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Biomedical subjects

Christine C Johnson

Publications and source records attributed to Christine C Johnson.

At least 19 recordsLinked to original sources
PubMed2026

Genome-wide association study of asthma with high treatment burden and/or worse outcomes defined using electronic healthcare data in UK Biobank.

BACKGROUND: In ∼10% of asthma patients, symptoms remain uncontrolled despite maximal treatment, representing an unmet clinical need. The causal variants, genes and pathways underlying genetic risk factors have not been fully elucidated, and it is unclear whether there are unique genetic risk factors for this asthma subtype. METHODS: We used electronic healthcare records linked to UK Biobank to identify asthma patients with high treatment burden and/or worse outcomes. We performed a genome-wide association study (GWAS) with this case population and healthy controls. We sought replication for associated (p≤5×10-6) signals in four independent studies (12 152 cases and 32 316 controls). Replicated signals were fine-mapped and linked to genes and pathways. RESULTS: In total, 7681 participants met our case definition and showed enrichment for adult-onset asthma, female gender and higher body mass index compared to asthma individuals not meeting case criteria. GWAS with 7681 cases and 38 405 controls revealed 21 reproducible association signals that had previously been associated with asthma, but had a larger effect size in our study. Variant-to-gene mapping highlighted 85 candidate genes, five of which were considered high confidence (BACH2, D2HGDH, IL1RL1, RPS26, SMAD3). CONCLUSION: We present the first use of electronic healthcare records in UK Biobank to identify a subtype of asthma enriched for patients with high treatment burden and/or worse outcomes. Our findings support the role of known asthma genes, highlighting genetic risk variants with stronger effect in these groups of patients. The prioritised genes provide potential therapeutic opportunities for this difficult-to-treat patient population.

Journal Article↗
PubMed2026

Upper airway microbiome interacts with GSDMB and ORMDL3 asthma risk SNPs to influence early-life wheeze risk.

BACKGROUND: Single-nucleotide polymorphisms (SNPs) in the chromosome 17q12-q21 region and, independently, early-life nasal microbiota dominated by Moraxella, Streptococcus, or Haemophilus (MSH) increase risk of chronic wheeze and asthma development. OBJECTIVE: We sought to determine whether 17q12-q21 risk SNPs and nasal microbiota interact to modulate childhood wheeze risk. METHODS: Nasal wash samples from 12-month-old infants in 2 birth cohorts, COAST (Childhood Origins of Asthma; n = 180) and URECA (Urban Environment and Childhood Asthma; n = 139), underwent 16S ribosomal RNA variable region 4 sequencing. Nasal microbiota dominated by MSH or Corynebacterium, Dolosigranulum, Staphylococcus, or Bacillus (CDSB) were assessed. Paired blood was genotyped for 9 17q12-q21 risk SNPs. Logistic regression tested interactions between 17q12-q21 SNPs and MSH or CDSB on wheeze risk in the first 3 years of life. A549 lung epithelial cells, CRISPR-edited to encode the rs7216389 risk genotype (rs7216389TT) were compared to the heterozygous (rs7216389CT) line using bulk RNA sequencing. RESULTS: SNPs, particularly those in the ORMDL3 (rs8076131; odds ratio [OR]: 1.72; 95% CI: 1.09-2.71; Pint = .031) and GSDMB (rs2305480; OR: 1.72; 95% CI: 1.09-2.71; Pint = 0.042; and rs7216389; OR: 1.73; 95% CI: 1.09-2.70; Pint = .047) genes, interact with MSH microbiota to increase early-life wheeze risk (false discovery rate Pint = .016 for all), while interactions with CDSB reduce risk. A549 airway epithelial cells homozygous for rs7216389TT exhibited decreased expression of genes involved in antimicrobial responses and neutrophil recruitment and evidence increased microbial adherence compared with the heterozygous cell line. CONCLUSION: Airway microbiota interact with SNPs at the 17q12-q21 locus in genes involved in sphingolipid metabolism and intracellular antimicrobial responses, to modulate wheeze risk.

Humans↗
PubMed2006

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↗
PubMed2006

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↗
PubMed2006

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↗
PubMed2006

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↗
PubMed2006

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↗
PubMed2005

Ovarian cancer screening in the Prostate, Lung, Colorectal and Ovarian (PLCO) cancer screening trial: findings from the initial screen of a randomized trial.

OBJECTIVE: Ovarian cancer screening with transvaginal ultrasound (TVU) and CA-125 was evaluated in the Prostate, Lung, Colorectal and Ovarian (PLCO) Trial. STUDY DESIGN: This was a randomized controlled trial of screening versus usual care. Baseline screening results are reported. RESULTS: Of 39,115 women randomized to receive screening, 28,816 received at least 1 test. Abnormal TVU was found in 1338 (4.7%), and abnormal CA-125 in 402 (1.4%). Twenty-nine neoplasms were identified (26 ovarian, 2 fallopian, and 1 primary peritoneal neoplasm). Nine were tumors of low malignant potential and 20 were invasive. The positive predictive value for invasive cancer was 3.7% for an abnormal CA-125, 1.0% for an abnormal TVU, and 23.5% if both tests were abnormal. CONCLUSION: The effect of screening on ovarian cancer mortality in the PLCO cohort has yet to be evaluated and will require longer follow-up. Screening identified both early- and late-stage neoplasms, and the predictive value of both tests was relatively low.

Aged↗
PubMed2005

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↗
PubMed2005

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↗
PubMed2005

Building a research consortium of large health systems: the Cancer Research Network.

Critical questions about cancer prevention, care, and outcomes increasingly require research involving large patient populations and their care delivery organizations. The Cancer Research Network (CRN) includes 11 integrated health systems funded by the National Cancer Institute (NCI) to conduct collaborative cancer research. This article describes the challenges of constructing a productive consortium of large health systems, and explores the CRN's responses. The CRN was initially funded through an NCI cooperative agreement in 1999 and has since received a second 4-year grant. Leadership and policy development are provided through a steering committee, subcommittees, and an external advisory committee. The CRN includes integral and affiliated research projects supported by a Scientific and Data Resources Core. Three characteristics of the CRN intensified the general challenges of consortium research: 1) its members are large health systems with legitimate concerns about confidentiality of data about enrollees, providers, and the organization; 2) CRN research projects often generate highly sensitive data about quality of care; and therefore 3) each participating organization wants a strong voice in CRN direction. CRN experience to date confirms that a consortium of health systems with internal research capacity can address a range of important cancer research questions that would be difficult to study in other venues. The advantages and challenges of consortium research are explored, with suggestions for the development, execution, and management of multisystem population laboratories.

Biomedical Research↗
PubMed2005

Racial and age differences in colon examination surveillance following a diagnosis of colorectal cancer.

PURPOSE: The purpose of this analysis is to describe factors associated with colorectal surveillance following diagnosis and treatment of nonmetastatic colorectal cancer. METHODS: Subjects were identified as part of the HMO Cancer Research Network's study of colorectal cancer survivors. To be eligible for the main study, patients had to be part of the staff model components of health maintenance organizations in southeastern Michigan and Minnesota. Using computerized databases, individuals were identified who were 40 years or older with incident nonmetastatic colorectal cancer diagnosed between January 1, 1990, and December 31, 2000. Using data current through 2002, we analyzed the cohort using chi-square test statistics, life tables, and Cox proportional hazards models to understand variations in posttreatment surveillance practices. Subjects were followed up from date of diagnosis to date of recurrence, death, disenrollment from the health plan, or loss to follow-up, which ever came first. We assessed factors associated with colorectal surveillance at 1, 3, and 5 years after treatment. We also included an analysis comparing those who received an exam and those who didn't regardless of exam timing. RESULTS: A total of 908 patients were eligible for the main study. Of these, we excluded subjects who were not white or African American (n = 27), resulting in an analytic sample of 881 (97% of the eligible cohort). Twenty-five percent of subjects were African American, 43% were female, and 48% were aged 70 years or older. The proportion who received an exam at 1 year was 18%, at 3 years was 60%, and at 5 years was 67%. Chi-square tests showed that African Americans were statistically significantly less likely than whites to receive an exam at all three time points. The Cox proportional hazards model for examinations regardless of timing and adjusted for confounders showed that African Americans were still less likely than whites to receive an exam (hazard ratio = 0.62; 95% confidence interval [CI] = 0.51 to 0.75). The same trend in undersurveillance was also observed for those 80 years of age or older at diagnosis, with an adjusted hazard ratio of 0.39 (95% CI = 0.26 to 0.57). CONCLUSION: Our data indicate that colorectal cancer survivors who are African American or aged 80 years or more at diagnosis are less likely to receive posttreatment colorectal surveillance. Whether these differences are due to system or patient level barriers needs further study.

Adult↗
PubMed2005

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↗
PubMed2005

Microsomal epoxide hydrolase polymorphisms and risk for advanced colorectal adenoma.

Cigarette smoking is a risk factor for colorectal adenoma, a precursor of colorectal cancer. Microsomal epoxide hydrolase (EPHX1) metabolizes polycyclic aromatic hydrocarbons, carcinogens found in cigarette smoke. Nonsynonymous variants of EPHX1 at Tyr(113)His (exon 3) and His(139)Arg (exon 4) are associated, respectively, with low ((113)His) and high ((139)Arg) predicted activity. Among participants randomized to the screening arm of the Prostate, Lung, Colorectal, and Ovarian Cancer Screening Trial, we evaluated risks for advanced adenoma in relation to cigarette use and these two EPHX1 variants. We compared 772 cases with advanced adenoma (adenoma >/=1 cm or containing high-grade dysplasia or villous, including tubulovillous, elements) of the distal colon (left-sided, descending colon and sigmoid or rectum) to 777 gender- and age-matched controls who were screen-negative for left-sided adenoma. Compared to those with homozygous genotypes predicting low EPHX1 activity, advanced adenoma risks tended to be elevated for carriers of (113)TyrTyr [odds ratios (OR), 1.5; 95% confidence intervals (CI), 1.0-2.2] and (139)ArgArg (OR, 1.4; 95% CI, 0.8-2.5) and for subjects who carried a greater number of the alleles ((113)Tyr or (139)Arg) associated with high predicted enzymatic activity (P(trend) = 0.03). The increased risk associated with the increasing number of putative high-activity alleles was most apparent among current and recent (quit <10 years) cigarette smokers (P(trend) = 0.02). In conclusion, EPHX1 variants at codon 113 and 139 associated with high predicted enzymatic activity appear to increase risk for colorectal adenoma, particularly among recent and current smokers.

Adenoma↗
PubMed2004

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↗
PubMed2004

Relationship between adherence to inhaled corticosteroids and poor outcomes among adults with asthma.

BACKGROUND: Regular use of inhaled corticosteroids (ICSs) can improve asthma symptoms and prevent exacerbations. However, overall adherence is poor among patients with asthma. Objective To estimate the proportion of poor asthma-related outcomes attributable to ICS nonadherence. METHODS: We retrospectively identified 405 adults age 18 to 50 years who had asthma and were members of a large health maintenance organization in southeast Michigan between January 1, 1999, and December 31, 2001. Adherence indices were calculated by using medical records and pharmacy claims. The main outcomes were the number of asthma-related outpatient visits, emergency department visits, and hospitalizations, as well as the frequency of oral steroid use. RESULTS: Overall adherence to ICS was approximately 50%. Adherence to ICS was significantly and negatively correlated with the number of emergency department visits (correlation coefficient [ R ] = -0.159), the number of fills of an oral steroid ( R = -0.179), and the total days' supply of oral steroid ( R = -0.154). After adjusting for potential confounders, including the prescribed amount of ICS, each 25% increase in the proportion of time without ICS medication resulted in a doubling of the rate of asthma-related hospitalization (relative rate, 2.01; 95% CI, 1.06-3.79). During the study period, there were 80 asthma-related hospitalizations; an estimated 32 hospitalizations would have occurred were there no gaps in medication use (60% reduction). CONCLUSIONS: Adherence to ICS is poor among adult patients with asthma and is correlated with several poor asthma-related outcomes. Less than perfect adherence to ICS appears to account for the majority of asthma-related hospitalizations.

Administration, Inhalation↗
PubMed2003

The relationship of housing and household characteristics to the indoor concentrations of Der f 1, Der p 1, and Fel d 1 measured in dust and air samples.

BACKGROUND: Indoor dust mite and cat allergens have been related to the risk of atopic conditions. If allergen levels are influenced by modifiable residential characteristics, potential interventions to prevent disease could be deployed. OBJECTIVE: To evaluate relationships between allergen concentrations in air and dust samples and selected house and household characteristics using a large prospective study with multiple sequential allergen measurements from each residence. METHODS: Fel d 1, Der f 1, and Der p 1 were measured in paired air and dust samples collected at intervals throughout 4 years in suburban homes. House and household characteristics were examined for relationships to allergen concentrations in both univariate and multiple variate analyses. RESULTS: The relationships between house and household characteristics and allergen concentrations in both air and dust were complex. When the housing variables were considered in multiple variate analysis, concentrations of Der f 1 in dust increased with increasing number of residents and relative humidity and declined when forced air heating was used. Dust concentrations of Der p 1 were lower in new homes and during forced air heating use but higher with higher relative humidity and in the presence of dogs. The presence of cats was the dominant determinant of Fel d 1 in both air and dust, but when homes without cats were analyzed separately, dust levels of Fel d 1 were inversely related with relative humidity. CONCLUSIONS: Air and dust concentrations of Der p 1 and Der f 1 were positively related to relative humidity and the size of the family. Fel d 1 was positively related to the presence of cats. The relationship of other house or household characteristics was inconsistent but different for Der f 1 and Der p 1.

Air Conditioning↗