The relationship between cigarette smoking intensity and chronic mucus hypersecretion (CMH) at different ages within a nationally representative birth cohort

Abstract

Background: Smokers with CMH are at greater risk of developing COPD, yet the relationship between smoking intensity, CMH and age is little studied. We investigated CMH prevalence according to concurrent smoking intensity at different ages within the MRC National Survey of Health and Development (NSHD) birth cohort. Methods: The MRC NSHD consists of a sample of men and women born in one week in March 1946 within England, Scotland and Wales. Cigarette smoking behaviour and MRC questionnaire defined CMH were recorded at the following ages (years): 20, 25, 36, 43, 53 & 63. We calculated CMH prevalence according to smoking intensity (number of cigarettes smoked daily). Results: 4427 individuals (52% male) contributed to ≥1 time-point. Between the ages 20 and 63 years the prevalence of active smoking decreased from 46% to 12%. CMH prevalence increased with concurrent smoking intensity and this relationship was amplified by age (See Figure 1). Conclusion: Within this birth cohort the strength of the relationship between concurrent smoking intensity and CMH prevalence increased with age, potentially representing a cumulative smoking effect and/or heightened susceptibility to the symptomatic consequences of smoking with ageing.