Update on the "Dutch hypothesis" for chronic respiratory disease.

BACKGROUND: Many patients with chronic obstructive lung disease show increased airways responsiveness to histamine. We investigated the hypothesis that increased airways responsiveness predicts the development and remission of chronic respiratory symptoms.
METHODS: We used data from 24-year follow-up (1965-90) of 2684 participants in a cohort study in Vlagtwedde and Vlaardingen, Netherlands. Increased airways responsiveness was defined as a PC10 value (concentration of histamine for which challenge led to a 10% fall in forced expiratory volume in 1 s) of less than 8 mg/ml. Information on respiratory symptoms was collected by means of a standard questionnaire every 3 years. Logistic regression was used to control for age, area of residence, cigarette smoking status, and sex.
FINDINGS: Participants with increased airways responsiveness (1281 observations) were more likely than those without increased airways responsiveness (5801 observations) to develop the following symptoms during any 3-year follow-up interval: chronic cough (odds ratio 1.9 [95% CI 1.2-2.9]), chronic phlegm (2.0 [1.3-3.0]), dyspnoea (2.3[1.5-3.5]), asthmatic attacks (3.7[2.2-6.1]), and persistent wheeze (2.7[1.7-4.4]). The estimate of the odds ratio for the development of any of the six symptoms was 1.7 (1.2-2.3). Participants with increased airways responsiveness were less likely than those without this characteristic to show remission of these respiratory symptoms. The estimate of the odds ratio for the remission of any of the six symptoms was 0.42 (0.28-0.61).
INTERPRETATION: These prospective analyses show that increased airways responsiveness is positively associated with the development of chronic respiratory symptoms and negatively associated with the remission of these symptoms in adults.