Estimated prevalences of respiratory symptoms, asthma and chronic obstructive pulmonary disease related to detection rate in primary health care

Objective - To assess the prevalence of respiratory symptoms, asthma and chronic obstructive pulmonary disease (COPD), and to relate it to an estimated detection rate in primary health care. Design - A two-staged study with a cross-sectional survey and a clinical validation. Setting - The adult population of Varmland, a county in Sweden. Subjects - 4814 persons completed the survey and 206 the confirmative validation study. Main outcome measures - Prevalence of respiratory symptoms, of asthma and COPD. Results - More than 40% reported respiratory symptoms. Wheeze was reported by 8.0%, shortness of breath by 11.4% and sputum production by 14.1%. Smoking was more common among women than among men. The prevalence of asthma was 8.2% and COPD 2.1%. Of persons with asthma, 33% were estimated to be undiagnosed, 67% used medication and nearly 60% attended primary health care services. Conclusion - Respiratory symptoms as well as asthma were common in this study and equivalent to earlier findings. The difference between the epidemiologically estimated prevalence of asthma and the lower detection rate in primary health care can be explained by at least three factors: persons who did not seek any care, were underdiagnosed or attended other health care providers.