OBJECTIVE: To assess the relation of socio-economic status to respiratory symptoms common in asthma and chronic bronchitis, and to compare risk factors for these symptoms between three neighbouring countries. DESIGN: A postal survey was performed in 1996 as a part of comparative studies in Finland, Sweden and Estonia (the FinEsS studies). A random sample of 58,661 subjects aged 20-64 years were invited, of whom 44,483 participated. RESULTS: Respiratory symptoms were most prevalent among manual workers, who were at significantly increased risk for chronic respiratory symptoms. The same pattern of increased risk appeared when the analyses were made among non-smokers only: for recurrent wheeze, manual workers in industry yielded an OR of 1.91 (95%CI 1.62-2.24) and in the service sector an OR of 1.50 (95%CI 1.27-1.78). The corresponding figures for chronic productive cough were 1.45 (95%CI 1.22-1.71) and 1.20 (95%CI 1.02-1.42), respectively. Risk factor profiles for respiratory symptoms were similar in Finland, Sweden and Estonia, except for gender differences in Estonia.CONCLUSIONS: Belonging to the socio-economic group of manual workers correlated with an increased risk for chronic respiratory symptoms, independently of smoking habits, in each country. Women manual workers in industry suffered most from respiratory symptoms

Background: The prevalence of chronic obstructive pulmonary disease (COPD) according to guidelines of today seems considerably higher than has been reported also in recent literature.

Aim: To estimate the prevalence of COPD as defined by British Thoracic Society (BTS) criteria and the recent global initiative for chronic obstructive lung disease (GOLD) criteria. Further aims were to assess the proportion of underdiagnosis and of symptoms in subjects with COPD, and to study risk factors for COPD.

Methods: In 1996, 5892 of the Obstructive Lung Disease in Northern Sweden (OLIN) Study's first cohort could be traced to a third follow-up survey, and 5189 completed responses (88%) were received corresponding to 79% of the original cohort from December 1985. Of the responders, a random sample of 1500 subjects were invited to a structured interview and a lung function test, and 1237 of the invited completed a lung function test with acceptable quality.

Results: In ages >45 years, the prevalence of COPD according to the BTS guidelines was 8%, while it was 14% according to the GOLD criteria. The absolutely dominating risk factors were increasing age and smoking, and approximately a half of elderly smokers fulfilled the criteria for COPD according to both the BTS and the GOLD criteria. Family history of obstructive airway disease was also a risk factor, while gender was not. Of those fulfilling the BTS criteria for COPD, 94% were symptomatics, 69% had chronic productive cough, but only 31% had prior to the study been diagnosed as having either chronic bronchitis, emphysema, or COPD. The corresponding figures for COPD according GOLD were 88, 51, and 18%.

Conclusions: In ages >45 years, the prevalence of COPD according to the BTS guidelines was 8%, and it was 14% according to the GOLD criteria. Fifty percent of elderly smokers had developed COPD. The large majority of subjects having COPD were symptomatic, while the proportion of those diagnosed as having COPD or similar diagnoses was small.

OBJECTIVE: To assess underdiagnosis of chronic obstructive pulmonary disease. MATERIAL AND METHODS: Two cross-sectional studies of respiratory symptoms and diseases in two population samples of the same age living in the same areas in northern Sweden were performed 6 years apart. In 1986, 5698 (86%) out of 6610 subjects aged 35-36, 50-51 and 65-66 years responded to a postal questionnaire. In 1992 an identical study was performed, and 5617 subjects (87%) out of 6434 responded. Lung function measurements were performed in stratified samples. RESULTS: Of the subjects diagnosed with chronic bronchitis only 25% in 1986 and 23% in 1992 had been diagnosed prior to the study as having chronic bronchitis, emphysema or chronic obstructive pulmonary disease (COPD). Chronic airflow limitation (CAL), used as a surrogate variable for COPD and defined as FEV1/VC <70% and FEV1 <80% of predicted value, was found in 171 subjects in 1986-1987 (12% of the examined subjects), and 166 subjects in 1993-1994 (11%). In 1986-1987, 26% of the subjects with CAL had been diagnosed as having chronic bronchitis or emphysema prior to the survey, while a diagnosis of either asthma, chronic bronchitis or emphysema, or use of asthma medicines, was found in 58%. The corresponding figures in 1993-1994 were 31% and 63%, respectively. The great majority of the subjects with CAL had recurrent wheeze, dyspnoea and chronic productive cough. CONCLUSION: Approximately 60% of the subjects with chronic airflow limitation had been diagnosed prior to the survey as having asthma, chronic bronchitis or emphysema, or were using asthma medicines. The results were similar in 1986-1987 and 1993-1994.

AB - STUDY OBJECTIVES: The influences of different smoking categories on the prevalence of respiratory symptoms, asthma, and chronic bronchitis have been examined in the most northern province of Sweden, Norrbotten, and in Lapland, Finland. The two areas have similar geographic and demographic conditions. METHODS AND STUDY POPULATION: The study is a part of the FinEsS studies, which are epidemiologic respiratory surveys in progress in Sweden, Finland, and Estonia. A random sample of 20- to 69-years-olds were invited to answer a postal questionnaire about respiratory symptoms, smoking habits, and occupation. In Norrbotten, 8,333 subjects were invited and 7,104 responded (85%). In Lapland, 8,005 were invited and 6,633 responded (83%). RESULTS: The participation by age and sex was similar in both countries. The prevalence of smokers in Lapland was 32% vs 26% in Norrbotten. Significantly more women than men in Norrbotten were smokers, while the opposite was true for Lapland. Sputum production was the most prevalent symptom in both areas, 25% in Lapland vs 19% in Norrbotten. The prevalence of chronic productive cough was 11% in Lapland and 7% in Norrbotten. Bronchitic symptoms were more prevalent in Lapland among both smokers and nonsmokers. A positive family history of chronic obstructive airway disease together with increased number of consumed cigarettes showed an additive effect for both chronic productive cough and wheezing. The odds ratio (OR) for wheezing during the last 12 months was 3.8 for subjects without a family history of obstructive airway disease who consumed > 14 cigarettes per day compared with nonsmokers, but if the subjects had a family history of obstructive airway disease, the risk for wheezing increased to OR 8.4. CONCLUSION: Bronchitic symptoms were more common in Finland. The difference remained also after correction for demographic variables including smoking habits, age and socioeconomic group, and family history of obstructive airway disease. Identical methods, sample composition, and the high participation rate contribute to the validity of the results. Air pollution, including environmental tobacco smoke, may contribute to the difference. To explain the difference, further analysis and investigations of social and environmental factors as well as genetic factors are needed.

To assess the relationship between chronic bronchitis and obstructive sleep apnoea, a postal survey was performed. A postal questionnaire was sent to 523 subjects identified as having chronic bronchitis or long-standing cough and sputum production in the Obstructive Lung Disease in Northern Sweden Study I (OLIN I). In 1986-88, all 6610 adults born in 1919-20, 1934-35 and 1949-50 living in representative areas in Northern Sweden were screened for airway diseases according to different methods. A random sample of healthy adults identified in the screening were chosen as references (n = 625). Subjects were asked about a variety of airway symptoms, smoking habits and symptoms related to obstructive sleep apnoea syndrome (OSAS). In the bronchitic group, 20% did not report bronchitic symptoms in the present study, and 26% of the formerly healthy reference group reported at least one bronchitic symptom in the present study. Snoring, apnoea and liability to 'nod off' during activity were much more common in the bronchitic group in both men and women, and most common in men, as expected. Snoring was reported by 29% of the men in the bronchitic group and by 14% in the reference group. In women, the corresponding figures were 14 and 8%, respectively, and for apnoea, the figures were 25 vs. 11% in men and 6 vs. 4% in women. The prevalence of OSAS symptoms was similar in subjects with attacks of breathlessness, long-standing cough, sputum production and recurrent wheezing. Bronchitic symptoms may influence quality of sleep and contribute to daytime tiredness, but this does not fully explain the high prevalence of snoring and apnoea reported by subjects in this cohort. This study indicates a positive correlation between chronic bronchitis and OSAS, but sleep studies are required to confirm this

SETTING: Cross-sectional epidemiological study based on a representative sample of the general population in northern Sweden. OBJECTIVES: To 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. DESIGN: The 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. RESULTS: 400 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. CONCLUSION: Impaired 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.