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Biomedical subjects

Dennis R Ownby

Publications and source records attributed to Dennis R Ownby.

At least 19 recordsLinked to original sources

Identifying students with self-report of asthma and respiratory symptoms in an urban, high school setting.

Strategies for identifying urban youth with asthma have not been described for high school settings. African-American high school students are rarely included in asthma studies, despite a high risk of asthma mortality when compared to other age and race groups. Identification and follow-up of children with uncontrolled respiratory symptoms are necessary to reduce the burden of asthma morbidity and mortality, especially in underserved areas. We describe a process used to identify high school students who could benefit from intervention based on self-report of asthma and/or respiratory symptoms, and the costs associated with symptom-identification. Letters announcing a survey were mailed to parents of 9th-11th graders by an authorized vendor managing student data for the school district. Scan sheets with student identifiers were distributed to English teachers at participating schools who administered the survey during a scheduled class. Forms were completed by 5,967 of the 7,446 students assigned an English class (80% response). Although prevalence of lifetime asthma was 15.8%, about 11% of students met program criteria for enrollment through report of an asthma diagnosis and recent symptoms, medication use, or health care utilization. Another 9.2% met criteria by reported symptoms only. Cost of symptom-identification was $5.23/student or $32.29/program-eligible student. There is a need for school-based asthma programs targeting urban adolescents, and program initiation will likely require identification of students with uncontrolled symptoms. The approach described was successfully implemented with a relatively high response rate. Itemized expenses are presented to facilitate modifications to reduce costs. This information may benefit providers, researchers, or administrators targeting similar populations.

Absenteeism↗

Race-ethnicity, crime, and other factors associated with adherence to inhaled corticosteroids.

BACKGROUND: Previous studies have shown differences in adherence to inhaled corticosteroids (ICSs) by race-ethnicity, yet little is known about factors that contribute to adherence within these groups. Environmental stressors, such as crime exposure, which has been associated with asthma morbidity, might also predict ICS adherence. OBJECTIVE: We sought to identify factors associated with ICS adherence among patients with asthma and among African American patients and white patients separately. METHODS: Study patients with asthma were aged 18 to 50 years and were enrolled in a large southeast Michigan health maintenance organization between January 1, 1999, and December 31, 2001. The primary outcome, ICS adherence, was calculated by linking prescription-fill data with dosage information. Predictor variables included age, sex, race-ethnicity, measures of socioeconomic status (SES), average ICS copay, existing comorbidities, and crime rate in area of residence. RESULTS: Adherence information was available for 176 patients. ICS adherence was lower among African American patients (n = 75) when compared with white patients (n = 94; 40% vs 58%, respectively; P = .002). Among white patients, adherence was significantly lower for women when compared with men. Among African American patients, age and residential crime rates were positively and negatively associated with ICS adherence, respectively. Area crime remained a predictor of adherence in African American patients, even after adjusting for multiple measures of SES. CONCLUSIONS: This study suggests that an environmental stressor, area crime, provides additional predictive insight into ICS-adherent behavior beyond typical SES factors. CLINICAL IMPLICATIONS: Better understanding of environmental factors that influence ICS adherence might aid in efforts to improve it.

Administration, Inhalation↗

Gene-environment interactions with CD14 C-260T and their relationship to total serum IgE levels in adults.

BACKGROUND: Both endotoxin exposure and a single nucleotide polymorphism in one of its receptors, CD14 C-260T, have been separately associated with total serum IgE levels. Furred pets might also influence IgE levels through their effects on endotoxin levels. However, how these factors interact to influence total IgE levels is not well known, especially in adults. OBJECTIVE: We sought to investigate the interactive relationship between endotoxin levels, pet exposure, and CD14 C-260T genotype on total serum IgE levels in adults. METHODS: Mothers enrolled in an ongoing cohort study were genotyped for the CD14 C-260T polymorphism. Exposure to pets was assessed by using questionnaires and dust allergen levels collected in the home. Endotoxin exposure was estimated by using dust collected from mothers' bedroom floors. The primary outcome measure was total serum IgE level. RESULTS: CD14 C-260T genotype was assessed in 517 (85.2%) of the 607 women enrolled in the study. The CD14 C-260T genotype was significantly associated with total IgE levels; however, this relationship appeared to be modified by the level of endotoxin exposure. Similar interactions between CD14 C-260T and pet exposure were not seen, regardless of the measure of pet exposure used. CONCLUSIONS: The CD14 C-260T genotype and endotoxin exposure together appear to influence total serum IgE levels in adults. The absence of a similar gene-environment interaction for pet exposure suggests separate mechanisms of action. CLINICAL IMPLICATIONS: A common polymorphism in the endotoxin receptor, CD14 C-260T, and dust endotoxin levels in the home might interact to influence total serum IgE levels into adulthood.

Adult↗

Applying epidemiologic concepts of primary, secondary, and tertiary prevention to the elimination of racial disparities in asthma.

Despite medical and scientific advances, racial and ethnic disparities persist in US asthma morbidity and mortality rates. Progress in the elimination of these disparities will involve disentangling the contribution of social constructs, such as race, socioeconomic status, and culture, from that of the physical environment and genetic susceptibility. One approach to reducing asthma disparities is through the traditional disease prevention stages of intervention. As such, primary prevention targets reductions in asthma incidence; secondary prevention is the mitigation of established disease and involves disease detection, management, and control; and tertiary prevention is the reduction of complications caused by severe disease. Once causative factors at each level of disease prevention are understood, this knowledge can be translated into clinical practice and public health policy.

Asthma↗

Relationship between extremely low total serum IgE levels and rhinosinusitis.

BACKGROUND: The few studies examining clinical manifestations in adults with serum IgE levels less than 2.0 IU/mL provide conflicting information. OBJECTIVE: To examine self-reported respiratory disease in women with total serum IgE levels less than 2.0 IU/mL to further elucidate previous reports of an association between IgE deficiency and chronic rhinosinusitis. METHODS: In a geographically based cohort of 626 pregnant women, total serum IgE levels were measured using a standard assay with a lower limit of detection of 2.0 IU/mL. Sera with IgE levels less than 2.0 IU/mL were assayed again using a low IgE protocol with a detection limit of 0.02 IU/mL. RESULTS: Twenty-one individuals (3.4%) were found to have IgE levels less than 2.0 IU/mL. On repeated assay, 20 of these individuals with available clinical data were found to have detectable IgE levels ranging from 0.5 to 2.1 IU/mL (geometric mean, 1.2 IU/mL). None of these individuals with low IgE levels had physician-diagnosed sinusitis compared with 19.3% (113/585) of those with IgE levels of 2.0 IU/mL or greater (P = .03). Physician-diagnosed asthma was also less prevalent (1/19, 5.3%) in the low IgE group compared with 20.6% in those with higher IgE levels, but this was not significant (P = .14). The low IgE group reported a higher prevalence of hay fever symptoms than the remaining cohort (31.6% vs 24.4%; P = .43) but had less physician-diagnosed hay fever (5.3% vs 15.8%; P = .34). CONCLUSIONS: Low serum IgE levels were relatively common in these pregnant women. In contrast to previous studies, a low IgE level was not associated with chronic rhinosinusitis.

Adult↗

Breastfeeding history and childhood allergic status in a prospective birth cohort.

BACKGROUND: Breastfeeding provides the best possible nutrition for newborns, but its role in the development of allergies is complex. OBJECTIVE: To examine the relationship between breastfeeding and early childhood skin sensitization. METHODS: In a birth cohort of 405 children from the Childhood Allergy Study, we used maternal report to classify children's duration of breastfeeding and whether they were breastfed only, formula fed only, or both. We examined the relationships between this information and childhood allergies as determined by skin prick testing for inhalant allergens at age 6 to 7 years. RESULTS: There was no association between duration of breastfeeding and risk of allergic sensitization. Overall, children who were breastfed only were 50% more likely to have allergic sensitization than those fed formula only (relative risk [RR], 1.5; 95% confidence interval [CI], 1.1-2.1). Although the estimates are imprecise, this RR was higher for children born to mothers reporting a history of allergy (RR, 1.8; 95% CI, 1.0-3.0) than for those born to mothers with no allergic history (RR, 1.3; 95% CI, 0.9-2.1), for children in households without (RR, 1.6; 95% CI, 1.1-2.2) vs with (RR, 1.0; 95% CI, 0.3-4.0) multiple pets, and for those with an older sibling (RR, 2.0; 95% CI, 1.2-3.3) vs firstborns (RR, 1.3; 95% CI, 0.8-2.1). CONCLUSIONS: Breastfeeding without formula supplementation may be associated with an increased risk of childhood allergies. However, this association may vary with birth order, exposure to household pets, and maternal allergic history.

Age of Onset↗

Agreement between teenager and caregiver responses to questions about teenager's asthma.

It is unknown if teenagers and caregivers give similar responses when interviewed about the teen's asthma. We analyzed data for 63 urban African-American teen-caregiver pairs. Caregivers underestimated teen smoking by 30%, gave lower estimates for teen exposure to passive smoke, and disagreed with teens on controller medication usage. Teen-caregiver responses were not significantly different for estimates of symptom-days, activity limitations, or nights awakened; nor were they significantly different for report of emergency department visits or hospitalizations. Agreement was weak for perceived asthma control and severity. Teen-caregiver agreement on asthma depends on the type of information being sought.

Adolescent↗

Ontogeny of the allergic inflammatory response.

The ability to produce allergic responses begins early in fetal life along with the development of other elements of the immune system. Among the most interesting questions related to the development of allergic disease are whether the fetus in utero commonly is exposed to sufficient allergen to induce IgE production and how much the mother's immune responses affect the developing fetal immune system. After birth, it seems that many factors, including the frequency and severity of infections and the timing and intensity of allergen and animal exposures, continue to influence immune development.

Allergens↗

Antibiotic exposure in early infancy and risk for childhood atopy.

BACKGROUND: The increase in pediatric allergy and asthma parallels the increase in use of antibiotics. Antibiotics disturb the flora of the gastrointestinal tract, possibly perturbing the developing immune system. OBJECTIVE: We evaluated whether antibiotic use during early infancy increased the risk for atopy. METHODS: Antibiotic prescriptions documented in medical records were collected from a birth cohort born from 1987 through 1989 (n = 725). At 6 to 7 years of age, 448 were followed by means of examination, including skin prick tests and serum IgE measurements to common allergens. RESULTS: Adjusted odds ratios (aORs) and 95% CIs were calculated comparing children with any versus those with no antibiotic use in the first 6 months and the outcomes of atopy (any positive skin test response), seroatopy (any positive specific IgE test result), either atopy or seroatopy, and both atopy and seroatopy. Atopy increased with antibiotic use approaching statistical significance (aOR, 1.48; 95% CI, 0.94-2.34; P = .09); however, the risk was concentrated among children with less than 2 pets in the home (aOR, 1.73; 95% CI, 1.07-2.80; P = .024) and children breast-fed for 4 or more months (aOR, 3.02; 95% CI, 1.27-7.17; P = .013). The aORs were generally in the same direction for seroatopy and the combined categories. CONCLUSION: Antibiotic use in early life appears to contribute to increased risk for atopy in certain subgroups of children.

Animals↗

Timing and intensity of early fevers and the development of allergies and asthma.

BACKGROUND: Early childhood fevers appear to protect against later allergies and asthma. What is not known is the time in which fevers exert this effect and whether the degree of temperature increase is important. OBJECTIVE: We sought to examine the relationship between the time and degree of early fevers and later allergies and asthma. METHODS: Eight hundred thirty-five children from southeast Michigan were enrolled at birth. Clinic records from their first 2 years were abstracted for episodes of fever. At age 6 to 7 years, children underwent allergy testing. We examined fevers occurring within 6-month intervals in the first 2 years of life and outcomes at age 6 to 7 years. The primary outcome measures were allergic sensitization, asthma, asthma with allergic sensitization, and asthma without allergic sensitization. RESULTS: In the unadjusted analysis each episode of fever between 7 and 12 months of age was associated with a lower odds of allergic sensitization (odds ratio [OR], 0.71; 95% CI, 0.54-0.93) and asthma with allergic sensitization (OR, 0.43; 95% CI, 0.21-0.90) at age 6 to 7 years. Likewise, every 1 degrees C increase in the maximum temperature between 7 and 12 months was associated with a lower odds of allergic sensitization (OR, 0.77; 95% CI, 0.61-0.96) and asthma with allergic sensitization (OR, 0.62; 95% CI, 0.40-0.94). After adjusting for potential confounders, each episode of fever between 7 and 12 months was associated with a lower likelihood of asthma with allergic sensitization (adjusted OR, 0.33; 95% CI, 0.11-0.94) at age 6 to 7 years. CONCLUSIONS: Both the timing and intensity of childhood fevers appear to be important factors in the development of allergies and asthma.

Asthma↗

The role of endotoxin and its receptors in allergic disease.

OBJECTIVE: To summarize the existing literature on the association of endotoxin with respiratory diseases and allergic sensitization and to review the potentially modifying effects of endotoxin receptor polymorphisms. DATA SOURCES: English-language articles were identified from the MEDLINE and PubMed databases using combinations of the following search terms: endotoxin, toll-like receptor, polymorphisms, atopy, asthma, and allergy. Other sources included experts in the field and the bibliographies of pertinent articles. STUDY SELECTION: Relevant articles were selected based on the authors' expert opinion. RESULTS: Cross-sectional studies, particularly those of children raised in rural European communities, suggest that early endotoxin exposure may protect against the development of allergic sensitization and atopic asthma. However, endotoxin exposure may also contribute to other nonatopic respiratory disorders and may exacerbate disease in individuals with preexisting asthma. Paradoxically, among individuals exposed to high levels of endotoxin, carriers of a functional mutation in toll-like receptor 4, which reduces cellular responsiveness to endotoxin, may be at lower risk of developing allergic sensitization. CONCLUSIONS: The effect of endotoxin exposure on allergic sensitization and asthma appears to be influenced by the timing of exposure, the presence or absence of preexisting disease, and polymorphisms in the genes that encode endotoxin receptors. Further studies are needed to define the window period for this effect, as well as the underlying immunologic mechanism.

Asthma↗

Asthma in rural America.

OBJECTIVES: To examine current trends of asthma prevalence, diagnosis, and utilization of care in rural areas, increase awareness about asthma disease burden, and provide general recommendations for improving care in this setting. DATA SOURCES: MEDLINE searches were conducted for articles published from 1966 onward, with human subjects and the English language as descriptors. Other terms used included undiagnosed frequent wheezing, hygiene hypothesis, atopic sensitization, endotoxin, telemedicine, and asthma prevalence and care in rural or urban areas. STUDY SELECTION: Review and original research studies that reported on asthma care in rural areas were selected for evaluation. RESULTS: Contrary to common belief, evidence suggests that asthma prevalence of rural and urban youth is comparable in the United States and may indeed be higher in rural areas. Data are not available to determine prevalence rates for rural adults in the United States. This review presents data suggesting that the utilization of asthma care among rural and urban residents may not be comparable. Rural residents are confronted with certain barriers to care that are not as common in the urban setting. These include lack of health care insurance, geographic obstacles to obtaining care, inability of getting suitable appointments, scarcity of health care professionals, and poor access to information about asthma. CONCLUSIONS: Current literature suggests that asthma in rural areas may be underdiagnosed and deserves additional study. Improving formal and continuing education of health care professionals, compensating for health care shortages by using existing resources, and facilitating patient support and education are some of the ways to address the special needs faced by rural residents.

Asthma↗

Blood lead level and risk of asthma.

Asthma and lead poisoning are prevalent among urban children in the United States. Lead exposure may be associated with excessive production of immunoglobulin E, possibly increasing asthma risk and contributing to racial disparities. The objective of this study was to examine racial differences in the association of blood lead level (BLL) to risk of developing asthma. We established and followed a cohort prospectively to determine asthma onset, using patient encounters and drug claims obtained from hospital databases. Participants were managed care enrollees with BLL measured and documented at 1-3 years of age. We used multiple variable analysis techniques to determine the relationship of BLL to period prevalent and incident asthma. Of the 4,634 children screened for lead from 1995 through 1998, 69.5% were African American, 50.5% were male, and mean age was 1.2 years. Among African Americans, BLL > or = 5 and BLL > or = 10 microg/dL were not associated with asthma. The association of BLL > or = 5 microg/dL with asthma among Caucasians was slightly elevated, but not significant [adjusted hazard ratio (adjHR) = 1.4; 95% confidence interval (CI), 0.7-2.9; p = 0.40]. Despite the small number of Caucasians with high BLL, the adjHR increased to 2.7 (95% CI, 0.9-8.1; p = 0.09) when more stringent criteria for asthma were used. When compared with Caucasians with BLL < 5 microg/dL, African Americans were at a significantly increased risk of asthma regardless of BLL (adjHR = 1.4-3.0). We conclude that an effect of BLL on risk of asthma for African Americans was not observed. These results demonstrate the need for further exploration of the complex interrelationships between race, asthma phenotype, genetic susceptibilities, and socioenvironmental exposures, including lead.

Black or African American↗

Airway hyperresponsiveness to methacholine at age 6 to 8 years in nonasthmatic patients is not related to increased health-care utilization for asthma in the ensuing 5 years: a longitudinal study of a birth cohort.

BACKGROUND: Children with heightened airway responsiveness have a greater tendency to develop asthma symptoms. Many existing studies describing this relationship have relied on self-reported symptoms that may be prone to recall bias. In addition, few studies have examined the relationship of airway hyperresponsiveness (AHR) to indicators of asthma severity such as health-care utilization. OBJECTIVE: To determine whether a positive response to methacholine challenge in children without current or physician-diagnosed asthma at age 6 to 8 years is predictive of the subsequent onset of asthma requiring medical evaluation or treatment in the ensuing 5 years. METHODS: Data were obtained from subjects in a population-based birth cohort (n = 835) enrolled from 1987 to 1989, who were members of a large medical group practice component of a health maintenance organization (HMO). We analyzed a subset of subjects (n = 245) who had completed a methacholine challenge at age 6 to 8 years, had no current or physician-diagnosed asthma, and were still served by the same medical group. These children were followed up from the time of methacholine challenge until HMO disenrollment or through June 2001 (ages 11 to 13 years), whichever came first. Pharmacy claims data and diagnostic codes from physician-patient encounters were evaluated for incident asthma. Incident cases of clinical asthma were defined as any child with two outpatient visits or one hospitalization, one emergency department encounter associated with an asthma diagnostic code (ie, 493.XX), or any child filling prescriptions for two bronchodilators or one antiinflammatory asthma medicine. Methacholine responsiveness was interpreted using American Thoracic Society criteria. RESULTS: Asthma incidence did not differ based on methacholine challenge results for children with normal, borderline, and mild AHR. No child in the study demonstrated moderate-to-severe AHR. CONCLUSION: Our data suggest that AHR with a borderline or weakly positive result in a methacholine challenge in children 6 to 8 years old without current or physician-diagnosed asthma is not related to increased health-care utilization for asthma in the ensuing 5 years.

Bronchial Hyperreactivity↗

Antibiotic use in children who have asthma: results of retrospective database analysis.

OBJECTIVE: Inappropriate antibiotic use is a well-recognized public health problem because of its association with the emergence of resistant bacteria. It also is a source of unnecessary health care costs and of potentially severe adverse drug reactions. Although there are no evidence-based indications for the use of antibiotics in the treatment of asthma in the absence of comorbid bacterial conditions, physicians might feel more pressure to prescribe them to children with this common chronic disease. The objectives of this study were to (a) determine if antimicrobial prescription utilization rates are higher for pediatric patients with asthma than a matched comparison group and (b) identify common variables (gender and age) that might explain higher antibiotic utilization rates in children. METHODS: Using administrative claims data, we conducted a retrospective cohort study of children with asthma (age range 5 to 18 years) who were members of a large health plan from January 1, 2000, to December 31, 2002, in the southeastern United States. A comparison group was created that was matched according to age, sex, regional codes, and insurance product line. International Classification of Diseases, Ninth Revision, Clinical Modification (ICD-9-CM) codes were used to identify asthmatic patients (493.xx), as well as to link antibiotic prescriptions to diagnosis codes from claims for medical office visits. RESULTS: Asthmatics consistently received significantly more services, including a mean of 1.74 (SD 1.82) antibiotics per patient per year (PPPY) compared with a mean of 0.96 (SD 1.32) antibiotics PPPY for nonasthmatics (t=25.71, P <0.001). Asthmatics received antibiotics more often for all diagnoses. The more frequent receipt of antibiotics was true for conditions related to the respiratory tract (e.g., upper respiratory infection and bronchitis) as well as for conditions unrelated to the respiratory tract (e.g., urinary tract infection and acne). A diagnosis of asthma significantly increased the likelihood of a prescribed antibiotic by 26% to 86%. CONCLUSION: This study demonstrated that pediatric asthmatic patients received significantly more antibiotic prescriptions than nonasthmatics for conditions caused by bacteria as well as for conditions more likely to be viral in origin. In this era of concern about the widespread use of antibiotics and consequent antimicrobial resistance, further research needs to be conducted concerning the appropriateness of antibiotics in the treatment of asthma. Studies on the appropriate use of antibiotics in asthma could help reduce the overall use of antibiotics in children.

Adolescent↗

Estrogen reduces carbachol-induced constriction of asthmatic airways by stimulating large-conductance voltage and calcium-dependent potassium channels.

Both the incidence and severity of asthma in women are influenced by fluctuations in estrogen (E(2)) levels, raising the possibility that E(2)s may reduce the hyperresponsiveness that is characteristic of asthma. We examined the effect of E(2) and its downstream signaling pathways in isolated mouse bronchial and tracheal rings passively sensitized either with serum from patients with atopic asthma (ATR) or with serum from control subjects (CTR). ATR exhibited significantly higher sensitivity to carbachol than CTR. Pretreatment of ATR with E(2) shifted the carbachol concentration-response curve (CCRC) toward that of CTR. The E(2) effect was abolished by the nitric oxide synthase inhibitor, L-nitroarginine methyl ester, the soluble guanyl cyclase inhibitor, quinoxalin-1, or the protein kinase G inhibitor, KT5823. Inhibition of the large-conductance, calcium-activated potassium (BK(Ca)) channel activity with iberiotoxin also attenuated the E(2) effect on ATR. In patch-clamp studies, E(2) increased by 50-fold the BK(Ca) channel activity in freshly isolated airway smooth muscle cells. This increase was completely blocked by KT5823. These studies suggest that, at physiologic concentrations, E(2) can prevent cholinergic-induced constriction of asthmatic tracheal rings by activating the nitric oxide-cGMP-protein kinase G pathway to increase BK(Ca) channel activity.

Airway Obstruction↗

The relationship between early fever and allergic sensitization at age 6 to 7 years.

BACKGROUND: The hygiene hypothesis suggests that early infections might protect against later allergic sensitization. OBJECTIVE: The purpose of this study was to determine whether fevers before age 1 year were associated with allergic sensitization at age 6 to 7 years. METHODS: Eight hundred thirty-five children from suburban Detroit, Michigan, were enrolled at birth. Clinic records from their first year were abstracted for episodes of fever, antibiotic use, and respiratory infections. Fever was defined as a rectal temperature of 38.3 degrees C (101 degrees F) or greater or its equivalent measured at another site. At age 6 to 7 years, 441 children underwent allergy testing. The primary outcome measures were atopy (>/=1 positive skin prick test result), seroatopy (>/=1 positive allergen-specific IgE level), and allergic sensitization (either seroatopy or atopy). RESULTS: By age 1 year, 207 (46.9%) of the 441 participants had a documented fever. Among children with 0, 1, or 2 or more fevers in the first year, 33.3%, 31.3%, and 26.0% demonstrated atopy at age 6 to 7 years, respectively (P =.504); 43.4%, 39.7%, and 25.0% had seroatopy, respectively (P =.032); and 50.0%, 46.7%, and 31.3% had allergic sensitization, respectively (P =.028). After adjusting for potential confounders, each febrile episode in the first year was associated with reduced odds for allergic sensitization (adjusted odds ratio, 0.69; 95% CI, 0.47-1.00). Febrile upper respiratory tract infections, in particular, were associated with lower odds of allergic sensitization (adjusted odds ratio, 0.55; 95% CI, 0.31-0.97) per episode. CONCLUSION: This study provides direct support for the hygiene hypothesis because children with fevers before age 1 year were less likely to demonstrate allergic sensitivity at age 6 to 7 years.

Adult↗