Incidence of chronic obstructive pulmonary disease in a cohort of young adults according to the presence of chronic cough and phlegm.
BACKGROUND
The few prospective studies aimed at assessing the incidence of chronic obstructive pulmonary disease (COPD) in relation to the presence of chronic cough/phlegm have produced contrasting results.


OBJECTIVE
To assess the incidence of COPD in a cohort of young adults and to test whether chronic cough/phlegm and dyspnea are independent predictors of COPD.


METHODS
An international cohort of 5,002 subjects without asthma (ages 20-44 yr) with normal lung function (FEV(1)/FVC ratio >/= 70%) from 12 countries was followed from 1991-2002 in the frame of the European Community Respiratory Health Survey II. Incident cases of COPD were those who had an FEV(1)/FVC ratio less than 70% at the end of the follow-up, but did not report having had a doctor diagnose asthma during the follow-up.


RESULTS
The incidence rate of COPD was 2.8 cases/1,000/yr (95% confidence interval [CI], 2.3-3.3). Chronic cough/phlegm was an independent and statistically significant predictor of COPD (incidence rate ratio [IRR], 1.85; 95% CI, 1.17-2.93) after adjusting for smoking habits and other potential confounders, whereas dyspnea was not associated with the disease (IRR = 0.98; 95% CI, 0.64-1.50). Subjects who reported chronic cough/phlegm both at baseline and at the follow-up had a nearly threefold-increased risk of developing COPD with respect to asymptomatic subjects (IRR = 2.88; 95% CI, 1.44-5.79).


CONCLUSIONS
The incidence of COPD is substantial even in young adults. The presence of chronic cough/phlegm identifies a subgroup of subjects with a high risk of developing COPD, independently of smoking habits.
de Marco
Roberto
R
Sezione di Epidemiologia & Statistica Medica, Dipartimento di Medicina e Sanità Pubblica, Università degli Studi di Verona, c/o Istituti Biologici II, Strada Le Grazie 8 37134, Verona, Italy. roberto.demarco@univr.it
Accordini
Simone
S
Cerveri
Isa
I
Corsico
Angelo
A
Antó
Josep M
JM
Künzli
Nino
N
Janson
Christer
C
Sunyer
Jordi
J
Jarvis
Deborah
D
Chinn
Susan
S
Vermeire
Paul
P
Svanes
Cecilie
C
Ackermann-Liebrich
Ursula
U
Gislason
Thorarinn
T
Heinrich
Joachim
J
Leynaert
Bénédicte
B
Neukirch
Françoise
F
Schouten
Jan P
JP
Wjst
Matthias
M
Burney
Peter
P
D000328:Adult; D002908:Chronic Disease; D015331:Cohort Studies; D003371:Cough / Q000175:diagnosis*; D004417:Dyspnea / Q000175:diagnosis; D005260:Female; D006801:Humans; D015994:Incidence; D008297:Male; D009093:Mucus; D029424:Pulmonary Disease, Chronic Obstructive / Q000453:epidemiology*