PMID- 24621681
OWN - NLM
STAT- MEDLINE
DCOM- 20140619
LR  - 20230125
IS  - 2213-2600 (Print)
IS  - 2213-2600 (Linking)
VI  - 2
IP  - 3
DP  - 2014 Mar
TI  - Minimum clinically important difference for the COPD Assessment Test: a 
      prospective analysis.
PG  - 195-203
LID - S2213-2600(14)70001-3 [pii]
LID - 10.1016/S2213-2600(14)70001-3 [doi]
AB  - BACKGROUND: The COPD Assessment Test (CAT) is responsive to change in patients 
      with chronic obstructive pulmonary disease (COPD). However, the minimum 
      clinically important difference (MCID) has not been established. We aimed to 
      identify the MCID for the CAT using anchor-based and distribution-based methods. 
      METHODS: We did three studies at two centres in London (UK) between April 1, 
      2010, and Dec 31, 2012. Study 1 assessed CAT score before and after 8 weeks of 
      outpatient pulmonary rehabilitation in patients with COPD who were able to walk 5 
      m, and had no contraindication to exercise. Study 2 assessed change in CAT score 
      at discharge and after 3 months in patients admitted to hospital for more than 24 
      h for acute exacerbation of COPD. Study 3 assessed change in CAT score at 
      baseline and at 12 months in stable outpatients with COPD. We focused on 
      identifying the minimum clinically important improvement in CAT score. The St 
      George's Respiratory Questionnaire (SGRQ) and Chronic Respiratory Questionnaire 
      (CRQ) were measured concurrently as anchors. We used receiver operating 
      characteristic curves, linear regression, and distribution-based methods (half 
      SD, SE of measurement) to estimate the MCID for the CAT; we included only 
      patients with paired CAT scores in the analysis. FINDINGS: In Study 1, 565 of 675 
      (84%) patients had paired CAT scores. The mean change in CAT score with pulmonary 
      rehabilitation was -2.5 (95% CI -3.0 to -1.9), which correlated significantly 
      with change in SGRQ score (r=0.32; p<0.0001) and CRQ score (r=-0.46; p<0.0001). 
      In Study 2, of 200 patients recruited, 147 (74%) had paired CAT scores. Mean 
      change in CAT score from hospital discharge to 3 months after discharge was -3.0 
      (95% CI -4.4 to -1.6), which correlated with change in SGRQ score (r=0.47; 
      p<0.0001). In Study 3, of 200 patients recruited, 164 (82%) had paired CAT 
      scores. Although no significant change in CAT score was identified after 12 
      months (mean 0.6, 95% CI -0.4 to 1.5), change in CAT score correlated 
      significantly with change in SGRQ score (r=0.36; p<0.0001). Linear regression 
      estimated the minimum clinically important improvement for the CAT to range 
      between -1.2 and -2.8 with receiver operating characteristic curves consistently 
      identifying -2 as the MCID. Distribution-based estimates for the MCID ranged from 
      -3.3 to -3.8. INTERPRETATION: The most reliable estimate of the minimum important 
      difference of the CAT is 2 points. This estimate could be useful in the clinical 
      interpretation of CAT data, particularly in response to intervention studies. 
      FUNDING: Medical Research Council and UK National Institute of Health Research.
CI  - Copyright (c) 2014 Elsevier Ltd. All rights reserved.
FAU - Kon, Samantha S C
AU  - Kon SS
AD  - NIHR Respiratory Biomedical Research Unit, Royal Brompton & Harefield NHS 
      Foundation Trust, London, UK; Imperial College, London, UK. Electronic address: 
      s.kon@rbht.nhs.uk.
FAU - Canavan, Jane L
AU  - Canavan JL
AD  - NIHR Respiratory Biomedical Research Unit, Royal Brompton & Harefield NHS 
      Foundation Trust, London, UK; Imperial College, London, UK.
FAU - Jones, Sarah E
AU  - Jones SE
AD  - NIHR Respiratory Biomedical Research Unit, Royal Brompton & Harefield NHS 
      Foundation Trust, London, UK; Imperial College, London, UK.
FAU - Nolan, Claire M
AU  - Nolan CM
AD  - NIHR Respiratory Biomedical Research Unit, Royal Brompton & Harefield NHS 
      Foundation Trust, London, UK; Harefield Pulmonary Rehabilitation Unit, Royal 
      Brompton & Harefield NHS Foundation Trust, London, UK; Imperial College, London, 
      UK.
FAU - Clark, Amy L
AU  - Clark AL
AD  - Harefield Pulmonary Rehabilitation Unit, Royal Brompton & Harefield NHS 
      Foundation Trust, London, UK.
FAU - Dickson, Mandy J
AU  - Dickson MJ
AD  - The Hillingdon Hospital NHS Foundation Trust, Uxbridge, UK.
FAU - Haselden, Brigitte M
AU  - Haselden BM
AD  - The Hillingdon Hospital NHS Foundation Trust, Uxbridge, UK.
FAU - Polkey, Michael I
AU  - Polkey MI
AD  - NIHR Respiratory Biomedical Research Unit, Royal Brompton & Harefield NHS 
      Foundation Trust, London, UK; Imperial College, London, UK.
FAU - Man, William D-C
AU  - Man WD
AD  - NIHR Respiratory Biomedical Research Unit, Royal Brompton & Harefield NHS 
      Foundation Trust, London, UK; Harefield Pulmonary Rehabilitation Unit, Royal 
      Brompton & Harefield NHS Foundation Trust, London, UK; Imperial College, London, 
      UK.
LA  - eng
GR  - G1002113/MRC_/Medical Research Council/United Kingdom
PT  - Journal Article
PT  - Research Support, Non-U.S. Gov't
DEP - 20140204
PL  - England
TA  - Lancet Respir Med
JT  - The Lancet. Respiratory medicine
JID - 101605555
SB  - IM
CIN - Lancet Respir Med. 2014 Mar;2(3):167-9. PMID: 24621674
MH  - Aged
MH  - Aged, 80 and over
MH  - Female
MH  - *Health Status Indicators
MH  - Hospitalization
MH  - Humans
MH  - Male
MH  - Middle Aged
MH  - Outcome Assessment, Health Care
MH  - Prospective Studies
MH  - Pulmonary Disease, Chronic Obstructive/complications/*diagnosis/therapy
MH  - ROC Curve
MH  - Reproducibility of Results
MH  - *Surveys and Questionnaires
EDAT- 2014/03/14 06:00
MHDA- 2014/06/20 06:00
CRDT- 2014/03/14 06:00
PHST- 2014/03/14 06:00 [entrez]
PHST- 2014/03/14 06:00 [pubmed]
PHST- 2014/06/20 06:00 [medline]
AID - S2213-2600(14)70001-3 [pii]
AID - 10.1016/S2213-2600(14)70001-3 [doi]
PST - ppublish
SO  - Lancet Respir Med. 2014 Mar;2(3):195-203. doi: 10.1016/S2213-2600(14)70001-3. 
      Epub 2014 Feb 4.