Background: COPD is a major cause of morbidity in smokers. The COPD

assessment test (CAT) is a validated test for evaluation of COPD impact on

health status. CAT is not a diagnostic test and pulmonary function test (PFT)

still remains the most important diagnostic test. However, its predictive value

for evaluation of disease impact is weak. The purpose of this study was to

determine the relationship between CAT score and PFT in COPD patients.

Materials and Methods: We evaluated 105 patients with stable COPD.

Demographic data were obtained at baseline. Severity of airflow obstruction

was assessed by standard spirometry and classified by the Global initiative for

Obstructive Lung Disease (GOLD) criteria. Then, the impact of COPD on health

status was assessed using CAT. The CAT scores were categorized into four

groups. We statistically compared the relationship between CAT score, COPD

stages, CAT groups and PFT.

Results: The mean age of patients and mean period of smoking (p/y) were

59.60±11.93SD and 35.43±15.33 SD yrs, respectively. The mean FEV1%predicted

was 71.01±26.70SD.The mean CAT score was 19.61±8.07 SD. The correlation

between the severity of smoking and GOLD classification was significant

(p=0.006).There was a significant association between the FEV1%predicted and

total CAT score (r= -0.55, p< 0.001).

The correlation between mean FEV1%predicted and mean score of CAT groups 1,

2, 3, and 4 was statistically significant (p<0.001).

Conclusion: The relationship between CAT score and FEV1%predicted suggests

that CAT is linked to severity of airflow limitation and GOLD classification in

stable COPD patients. Health status as measured by CAT worsens with severity

of airflow limitation

صادقیه اهری, سعید

قبادی مراللو, حسن

محمدزاده لاری, شهرزاد

کاملی, آزاده

English

ArUMS Digital Repository (سامانه اطلاعات زیست پزشکی و سلامت)

Original Article  
2012 NRITLD, National Research Institute of Tuberculosis and Lung Disease, Iran  
ISSN: 1735-0344     Tanaffos 2012; 11(2): 22-26 
 
 
The  Relationship  between  COPD  Assessment  Test (CAT)  
Scores  and  Severity  of  Airflow  Obstruction  in  Stable  
COPD  Patients  
 
Hassan Ghobadi 1, Saeid Sadeghieh 
Ahari 2, Azadeh Kameli 1, Sharzad   
M.Lari 3 
 
1 Department of Internal Medicine, Pulmonary 
Division, 2 Department of Community Medicine, 
Ardabil University of Medical Sciences, Ardabil, Iran,  
3 Department of Internal Medicine, Pulmonary 
Division, Mashhad University of Medical Sciences, 
Mashhad, Iran. 
 
Received: 24 December 2011 
Accepted: 27 February 2012 
 
 Correspondence to: Sadeghieh Ahari S 
Address: Department of Community Medicine, 
Ardabil University of Medical Sciences, Ardabil, 
Iran 
Email address: s.sadeghieh@arums.ac.ir 
Background: COPD is a major cause of morbidity in smokers. The COPD 
assessment test (CAT) is a validated test for evaluation of COPD impact on 
health status. CAT is not a diagnostic test and pulmonary function test (PFT) 
still remains the most important diagnostic test. However, its predictive value 
for evaluation of disease impact is weak. The purpose of this study was to 
determine the relationship between CAT score and PFT in COPD patients.  
Materials and Methods: We evaluated 105 patients with stable COPD. 
Demographic data were obtained at baseline. Severity of airflow obstruction 
was assessed by standard spirometry and classified by the Global initiative for 
Obstructive Lung Disease (GOLD) criteria. Then, the impact of COPD on health 
status was assessed using CAT. The CAT scores were categorized into four 
groups. We statistically compared the relationship between CAT score, COPD 
stages, CAT groups and PFT. 
Results: The mean age of patients and mean period of smoking (p/y) were 
59.60±11.93SD and 35.43±15.33 SD yrs, respectively. The mean FEV1%predicted  
was 71.01±26.70SD.The mean CAT score was 19.61±8.07 SD. The correlation 
between the severity of smoking and GOLD classification was significant 
(p=0.006).There was a significant association between the FEV1%predicted  and 
total CAT score (r= -0.55, p< 0.001). 
The correlation between mean FEV1%predicted  and mean  score  of  CAT groups 1, 
2, 3, and 4 was statistically significant (p<0.001). 
Conclusion: The relationship between CAT score and FEV1%predicted  suggests 
that CAT is linked to severity of airflow limitation and GOLD classification in 
stable COPD patients. Health status as measured by CAT worsens with severity 
of airflow limitation.  
  
 
 
Key words: COPD, COPD Assessment Test (CAT), Health status, 
Pulmonary function test 
 
 
INTRODUCTION 
Chronic  obstructive  pulmonary  disease  (COPD)  is  a  
progressive  condition  leading  to morbidity  and  
mortality  and  is  characterized  by  cough, dyspnea  and  
sputum  production. COPD is a condition  with  persistent  
airflow  limitation  and  systemic  inflammation  affecting  
the  lungs  and  other  organs  and  impairing  quality  of  
life  by several  mechanisms (1-3). 
 
Although  the  severity  of  airflow  obstruction  is  
evaluated  by  forced  expiratory  volume  in  one  second  
(FEV1),  this  test  does  not  show  the  multidimensional  
effect  of  systemic  inflammation  on  health  status (4, 5).  
TANAFFOS  
Ghobadi H, et al.   23 
Tanaffos 2012; 11(2): 22-26 
On  the  other  hand,  COPD  is  a  complex  disease  with  
multiple  consequences  including  breathlessness,  exercise  
limitation,  muscle  wasting,  weight  loss,  increased  
hypercoagulability,  depression,  coronary  artery disease  
and  other  systemic  inflammatory  effects (6,7). 
Recently a new simple system evaluating health status 
was  approved to evaluate the impact of COPD  on  health  
status (8).  The  COPD  Assessment  Test  (CAT)  is  a  new  
scoring  system  for  COPD  patients,  which  provides  a  
simple  method  for  assessing  the  impact  of  COPD  on  
the  patient`s  health.  The  validation  studies  have  shown  
that  it  has  similar  properties  as  St.  George`s 
Respiratory Questionnaire (SGRQ) (9-11). 
The  CAT  and  FEV1  are  complementary  
measurements  for  assessment  and  management  of  
COPD (9,10). The  CAT  is  a  standard  and  validated test  
containing  eight  items  for  the  evaluation  of  the  impact  
of  COPD  on  health  status (8,9).  It  is  a  tool  for  the  
measurement  of  disease  impact  on  health  status,  but  
FEV1 is  essential  to  establish  a  diagnosis  and  to  
confirm  the  severity  of  airway  obstruction  in  
symptomatic  COPD  patients (5). 
The  CAT  and  FEV1 are  both reliable  methods  for  
assessing  the  treatment  response  and  progression  of  
disease  severity  in  COPD  patients (10). 
In  some  studies  FEV1 was  poorly  correlated  with  
quality  of  life,  yet  several researchers  have  reported  a  
weak  correlation  between  health  status  score  and  FEV1 
(10). 
The  aim  of  this  study  was  to  evaluate  the  
correlation  between  airflow  obstruction  by  FEV1  and  
Global  initiative  for Obstructive Lung Disease (GOLD)  
classification  and  health  status  of  COPD patients  by  
CAT  score  and  CAT  groups. 
 
MATERIALS AND METHODS 
Between  March  2010  and  April  2011  a total of 105 
COPD patients  of various severity were  enrolled  in  this  
cross-sectional  study  in  Imam  Khomeini  Hospital  of  
Ardabil  University  of  Medical  Sciences.  All patients 
received the optimal treatment according to the GOLD 
classification. 
The  diagnosis  of  COPD  was  established  based on  a  
medical  history  of  smoking,  current  symptoms  of  
cough,  dyspnea  or  sputum  production  and  available  
standard  pulmonary  function  test  which  was  
performed  by  a spirometer (Chest  Inc.,  801,  Tokyo,  
Japan) according to the ATS standards(American Thoracic 
Society). In case of disparity between the clinical criteria 
and the ATS standards, a preference was given to clinical 
criteria. The severity of COPD was assessed according to 
GOLD classifications as follows: 
Stage 0 (at risk), stage 1(mild), stage 2(moderate), stage 
3(severe) and stage 4 (very severe). 
All patients were clinically stable during the past  four  
weeks.  The  exclusion  criterion  was presence of  an  
illness  other  than  COPD  such  as  bronchial  asthma,  
tuberculosis,  bronchiectasis,  ischemic  heart  disease  or  
malignancy. 
This  study  was  approved  by  the  Institutional  Ethics  
Committee  and  all  patients  provided  written  informed 
consent. 
 
CAT score 
After  history taking  and  physical  examination,  all  
patients  completed  the Persian  version  of  CAT  
respiratory  questionnaire.   
The  total  CAT  score  was  calculated  for  each  
individual  by  summing  the  points  for  each  variable. 
CAT has a scoring range of zero to 40.  The  CAT  score  
was classified  into  four  groups  of  low(1) ,  medium(2),  
high(3)  and  very  high(4)  based on  the  impact  level  of  
disease  on  health  status  as  shown  in  Table 1. 
 
Table 1. Impact  level  of  COPD  on  health  status. 
 
CAT score Impact level 
< 10 Low 
10 – 20 Medium 
21 - 30 High 
> 30 Very high 
24   COPD Assessment Test (CAT) scores and airflow obstruction in COPD 
Tanaffos 2012; 11(2): 22-26 
Analysis 
Data were described as means ± standard deviation. 
Differences  between  means  were tested  with  student`s t-
test  and  reported  with  95%  confidence  interval  (95% 
CI). 
The  correlation  between  the  CAT  score  and  GOLD  
classification  was  tested  by  one way  ANOVA. In order 
to evaluate the  correlation  between  parametric variables, 
the  Pearson’s correlation coefficient was  utilized.  Data 
analysis was performed  using  SPSS version  16 software.  
P<0.05 was considered statistically significant. 
 
RESULTS 
A total of 105 male  patients  were  included  in  this  
study.  General  characteristics  of  these  patients  are  
shown  in  Table  2. 
 
Table 2. General  characteristics  of  patients. 
 
General Characteristics Data 
Male (No.) 105 
Age, years 59.60±11.93 
FEV1%predicted 71.01±26.70 
FVC%predicted 91.39±27.45 
FEV1 / FVC 61.10±13.05 
Total CAT score 19.61±8.07 
Smoking, P/Y 35.43±15.33 
Values are presented as means ± standard deviation 
 
The  mean  CAT  score  was  19.61±8.07  SD with a  
minimum  score  of  2  and a  maximum  score  of  34. The 
correlation between the  number  of  patients  in  stage  0  
to stage IV of  COPD  severity  by  GOLD  classification  
and their  mean  CAT  score  in  each  stage  was  statically  
significant ( P<0.001) as  shown  in  Table  3 . 
 
Table 3. Correlation between the  number  of  patients  in  stage  0  to stage IV of  
COPD  severity  by  GOLD  classification  and their  mean  CAT  score   
 
 GOLD  
0 
GOLD  
I 
GOLD 
II 
GOLD 
III 
GOLD 
IV  
Number of patients 17 22 39 22 5 
CAT score 13.12 14.55 21.08 25.09 28.40 
P value P< 0.001 
 
The  mean  age  of  patients  and  the  mean  period  of  
smoking  pack/year(P/Y)  were  59.60±11.93 and  
35.43±15.3,  respectively.  The  mean  FEV1%predicted  was  
71.01±26.70  and  the  mean  FVC%predicted was  91.39±27.45,  
respectively.  The mean  FEV1/FVC  was  61.10±13.05. 
The  correlation  between  FEV1  value  and  total  CAT  
score  was  significant (r= -0.55 ,P<0.001).  The correlation  
between  total  score  of  CAT  and  FVC%predicted was  
significant as well (r= -0.49 ,P<0.001). 
The amount of smoking  by P/Y  increased  
significantly  with  higher  GOLD classification stages  
(P=0.006)  and  the  differences  between the  stage  II,  and  
stage  III  and  IV(P=0.003  and  P=0.05  respectively)  were 
statistically significant but  no  differences  were  noticed  
between  stage I  and  II by GOLD  classification (P=0.65). 
The correlation between  the  CAT  score  and  amount  
of  smoking  by  P/Y  appeared  to  be  significant (P<0.001,  
r= 0.35).  The correlation between  FEV1%predicted  and  
amount  of  smoking  by  P/Y  was  found  to  be 
statistically significant as well (P=0.007). 
The comparison  of  mean  FEV1%predicted  with  mean 
score  of  CAT  groups  1(low  impact  level)  to 4 (very 
high impact level)  were  90.15±21.11 ,  81.52±24.05 ,  
61.15±24.50  and  46.91±16.38  respectively (P<0.001). 
The  mean  FEV1/FVC  in  the  CAT  groups  1,  2,  3,  
and  4  was  64.46±11.37 ,  65.25±12.74 ,  59.05±13.03  and  
49.73±7.82,  respectively (P<0.001). 
 
DISCUSSION 
COPD  is  a  systemic  disease  with  airflow  
obstruction,  systemic  inflammation,  multi -organ  
damage  and  impairment (1). This  study  demonstrated  
that  CAT  questionnaire  which  is  a  patient-completed  
instrument  for  estimating  the  impact  of  COPD  on  
health  status  has  a  better  correlation  with  severity  of  
airflow  obstruction  by  FEV1  in  stable  COPD  patients. 
COPD  is  a  complex  multidimensional  disease  that  
affects  the  lungs  as well as  other  organs  through  
Ghobadi H, et al.   25 
Tanaffos 2012; 11(2): 22-26 
chronic  systemic  inflammation  and  increased  
inflammatory  markers  that  do not  correctly address  the  
severity  of  airflow  limitation. 
In this  study  no  differences  were  found  between  
CAT  score  of  male  and  female  patients. This  fact     
may be  due  to the nature  of  COPD  that  is  not  
influenced  by  gender and  the  major  risk  factor  of  
disease  is  smoking. This  is  in  line  with  some  previous  
researches (10,12,13). 
We  found  that  FEV1%predicted and FEV1/FVC  were  
reduced  in  COPD  patients  and  the  correlation  of  
smoking  with  airflow  limitation  is  in  concordance  with  
previous  researches. 
Airflow  obstruction  as  measured  by  FEV1  in  
symptomatic  patients is  a  diagnostic  tool  but it is not 
suitable  for  monitoring  disease  progression.  However , 
the  FEV1  does  not  adequately  reflect  all  the  systemic  
manifestations  of  COPD  patients.  It is an important 
assay for staging of COPD (4,5). 
CAT  is  not  a  diagnostic  tool  but  it  can  identify  the  
health  impairment  of  COPD  patients  and  is  better  
correlated  with  disease  progression. 
The  multiple  consequences  of  COPD  have  no  
relationship  with  airflow  limitation  and FEV1 cannot  
reflect the total  impairment  caused by the  disease.  Some  
patients  experience  improvement  in  health  status  
without  change  in their FEV1  after  optimal  treatment  
for  COPD (5). 
Several  studies  have  shown  weak  correlation  
between  FEV1  and  health  status  questionnaire.  Other 
researchers showed  that  the  health  status  was  only  
weakly  correlated  with  the  decline  in  FEV1. 
Our  findings  confirm  that  airflow  limitation  
increased  with  disease  severity  is  better  accompanied  
by  increasing  CAT  scores. 
We  observed  that  health  status  decline  evaluated  
by  CAT  is  correlated  with  the  decline  of  airflow  
obstruction  and  patients  with  more  severe  COPD ( as  
defined  by FEV1)  had  higher  CAT  scores (10). 
One  of  the  most  important  findings  of  the  current  
study  is  the  inverse  correlation  between  FEV1  and  
CAT  groups. These  results  suggest  that  a  lower  FEV1  
indicates  high  CAT  score  and  health  impairment  due  
to  COPD (Figure 1). 
 
 
 
 
 
 
 
 
 
 
 
Figure 1. Correlation between FEV1 and CAT groups. 
 
Results  for  CAT  score  and  GOLD  classification  
revealed  a  strong  positive  correlation  between  the  tests 
(Figure 2). 
 
 
 
 
 
 
 
 
 
 
 
Figure 2. Correlation between CAT score and Gold classification. 
 
The  present  study  suggests  that  COPD  severity  
assessed  by  the  CAT  score  can  be  directly  related  to  
airflow  limitation.  On  the  other  hand,  the  CAT  
questionnaire  can  be  employed  as  a  predictor  of  
severity  of  airway  obstruction  in  COPD patients. 
26   COPD Assessment Test (CAT) scores and airflow obstruction in COPD 
Tanaffos 2012; 11(2): 22-26 
It  was  also  observed  that  the  period  of  
smoking(P/Y)  is  inversely  correlated  with  FEV1  as  the  
most  important  risk  factor  for  COPD. 
Our study had some limitations.  The  first  limitation  
was  the  lack  of  serum  level  of  inflammatory  markers  
and  other  physiologic  parameters  such  as  Modified  
Medical  Research  Council (MMRC)  and  6-minute  
walking  distance(6MWT)  to  evaluate  the  correlation  of  
these parameters  with  CAT  score  and  airflow  
obstruction.  Secondly, our   sample size was relatively 
small.  
In  conclusion,  this  study  supported  the  hypothesis  
that  there  is  a  correlation  between  airflow  limitation  
and  health  status  questionnaires like  CAT.  FEV1  is  
essential  for  diagnosis  of  the  respiratory  impairment  
resulting  from  COPD  but,  the  CAT  is  not  a  diagnostic  
tool  in  COPD  patients. However,  in  previously  
diagnosed  COPD  patients  the  CAT  is a better  assay  for  
evaluating the  severity  of  disease,  management  of  
patient  response  to  treatment  and  prognosis.  Finally,  it  
is  likely  that  airflow  limitation  and  systemic  alteration  
in  COPD  both  happen  in  one  inflammatory  
environment. 
Conflict of Interest: the authors report no conflict of 
interns in this work. 
 
Acknowledgment 
This  study  was  supported  financially  by  the  
Ardabil  University  of  Medical  Sciences  ,  Ardabil,  Iran 
 
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The Relationship between COPD Assessment Test (CAT)Scores and Severity of Airflow Obstruction in StableCOPD Patients

http://eprints.arums.ac.ir/3399/1/Obstruction.pdf

The Relationship between COPD Assessment Test (CAT)Scores and Severity of Airflow Obstruction in StableCOPD Patients

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