title: Minimum clinically important difference in diffusing capacity of the lungs for carbon monoxide among patients with severe and very severe chronic obstructive pulmonary disease.
abstract: BACKGROUND
  The minimum clinically important difference (MCID) for diffusing capacity of the lungs for carbon monoxide (DLCO) has not yet been solidly established.
  
  
  METHODS
  We used the dataset of surgical cohort of National Emphysema Treatment Trial. Briefly, severe and very severe chronic obstructive pulmonary disease (COPD) patients who were candidate for volume reduction surgery and who could provide sufficient data at 12-month follow-up were included. We used two anchor methods using 6-minute walk distance (6MWD. MCID = 40 m) and forced expiratory volume in 1 sec (FEV1. MCID = 100 ml) as anchors, and two distribution methods. We proposed MCID with a median of estimated values. We estimated MCID for DLCO in raw value and % change from the baseline independently.
  
  
  RESULTS
  The surgical cohort included 356 patients, whose average age was 66.6 ± 5.5 years, and the average % predicted FEV1 was 27.8 ± 7.3%. The estimated MCID for DLCO in raw value and % change from the baseline were as follows: anchor method (average, 6MWD) 1.2 ml/min/mmHg, 17%; anchor method (average, FEV1) 0.7 ml/min/mmHg, 11%; anchor method (receiver operating characteristic, 6MWD) 1.1 ml/min/mmHg, 10%; anchor method (receiver operating characteristic, FEV1) 1.2 ml/min/mmHg, 3%; distribution method (0.3 units of standard deviation), 0.9 ml/min/mmHg, 11%; distribution method (standard error of measurement), 1.1 ml/min/mmHg. The median of these values was 1.1 ml/min/mmHg and 11%.
  
  
  CONCLUSIONS
  We estimated the group-level MCID for DLCO for patients with severe and very severe COPD patients as 1.1 ml/min/mmHg and 11% of baseline DLCO.
authors.affiliation: 1Department of Internal Medicine and Clinical Immunology, Yokohama City University Graduate School of Medicine , Yokohama , Japan.
authors.forename: Nobuyuki
authors.initials: N
authors.lastname: Horita
authors.forename: Naoki
authors.initials: N
authors.lastname: Miyazawa
authors.forename: Ryota
authors.initials: R
authors.lastname: Kojima
authors.forename: Miyo
authors.initials: M
authors.lastname: Inoue
authors.forename: Yoshiaki
authors.initials: Y
authors.lastname: Ishigatsubo
authors.forename: Takeshi
authors.initials: T
authors.lastname: Kaneko
mesh_terms: D000368:Aged; D015415:Biomarkers / Q000378:metabolism; D002248:Carbon Monoxide / Q000378:metabolism*; D005080:Exercise Test; D005260:Female; D005500:Follow-Up Studies; D005541:Forced Expiratory Volume; D006801:Humans; D008297:Male; D008875:Middle Aged; D011013:Pneumonectomy; D011653:Pulmonary Diffusing Capacity; D029424:Pulmonary Disease, Chronic Obstructive / Q000503:physiopathology* / Q000601:surgery / Q000628:therapy; D015203:Reproducibility of Results; D012720:Severity of Illness Index; D016896:Treatment Outcome
chemical_list: D015415:Biomarkers; D002248:Carbon Monoxide
keywords: differential threshold; emphysema; respiratory function tests; surgery