung function measurements were obtained. We identified four principal components that explained 62% of the variance in gene expression. The dominant principal component, which explained 29% of the total variance in gene expression, was strongly associated with self-identified race (P<10−16). The impact of these racial differences was observed when we performed differential gene expression analysis of lung function. Using multivariate linear models, we tested whether gene expression was associated with a quantitative measure of lung function: pre-bronchodilator forced expiratory volume in one second (FEV1). Though unadjusted linear models of FEV1 identified several genes strongly correlated with lung function, these correlations were due to racial differences in the distribution of both FEV1 and gene expression, and were no longer statistically significant following adjustment for self-identified race. These results suggest that self-identified race is a critical confounding covariate in epidemiologic studies of gene expression and that, similar to genetic studies, careful consideration of self-identified race in gene expression profiling studies is needed to avoid spurious association.
ancestry; gene expression; population stratification; self-identified race
William Martin and colleagues report on their stakeholder meetings that reviewed the health risks of household air pollution and cookstoves, and identified research priorities in seven key areas.
Please see later in the article for the Editors' Summary
Staphylococcus aureus in home environments may serve as a reservoir for human colonization, making sampling of indoor surfaces relevant to exposure assessment. Using laboratory experiments and application to homes of asthmatic children in Barbados, we characterize microbiological methods adapted for settings with transportation delays between sampling and initiation of culture.
According to National Institutes of Health (NIH) guidelines, asthma control and severity are unique constructs. Little is known about how asthma control and severity are distinguished by pediatricians and if they influence treatment recommendations.
We conducted a random-sample survey of 500 pediatricians using patient vignettes with different asthma status indicators (recent hospitalization, parental report of bother from asthma, frequent symptoms, parental report of worsening asthma, and wheeze during physical exam) and a visual analog scale (VAS) to rate control and severity. Regression models assessed the independent effects of these indicators on asthma control and severity ratings, and the effects of these ratings on treatment recommendations.
A total of 270 respondents provided usable data. Compared to patients with well-controlled asthma: (1) medication intensity influenced only severity ratings; (2) frequent symptoms and recent hospitalization influenced control and severity ratings; (3) wheeze and bother influenced control ratings only (p<0.001 for all comparisons); (4) a report of worse asthma did not significantly affect any ratings (p>0.2). Poorer VAS control ratings were associated with recommendations to step-up treatment (odds ratio [OR] 2.61, 95% confidence interval [CI], 2.2–3.1, p<0.001), but more severe VAS ratings were not (OR 1.02, 95% CI, 0.9–1.2, p=0.8). Recommendations to step-down treatment were associated with poorer VAS control ratings (OR 0.70, 95% CI, 0.6–0.8, p<0.001) and more severe VAS ratings (OR 0.82, 95% CI, 0.7–0.9, p<0.001).
Pediatricians who step-up asthma treatment base their assessments on asthma control, while assessments of both control and severity factor into their decision to step-down asthma therapy.
Genome-wide association studies of human gene expression promise to identify functional regulatory genetic variation that contributes to phenotypic diversity. However, it is unclear how useful this approach will be for the identification of disease-susceptibility variants. We generated gene expression profiles for 22 184 mRNA transcripts using RNA derived from peripheral blood CD4+ lymphocytes, and genome-wide genotype data for 516 512 autosomal markers in 200 subjects. We screened for cis-acting variants by testing variants mapping within 50 kb of expressed transcripts for association with transcript abundance using generalized linear models. Significant associations were identified for 1585 genes at a false discovery rate of 0.05 (corresponding to P-values ranging from 1 × 10−91 to 7 × 10−4). Importantly, we identified evidence of regulatory variation for 119 previously mapped disease genes, including 24 examples where the variant with the strongest evidence of disease-association demonstrates strong association with specific transcript abundance. The prevalence of cis-acting variants among disease-associated genes was 63% higher than the genome-wide rate in our data set (P = 6.41 × 10−6), and although many of the implicated loci were associated with immune-related diseases (including asthma, connective tissue disorders and inflammatory bowel disease), associations with genes implicated in non-immune-related diseases including lipid profiles, anthropomorphic measurements, cancer and neurologic disease were also observed. Genetic variants that confer inter-individual differences in gene expression represent an important subset of variants that contribute to disease susceptibility. Population-based integrative genetic approaches can help identify such variation and enhance our understanding of the genetic basis of complex traits.
High frequency chest wall oscillation (HFCWO) is used for airway mucus clearance. The objective of this study was to evaluate the use of HFCWO early in the treatment of adults hospitalized for acute asthma or chronic obstructive pulmonary disease (COPD).
Randomized, multi-center, double-masked phase II clinical trial of active or sham treatment initiated within 24 hours of hospital admission for acute asthma or COPD at four academic medical centers. Patients received active or sham treatment for 15 minutes three times a day for four treatments. Medical management was standardized across groups. The primary outcomes were patient adherence to therapy after four treatments (minutes used/60 minutes prescribed) and satisfaction. Secondary outcomes included change in Borg dyspnea score (≥ 1 unit indicates a clinically significant change), spontaneously expectorated sputum volume, and forced expired volume in 1 second.
Fifty-two participants were randomized to active (n = 25) or sham (n = 27) treatment. Patient adherence was similarly high in both groups (91% vs. 93%; p = 0.70). Patient satisfaction was also similarly high in both groups. After four treatments, a higher proportion of patients in the active treatment group had a clinically significant improvement in dyspnea (70.8% vs. 42.3%, p = 0.04). There were no significant differences in other secondary outcomes.
HFCWO is well tolerated in adults hospitalized for acute asthma or COPD and significantly improves dyspnea. The high levels of patient satisfaction in both treatment groups justify the need for sham controls when evaluating the use of HFCWO on patient-reported outcomes. Additional studies are needed to more fully evaluate the role of HFCWO in improving in-hospital and post-discharge outcomes in this population.
asthma; chronic obstructive pulmonary disease; high frequency chest wall oscillation; airway mucus clearance
Bone marrow aspiration and biopsy (BMAB) is painful when performed with only local anesthetic. Our objective was to determine whether viewing nature scenes and listening to nature sounds can reduce pain during BMAB.
This was a randomized, controlled clinical trial. Adult patients undergoing outpatient BMAB with only local anesthetic were assigned to use either a nature scene with accompanying nature sounds, city scene with city sounds, or standard care. The primary outcome was a visual analog scale (0–10) of pain. Prespecified secondary analyses included categorizing pain as mild and moderate to severe and using multiple logistic regression to adjust for potential confounding variables.
One hundred and twenty (120) subjects were enrolled: 44 in the Nature arm, 39 in the City arm, and 37 in the Standard Care arm. The mean pain scores, which were the primary outcome, were not significantly different between the three arms. A higher proportion in the Standard Care arm had moderate-to-severe pain (pain rating ≥4) than in the Nature arm (78.4% versus 60.5%), though this was not statistically significant (p = 0.097). This difference was statistically significant after adjusting for differences in the operators who performed the procedures (odds ratio = 3.71, p = 0.02).
We confirmed earlier findings showing that BMAB is poorly tolerated. While mean pain scores were not significantly different between the study arms, secondary analyses suggest that viewing a nature scene while listening to nature sounds is a safe, inexpensive method that may reduce pain during BMAB. This approach should be considered to alleviate pain during invasive procedures.
Community exposures to environmental contaminants from industrial scale dairy operations are poorly understood. The purpose of this study was to evaluate the impact of dairy operations on nearby communities by assessing airborne contaminants (particulate matter, ammonia, and cow allergen, Bos d 2) associated with dairy operations inside and outside homes.
The study was conducted in 40 homes in the Yakima Valley, Washington State where over 61 dairies operate.
A concentration gradient was observed showing that airborne contaminants are significantly greater at homes within one-quarter mile (0.4 km) of dairy facilities, outdoor Bos d 2, ammonia, and TD were 60, eight, and two times higher as compared to homes greater than three miles (4.8 km) away. In addition median indoor airborne Bos d 2 and ammonia concentrations were approximately 10 and two times higher in homes within one-quarter mile (0.4 km) compared to homes greater than three miles (4.8 km) away.
These findings demonstrate that dairy operations increase community exposures to agents with known human health effects. This study also provides evidence that airborne biological contaminants (i.e. cow allergen) associated with airborne particulate matter are statistically elevated at distances up to three miles (4.8 km) from dairy operations.
The purpose of this article is to review indoor air pollution factors that can modify asthma severity, particularly in inner-city environments. While there is a large literature linking ambient air pollution and asthma morbidity, less is known about the impact of indoor air pollution on asthma. Concentrating on the indoor environments is particularly important for children, since they can spend as much as 90% of their time indoors. This review focuses on studies conducted by the Johns Hopkins Center for Childhood Asthma in the Urban Environment as well as other relevant epidemiologic studies. Analysis of exposure outcome relationships in the published literature demonstrates the importance of evaluating indoor home environmental air pollution sources as risk factors for asthma morbidity. Important indoor air pollution determinants of asthma morbidity in urban environments include particulate matter (particularly the coarse fraction), nitrogen dioxide, and airborne mouse allergen exposure. Avoidance of harmful environmental exposures is a key component of national and international guideline recommendations for management of asthma. This literature suggests that modifying the indoor environment to reduce particulate matter, NO2, and mouse allergen may be an important asthma management strategy. More research documenting effectiveness of interventions to reduce those exposures and improve asthma outcomes is needed.
particulate matter; air pollution; pediatric; urban; bronchial hyperreactivity
Epidemiologic findings support a positive association between asthma and obesity.
Determine whether obesity or increasing level of body mass index (BMI) are associated with worse asthma control in an ethnically diverse urban population.
Cross sectional assessment of asthma control was done in asthmatics recruited from primary care offices using four different validated asthma control questionnaires: the Asthma Control and Communication Instrument (ACCI), the Asthma Control Test (ACT), the Asthma Control Questionnaire (ACQ) and the Asthma Therapy Assessment Questionnaire (ATAQ). Multiple linear regression analysis was performed to evaluate the association between obesity and increasing BMI level and asthma control.
Of 292 subjects mean age of 47 years, the majority were women (82%) and African American (67%). There was a high prevalence of obesity with 63%, with only 15% being normal weight. The mean score from all four questionnaires showed an average sub-optimal asthma control (mean score/maximum possible score): ACCI (8.3/19), ACT (15.4/ 25), ACQ (2.1/ 6), and ATAQ (1.3/ 4). Regression analysis showed no association between obesity or increasing BMI level and asthma control using all four questionnaires. This finding persisted even after adjusting for FEV1, smoking status, race, gender, selected co-morbid illnesses, and long-term asthma controller use.
Using four validated asthma control questionnaires, we failed to find an association between obesity and asthma control in an urban population with asthma. Weight loss may not be an appropriate strategy to improve asthma control in this population.
Using four different validated asthma control measures, there was no association between obesity or increasing body mass index and asthma control in a largely obese urban outpatient minority population.
asthma; asthma Control; obesity; overweight; body mass index; inner city; asthma communication control instrument; ACCI; African-American
Although asthma is often inappropriately treated in children, little is known about what information pediatricians use to adjust asthma therapy. The purpose of this work was to assess the importance of various dimensions of patient asthma status as the basis of pediatrician treatment decisions.
PATIENTS AND METHODS
We conducted a cross-sectional, random-sample survey, between November 2005 and May 2006, of 500 members of the American Academy of Pediatrics using standardized case vignettes. Vignettes varied in regard to (1) acute health care use (hospitalized 6 months ago), (2) bother (parent bothered by the child’s asthma status), (3) control (frequency of symptoms and albuterol use), (4) direction (qualitative change in symptoms), and (5) wheezing during physical examination. Our primary outcome was the proportion of pediatricians who would adjust treatment in the presence or absence of these 5 factors.
Physicians used multiple dimensions of asthma status other than symptoms to determine treatment. Pediatricians were significantly more likely to increase treatment for a recently hospitalized patient (45% vs 18%), a bothered parent (67% vs 18%), poorly controlled symptoms (4–5 times per week; 100% vs 18%), or if there was wheezing on examination (45% vs 18%) compared with patients who only had well-controlled symptoms. Pediatricians were significantly less likely to decrease treatment for a child with well-controlled symptoms and recent hospitalization (28%), parents who reported being bothered (43%), or a child whose symptoms had worsened since the last doctor visit (10%) compared with children with well-controlled symptoms alone.
Pediatricians treat asthma on the basis of multiple dimensions of asthma status, including hospitalization, bother, symptom frequency, direction, and wheezing but use these factors differently to increase and decrease treatment. Tools that systematically assess multiple dimensions of asthma may be useful to help further improve pediatric asthma care.
asthma; pediatrics; treatment; decision-making; survey
Prior studies have related community violence to depression among children, but few studies have examined this relationship among adults. We hypothesized that victimization, awareness, and fear of neighborhood violence would increase the odds of depression among adult caregivers of children with asthma. We surveyed caregivers in the Baltimore Indoor Environment Study of Asthma in Kids (BIESAK), USA. The primary outcome was screening positive for depression on the Center for Epidemiological Studies Depression index. We assessed victimization, awareness, and fear of neighborhood violence, and conducted spatial analysis identifying subject homes within 500 ft of a homicide to validate survey measures of neighborhood violence. A multilevel logistic model with clustering by neighborhood estimated odds ratios and 95% confidence intervals. Survey responses about fear of neighborhood violence were strongly predicted by having a home within 500 ft of a homicide. Of 150 caregivers of children with asthma, 49% were aware of a neighborhood violent event, 36% were fearful of neighborhood violence, 22% reported victimization, and 27% had a homicide within 500 ft of the home. In our multilevel model, fear of violence increased the odds of depression by 6.7. Victimization was associated with a possible trend towards depression, and awareness of neighborhood violence did not increase the odds of depression. Based on our findings, personal experience with neighborhood violence may be more important than simple awareness. Health care workers should consider screening for depression among patients exposed to community violence.
CES-D; Community; Inner-city; Mental health; Survey; USA
Critically ill patients and families rely upon physicians to provide estimates of prognosis and recommendations for care. Little is known about patient and clinician factors which influence these predictions. The association between these predictions and recommendations for continued aggressive care is also understudied.
We administered a mail-based survey with simulated clinical vignettes to a random sample of the Critical Care Assembly of the American Thoracic Society. Vignettes represented a patient with septic shock with multi-organ failure with identical APACHE II scores and sepsis-associated organ failures. Vignettes varied by age (50 or 70 years old), body mass index (BMI) (normal or obese) and co-morbidities (none or recently diagnosed stage IIA lung cancer). All subjects received the vignettes with the highest and lowest mortality predictions from pilot testing and two additional, randomly selected vignettes. Respondents estimated outcomes and selected care for each hypothetical patient.
Despite identical severity of illness, the range of estimates for hospital mortality (5th to 95th percentile range, 17% to 78%) and for problems with self-care (5th to 95th percentile range, 2% to 74%) was wide. Similar variation was observed when clinical factors (age, BMI, and co-morbidities) were identical. Estimates of hospital mortality and problems with self-care among survivors were significantly higher in vignettes with obese BMIs (4.3% and 5.3% higher, respectively), older age (8.2% and 11.6% higher, respectively), and cancer diagnosis (5.9% and 6.9% higher, respectively). Higher estimates of mortality (adjusted odds ratio 1.29 per 10% increase in predicted mortality), perceived problems with self-care (adjusted odds ratio 1.26 per 10% increase in predicted problems with self-care), and early-stage lung cancer (adjusted odds ratio 5.82) were independently associated with recommendations to limit care.
The studied clinical factors were consistently associated with poorer outcome predictions but did not explain the variation in prognoses offered by experienced physicians. These observations raise concern that provided information and the resulting decisions about continued aggressive care may be influenced by individual physician perception. To provide more reliable and accurate estimates of outcomes, tools are needed which incorporate patient characteristics and preferences with physician predictions and practices.
Asthma disproportionately affects inner-city, minority children in the U.S. Outdoor pollutant concentrations, including particulate matter (PM), are higher in inner-cities and contribute to childhood asthma morbidity. Although children spend the majority of time indoors, indoor PM exposures have been less extensively characterized. There is a public health imperative to characterize indoor sources of PM within this vulnerable population to enable effective intervention strategies. In the present study, we sought to identify determinants of indoor PM in homes of Baltimore inner-city pre-school children.
Children ages 2-6 (n=300) who were predominantly African-American (90%) and from lower socioeconomic backgrounds were enrolled. Integrated PM2.5 and PM10 air sampling was conducted over a 3-day period in the children’s bedrooms and at a central monitoring site while caregivers completed daily activity diaries. Homes of pre-school children in inner-city Baltimore had indoor PM concentrations that were twice as high as simultaneous outdoor concentrations. The mean indoor PM2.5 and PM10 concentrations were 39.5±34.5 μg/m3 and 56.2±44.8 μg/m3, compared to the simultaneously measured ambient PM2.5 and PM10 (15.6±6.9 and 21.8±9.53 μg/m3, respectively). Common modifiable household activities, especially smoking and sweeping, contributed significantly to higher indoor PM, as did ambient PM concentrations. Open windows were associated with significantly lower indoor PM. Further investigation of the health effects of indoor PM exposure is warranted, as are studies to evaluate the efficacy of PM reduction strategies on asthma health of inner-city children.
Particulate matter; Air pollution; Asthma; Pediatric; Urban
Although outdoor particulate matter (PM) has been linked to mortality and asthma morbidity, the impact of indoor PM on asthma has not been well established.
This study was designed to investigate the effect of in-home PM on asthma morbidity.
For a cohort of 150 asthmatic children (2–6 years of age) from Baltimore, Maryland, a technician deployed environmental monitoring equipment in the children’s bedrooms for 3-day intervals at baseline and at 3 and 6 months. Caregivers completed questionnaires and daily diaries during air sampling. Longitudinal data analyses included regression models with generalized estimating equations.
Children were primarily African Americans (91%) from lower socioeconomic backgrounds and spent most of their time in the home. Mean (± SD) indoor PM2.5–10 (PM with aerodynamic diameter 2.5–10 μm) and PM2.5 (aerodynamic diameter < 2.5 μm) concentrations were 17.4 ± 21.0 and 40.3 ± 35.4 μg/m3. In adjusted models, 10-μg/m3 increases in indoor PM2.5–10 and PM2.5 were associated with increased incidences of asthma symptoms: 6% [95% confidence interval (CI), 1 to 12%] and 3% (95% CI, –1 to 7%), respectively; symptoms causing children to slow down: 8% (95% CI, 2 to 14%) and 4% (95% CI, 0 to 9%), respectively; nocturnal symptoms: 8% (95% CI, 1 to 14%) and 6% (95% CI, 1 to 10%), respectively; wheezing that limited speech: 11% (95% CI, 3 to 19%) and 7% (95% CI, 0 to 14%), respectively; and use of rescue medication: 6% (95% CI, 1 to 10%) and 4% (95% CI, 1 to 8%), respectively. Increases of 10 μg/m3 in indoor and ambient PM2.5 were associated with 7% (95% CI, 2 to 11%) and 26% (95% CI, 1 to 52%) increases in exercise-related symptoms, respectively.
Among preschool asthmatic children in Baltimore, increases in in-home PM2.5–10 and PM2.5 were associated with respiratory symptoms and rescue medication use. Increases in in-home and ambient PM2.5 were associated with exercise-related symptoms. Although reducing PM outdoors may decrease asthma morbidity, reducing PM indoors, especially in homes of inner-city children, may lead to improved asthma health.
air pollution; asthma; indoor; particulate matter; pediatric; urban
The effect of indoor nitrogen dioxide concentrations on asthma morbidity among inner-city preschool children is uncertain.
Our goal was to estimate the effect of indoor NO2 concentrations on asthma morbidity in an inner-city population while adjusting for other indoor pollutants.
We recruited 150 children (2–6 years of age) with physician-diagnosed asthma from inner-city Baltimore, Maryland. Indoor air was monitored over a 72-hr period in the children’s bedrooms at baseline and 3 and 6 months. At each visit, the child’s caregiver completed a questionnaire assessing asthma symptoms over the previous 2 weeks and recent health care utilization.
Children were 58% male, 91% African American, and 42% from households with annual income < $25,000; 63% had persistent asthma symptoms. The mean (± SD) in-home NO2 concentration was 30.0 ± 33.7 (range, 2.9–394.0) ppb. The presence of a gas stove and the use of a space heater or oven/stove for heat were independently associated with higher NO2 concentrations. Each 20-ppb increase in NO2 exposure was associated significantly with an increase in the number of days with limited speech [incidence rate ratio (IRR) = 1.15; 95% confidence interval (CI), 1.05–1.25], cough (IRR = 1.10; 95% CI, 1.02–1.18), and nocturnal symptoms (IRR = 1.09; 95% CI, 1.02–1.16), after adjustment for potential confounders. NO2 concentrations were not associated with increased health care utilization.
Higher indoor NO2 concentrations were associated with increased asthma symptoms in preschool inner-city children. Interventions aimed at lowering NO2 concentrations in inner-city homes may reduce asthma morbidity in this vulnerable population.
asthma; indoor pollutants; inner city; nitrogen dioxide; preschool
Racial differences in asthma care are not fully explained by socioeconomic status, care access, and insurance status. Appropriate care requires accurate physician estimates of severity. It is unknown if accuracy of physician estimates differs between black and white patients, and how this relates to asthma care disparities.
We hypothesized that: 1) physician underestimation of asthma severity is more frequent among black patients; 2) among black patients, physician underestimation of severity is associated with poorer quality asthma care.
Design, Setting and Patients
We conducted a cross-sectional survey among adult patients with asthma cared for in 15 managed care organizations in the United States. We collected physicians’ estimates of their patients’ asthma severity. Physicians’ estimates of patients’ asthma as being less severe than patient-reported symptoms were classified as underestimates of severity.
Frequency of underestimation, asthma care, and communication.
Three thousand four hundred and ninety-four patients participated (13% were black). Blacks were significantly more likely than white patients to have their asthma severity underestimated (OR = 1.39, 95% CI 1.08–1.79). Among black patients, underestimation was associated with less use of daily inhaled corticosteroids (13% vs 20%, p < .05), less physician instruction on management of asthma flare-ups (33% vs 41%, p < .0001), and lower ratings of asthma care (p = .01) and physician communication (p = .04).
Biased estimates of asthma severity may contribute to racially disparate asthma care. Interventions to improve physicians’ assessments of asthma severity and patient–physician communication may minimize racial disparities in asthma care.
asthma; racial disparities; patient–physician communication
Asthma is a chronic inflammatory disease of the lungs, characterized by airway hyperreactivity, mucus hypersecretion, and airflow obstruction. Despite recent advances, the genetic regulation of asthma pathogenesis is still largely unknown. Gene expression profiling techniques are well suited to study complex diseases and hold substantial promise for identifying novel genes and pathways in asthma; however, relatively few studies have been completed in human asthma. The few studies that have been done have identified many novel candidate genes and pathways in asthma pathogenesis, including ALOX15 and serine proteinase inhibitors cathepsin C and G. The interpretation of results of these studies should be cautious, as limitations include small sample sizes and heterogeneity of study populations and tissues sampled. In the future, the promise of gene expression studies would be enhanced by the use of larger sample sizes and attempts to standardize phenotype, sample collection techniques, and analysis. As the field of expression profiling in asthma advances, we hope it will improve our understanding of critical questions about mechanisms involved in susceptibility to the disease, as well as help to personalize care by improving appropriate selection of patients for prevention and treatment strategies.
airway; atopy; gene expression; inflammation; microarray
Evidence for environmental causes of asthma is limited, especially among African Americans. To look for systematic differences in early life domestic exposures between inner-city preschool children with and without asthma, we performed a study of home indoor air pollutants and allergens.
Children 2–6 years of age were enrolled in a cohort study in East Baltimore, Maryland. From the child’s bedroom, air was monitored for 3 days for particulate matter ≤ 2.5 and ≤ 10 μm in aerodynamic diameter (PM2.5, PM10), nitrogen dioxide, and ozone. Median baseline values were compared for children with (n = 150) and without (n = 150) asthma. Housing characteristics related to indoor air pollution were assessed by caregiver report and home inspection. In addition, indoor allergen levels were measured in settled dust.
Children were 58% male, 91% African American, and 88% with public health insurance. Housing characteristics related to pollutant exposure and bedroom air pollutant concentrations did not differ significantly between asthmatic and control subjects [median: PM2.5, 28.7 vs. 28.5 μg/m3; PM10, 43.6 vs. 41.4 μg/m3; NO2, 21.6 vs. 20.9 ppb; O3, 1.4 vs. 1.8 ppb; all p > 0.05]. Settled dust allergen levels (cat, dust mite, cockroach, dog, and mouse) were also similar in bedrooms of asthmatic and control children.
Exposures to common home indoor pollutants and allergens are similar for inner-city preschool children with and without asthma. Although these exposures may exacerbate existing asthma, this study does not support a causative role of these factors for risk of developing childhood asthma.
African American; air pollution; allergens; asthma; particulate matter; pediatric; urban
Rationale: Hospitalizations for asthma exacerbations are common in the United States, but there are no national estimates of outcomes in this population. It is also not known if race disparities in asthma deaths exist among hospitalized patients.
Objectives: To estimate outcomes of patients hospitalized for asthma in the United States and to determine if the risk of death in this population is higher among black patients compared with white patients.
Methods: We used the Nationwide Inpatient Sample for 2000. Admissions for asthma exacerbations among patients > 5 yr of age were included. Mortality was the primary outcome; secondary outcomes were length of stay and total hospital charges.
Measurements and Main Results: In-hospital asthma mortality was 0.5% (99% confidence interval [CI], 0.4–0.6), with mean hospital stay of 2.7 d (99% CI, 2.6–2.8 d) and $9,078 (99% CI, $8,300–9,855) in hospital charges. Deaths in this population accounted for about one-third of all asthma deaths reported in the United States. Black patients hospitalized for asthma exacerbations were less likely to die when compared with white patients (0.3 vs. 0.6%; p < 0.001). However, in multivariable analyses, there were no significant race differences in hospital deaths.
Conclusions: Mortality among patients hospitalized for asthma exacerbations accounts for one-third of all deaths from asthma. The higher overall risk of death from asthma in black patients compared with white patients in the United States is not explained by race differences in hospital deaths and therefore is attributable to factors preceding hospitalization.
costs; epidemiology; length of stay; mortality; race
To develop a propensity score-based risk adjustment method to estimate the performance of 20 physician groups and to compare performance rankings using our method to a standard hierarchical regression-based risk adjustment method.
Data Sources/Study Setting
Mailed survey of patients from 20 California physician groups between July 1998 and February 1999.
A cross-sectional analysis of physician group performance using patient satisfaction with asthma care. We compared the performance of the 20 physician groups using a novel propensity score-based risk adjustment method. More specifically, by using a multinomial logistic regression model we estimated for each patient the propensity scores, or probabilities, of having been treated by each of the 20 physician groups. To adjust for different distributions of characteristics across groups, patients cared for by a given group were first stratified into five strata based on their propensity of being in that group. Then, strata-specific performance was combined across the five strata. We compared our propensity score method to hierarchical model-based risk adjustment without using propensity scores. The impact of different risk-adjustment methods on performance was measured in terms of percentage changes in absolute and quintile ranking (AR, QR), and weighted κ of agreement on QR.
The propensity score-based risk adjustment method balanced the distributions of all covariates among the 20 physician groups, providing evidence for validity. The propensity score-based method and the hierarchical model-based method without propensity scores provided substantially different rankings (75 percent of groups differed in AR, 50 percent differed in QR, weighted κ=0.69).
We developed and tested a propensity score method for profiling multiple physician groups. We found that our method could balance the distributions of covariates across groups and yielded substantially different profiles compared with conventional methods. Propensity score-based risk adjustment should be considered in studies examining quality comparisons.
Physician group; profiling; propensity score; regression-to-the-mean; risk adjustment