N. Stjernberg

Prevalence of positive skin prick tests, allergic asthma, and rhinoconjunctivitis in teenagers in northern Sweden

The prevalence of positive skin prick tests (SPT) for common allergens and symptoms of allergic rhinoconjunctivitis or asthma was investigated in Umeå in northern Sweden in 1987. Skin prick tests with 10 allergens common in Sweden and a questionnaire were used to examine 1112 teenagers. All subjects with a positive skin prick test or symptoms were interviewed, and they were further investigated by a serum specific IgE test, a ventilatory lung function test, and a physical examination. At least one skin prick test was positive in 43% of the subjects. Ninety‐three percent had at least one positive skin prick test to one of the three most common allergens: cat, timothy grass, and birch. The prevalence of current allergic rhinoconjunctivitis was 17%, current allergic asthma 2.8%, and current asthma (both allergic and nonallergic) 6.8%. Multiple logistic regression analysis showed that the most important risk factors for current asthma were sex (being a girl) and atopy. Heredity of asthma or rhinoconjunctivitis and being born in the winter (October‐March) also increased the risk. In atopic subjects, having a mother who smoked and heredity of asthma increased the risk. For allergic rhinoconjunctivitis, heredity increased the risk of getting rhinoconjunctivitis.

AN INTERVIEW STUDY TO ESTIMATE PREVALENCE OF ASTHMA AND CHRONIC BRONCHITIS The Obstructive Lung Disease in Northern Sweden Study

A questionnaire of respiratory symptoms and diseases completed by 6610 adults in 3 age cohorts (35–36 y; 50–51 y and 65–66 y) in northern Sweden was followed-up by interview and lung function testing of 1243 subjects with asthmatic or bronchitic symptoms and 263 subjects assessed from the postal questionnaire as being healthy. We report the results of this follow-up study.According to the criteria used, 292 subjects (5.1% of the original study sample) were diagnosed as having asthma. Out of the 1243 subjects 334 (5.9% of the original study population) were diagnosed as having chronic bronchitis.However, examination of the 263 subjects who were healthy according to the postal questionnaire showed that elderly smokers, in particular, under-reported bronchitic symptoms; taking this into account, the prevalence of chronic bronchitis is estimated to be of the order of 9%. Diagnostic difficulties were noted in 70 subjects (corresponding to 1.2% of the original study sample) in whom asthma or chronic bronchitis were strongly suspected. Further investigation of these subjects was considered necessary. In this cross-sectional study, FEV1 <80% of predicted values was found in 36% of subjects diagnosed as having asthma and in 31% of those with chronic bronchitis. Among subjects with attacks of breathlessness and wheezing, diagnostic criteria often used for asthma in questionnaire studies, 70% were diagnosed as having asthma. Of those with chronic productive cough, 62% were diagnosed as having chronic bronchitis. We consider that trained nurses provide reliable data that may be used in epidemiological surveys of obstructive lung diseases.

Prevalence and incidence of asthma and rhinoconjunctivitis in Swedish teenagers

In 1987. we studied the prevalence of asthma and rhinoconjunctivitis in 1112 grade‐eight students in the town of Umeå. northern Sweden. The present study IS based on the same cohort, reinvestigated in 1991. We aimed to estimate the changes in the prevalence of asthma and rhinoconjunctivitis and to examine some presumed risk factors of asthma and rhinoconjunctivitis. A postal questionnaire on present asthma, rhinoconjunctivitis, symptoms from the upper and lower airways, and the need for medication was used. Questions about living conditions, smoking and present education were also included. The questionnaire was answered by 89% (990) of the subjects. The prevalence of self‐reported asthma was 10.8% (boys 7.9%. girls 13.7%). The incidence rate/year was 1.1%, the remission rate/year was 5.7%, and the relapse rate/year was 10%. The risk factors for developing asthma appeared to be atopy, having a family history of asthma or rhinoconjunctivitis. and smoking. The prevalence of selfreported rhinoconjunctivitis was 14.3% (boys 15.6%, girls 13.1%). The incidence rate/year was 1%, the remission rate/year was 22%, and the relapse rate/year was 11%. Stopping smoking and having no family history of rhinoconjunctivitis or asthma appeared to favor remission in rhinoconjunctivitis.

Epidemiology of respiratory symptoms, lung function and important determinants : Report from the Obstructive Lung Disease in Northern Sweden project

SETTINGnCross-sectional epidemiological study based on a representative sample of the general population in northern Sweden.nnnOBJECTIVESnTo assess the prevalence of respiratory symptoms, the role of respiratory symptoms as indicators of impairment of lung function, and to define risk factors for respiratory symptoms and lung function impairment.nnnDESIGNnThe 1340 subjects of 6610 who reported respiratory symptoms suggestive of asthma or chronic bronchitis in a postal questionnaire study were invited to a structured interview and lung function tests. A control group of 315 subjects was also invited. Risk factors were assessed from the postal questionnaire.nnnRESULTSn400 subjects in the symptomatic group had attacks of breathlessness and wheezing, while none in the control group had them, corresponding to 7% of the original study population. Chronic productive cough was present in 537 subjects, of whom 13 were from the control group, suggesting that 12% of the original study population had this symptom. Persistent wheeze was the symptom that predicted the greatest proportion of cases of impaired lung function. Attacks of breathlessness, wheezing, long-standing cough and sputum production were all related to age, smoking and a family history of asthma. Both chronic productive cough and impaired lung function correlated strongly with smoking and age, and their prevalences differed in different socio-economic groups.nnnCONCLUSIONnImpaired lung function can be predicted from respiratory symptoms. Data collected in postal questionnaires suffice for the identification of risk factors. Combinations of symptoms gave greater odds ratios than individual symptoms.

Inflammatory response in bronchoalveolar lavage fluid after inhaling histamine

To examine the influence of the histamine chloride challenge test on the bronchoalveolar lavage cell population, lavage fluid from 15 subjects was collected 24 h after the histamine test, and was compared with the lavage fluid from a reference group of 25 subjects. Inhaled histamine is commonly used to quantitate non‐specific bronchial responsiveness. Increase in airway responsiveness after exposure to ozone or allergen is associated with airway inflammation. Bronchoalveolar lavage, has therefore become a valuable tool in the study of bronchoalveolar cells and mediators in subjects with asthma and bronchial hyperresponsiveness. The total cell number and differential cell counts in bronchoalveolar lavage fluid 24 h after inhalation challenge test with histamine‐chloride were studied. There was a significant increase in lymphocytes, mast cells and neutrophils after histamine test. The conclusion was that inhaled histamine‐chloride can induce an inflammatory cell response in the lung. Thus the histamine‐chloride test should not be performed before bronchoalveolar lavage.

Methacholine reactivity and asthma. Report from the Northern Sweden Obstructive Lung Disease Project.

Methacholine tests were used in an epidemiologic study of the prevalence of asthma and chronic bronchitis in northern Sweden. Of 6610 subjects in three age groups from eight representative geographic areas in the northernmost province of Sweden, 5698 (86%) completed a postal questionnaire on respiratory symptoms, and 1506 underwent a structured interview and a lung function test. A total of 292 (5%) were diagnosed as having asthma. A subsample of 284 subjects (of 320 invited) classified at the interview as having asthma (n= 98) or as having respiratory symptoms that might be due to asthma but not fulfilling the interview criteria for the diagnosis of asthma (n= 186) underwent a methacholine test. Subjects who, before the interview study, already had a well‐defined asthma diagnosis were not invited to the methacholine testing. Of those 98 subjects classified as having asthma, 61 % reacted to methacholine doses ≤ 4 mg/ml and 79% to doses ≤ 8 mg/ml, while the corresponding figures in the symptomatic but nonasthma group were 20% and 34%, respectively. The results show that a carefully performed structured interview accurately diagnoses asthma in epidemiologic studies. The methacholine tests provide important diagnostic information primarily in subjects in whom the medical history is equivocal.

Association between Haptoglobin Groups and Hereditary Predisposition for Bronchial Asthma

Haptoglobin (Hp) groups were investigated in 148 patients with bronchial asthma. A significant (p less than 0.005) deviation from the expected Hardy-Weinberg equilibrium, with a decreased frequency of heterozygotes, was observed among patients with a family history of asthma. This deviation was more pronounced among patients with adult onset of asthma. The presence or absence of atopy had no significant influence on the phenotype distribution.

Alpha-1-Antitrypsin Types and Pulmonary Disease among Employees at a Sulphite Pulp Factory in Northern Sweden

Alpha-1-antitrypsin (alpha 1-AT) phenotypes and serum levels were measured in 518 employees at a sulphite pulp factory. There were 439 men and 79 women with the mean age of 42 years (range 18-65 years). Mean time of employment at the factory was 17.5 years and 216 (42%) individuals had been employed for more than 20 years. Chronic bronchitis was present in 47 (9.1%) individuals. alpha 1-AT rare types (MZ, MS, MF) were present in 12.8% of the individuals with chronic bronchitis compared to 8.4% in employees with no respiratory symptoms, the difference being not statistically significant. Individuals with chronic bronchitis and rare types were evenly distributed with regard to work place at the factory. Serum levels of alpha 1-AT were somewhat higher in smokers compared to non-smokers, but the difference was not statistically significant. Exposure to SO2 and chlorine did not seem to affect the serum levels of alpha 1-AT in M type individuals. In the present study, individuals heterozygous for alpha 1-AT deficiency phenotypes (MZ, MS, MF) did not seem to have an increased rate of chronic bronchitis. However, the rate of chronic bronchitis in factory employees was significantly increased compared to that among non-employees in the surrounding community. This increase appears to be due to a higher rate of smoking and to occupational exposure (SO2 and chlorine) among the sulphite pulp factory workers.

Epidemiology of respiratory symptoms, lung function and important determinants

SETTINGnCross-sectional epidemiological study based on a representative sample of the general population in northern Sweden.nnnOBJECTIVESnTo assess the prevalence of respiratory symptoms, the role of respiratory symptoms as indicators of impairment of lung function, and to define risk factors for respiratory symptoms and lung function impairment.nnnDESIGNnThe 1340 subjects of 6610 who reported respiratory symptoms suggestive of asthma or chronic bronchitis in a postal questionnaire study were invited to a structured interview and lung function tests. A control group of 315 subjects was also invited. Risk factors were assessed from the postal questionnaire.nnnRESULTSn400 subjects in the symptomatic group had attacks of breathlessness and wheezing, while none in the control group had them, corresponding to 7% of the original study population. Chronic productive cough was present in 537 subjects, of whom 13 were from the control group, suggesting that 12% of the original study population had this symptom. Persistent wheeze was the symptom that predicted the greatest proportion of cases of impaired lung function. Attacks of breathlessness, wheezing, long-standing cough and sputum production were all related to age, smoking and a family history of asthma. Both chronic productive cough and impaired lung function correlated strongly with smoking and age, and their prevalences differed in different socio-economic groups.nnnCONCLUSIONnImpaired lung function can be predicted from respiratory symptoms. Data collected in postal questionnaires suffice for the identification of risk factors. Combinations of symptoms gave greater odds ratios than individual symptoms.