Combining Both Generic and Disease-Specific Properties: Development of the McGill COPD Quality of Life Questionnaire

Figures & data

Table 1  Baseline sociodemographic and clinical characteristics of the study population (n = 142)

	Mean(sd)	Range
Age (years)	65.6 (8.1)	36 –83
Sex(F/M)	62/80
Race	130-White
	1-Other
	11-Missing
BMI (kg/M^2)	26.7 (5.4)	16.2 –43.6
Pack*years	58.7 (26.8)	7.2 –168
MRC Dyspnea score	2.9 (0.96)	1 –5
FEV1 (L)	1.18 (0.41)	0.49 –2.43
FEV1%	48.0% (15.6)	18 –89
FEV1/FVC	48.1 (13.7)	17 –84
SGRQ symptom	49.3 (19.5)	8.9 –90.5
SGRQ Activity	64.5 (19.1)	5.6 –100
SGRQ Impact	31.3 (17.6)	0 –76.2
SGRQ Total	44.3 (15.6)	11.2 –76.6

BMI-body mass index; MRC-Medical Research Council; FEV₁-post-bronchodialator forced expiratory volume in 1 second; FEV₁% –percent predicted FEV₁; FVC-forced vital capacity; SGRQ-St. George Respiratory Questionnaire.

Table 2  Additional item selection from SF-36 based on face/content validity, item-to-item correlation between SF-36 and COPD module items or response to pulmonary rehabilitation

		Decision based upon
Number	SF-36 Item and question	Face/content validity	Item-to-item correlation	Response to PR
1	SFgh-1 In general would you say your health is: Excellent, very good, good, fair, poor	Removed
2	SFht Compared to one year ago, how would you rate your health in general now?	Removed
3	SFpf-1 Vigorous activities, such as running, lifting heavy objects, participating in strenuous sports		Removed
4	SFpf-2 Moderate activities, such as moving a table, pushing a vacuum cleaner, bowling or playing golf		Removed
5	SFpf-3 Lifting or carrying groceries		Removed
6	SF-pf-4 Climbing several flights of stairs			Removed
7	SF-pf-5 Climbing one flight of stair			Included
8	SFpf-6 Bending, kneeling, stooping			Included
9	SF-pf-7 Walking more than a kilometer			Included
10	SFpf-8 Walking several hundred meters		Removed
11	SFpf-9 Walking one hundred meter		Removed
12	SFpf-10 Bathing or dressing yourself		Removed
13	SFrp-1 Cut down the amount of time you spent on work or other activities			Included
14	SFrp-2 Accomplished less than you would like			Included
15	SFrp-3 Were limited in the kind of work or other activities			Removed
16	SFrp-4 Had difficulty performing the work or other activities (for example took extra effort)			Included
17	SFre-1 Cut down the amount of time you spent on work or other activities			Removed
18	SFre-2 Accomplished less than you would like			Removed
19	SFre-3 Did work or other activities less carefully as usual		Removed
20	SFsf-1 During the past 4 weeks, to what extent has your physical health or emotional problems interfered with your normal social activities with family, friends, neighbors, or groups?			Included
21	SFbp-1 How much bodily pain have you had during the past 4 weeks?			Removed
22	SFbp-2 During past 4 weeks, how much did pain interfere with your normal work?		Removed
23	SFvt-1 Did you feel full of life?			Included
24	SFmh-1 Have you been very nervous?			Included
25	SFmh-2 Have you felt so down in the dumps that nothing could cheer you up?			Removed
26	SFmh-3 Have you felt calm and peaceful?			Removed
27	SFvt-2 Did you have a lot of energy?		Removed
28	SFmh-4 Have you felt downhearted and depressed?			Included
29	SFvt-3 Did you feel worn out?			Included
30	SFmh-5 Have you been happy?			Removed
31	SFvt-4 Did you feel tired?			Removed
32	SFsf-2 During the past 4 weeks, how much of the time has your physical health or emotional problems interfered with your social activities (like visiting friends, relatives etc.)?		Removed
33	SFgh-2 I seem to get sick a little easier than other people.			Removed
34	SFgh-3 I am as healthy as anybody I know.			Removed
35	SFgh-4 I expect my health to get worse.			Removed
36	SFgh-5 My health is excellent.			Included

PR = pulmonary rehabilitation; SFgh = SF- general health; SFht = SF-health transition; SFpf = SF –physical function; SFrp = SF –role physical; SFre = SF –role emotional; SFsf = SF- social function; SFbp = SF- bodily pain; SFvt = SF –vitality

*Item to item correlation in SF-36 and COPD module items (removed if >0.6)

Table 3  Confirmatory Factor Analysis (subjects = 142)

	Loadings
	Factor I	Factor II	Factor III
Eigenvalue	12.209	5.353	4.033
% of variance accounted for	32.1%	14.1%	10.6%
COPD-specific module Items
How much fatigue have you experienced in the last four weeks ?	0.753	0.286
How often have you coughed on an average day during the past four weeks?	0.658
How often did you bring up phlegm on an average day during the past four weeks?	0.683
On an average day during the past four weeks, how much shortness of breath did you have while: Doing you normal daily activities?	0.794		0.187
On an average day during the past four weeks, how much shortness of breath did you have while: Performed activities that required you to raise your arms overhead?	0.752	0.191	0.227
On an average day during the past four weeks, how much shortness of breath did you have while: Walking on the level at your own pace?	0.806		0.239
During the last four weeks, how often did the fear of becoming short of breath limit you in your activities of daily life ?	0.654	0.288	0.219
In the past 4 weeks: Frightened or worried about not being able to breathe	0.553	0.371
In the past 4 weeks: Frustrated or impatient	0.578	0.449
In the past 4 weeks: That everything seems too much of an effort	0.675	0.451	0.160
In the past 4 weeks: Unable to accept your pulmonary condition	0.508	0.429
Compared to a person your own age, how much more time does it take you to perform your daily activities?	0.799	0.160	0.217
Climbing a slope or hill	0.851		0.201
Being autonomous in your own home ie. not requiring any assistance.	0.743	0.200
Being able to function sexually (If sexual activity is not an issue for you, answer not limited at all)	0.604		0.133
Getting outside the house	0.778	0.170	0.175
Going outside on days which are hot/sunny, cold/damp or windy, or have elevated dust/pollution levels.	0.766	0.126	0.208
SF-36 Items
Climbing one flight of stairs.		0.165	0.642
Bending, kneeling, or stooping	0.106	0.201	0.543
Walking more than a kilometer	0.184	0.107	0.691
Cut down the amount of time you spent on work or other activities	0.205	0.434	0.523
Accomplished less than you would like	0.181	0.572	0.528
Had difficulty performing the work or other activities (for example, it took extra effort)	0.250	0.487	0.560
During the past 4 weeks, to what extent has your physical health or emotional problems interfered with your normal social activities with family, friends, neighbors, or groups?	0.261	0.648	0.212
During the past 4 weeks: Did you feel full of life?	0.242	0.586	0.229
During the past 4 weeks: Have you been very nervous?		0.665	0.191
During the past 4 weeks: Have you felt downhearted and depressed?		0.795
During the past 4 weeks: Did you feel worn out?	0.129	0.714	0.310
My health is excellent.	0.240	0.410	0.323

FIGURE 1  Composition of the McGill COPD Quality of Life Questionnaire.