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Respir Med. 2014 Mar;108(3):491-9. doi: 10.1016/j.rmed.2013.11.003. Epub 2013 Nov 15.

The clinical impact of non-obstructive chronic bronchitis in current and former smokers.

Author information

Pulmonary & Critical Care Division, University of Michigan Health System, Ann Arbor, MI, USA. Electronic address:
Division of Pulmonary and Critical Care, Temple University School of Medicine, Philadelphia, PA, USA.
Respiratory Department, Peking University Third Hospital, Beijing, China.
Department of Radiology, University of Michigan, Ann Arbor, MI, USA.
School of Public Health, University of Michigan, Ann Arbor, MI, USA.
Pulmonary & Critical Care Division, University of Michigan Health System, Ann Arbor, MI, USA; Medicine Service, VA Healthcare System, Ann Arbor, MI, USA.
Department of Medicine, National Jewish Medical and Research Center, Denver, CO, USA.
Channing Division of Network Medicine and Pulmonary and Critical Care Division, Brigham and Women's Hospital, Boston, MA, USA.
Pulmonary & Critical Care Division, University of Michigan Health System, Ann Arbor, MI, USA.



As the clinical significance of chronic bronchitis among smokers without airflow obstruction is unclear, we sought to determine morbidity associated with this disorder.


We examined subjects from the COPDGene study and compared those with FEV1/FVC ≥ 0.70, no diagnosis of asthma and chronic bronchitis as defined as a history of cough and phlegm production for ≥ 3 months/year for ≥ 2 years (NCB) to non-obstructed subjects without chronic bronchitis (CB-). Multivariate analysis was used to determine factors associated with and impact of NCB.


We identified 597 NCB and 4283 CB- subjects. NCB participants were younger (55.4 vs. 57.2 years, p < 0.001) with greater tobacco exposure (42.9 vs. 37.8 pack-years, p < 0.001) and more often current smokers; more frequently reported occupational exposure to fumes (52.8% vs. 42.2%, p < 0.001), dust for ≥ 1 year (55.3% vs. 42.0%, p < 0.001) and were less likely to be currently working. NCB subjects demonstrated worse quality-of-life (SGRQ 35.6 vs. 15.1, p < 0.001) and exercise capacity (walk distance 415 vs. 449 m, p < 0.001) and more frequently reported respiratory "flare-ups" requiring treatment with antibiotics or steroids (0.30 vs. 0.10 annual events/subject, p < 0.001) prior to enrollment and during follow-up (0.34 vs. 0.16 annual events/subject, p < 0.001). In multivariate analysis, current smoking, GERD, sleep apnea and occupational exposures were significantly associated with NCB.


While longitudinal data will be needed to determine whether NCB progresses to COPD, NCB patients have poorer quality-of-life, exercise capacity and frequent respiratory events. Beyond smoking cessation interventions, further research is warranted to determine the benefit of other therapeutics in this population. Clinical Trials Registration # NCT00608764 ( Link to study protocol:


Cough; GERD; Gastroesophageal reflux; Occupational exposure; Quality of life; Tobacco

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