A review of the most common patient-reported outcomes in COPD – revisiting current knowledge and estimating future challenges

Figures & data

Table 1 Overview of patient-reported outcome measures in COPD

PRO	Developers	Purpose of tool	Domains	Number of items	Recall period	Mode of administration	Response scale	Scoring	MCID
Frequently used PRO measures in COPD
St George’s Respiratory Questionnaire (SGRQ)	Jones et al^Citation21,Citation22	To assess health impairment in chronic airflow limitation	Symptoms; activity; impacts on daily life	50	Last 4 weeks Last 3 months Last year	Self-administered Telephone-administered Electronic version	3–5 point Likert scales Yes/no	Total subscale scores calculated from the summed weights for questions 1–8 in symptoms; 11–15 in activity; and 9–10, 12–14 and 16–27 in impact. Total score sums all positive responses and expresses these as a percentage of the total weight of the questionnaire.	Improvement of 4 points on the separate domains and the total score is most commonly used, although changes of 2 to 8 are also sometimes considered.
St George’s Respiratory Questionnaire for COPD (SGRQ-C)	Meguro et al^Citation31	To assess COPD in a way that allows scores to be directly compared to the SGRQ but with the weakest items removed	Symptoms; activity; impacts on daily life	40	No standard recall	Self-administered Telephone-administered Electronic version	3–5-point Likert scales Yes/no	Specific scoring algorithm was developed to make sure that the revised scoring is equivalent to the original scale.	Improvement of 4 points on the separate domains and the total score is most commonly used, although changes of 2 to 8 are also sometimes considered.
Chronic Respiratory Disease Questionnaire (CRQ)	Guyatt et al^Citation33	To measure health-related quality of life in patients with chronic respiratory disease	Mastery; fatigue; emotional function; dyspnea	20	Last 2 weeks	Self-administered Telephone-administered Interviewer-administered	7-point Likert scale Yes/no	Total score and subscores can be calculated; higher scores indicate better health-related quality of life. A score of 1–7 can be calculated, or a score of 20–140.	0.5 on 7-point scale, 10 on the scale of 140
Short Form Chronic Respiratory Disease Questionnaire (SF-CRQ)	Tsai et al^Citation38	To measure health-related quality of life in patients with chronic respiratory disease	Mastery; fatigue; emotional function; dyspnea	8	mstandard recall period	Self-administered Telephone-administered	7-point Likert scale	Total score and subscores can be calculated; higher scores indicate better health-related quality of life.	0.5 on 7-point scale
Clinical COPD Questionnaire (CCQ)	van der Molen et al^Citation39	To assess health status in a primary setting	Symptoms; functional state; mental state	10	Last 7 days Last 24 hours	Self-administered	7-point Likert scale	The final score is the mean of all ten items, and domain-specific scores can be calculated separately if required.	0.4
COPD Assessment Test (CAT)	Jones et al^Citation8	To quantify the symptom burden of COPD in a short, simple measure	Energy; sleep; confidence; activities; breathlessness; chest tightness; phlegm; cough	8	Not specified	Self-administered; pen and paper	6-point numeric rating scale	There is a total score of 40; scores of 0–10, 11–20, 21–30, and 31–40 represent mild, moderate, severe, or very severe clinical impact, respectively.	Estimated at 1–3 points, but unclear.
Exacerbations of Chronic Pulmonary Disease Tool (EXACT-PRO)	Leidy et al^Citation46	To evaluate the frequency, severity, and duration of acute exacerbations of COPD and chronic bronchitis	Breathlessness; cough and sputum; chest symptoms	14	Today	Self-administered Electronic	m6-point Likert scales	Items are scored according to the 5-6 point scales and summed to find a total score; the total score then is converted to a 0–100 scale, with higher scores indicating more severe health state or exacerbation.	Yet to be established.
Exacerbations of Chronic Pulmonary Disease Respiratory Symptoms (E-RS)	Leidy et al^Citation50	To assess the effect of treatment on the severity of respiratory symptoms of COPD	Breathlessness; cough and sputum; chest symptoms	11	Today	Self-administered Electronic	5- and 6-point Likert scales	Total score ranges from 0–40, with score ranges of 0–17 for breathlessness, 0–12 for chest symptoms, and 0–11 for cough and sputum.	3-point change in E-RS total score. 2-point change in E-RS breathlessness domain. 1-point change in E-RS cough domain. 1-point change in E-RS chest symptom domain.
The Breathlessness Cough and Sputum Scale (BCSS)	Leidy et al^Citation52	To track the severity of respiratory symptoms and evaluate the efficacy of treatment in clinical trials of patients with COPD	Breathlessness; cough; sputum	3	Daily diary	Self-administered	5-point Likert scale	A daily total is expressed as the sum of three item scores, with a range of 0–12 for which a higher score indicates a more severe manifestation of symptoms.	A mean ΔBCSS total score >1.0 represents substantial symptomatic improvement; changes of approximately 0.6 can be interpreted as moderate, and changes of 0.3 can be considered small.
Baseline and Transition Dyspnea Indexes (BDI-TDI)	Mahler et al^Citation54–Citation56	To provide a multidimensional measurement of dyspnea based on activities of daily living insymptomatic individuals	BDI: functional impairment; magnitude of task; magnitude of effort TDI: functional impairment; magnitude of task; magnitude of effort	BDI: 3 TDI: 3	Last 2 weeks	Self-administered Physician-administered Electronic version (self-administered)	Grades are based on patient responses	Score range in BDI is 0–12, score range in TDI is -9 to 9.	1 unit change in TDI.
Medical Research Council (MRC) Dyspnea Scale	Medical Research Council^Citation9	To categorize disability in COPD	Not applicable; unidimensional	1	Not specified	Originally physician administered Self-administered; pen and paper	5-point numeric rating scale	Patients are classified into one of the 5 MRC grades on the basis of their perceived level of disability.	Yet to be established.
Modified Medical Research Council (m-MRC) Dyspnea Scale	Aaron et al^Citation62	To categorize disability in COPD	Not applicable; unidimensional	1	Not specified	Self-administered; pen and paper	5-point numeric rating scale	Patients are classified into one of the 5 MRC grades on the basis of their perceived level of disability.	Changes in the CRQ dyspnea score and TDI correlated with each other (r=0.78; P=0.0001) and with changes in FEV1 (CRQ, r=0.48 and P=0.0001; TDI, r=0.46 and P=0.0002).
McGill COPD Quality of Life Questionnaire	Pakhale et al^Citation63,Citation64	To combine generic health status with disease-specific modules for COPD health status	Physical function; feelings; and symptoms	29	Last 4 weeks	Self-administered pen and paper	5-point numeric rating scale	Feelings, physical function, and three separate subscale symptoms.	Yet to be established.
The Visual Simplified Respiratory Questionnaire (VSRQ)	Perez et al^Citation65	To evaluate quality of life in COPD patients	Dyspnea; anxiety; depressed mood; sleep; energy; daily activities; social activities; sexual life	8		Physician administered	Unidimensional scale	Good level of consistency between the concepts measured by VSRQ and those by SGRQ, but no redundancy (correlations of −0.70 between VSRQ global score and SGRQ total score). The VSRQ global score was found to be more strongly correlated with the SGRQ activities and impacts subscores than with the symptoms subscore.	3.4
Dyspnea-12	Yorke et al^Citation66,Citation67	To measure the current level of a patient’s breathlessness severity	Not applicable; unidimensional	12	These days	Self-administered pen and paper	4-point numeric rating scale	A total score is calculated from 12 items (although 3 items may be missing) and then a weighted scoring is applied.	Yet to be established.
Dyspnea Management Questionnaire Computer Adaptive Test (DMQ-CAT)	Norweg et al^Citation69	To compare dyspnea scores obtained before and after treatment of individual patients and of groups of patients	Dyspnea intensity; dyspnea-related anxiety; activity avoidance; activity self-efficacy	71	Last 2 weeks	Self-administered	Variable (1–6-point scale with separate category for not relevant)	Uses CAT so that only the most informative items are used.	Using CAT simulation analyses, the DMQ-CAT showed higher measurement accuracy compared to the total item pool (r=0.83–0.97, P<0.0001), and it showed evidence of good to excellent concurrent (r=-0.61 to −0.80, P<0.0001) validity
Shortness of Breath with Daily Activities Questionnaire (SOBDA)	Wilcox et al^Citation70	To measure dyspnea during daily activities	Not applicable; unidimensional	13	Daily	Self-administered electronic diary	Slightly, moderately, severely, and so severe that I could not do the Activity	Weekly mean score ranging from 1–4, with higher scores indicating more severe breathlessness.	Yet to be established
Global Chest Symptoms Questionnaire (GCSQ) Capacity of Daily Living during the Morning questionnaire (CDLM)	Partridge et al^Citation71	To assess the burden and extent of morning symptoms and the ability of patients to perform morning activities	The patient’s ability to carry out morning activities; shortness of breath; chest tightness	GCSQ –2 CDLM –6	Daily	Self-administered	5-point numeric rating scale	A total score can be calculated as an average of the questions on each questionnaire.	Estimated to be 0.20 for CDLM and 0.15 for GCSQ
Living with COPD (LCOPD)	McKenna et al^Citation77	To assess the overall impact of COPD from a patient’s perspective	Not applicable unidimensional	22	Not mentioned	Self-administered	True/not true	A total score can be calculated.	Yet to be established

Abbreviations: MCID, minimal clinically important difference; PRO, patient-reported outcome; FEV₁, forced expiratory volume in 1 second.

Table 2 Psychometric properties of patient reported outcomes in COPD

PRO instrument	Reliabilitya	Validity
Frequently used PRO measures in COPD
St George’s Respiratory Questionnaire (SGRQ)	Acceptable internal consistency reliability; Cronbach’s alpha >0.7 test–retest reliability: ICC =0.8–0.9	Convergent validity SGRQ scores correlated with appropriate comparison measures. For example, symptom score versus frequency of wheeze, r^2=0.32, P<0.0001; activity versus 6-MWD, r^2=0.50, P<0.0001; impact versus anxiety, r^2=0.38, P<0.0001
St George’s Respiratory Questionnaire for COPD (SGRQ-C)	Excellent internal consistency reliability; ICC =0.96–0.99	Correlations with other measures of disease were very similar to those obtained with the SGRQ.
Chronic Respiratory Disease Questionnaire (CRQ)	Good internal consistency reliability; Cronbach’s alpha =0.80 test–retest reliability: ICC =0.83–0.95 (short-term) and ICC =0.83–0.90 (long-term)	Convergent validityb a) Moderate correlation of CRQ dyspnea domain with the global rating of dyspnea (r=0.61) and CRQ fatigue domain with the global rating of emotions (r=0.53) b) Strong correlation of CRQ and SGRQ (r=0.72–0.88) c) Strong correlation of CRQ with BPQ (r=0.75)
Short Form-Chronic Respiratory Disease Questionnaire (SF-CRQ)	Good internal consistency reliability; Cronbach’s alpha =0.82	Significant convergent validity with dimension-specific instruments, such as the SAS and VAS for dyspnea
Clinical COPD Questionnaire (CCQ)	Excellent internal consistency reliability; Cronbach’s alpha =0.91 test–retest reliability: ICC =0.94	Discriminant validityc a) Significant differences in CCQ scores for healthy (ex) smokers and for patients with or at risk for COPD b) Significant differences in CCQ scores between different disease-severity stages of COPD Convergent validity: Significant correlations (P<0.01) between the CCQ total score and domains of the SF-36 (ρ=0.48–0.69) and the SGRQ (ρ=0.72) Divergent validity: CCQ scores and FEV1 %predicted correlated significantly in patients with COPD (stages I–III), with the highest correlation between the total score and FEV1 %predicted (ρ=−0.49: P<0.01)
Chronic obstructive pulmonary disease (COPD) Assessment Test (CAT)	Good internal consistency; Cronbach’s alpha =0.88 test–retest reliability: ICC =0.8	Correlates well with the SGRQ (across seven European countries r=0.84) and in the US (r=0.80)
Exacerbations of Chronic Pulmonary Disease Tool (EXACT-PRO)	Excellent internal consistency reliability; Pearson separation index =0.92 test–retest reliability: ICC =0.77	EXACT scores correlated with SGRQ-C (r=0.64; P<0.0001) and differentiated acute and stable patients (P<0.0001)
The Breathlessness Cough and Sputum Scale (BCSS)	Acceptable internal consistency reliability; Cronbach’s alpha =0.70 daily, 0.95–0.99 over time test–retest reliability: ICC =0.77–0.788	Correlations with pulmonary function (FEV %predicted) were −0.01 1 (ns) to −0.36 (P<0.001). Correlations with the SGRQ total and SF-36 Physical Functioning subscale were 0.44–0.59 (P<0.0001)
Baseline and Transition Dyspnea Indexes (BDI-TDI)	Good internal consistency reliability; Cronbach’s alpha =0.80 test–retest reliability: ICC =0.76	Baseline focal score had the highest correlation (r=0.60; P<0.001) with the 12-MWD and significant but lower correlations for lung function. For the transition focal score, there was a significant correlation with the 12-MWD (r=0.33; P=0.04)
Medical Research Council (MRC) Dyspnea Scale		Significant association between MRC grade and shuttle distance, SGRQ and CRQ scores, mood state and EADL. FEV1 was not associated with MRC grade.
McGill COPD Quality of Life Questionnaire	Internal consistency reliability; Cronbach’s alpha =0.68–0.82 test–retest reliability: ICC =0.74–0.96 for the subscales and 0.95 for the total score	Convergent validity (correlation with the SGRQ was moderately high, r=−0.88 [95% CI, −0.84 to 0.91])
The Visual Simplified Respiratory Questionnaire (VSRQ)	Good internal consistency reliability; Cronbach’s alpha =0.84 test–retest reliability: ICC =0.77	Good concurrent validity with SGRQ (Spearman’s coefficient =−0.70)
Exacerbations of COPD Respiratory Symptoms (E-RS)	Good internal consistency reliability: Cronbach’s alpha =0.88 test–retest reliability: ICC =0.90	Total scores correlated significantly (P<0.0001) with SGRQ: total (r=0.75), symptoms (r=0.66), activity (r=0.57), impact (r=0.70) scores; subscale correlations were also significant (r=0.26, P<0.05 [RS-Chest Symptoms with Activity] and r=0.69, P<0.0001 [E-RS-Cough and Sputum with Symptoms]). RS-Breathlessness correlated with rescue medication use (r=0.32, P<0.0001), clinician-reported mMRC (r=0.33, P<0.0001), and FEV1%predicted (r=−0.17, P<0.05)
Dyspnea-12	Good internal consistency reliability; Cronbach’s alpha =0.93 test–retest reliability: ICC =0.94	Its scores were significantly associated with MRC grade (r=0.59; P=0.001), SGRQ (symptoms, r=0.57; activities, r=0.78; impacts, r=0.75; total, r=0.79; P<0.001)
Dyspnea Management Questionnaire Computer Adaptive Test (DMQ-CAT)	Good internal consistency reliability; Cronbach’s alpha =0.92–0.98 test–retest reliability: ICC =0.58–0.82	Good to high concurrent validity with comparative questionnaires (UCSD, SOBQ, CRQ, CSES, and HADS) (r=−0.80 to −0.61)
Shortness of Breath with Daily Activities Questionnaire (SOBDA)	Good internal consistency reliability; Cronbach’s alpha =0.87 test–retest reliability: ICC =0.91	Convergent validity was demonstrated by moderate^f correlation with CRQ-SAS (0.60) and SGRQ-C (0.61)
Global Chest Symptoms Questionnaire (GCSQ)	Good to high reliability: Cronbach’s alpha =0.75–0.93	Validity was found to be significant P<0.001
Capacity of Daily Living during the Morning Questionnaire (CDLM)
Living with COPD (LCOPD)	Good and high reliability; Cronbach’s alpha =0.92 test–retest reliability was also 0.83	Convergent validity was demonstrated by moderate correlations with SGRQ (Symptoms) 0.66; SGRQ (Activity) 0.79; and SGRQ (Impact) 0.85 All the values were found to be significant P=0.01

Notes:

a Characterization of Cronbach’s alpha: α≥0.9= excellent; 0.9>α≥0.8= good; 0.8>α≥ 0.7= acceptable; 0.7>α≥0.6= questionable; 0.6>α≥0.5= poor; 0.5>α= unacceptable.

b Characterization of Pearson correlation r: 0.9–1= very high, 0.7–0.9= high, 0.5–0.7= moderate, 0.3–0.5= low, and 0–0.3= little or no correlation.

c Spearman-rank correlation used to assess discriminant, convergent, and divergent validity.

Abbreviations: BPQ, Breathing Problems Questionnaire; CCQ, Clinical COPD Questionnaire; CI, confidence interval; CRQ, Chronic Respiratory Disease Questionnaire; CSES, COPD self-efficacy scale; EADL, Nottingham Extended Activity of Daily Living Questionnaire; FEV₁, forced expiratory volume in 1 second; HADS, Hospital Anxiety and Depression Score; ICC, intraclass coefficient correlation; MWD, minute walking distance; ns, not significant; PRO, patient-reported outcome; SAS, Symptom and Activity Scale; VAS, visual analog scale; UCSD SOBQ, University of California, San Diego Shortness of Breath Questionnaire.

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