Gastroesophageal reflux disease is a risk factor for sputum production in the general population: the Nagahama study

Table 1 Participant demographics (baseline assessment)

Characteristics	All subjects n = 9804	Transient sputum production^a n = 1022	Persistent sputum production^a n = 1609	Sputum production at follow-up only^a,b n = 1256	No sputum production at both assessments^a n = 4406	p value among the four groups
Age, years	53.6 ± 13.4	53.6 ± 13.8	54.9 ± 13.3	53.7 ± 12.4	53.8 ± 12.9	0.01
Sex (male/female), %	32.8/67.2	40.6/59.4	50.4/49.6	30.8/69.2	23.7/76.3	< 0.0001
Sputum production (baseline/follow-up), %	32.0/34.5	100/0	100/100	0/100	0/0	–
Sputum production on awakening (baseline/follow-up), %	16.7/19.6	32.9/8.5	49.0/58.8	8.9/38.4	3.9/2.5	< 0.0001/< 0.0001
Smoking history (ex or current), %	35.0	40.9	49.8	33.4	26.1	< 0.0001
COPD, %	1.1	1.5	2.1	1.1	0.5	< 0.0001
Asthma, %	4.1	5.5	6.6	4.0	2.9	< 0.0001
Prolonged cough, %	10.4	14.7	18.3	10.4	7.0	< 0.0001
Sinusitis, %	10.2	12.5	15.7	10.5	7.9	< 0.0001
Post-nasal drip (baseline/follow-up), %	21.1/24.9	28.8/24.7	35.5/39.7	22.1/36.6	14.4/16.2	< 0.0001/< 0.0001
FSSG score ≥ 8 (baseline/follow-up), %	22.7/22.0	26.7/23.4	36.5/36.3	25.2/28.1	15.8/14.8	< 0.0001/< 0.0001

Data is presented as mean ± SD. Data at baseline assessment is presented unless otherwise specified. Transient; sputum production at baseline only. Persistent; sputum production at both baseline and follow-up assessments
COPD chronic obstructive pulmonary disease, FSSG Frequency Scale for Symptoms of Gastroesophageal Reflux Disease
^a among 8293 participants who were followed from 2013 to 2015
^b among 8292 for post-nasal drip and FSSG score

ISSN: 1465-993X