Age-specific characteristics of inpatients with severe asthma exacerbation

BACKGROUND

The characteristics of inpatients with severe asthma exacerbation remain unclear. It is considered that the characteristics of inpatients with severe asthma vary depending on age. However, these are rarely investigated. The objective of this study is to investigate the differences in characteristics among different age groups. We considered that it is necessary to understand the characteristics of each age group so that we can establish strategies in preventing severe asthma exacerbation.

METHODS

All asthma inpatients who were hospitalized between 2004 and 2011 with SpO2 <90% (in room air), were breathless at rest, and showed increased respiratory rate and pulse rate were examined. We compared the characteristics among the young age group, middle age group, and advanced age group.

RESULTS

The total number of patients was 204. In the young age group, the percentages of patients with irregular visits and non visits to a medical institution were high. This group showed high percentages of smokers and pet owners. The percentage of continuous ICS users in this group was 25.9%. The middle age group had high rates of aspirin-intolerant asthma. The percentage of continuous ICS users in this group was 60.2%. In the advanced age group, the percentages of patients with hypertension/heart disease, diabetes mellitus, and COPD were high. This group showed good treatment adherence. The percentage of continuous ICS users in this group was 77.4%.

CONCLUSIONS

The characteristics of inpatients with severe asthma vary depending on age. We need to establish countermeasures for asthma exacerbation according to the characteristics of patients depending on age.

Sensitization to acid-hydrolyzed wheat protein by transdermal administration to BALB/c mice, and comparison with gluten

BACKGROUND

An increasing number of studies have shown that hydrolyzed wheat protein (HWP) can induce IgE-mediated hypersensitivity by skin contact and/or food ingestion. However, there has been no study of the sensitizing potential of HWP. In this study, the possibility of transdermal pathway for sensitization to acid-HWP (HWP1) was investigated using BALB/c mice, and compared with that of gluten.

METHODS

HWP1 or gluten (500 μg/mouse) was transdermally administered using patches. After three or four cycles of sensitization for 3 days/week, active systemic anaphylaxis (ASA) was induced by intraperitoneal injection of the antigen, and rectal temperatures, scores of anaphylactic responses, and plasma histamine levels were determined. Because HWP1 was included in facial soap in Japan, the effect of detergent on the sensitizing potential was also investigated.

RESULTS

Transdermal administration of HWP1 induced dose-dependent production of IgE and IgG1. After sensitization for 3 or 4 weeks, intraperitoneal injection of HWP1 caused ASA, leading to decreased rectal temperatures, increased anaphylaxis scores, and increased plasma histamine levels. In addition, splenocytes harvested after ASA produced IL-4, IL-5, and IL-10 by re-stimulation with HWP1. Transdermal exposure to gluten also induced IgE and IgG1 production, and intraperitoneal injection of gluten also induced ASA only in mice sensitized in the presence of sodium dodecyl sulfate.

CONCLUSIONS

Transdermal exposure to HWP1 is sufficient to activate key immune pathways necessary for sensitizing mice for immediate hypersensitivity reactions. This study shows that HWP has a sensitizing potential as well as gluten, whereas its allergenicity may be different from that of gluten.

Evaluation of allergenicity of acid-hydrolyzed wheat protein using an in vitro elicitation test

BACKGROUND

We performed an in vitro elicitation test to determine the ability of different types of wheat-allergic patients' IgE to induce humanized mast cell activation after the addition of various time-treated acid-hydrolyzed wheat proteins (HWPs).

METHODS

The reactivity of heat- and various time-treated acid-hydrolyzed glutens (acid-HGs) and commercial acid-HWP (HWP1), using serum IgE from wheat allergy accompanied by skin and rhinoconjunctival sensitization to HWP1 in the facial soap, pediatric subjects with food allergy to native wheat, adult wheat-dependent exercise-induced anaphylaxis subjects, and nonatopic healthy subjects, was elucidated by dot blot and a luciferase assay-based in vitro elicitation test (EXiLE test).

RESULTS

Serum from subjects sensitized with HWP1 reacted only to acid-HGs (acid-HGs treated for 0.5-3 or 6 h), but not native gluten, in the results of the dot blot. In contrast, sera from pediatric subjects sensitized with native wheat reacted to native gluten more strongly and showed only slight reactions to 0.5- to 1-hour-treated acid-HGs. The results of the in vitro elicitation test showed that acid hydrolyzation of the gluten attenuated antigen-induced luciferase expression in a time-dependent manner for sera from native-wheat-sensitized pediatric subjects. On the other hand, in the sera from HWP1-sensitized subjects, acid hydrolyzation of the gluten for 0.5 h dramatically increased luciferase expression.

CONCLUSIONS

Even after prolonged hydrolyzation, acid-HGs still retained the ability to activate mast cells in the case of HWP1-sensitized subjects.

The prevalence of rhinitis and its association with smoking and obesity in a nationwide survey of Japanese adults

BACKGROUND

Rhinitis is a common disease, and its prevalence is increasing worldwide. Several studies have provided evidence of a strong association between asthma and rhinitis. Although smoking and obesity have been extensively analyzed as risk factors of asthma, associations with rhinitis are less clear.

OBJECTIVE

The aims of our study were (i) to evaluate the prevalence of rhinitis using the European Community Respiratory Health Survey (ECRHS) questionnaire in Japanese adults and (ii) to evaluate the associations of smoking and body mass index (BMI) with rhinitis.

METHODS

Following our study conducted in 2006-2007 to determine the prevalence of asthma using the ECRHS questionnaire, our present analysis evaluates the prevalence of rhinitis and its association with smoking and BMI in Japanese adults 20-79 years of age (N = 22819). We classified the subjects (20-44 or 45-79 years) into four groups as having (i) neither rhinitis nor asthma; (ii) rhinitis without asthma; (iii) asthma without rhinitis; or (iv) rhinitis with asthma. We then evaluated associations with smoking and BMI in each group.

RESULTS

The overall age-adjusted prevalence of rhinitis was 35.1% in men and 39.3% in women. A higher prevalence was observed in the younger population than in the older population. Active smoking and obesity were positively associated with asthma without rhinitis. In contrast, particularly in the 20- to 44-year age-group, active smoking and obesity were negatively associated with rhinitis without asthma.

CONCLUSION

The results of the present study suggest that smoking and obesity may have different effects on the development of rhinitis and asthma.

Persistent airflow obstruction in young adult asthma patients

BACKGROUND

Lung function determined by spirometry and the severity of dyspnea correlate weakly in asthma patients. We attempted to determine the risk factors in asthma patients having persistent airway obstruction despite of having only mild subjective symptoms, and to examine the possibility of improving FEV1 by treating asthma on the basis of the bronchodilator change in FEV1.

METHODS

We examined asthma patients in their 20s and who visited Sagamihara National Hospital for the first time over a period of four years, by reviewing their clinical records. They underwent tests on the bronchodilator change in FEV1 and a test of airway hyperresponsiveness to histamine dihydrochloride.

RESULTS

One hundred thirty-eight subjects (mean age, 25.6 years; 51 males, 87 females; current smoking, 30.4%; history of childhood asthma, 48.6%) were enrolled. Among them, 18.8% (26/138) showed persistent airway obstruction (postbronchodilator FEV1/FVC (%) <80%). Using the multiple logistic regression model, we found that history of childhood asthma and smoking history were the significant isolated risk factors for persistent airway obstruction. Moreover, we determined that the factors associated with the reversibility of airway obstruction in asthma patients without subjective symptoms were history of childhood asthma.

CONCLUSIONS

In this study, patients not undergoing treatment for asthma were examined. History of childhood asthma and smoking history may be the risk factors for persistent airway obstruction in the asthma patients with mild subjective symptoms. Tests on the bronchodilator change in FEV1 should be performed in patients with history of childhood asthma and smoking history, even if they have only mild subjective symptoms.

The differences in the involvements of loci of promoter region and Ile50Val in interleukin-4 receptor α chain gene between atopic dermatitis and Japanese cedar pollinosis

BACKGROUND

Atopic dermatitis (AD) and Japanese cedar pollinosis (JCP) are common chronically allergic diseases associated with the activation of T-helper 2 cells. Recent studies have shown that polymorphisms in the genes for IL-4 receptor α chain (IL4RA) may contribute to susceptibility of AD and JCP, although the differences in the involvements of loci of IL4RA gene between AD and JCP are unclear. In this study, we investigated the role of polymorphisms in IL-4RA gene in conferring susceptibility to the development of AD and/or JCP using a family analysis and an association analysis in a Japanese population.

METHODS

Five polymorphisms in the IL-4RA gene, C-3223T, T-1914C, T-890C, Ile50Val and Glu375Ala, have been genotyped using PCR-based methods in 75 trios families, including 15 AD families, 30 JCP families, and 30 families with combination of AD and JCP in the family analysis. Forty-five AD, 60 JCP and 125 control children constituted the association study.

RESULTS

The transmission disequilibrium test showed that the allele of Ile50 was significantly transmitted to children with JCP alone (p < 0.05). Haplotype analysis showed that the -3223T/Ile50 haplotype was preferentially transmitted to both AD (p < 0.01) and JCP children (p < 0.01), while that the C-3223/Ile50 haplotype was preferentially transmitted to only JCP children (p < 0.01). The association study showed that -3223T and haplotype of -3223T/Ile50 were associated with AD children, but not with JCP. Ile50 was associated with both AD and JCP.

CONCLUSIONS

Our data suggest that -3223T and the -3223T/Ile50 haplotype were risk factors for AD. Ile50 allele seems to be involved in both JCP and AD. Interactions of the IL-4RA loci may play a role both conferring susceptibility and modulating severity of AD.

[Use of forced oscillation technique to detect airflow limitations in adult Japanese asthmatics]

BACKGROUND

The forced oscillation technique (FOT) is a noninvasive method that is used to measure respiratory mechanics, including respiratory resistance and reactance at multiple frequencies. The advantage of FOT over spirometry is that FOT does not require forced expiratory maneuvers. Moreover, a new FOT machine called MostGraph (Chest Co. Ltd., Tokyo, Japan), has been developed in Japan, and can be used clinically to diagnose and monitor asthma. The purpose of this study is to show the standard of FOT measured with MostGraph in adult Japanese asthmatics.

METHODS

From our outpatient clinic, we recruited 151 stable asthmatics who were being treated with inhaled corticosteroids at the time of the study. For each subject, we measured the fraction of exhaled nitric oxide (FeNO) by using a chemiluminescent nitric oxide analyzer (Sievers280, GE, Boulder, Co); we determined the levels of forced expiratory volume in 1s (%FEV1) and maximum mid-expiratory flow rate (%MMF) by using spirometory; and we measured resistance at 5 Hz(R5), resistance at 20 Hz(R20), R5-R20, reactance at 5 Hz(X5), frequency of resonance (Fres), and low-frequency reactance area (ALX), by using a MostGraph FOT machine.

RESULTS

Each of the FOT parameters measured by using the MostGraph machine was significantly correlated with %FEV1 and %MMF (p<0.001), with Fres showing the strongest association. Three of the FOT parameters, X5, Fres, and ALX, were significantly associated with the subject's age (p=0.01, p<0.001, p<0.001, respectively), and all FOT parameters were significantly associated with the subject's body mass index (BMI) (p<0.001 to p=0.018). The results of multiple regression analyses between FOT parameters and FEV1, age, BMI, and FeNO, showed that Fres was significantly associated with FEV1(p<0.001) and BMI (p<0.001). From the results of the simple linear regression between Fres and FEV1, we estimated that Fres values of 17.5 Hz corresponded to %FEV1 values of 60%; Fres values of 11.3 Hz corresponded to %FEV1 values of 80%; and Fres values of 4.94 Hz corresponded to %FEV1 values of 100%.

CONCLUSION

FOT parameters measured by using a MostGraph machine can be used successfully to assess the level of airflow limitation in adult stable asthmatics.

283 Relationship between Aeroallergen Sensitization and Asthma Severity in Patients with Aspirin-Exacerbated Respiratory Disease

Background

The pathogenesis of aspirin-exacerbated respiratory disease (AERD) is presumed to involve the aspirin/non steroidal anti-inflammatory drug (NSAID)-induced abnormal metabolism of arachidonic acid, resulting in the production of 5-lipoxygenase metabolites, particularly leukotriene C4. Aspirin intolerance occurs around the same time as asthma onset, and a few of the patients with AERD had suffered from pediatric asthma. Although atopy is not associated with the pathogenesis of AERD, some of the patients with AERD have aeroallergen sensitization. There are few studies in which the association between the pathogenesis of AERD and atopy has been clarified.

Methods

Ninety AERD patients, whose aspirin sensitivity was determined by the aspirin challenge test, and 100 aspirin-tolerant asthma (ATA) patients, whose age and sex were adjusted, participated in this study. Atopy was defined as a positive reaction in an intradermal test to one or more of 19 common aeroallergens, or a positive reaction above class one in Immuno CAP RAST. We analyzed the relationships between aeroallergen sensitization and clinical settings of AERD patients.

Results

The atopic and non atopic AERD groups showed median serum total IgE concentrations of 464 and 130 IU/l (P value = 0.004), respectively. The asthma of atopic patients with AERD was milder than that of non atopic patients with AERD. (P value = 0.05) The Lund-Mackay score of atopic patients with AERD was lower than that of non atopic patients with AERD. (P value = 0.02)

Conclusions

Two-thirds of the patients with AERD showed aeroallergen sensitization. The asthma and sinusitis in atopic patients with AERD were significantly milder than those in non atopic patients with AERD. Aeroallergen sensitization might prevent the worsening of asthma in patients with AERD.

Time trend in the prevalence of adult asthma in Japan: findings from population-based surveys in Fujieda City in 1985, 1999, and 2006

BACKGROUND

The burden of asthma is recognized as an important public health problem worldwide. In most countries, the prevalence of asthma has been reported to increase in the last few decades. However, more recent epidemiological studies have shown that the prevalence of asthma has been flat or even decreasing after the 1990 s in some developed countries. The recent time trend in the prevalence of adult asthma in Japan is unknown.

METHODS

Population-based surveys were conducted three times in the same region, in 1985, 1999, and 2006, at Fujieda City, Shizuoka, Japan, and the results were reported previously. We compared the results of these surveys to reveal the time trend in the prevalence of adult asthma. Although the questionnaires used in these surveys were not exactly the same, the time trend was assessed by comparing the responses to relevant questions between questionnaires.

RESULTS

The prevalences of wheeze following a common cold and dyspneal feeling at night increased significantly from 1985 to 1999 (4.2% to 7.6%, and 3.2% to 5.3%, respectively). The prevalences of lifetime asthma and current asthma also significantly increased from 1999 to 2006 (5.1% to 6.7%, and 1.5% to 3.4%, respectively).

CONCLUSIONS

The prevalences of asthma among adults in Fujieda City consistently increased from 1985 to 2006. There was no evidence that the prevalences were in plateau or decreasing. These findings suggest that more efforts are required to stop the increase in the burden of this disease in Japan.

Allergenicity and cross-reactivity of booklice (Liposcelis bostrichophila): a common household insect pest in Japan

BACKGROUND

Booklice (Liposcelis bostrichophila) are a common household insect pest distributed worldwide. Particularly in Japan, they infest 'tatami' mats and are the most frequently detected insect among all detectable insects, present at a frequency of about 90% in dust samples. Although it has been hypothesized that they are an important indoor allergen, studies on their allergenicity have been limited.

METHODS

To clarify the allergenicity of booklice and the cross-reactivity of this insect allergen with allergens of other insects, patients sensitized to booklice were identified from 185 Japanese adults with allergic asthma using skin tests and IgE-ELISA. IgE-inhibition analysis, immunoblotting and immunoblotting-inhibition analysis were performed using sera from these patients. Allergenic proteins contributing to specific sensitization to booklice were identified by two-dimensional electrophoresis and two-dimensional immunoblotting.

RESULTS

The booklouse-specific IgE antibody was detected in sera from 41 patients (22% of studied patients). IgE inhibition analysis revealed that IgE reactivity to the booklouse allergen in the sera from one third of booklouse-sensitized patients was not inhibited by preincubation with extracts from any other environmental insects in this study. Immunoblotting identified a 26-kD protein from booklouse extract as the allergenic protein contributing to specific sensitization to booklice. The amino acid sequence of peptide fragments of this protein showed no homology to those of previously described allergenic proteins, indicating that this protein is a new allergen.

CONCLUSIONS

Sensitization to booklice was relatively common and specific sensitization to this insect not related to insect panallergy was indicated in this population.

Association between body mass index and asthma among Japanese adults: risk within the normal weight range

BACKGROUND

Increasing amounts of data have shown that some Asian populations are more susceptible to increased weight and development of noncommunicable disease than Western populations. However, little is known about the association between increased weight, particularly within the normal range, and the development of asthma among Asian populations.

METHODS

To examine the association between increased body mass index (BMI) and asthma among Japanese adults, data from a nationwide population-based cross-sectional survey of asthma prevalence in Japan were analyzed (n = 22,962; age range 20-79 years). BMIs were classified into 7 categories considering WHO recommendations (cutoff points: 17.00, 18.50, 23.00, 25.00, 27.50 and 30.00), and the association between BMI and the prevalences of asthma as well as asthma symptoms were assessed by multivariate logistic regression.

RESULTS

The prevalences of obesity (BMI ≥ 30.00) in this population were relatively low (males 3.0%, females 2.3%). BMI categories of 25.00 or higher in both genders were significantly associated with an increased risk of asthma compared with the reference category (BMI 18.50-22.99). Even in females with a BMI of 23.00-24.99, the prevalence of asthma significantly increased (adjusted odds ratio 1.49, 95% confidence interval 1.16-1.92) compared with that in the reference category.

CONCLUSIONS

An increase in the prevalence of asthma among Japanese females starts at a BMI of 23.00, which was relatively lower than those reported from Western countries. This finding suggests that the Japanese population is likely to have asthma with a lesser degree of obesity than Western populations.

Obesity and aspirin intolerance are risk factors for difficult-to-treat asthma in Japanese non-atopic women

BACKGROUND

Asthma is a clinical syndrome characterized by variabilities in disease expression and severity. The pathophysiological mechanism underlying anti-asthma treatment resistance is also assumed to be different between disease phenotypes.

OBJECTIVE

To elucidate the effect of gender and atopic phenotype on the relationship between clinical factors and the risk of treatment resistance.

METHODS

We compared outpatients with difficult-to-treat asthma (DTA; n = 486) in a tertiary hospital for allergic diseases in central Japan with those with controlled severe asthma (n = 621) with respect to clinical factors including body mass index (BMI) and aspirin intolerance using multivariate logistic regression analysis stratified by gender and atopic phenotype.

RESULTS

When analysis was performed on the entire study populations, obesity (BMI ≥ 30 kg/m(2); adjusted odds ratio (OR) 1.92; 95% confidence interval (95% CI: 1.07-3.43) and aspirin intolerance (OR: 2.56, 95% CI: 1.44-4.57) were found to be the significant risk factors for DTA. However, after the stratification by gender and atopic phenotype, the association between obesity and DTA was significant only in women (OR: 2.76, 95% CI: 1.31-5.78), but not in men (OR: 1.03, 95% CI: 0.38-2.81), and only in non-atopics (OR: 4.03, 95% CI: 1.15-14.08), but not in atopics (OR: 1.54, 95% CI: 0.79-3.02). The similar gender and phenotypic differences were also observed in the association between aspirin intolerance and DTA: namely, the association was significant only in women (OR: 3.96, 95% CI: 1.84-8.50), but not in men (OR: 1.19, 95% CI: 0.46-3.05); and only in non-atopics (OR: 5.49, 95% CI: 1.98-15.19), but not in atopics (OR: 1.39, 95% CI: 0.65-2.98).

CONCLUSIONS AND CLINICAL RELEVANCE

Significant associations of obesity and aspirin intolerance with DTA were observed only in women and in non-atopics. These findings suggest that a phenotype-specific approach is needed to treat patients with DTA.

Increase in salivary cysteinyl-leukotriene concentration in patients with aspirin-intolerant asthma

BACKGROUND

Cysteinyl-leukotrienes (CysLTs; LTC4, LTD4, and LTE4) play a considerable role in the pathophysiology of aspirin-intolerant asthma (AIA). Saliva has recently been validated as novel, simple, and noninvasive method for investigating inflammation in patients with asthma. The aim of this study is to clarify the molecular species of CysLT in saliva and to evaluate the CysLT and LTB4 concentrations in saliva in AIA patients. We also examined how the CysLT concentration in saliva reflects that of their corresponding urinary metabolite.

METHODS

We preformed an analytical cross-sectional study. CysLT and LTB4 concentrations in saliva were quantified by enzyme immunoassay (EIA) following purification by high-performance liquid chromatography (HPLC).

RESULTS

1. When analyzed by EIA in combination with HPLC, saliva was found to consist of LTC4, LTD4 and LTE4 in similar amounts. 2. In saliva analysis among the three groups (AIA patients, aspirin-tolerant asthma [ATA] patients, and healthy subjects), both the concentrations of CysLTs and LTB4 were significantly higher in AIA patients than in ATA patients and healthy subjects. 3. We found significant correlations between CysLT concentration and LTB4 concentration in saliva in each group. 4. No significant correlation was found between the concentration of LTE4 in urine and that of CysLTs in saliva.

CONCLUSIONS

In this study, we found higher concentrations of CysLTs and LTB4 in saliva from AIA patients than in saliva from ATA patients, suggesting that the quantification of CysLT and LTB4 concentrations in saliva may be another diagnostic strategy for AIA.

Actual control state of intermittent asthma classified on the basis of subjective symptoms

BACKGROUND

Many primary care physicians begin treatment of asthma patients on the basis of their subjective symptoms. We hypothesized that patients diagnosed as having intermittent asthma on the basis of subjective symptoms by a primary care physician may have their asthma severity underestimated.

METHODS

We investigated 293 patients who were in their 20s and diagnosed as having asthma. Two hundred and fifteen patients with intermittent asthma diagnosed on the basis of subjective symptoms were chosen. We evaluated their asthma severity using FEV(1) (% predicted), airway hyperresponsiveness to histamine dihydrochloride, and exhaled nitric oxide level as factors that determine asthma severity.

RESULTS

Among these patients, 27.8% were determined to have moderate or severe asthma by the pulmonary function test. History of childhood asthma was the only significant risk factor for a low pulmonary function. Among the patients, 60.9% showed moderate or severe airway hyperresponsiveness. History of childhood asthma was the only significant risk factor for the increase in airway hyperresponsiveness. Moreover, 53.8% showed a high exhaled nitric oxide level. History of childhood asthma was associated with an increased risk of a high eNO level as determined by univariate analysis, but no significant difference was observed in the comparison by multiple logistic regression analysis. The percentage of subjects classified into the mild group by all of the results of the three tests was only 20.6%.

CONCLUSION

We showed that asthma severity classified on the basis of only subjective symptoms may be underestimated in young adults. We showed that the diagnosis of mild intermittent asthma needs to be determined carefully.

Latex anaphylaxis caused by a Swan-Ganz catheter

A 78-year-old woman visited the division of cardiovascular disease in our hospital. She underwent a cardiac catheter examination, and a Swan-Ganz catheter was inserted. Several minutes later, she developed anaphylactic shock. She had no past history of latex allergy, but did have a banana allergy. Skin prick tests showed a positive reaction to an extract of latex gloves and an extract of the balloon of a Swan-Ganz catheter. Anaphylactic shock caused by the latex balloon of a Swan-Ganz catheter was diagnosed. It is necessary to pay attention to not only latex allergy but also fruit allergies with a cross-reactivity to latex.

[Differences in fraction of exhaled nitric oxide values measured by two offline methods or NIOXmino in adult Japanese asthmatics]

BACKGROUND

The fraction of exhaled nitric oxide (FeNO) is a useful marker of asthma control. The FeNO measurement with two offline methods and NIOXmino may be more affordable, no studies have examined the differences in FeNO values measured with various methods in adult asthmatics.

METHODS

The study population comprised 39 stable asthmatics treated with inhaled steroids at our outpatient clinic. FeNO values were measured by two offline methods (Sievers and CEIS), NIOXmino.

RESULTS

FeNO(NIOXmino) values were significantly correlated with those of FeNO(Sievers) (r=0.935, P< 0.001) and FeNOCEIS (r=0.908, P< 0.001). However, FeNO(NIOXmino) values were low compared with FeNO(Sievers) (FeNO(NIOXmino)=0.848 x FeNO(Sievers)) and FeNO(CEIS) (FeNO(NIOXmino)=0.672 x FeNO(CEIS)).

CONCLUSION

Differences exist in the values of FeNO measured by various methods: conversion equations are needed to compare the FeNO values among these three methods.

Nationwide cross-sectional population-based study on the prevalences of asthma and asthma symptoms among Japanese adults

BACKGROUND

Asthma is a common respiratory disease worldwide. However, few reports are available on the prevalences of asthma and asthma symptoms among Asian subjects.

METHODS

To determine the prevalences of asthma and asthma symptoms among Japanese subjects, we performed a nationwide cross-sectional, population-based study on Japanese adults aged 20-79 years. Ten areas spread throughout the country were randomly selected. Door-to-door or postal surveys were performed using a translated version of the European Community Respiratory Health Survey questionnaire.

RESULTS

The survey was completed by 23,483 participants. The overall response rate was 70.6%. The prevalences of wheeze and current asthma among all participants aged 20-79 years were 10.1% (95% CI: 9.7-10.5%) and 4.2% (95% CI: 4.0-4.5%), respectively. The prevalences among young adults aged 20-44 years were 9.3% (95% CI: 8.7-9.9%) and 5.3% (95% CI: 4.8-5.8%), respectively. The prevalence of current asthma was highest in females aged 30-39 years in comparison with the other gender and age groups.

CONCLUSIONS

This nationwide study determined the prevalences of asthma and asthma symptoms among Japanese adults. The results provide fundamental information on the respiratory health of Japanese adults.