title: Longitudinal inspiratory capacity changes in chronic obstructive pulmonary disease.
abstract: BACKGROUND
  The changes in inspiratory capacity (IC) over time in chronic obstructive pulmonary disease (COPD) patients are unknown. The Understanding Potential Long-term Impacts on Function with Tiotropium (UPLIFT®) trial included IC measurements.
  
  
  METHODS
  IC analysis from UPLIFT® (N = 5992) was performed at 1 and 6 months, and every 6 months through 4 years. Annualized rate of decline in pre- and post-bronchodilator IC and mean differences at each time point were analyzed by mixed-effects models. The relationships between baseline IC and exacerbation rate and mortality were explored using Cox regression analysis.
  
  
  RESULTS
  Baseline characteristics: age, 65 years; 75% men; post-bronchodilator forced expiratory volume in 1 second, 1.32 L (48% predicted); pre- and post-bronchodilator IC, 2.03 and 2.33 L. Mean IC rate of decline (mL/year) was 34 ± 2 (1.7% of baseline) and 50 ± 3 (2.1% of baseline) pre- and post-bronchodilator, respectively, without significant between-group differences. Morning pre-bronchodilator (trough) IC improved with tiotropium versus placebo: 124 mL (1 month), 103 mL (1 year), 107 mL (2 years), 98 mL (3 years), and 97 mL (4 years) (all p < 0.001). Post-bronchodilator improvements were similar between treatment groups. Lower baseline IC values were associated with reduced time to first exacerbation. For the lowest quartile (n = 1413) the values in months were 14.3 (11.7-17.0) for tiotropium and 10.3 (8.8-11.7) for controls (p < 0.01).
  
  
  CONCLUSIONS
  IC declines from approximately 34 to 50 mL/year in patients with stage II to IV COPD. Tiotropium treatment does not change the IC decline rate but provides 24-hour improvements in IC sustained over the long term. Trough IC differences suggest that tiotropium provides sustained decrease in end-expiratory lung volume.
authors.affiliation: Pulmonary Division, Brigham and Women's Hospital, Boston, MA, USA. bcelli@copdnet.org
authors.forename: Bartolome R
authors.initials: BR
authors.lastname: Celli
authors.forename: Marc
authors.initials: M
authors.lastname: Decramer
authors.forename: Theodore
authors.initials: T
authors.lastname: Lystig
authors.forename: Steven
authors.initials: S
authors.lastname: Kesten
authors.forename: Donald P
authors.initials: DP
authors.lastname: Tashkin
mesh_terms: D000368:Aged; D001993:Bronchodilator Agents / Q000494:pharmacology / Q000627:therapeutic use; D018450:Disease Progression; D005260:Female; D005541:Forced Expiratory Volume / Q000187:drug effects / Q000502:physiology; D006801:Humans; D007320:Inspiratory Capacity / Q000187:drug effects / Q000502:physiology*; D008137:Longitudinal Studies; D008297:Male; D008875:Middle Aged; D029424:Pulmonary Disease, Chronic Obstructive / Q000188:drug therapy / Q000401:mortality / Q000503:physiopathology*; D012044:Regression Analysis; D012602:Scopolamine Derivatives / Q000494:pharmacology / Q000627:therapeutic use; D012720:Severity of Illness Index; D000069447:Tiotropium Bromide
chemical_list: D001993:Bronchodilator Agents; D012602:Scopolamine Derivatives; D000069447:Tiotropium Bromide