title: The effect of chronic sputum production on respiratory symptoms in severe COPD.
abstract: BACKGROUND
  Chronic sputum production is a significant but variable complaint in COPD; its effect on symptom burden has not been comprehensively described. We sought to characterize the daily burden of chronic sputum production in severe COPD and the phenotype of those with chronic sputum symptoms.
  
  
  METHODS
  We studied 50 outpatients with severe COPD who used an electronic diary to document peak expiratory flow (PEF) and respiratory symptoms daily for up to 2 years. A sputum index was derived based on complaints of sputum quantity, color, and consistency, and patients were divided into groups based on average daily sputum index (Low, Medium, High). The presence and severity of respiratory symptoms were scored by a novel method using daily changes in symptoms and PEF from baseline and were categorized into mild, moderate, and severe. Percent emphysema was measured using quantitative CT.
  
  
  RESULTS
  In the 14,500 observation days, severe symptom days were greater in the Medium and High groups (379/6089, 1609/4091, and 2624/4317 observation days in Low, Medium, and High, p < 0.0001). The same trend was found even when sputum complaints were removed from the symptom severity score. Observed/predicted PEF ratio was lower in the High group (0.56 ± 0.24, 0.55 ± 0.19, and 0.42 ± 0.12 in each group, p < 0.05 for High compared to Medium and Low). Percent emphysema inversely correlated with average sputum index and quantity (r = -0.449 and r = -0.584, respectively, p < 0.05).
  
  
  CONCLUSIONS
  Increased sputum production in severe COPD is frequently encountered daily and is associated with more respiratory symptoms, worse airflow obstruction, and less emphysema.
authors.affiliation: Division of Pulmonary and Critical Care Medicine, Temple University School of Medicine, Philadelphia, Pennsylvania 19140, USA. victor.kim@tuhs.temple.edu
authors.forename: Victor
authors.initials: V
authors.lastname: Kim
authors.forename: Jamie L
authors.initials: JL
authors.lastname: Garfield
authors.forename: Carla L
authors.initials: CL
authors.lastname: Grabianowski
authors.forename: Jason S
authors.initials: JS
authors.lastname: Krahnke
authors.forename: John P
authors.initials: JP
authors.lastname: Gaughan
authors.forename: Michael R
authors.initials: MR
authors.lastname: Jacobs
authors.forename: Gerard J
authors.initials: GJ
authors.lastname: Criner
mesh_terms: D000368:Aged; D005260:Female; D006801:Humans; D008297:Male; D008499:Medical Records; D008875:Middle Aged; D010366:Peak Expiratory Flow Rate; D029424:Pulmonary Disease, Chronic Obstructive / Q000150:complications* / Q000503:physiopathology*; D011656:Pulmonary Emphysema / Q000150:complications; D012720:Severity of Illness Index; D013183:Sputum / Q000378:metabolism*