Introduction Chronic mucus hypersecretion (CMH) is associated with COPD development and progression. CMH presence across adult life is dynamic, influenced by factors such as smoking behaviour. CMH is usually considered a binary phenotype and the potential influence of longitudinal CMH pattern on concurrent FEV₁ decline has not been explored. We investigated how longitudinal prevalence of CMH relates to concurrent FEV₁ decline.

Methods The MRC National Survey of Health and Development consists of a sample of men and women born in one week in March 1946 within England, Scotland and Wales. Smoking behaviour, MRC questionnaire defined CMH, height, weight and pre-bronchodilator spirometry were recorded at three ages: 43, 53 and (60–64) years.

We used the number occasions that CMH was positively reported (0–3) as a measure of longitudinal prevalence of CMH. Multilevel models adjusted for sex were used to analyse the relationship between longitudinal prevalence of CMH and concurrent FEV₁ decline (between ages 43 and (60–64)), allowing both intercept and slope to vary according to the longitudinal prevalence of CMH score. Height, weight and mean FEV₁ at age 43 years were then included in the model. Smoking status (current, ex and never-smoker) and number of cigarettes smoked daily were included as time-varying covariates capable of influencing both intercept and slope.

Results 1960 individuals contributed data to the multilevel model: 46% male; 59% ever-smoker and mean FEV₁ at age 43 years = 3.00 L. 13% reported CMH ≥ once between ages 43 and 60–64 years. After full adjustment, longitudinal prevalence of CMH was significantly associated with both a lower FEV₁ at age 43 (intercept p < 0.001) and a faster decline (slope p = 0.003) (See Table 1). For each additional occasion CMH was reported there was an additional 3.2 ml/yr decline in FEV₁ (p = 0.003) i.e. presence of CMH on all three occasions was associated with an additional 9.6 ml/year FEV₁ decline compared with those without CMH on any occasion.

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Abstract P217 Table 1

The association between longitudinal prevalence of CMH (number of occasions CMH reported) and FEV₁ between ages 43 and 60–64 years. Multilevel model includes 1960 individuals

Conclusion Longitudinal prevalence of CMH is associated with concurrent FEV₁ decline independent of concurrent smoking history. Rather than CMH being solely an airway disease phenotype, the longitudinal course of CMH may represent a biomarker of concurrent disease activity.