Response of the COPD Assessment Test to pulmonary rehabilitation in unselected chronic respiratory disease

Changes in Exercise Capacity and Health-Related Quality of Life at Four and Eight Weeks of a Pulmonary Rehabilitation Program in People with COPD

Pulmonary Rehabilitation (PR) is a key intervention in the management of people with chronic obstructive pulmonary disease (COPD), though few studies have assessed where changes in outcomes occur during a PR program. The aim of this study was to determine the changes in exercise capacity and health-related quality of life at four and eight weeks during a twice-weekly supervised PR program in people with COPD. Fifty participants with COPD were recruited and attended PR twice-weekly for eight weeks. The outcome measures were the endurance shuttle walk test (ESWT), six-minute walk distance (6MWD), St George's Respiratory Questionnaire (SGRQ), COPD Assessment Test (CAT) and the Hospital Anxiety and Depression Scale (HADS) which were measured at baseline, four and eight weeks. Compared to baseline, at week four there were significant improvements in ESWT (mean difference [95%CI] 197 [89 to 305] seconds), 6MWD (22 [8 to 36] metres), SGRQ symptom score (-6 [-12 to -1] points) and SGRQ total score (-4 [-7 to -1] points). Between week four and eight there were further significant improvements in ESWT (94 [8 to 181] seconds) only. By week eight, ESWT, 6MWD, SGRQ symptoms and total score, and CAT had all improved significantly compared to baseline measures. This study demonstrated that participants with moderate to very severe COPD who participated in a twice weekly, eight-week PR program (16 sessions) had significant improvement in ESWT, 6MWD, SGRQ, and CAT score with the greatest improvements occurring in the first four weeks of the program.Supplemental data for this article is available online at https://doi.org/10.1080/15412555.2021.2013793 .

Validation of the COPD Assessment Test (CAT) as an Outcome Measure in Bronchiectasis

BACKGROUND

Objective assessment of symptoms in bronchiectasis is important for research and in clinical practice. The COPD Assessment Test (CAT) is a short, simple assessment tool widely used in COPD. The items included in the CAT are not specific to COPD and also reflect the dominant symptoms of bronchiectasis. We therefore performed a study to validate the CAT as an outcome measure in bronchiectasis.

METHODS

The CAT was administered to two cohorts of bronchiectasis patients along with other quality of life questionnaires. Patients underwent comprehensive clinical assessment. One cohort had repeated questionnaires collected before-and-after treatment of acute exacerbations. We analyzed convergent validity, repeatability, and responsiveness of the score and calculated the minimum clinically important difference (MCID) using a combination of distribution and anchor-based methods.

RESULTS

In both cohorts there were positive correlations between the CAT and the St. George's Respiratory Questionnaire (r = 0.90, P < .0001 and r = 0.87, P < .0001). There was an inverse relationship between CAT and Quality of Life - Bronchiectasis Respiratory Symptoms Scale (r = -0.75, P < .0001) and Leicester Cough Questionnaire score (r = -0.77, P < .0001). Patients with more severe disease, based on the bronchiectasis severity index, had significantly higher CAT scores. CAT also correlated with FEV₁ % predicted and 6-min walk distance (6MWD). CAT increased significantly at exacerbation and fell at recovery. The intraclass correlation coefficient for two measurements four-weeks apart while clinically stable was 0.88 (95% CI, 0.73-0.95, P < .0001). An MCID of 4 was most consistent.

CONCLUSIONS

CAT is a valid, responsive symptom assessment tool in bronchiectasis. The MCID is estimated as 4 points.

The Effects of a Nurse-Led Education and Counseling Program on Dyspnea, Health Status, and Care Dependency in Patients With Chronic Obstructive Pulmonary Disease: A Feasibility Study

The aim of this feasibility study was to determine the effects of a nurse-led education and counseling program for chronic obstructive pulmonary disease (COPD-ECP) on dyspnea, health status, and care dependency in patients. A quasi-experimental, pre-posttest research design without a control group was performed on 30 COPD patients. The patients received an 8-week COPD-ECP via home visits during the first 4 weeks and via phone interviews in the subsequent 4 weeks. After completion of COPD-ECP and a 4-week break, a final follow-up was conducted at the end of 12th week. The Dyspnea-12, COPD Assessment Test (CAT), and Care Dependency Scale (CDS) scores were calculated during the first interview, and on the 4th, 8th, and 12th week of the study. The patients completed all sessions of COPD-ECP without side effects. There was a significant decrease in the total Dyspnea-12 scores at the end of the study period. Compared to the baseline assessment, CAT total scores significantly decreased in the 4th, 8th, and 12th week ( p < 0.05), and CDS scores showed a significant reduction at the 12th week ( p < 0.05). In conclusion, COPD-ECP is feasible in regular clinical practice and well accepted by patients, and it seems to improve health status and decrease dyspnea, and care dependency. Future randomized controlled studies are warranted to explore the effects of COPD-ECP on fatigue, cough and sleep problems, and the best innovative strategies to improve the efficiency of COPD-ECP.

Comparison of Compliance Rates and Treatment Efficiency in Home-Based with Hospital-Based Pulmonary Rehabilitation in COPD

OBJECTIVES

The aim of the present study was to compare the home-based pulmonary rehabilitation (PR) with the hospital-based PR with respect to exercise compliance rates and efficiency of therapy in stable chronic obstructive pulmonary disease (COPD).

MATERIALS AND METHODS

Patients with stable severe and very severe COPD who were admitted consequently to our PR clinic were prospectively included in the study. Patients who completed the home-based PR for at least 4 days/week for 2 months as recommended were classified as the study group. Patients who completed the hospital-based PR in our clinic before the present study were classified as the control group.

RESULTS

Thirty-five patients were included in the home-based PR, but 10 patients were incompatible with the exercise training, and four patients were out of follow-up. Twenty-one patients successfully completed the home-based PR (study group), and compliance rate was 60%. Thirty-seven patients previously underwent the hospital-based PR, and 25 patients completed the exercise program (control group); thus, their compliance rate was 67%. There was no difference between the two groups with respect to treatment compliance rates. The significant improvement in six-minute walking distance, modified Medical Research Council dyspnea, and COPD Assessment Test scores were observed after PR in both groups, and there was no difference with respect to the levels of improvement.

CONCLUSION

The present study showed that approximately two-thirds of patients with COPD successfully completed the home-based PR, and that this program also provided similar benefits with respect to the quality of life and exercise capacity compared with the hospital-based PR.

COPD Assessment Test in Bronchiectasis: Minimum Clinically Important Difference and Psychometric Validation: A Prospective Study

BACKGROUND

Health-related quality of life (QoL) is one of the most important end points in bronchiectasis (BE). However, the majority of health-related QoL questionnaires are time-consuming or not validated in BE. The COPD Assessment Test (CAT) is an easy-to-use questionnaire. The objective of this study was to perform a complete validation of the CAT in BE.

METHODS

This was an observational, multicenter, prospective study in patients with BE. Psychometric properties of the CAT were measured: internal consistency (Cronbach α), repeatability (test-retest; intraclass correlation coefficient), discriminant validity (correlation with severity scores), convergent validity (correlation with some validated QoL questionnaire and other clinical variables of interest), longitudinal validity (measuring before and after each exacerbation during follow-up to determine the sensitivity to change and responsiveness), predictive validity to future exacerbations, and finally minimum clinically important difference.

RESULTS

Ninety-six patients were included and followed up for 1 year. Their mean age was 62.2 (15.6) years (79.2% women). The CAT showed excellent internal consistency (α, 0.95) and repeatability (intraclass correlation coefficient, 0.95). The validity of the CAT was excellent in all the measures (almost all with a Pearson coefficient > 0.40) except for the correlations with severity scores (Pearson coefficient between 0.22 and 0.26). Sensitivity to change before and after exacerbations was set at between 5.4 and 5.8 points. A CAT value ≥ 10 points showed prognostic value for patients with more than one exacerbation, and finally the minimum clinically important difference was set at 3 points.

CONCLUSIONS

The CAT presented excellent psychometric properties and is a questionnaire that is easy to use and interpret in patients with BE.

Minimal clinically important difference of 3-minute chair rise test and the DIRECT questionnaire after pulmonary rehabilitation in COPD patients

BACKGROUND

The 3-minute chair rise test (3-minute CRT) and the Disability Related to COPD Tool (DIRECT) are two reproducible and valid short tests that can assess the benefit of pulmonary rehabilitation (PR) in terms of functional capacity and dyspnea in everyday activities.

METHODS

We determined the minimal clinically important difference (MCID) of the DIRECT questionnaire and 3-minute CRT using distribution methods and anchor encroaches with a panel of eight standard tests in a cohort of 116 COPD patients who completed a PR program in real-life settings.

RESULTS

The estimated MCID for the 3-minute CRT and DIRECT scores was five repetitions and two units, respectively, using separate and combined independent anchors. The all-patient (body mass index-obstruction-dyspnea-exercise [BODE] scores 0-7), BODE 0-2 (n=42), and BODE 3-4 (n=50) groups showed improvements greater than the MCID in most tests and questionnaires used. In contrast, the BODE 5-7 group (n=24) showed improvements greater than MCID in only the 3-minute CRT, 6-minute walk test, endurance exercise test, and DIRECT questionnaire.

DISCUSSION AND CONCLUSION

This study demonstrates that the short and simple DIRECT questionnaire and 3-minute CRT are responsive to capture the beneficial effects of a PR program in COPD patients, including those with severe disease.

TRIAL REGISTRATION NUMBER

NCT03286660.

Web-based Health Information Seeking and eHealth Literacy among Patients Living with Chronic Obstructive Pulmonary Disease (COPD)

Many people living with Chronic Obstructive Pulmonary Disease (COPD) have low general health literacy; however, there is little information available on these patients' eHealth literacy, or their ability to seek, find, understand, and appraise online health information and apply this knowledge to address or solve disease-related health concerns. A nationally representative sample of patients registered in the COPD Foundation's National Research Registry (N = 1,270) was invited to complete a web-based survey to assess socio-demographic (age, gender, marital status, education), health status (generic and lung-specific health-related quality of life), and socio-cognitive (social support, self-efficacy, COPD knowledge) predictors of eHealth literacy, measured using the 8-item eHealth literacy scale (eHEALS). Over 50% of the respondents (n = 176) were female (n = 89), with a mean age of 66.19 (SD = 9.47). Overall, participants reported moderate levels of eHealth literacy, with more than 70% feeling confident in their ability to find helpful health resources on the Internet. However, respondents were much less confident in their ability to distinguish between high- and low-quality sources of web-based health information. Very severe versus less severe COPD (β = 4.15), lower lung-specific health-related quality of life (β = -0.19), and greater COPD knowledge (β = 0.62) were significantly associated with higher eHealth literacy. Higher COPD knowledge was also significantly associated with greater knowledge (ρ = 0.24, p = .001) and use (ρ = 0.24, p = .001) of web-based health resources. Findings emphasize the importance of integrating skill-building activities into comprehensive patient education programs that enable patients with severe cases of COPD to identify high-quality sources of web-based health information. Additional research is needed to understand how new social technologies can be used to help medically underserved COPD patients benefit from web-based self-management support resources.

COPD Assessment Test (CAT) is a Valid and Simple Tool to Measure the Impact of Bronchiectasis on Affected Patients

The COPD assessment test (CAT) is a short questionnaire developed to help patients and clinicians to assess the impact of symptoms in routine clinical practice. We aimed to validate and to test the reproducibility of CAT in patients with bronchiectasis and correlate with the severity of dyspnea, aerobic and functional capacity, and physical activity in daily life. This is a cross-sectional study, patients with bronchiectasis underwent spirometry, cardiopulmonary exercise test (CPET), incremental shuttle walk test (ISWT), Saint George`s Respiratory Questionnaire (SGRQ), and received pedometer. CAT was applied twice (CAT-1 and CAT-2, 7 to 10 days apart). The severity of bronchiectasis was assessed by E-FACED and bronchiectasis severity index (BSI). A total of 100 patients were evaluated (48 ± 14 years, 59 women, FVC: 67 ± 22% pred, FEV₁: 52 ± 25% pred). According to CAT, 14% patients presented low, 40% medium, 32% high, and 14% very high impact. The higher the CAT, the worse the severity of bronchiectasis, dyspnea, quality of life, performance on the CPET, and smaller the distance walked (DW) on the ISWT and number of steps (NS) per day. There was significant correlation between CAT and SGRQ, E-FACED, BSI, NS, ISWT, oxygen uptake, and workload at CPET. CAT-1 and CAT-2 presented similar values: 21 (13-26) and 19 (13-26), respectively. The CAT is a valid and reproducible instrument in patients with bronchiectasis presenting good correlation with clinical, functional, and quality of life measurements. This easy-to-use, easy-to-understand, quick, and useful tool may play an important role to assess the impact of bronchiectasis on both daily medical practice and clinical trial settings.

Contribution of individual COPD assessment test (CAT) items to CAT total score and effects of pulmonary rehabilitation on CAT scores

BACKGROUND

The COPD Assessment Test (CAT) contains eight items (cough, phlegm, chest tightness, breathlessness, limited activities, confidence leaving home, sleeplessness and energy). The current study aimed 1) to better understand the impact of the respiratory and non-respiratory CAT item scores on the CAT total score; and 2) to determine the impact of pulmonary rehabilitation (PR) on CAT items and CAT total score.

METHODS

CAT total score of ≥10 or ≥ 18 points was used to classify patients as highly symptomatic, a decrease of 2 points was considered as clinically relevant improvement. 'Cough', 'phlegm', 'chest tightness', 'breathlessness' were defined as respiratory items; ≥3 points on each item was defined as highly symptomatic.

RESULTS

In total, 497 clinically stable patients (55% male, age 64.0 (57.5-71.0) years, FEV1 46.0 (32.0-63.0)% predicted, CAT total score 22.0 (17.5-26.0) points) were included. 95% had CAT score ≥ 10 points and 75% ≥18 points. Respectively, 45% and 54% of subjects scored high on 3 or 4 of the respiratory CAT items. Following PR, 220 patients (57.7%) reported an improved health status as assessed by CAT total score (- 3.0 (- 7.0-1.0) points). Change in CAT item scores ranged from 0.0 (- 1.0-0.0) to - 1.0 (- 2.0-0.0) points) with best improvements in 'energy' (- 1.0 (- 2.0-0.0)points).

CONCLUSIONS

A substantial number of patients classified as highly symptomatic did not report a high level of respiratory symptoms, indicating that non-respiratory symptoms impact on disease classification and treatment algorithm. The impact of PR on CAT item scores varied by individual item.

TRIAL REGISTRATION

Netherlands National Trial Register ( NTR3416 ). Registered 2 May 2012.

COPD assessment test as a possible tool for evaluating health-related quality of life in lymphangioleiomyomatosis

BACKGROUND

Lymphangioleiomyomatosis (LAM) is a progressive, cystic lung disease that causes an obstructive ventilatory impairment similar to chronic obstructive pulmonary disease (COPD) and impairs the health-related quality of life (HRQoL). Here, we extended the use of the COPD assessment test (CAT) to patients with chronic respiratory diseases other than COPD. Specifically, the CAT was administered to patients with LAM for the first time.

METHODS

Using data from 25 patients with LAM at Juntendo University who participated in the Multicenter Lymphangioleiomyomatosis Sirolimus Trial for Safety (MLSTS), we evaluated changes in pulmonary function, responses to HRQoL questionnaires (the CAT, St. George׳s Respiratory Questionnaire [SGRQ], EuroQOL Visual Analogue Scale [EuroQOL-VAS], and Functional Performance Inventory [FPI]), and the association between pulmonary function and HRQoL during a 24-month period of sirolimus treatment.

RESULTS

Forced expiratory volume in one second (FEV₁), forced vital capacity (FVC), and CAT total scores improved over the 24 months of sirolimus treatment (5.33 ± 1.20 ml/month, 2.61 ± 1.16 ml/month, and -0.127 ± 0.022 score/month, respectively), whereas SGRQ total score, EuroQOL-VAS score, and FPI score did not. Most pulmonary functions at baseline were associated with the CAT breathlessness score during the first year. Longitudinal changes in FEV₁, FEV_1%predicted, or FEV₁/FVC correlated significantly with the scores of CAT total, CAT breathlessness, and SGRQ activity. When analyzed by stepwise multivariate regression within a linear mixed-effects model, CAT breathlessness and confidence scores were significantly associated with a change in FEV₁ from the baseline value (P = 0.0011, and P = 0.0441).

CONCLUSION

Our results suggest that the CAT is a useful instrument for assessing HRQoL in sirolimus-treated patients with LAM.

Does the COPD assessment test reflect functional status in patients with COPD?

The aim of this study was to investigate whether the chronic obstructive pulmonary disease (COPD) assessment test (CAT) reflects the functional status of patients with COPD. Forty-seven patients underwent anthropometric assessment, spirometry, the 6-minute walk test (6MWT), the Glittre-activity of daily living (ADL) test (TGlittre), the London Chest ADL (LCADL) scale, and the CAT. The total score of the CAT correlated with 6MWT distance, TGlittre time spent, and LCADL_%total ( r = -0.56, 0.52, and 0.78, respectively; p < 0.05 for all). There was significant difference in 6MWT distance (490 ± 85.4 m vs. 387 ± 56.8 m), TGlittre time spent (3.67 ± 1.07 min vs. 5.03 ± 1.32 min), and LCADL_%total (24.2 ± 3.02% vs. 44.4 ± 13.3%) between the low and high impacts of COPD on health status (respectively, p < 0.05 for all) as well as in the LCADL_%total between medium and high impact of COPD on health status (31.3 ± 7.35% vs. 44.4 ± 13.3%; p = 0.001). In conclusion, the CAT reflects the functional status of patients with COPD.

Effectiveness of the Assessment of Burden of COPD (ABC) tool on health-related quality of life in patients with COPD: a cluster randomised controlled trial in primary and hospital care

OBJECTIVE

Assessing the effectiveness of the Assessment of Burden of COPD (ABC) tool on disease-specific quality of life in patients with chronic obstructive pulmonary disease (COPD) measured with the St. George's Respiratory Questionnaire (SGRQ), compared with usual care.

METHODS

A pragmatic cluster randomised controlled trial, in 39 Dutch primary care practices and 17 hospitals, with 357 patients with COPD (postbronchodilator FEV1/FVC ratio <0.7) aged ≥40 years, who could understand and read the Dutch language. Healthcare providers were randomly assigned to the intervention or control group. The intervention group applied the ABC tool, which consists of a short validated questionnaire assessing the experienced burden of COPD, objective COPD parameter (eg, lung function) and a treatment algorithm including a visual display and treatment advice. The control group provided usual care. Researchers were blinded to group allocation during analyses. Primary outcome was the number of patients with a clinically relevant improvement in SGRQ score between baseline and 18-month follow-up. Secondary outcomes were the COPD Assessment Test (CAT) and the Patient Assessment of Chronic Illness Care (PACIC; a measurement of perceived quality of care).

RESULTS

At 18-month follow-up, 34% of the 146 patients from 27 healthcare providers in the intervention group showed a clinically relevant improvement in the SGRQ, compared with 22% of the 148 patients from 29 healthcare providers in the control group (OR 1.85, 95% CI 1.08 to 3.16). No difference was found on the CAT (-0.26 points (scores ranging from 0 to 40); 95% CI -1.52 to 0.99). The PACIC showed a higher improvement in the intervention group (0.32 points (scores ranging from 1 to 5); 95% CI 0.14 to 0.50).

CONCLUSIONS

This study showed that use of the ABC tool may increase quality of life and perceived quality of care.

TRIAL REGISTRATION NUMBER

NTR3788; Results.

Assessment of pulmonary rehabilitation efficacy in chronic obstructive pulmonary disease patients using the chronic obstructive pulmonary disease assessment test

AIM

We evaluated the relationship between chronic obstructive pulmonary disease (COPD) assessment test (CAT) and improvements after pulmonary rehabilitation (PR) and PR efficiency in COPD patients.

METHODS & RESULTS

Forty COPD patients completed PR. After PR, mean change in CAT score was found to be 13 (p < 0.001), Medical Research Council (MRC), St George's Respiratory Questionnaire (SRGQ) and London Chest Activity Daily Living (LCADL) scores decreased, while Endurance Shuttle Walking Test (ESWT) time and Incremental Shuttle Walking Test (ISWT) distance increased significantly. Baseline CAT scores correlated with MRC, SRGQtotal, %FVC, ISWT, ESWT, LCADL. Change in CAT was significantly correlated with changes in MRC, SGRQtotal, LCADL-leisure scores, and ESWT.

CONCLUSION

CAT score shows moderate degree correlation with some measures of outcome of PR and response to PR efficacy.

An evaluation of factors associated with completion and benefit from pulmonary rehabilitation in COPD

BACKGROUND

Pulmonary Rehabilitation (PR) is an important treatment for patients with chronic obstructive pulmonary disease (COPD) but it is not established whether any baseline parameter can predict response or compliance.

AIM

To identify whether baseline measures can predict who will complete the programme and who will achieve a clinically significant benefit from a Minimum Clinical Important Difference (MCID) in terms of exercise capacity and health-related quality of life (HRQoL).

METHODS

Data were collected prospectively from patients with COPD at their baseline assessment for an outpatient PR programme in one of eight centres across London. 'Completion' was defined as attending at least 75% of the designated PR visits and return for the follow-up evaluation. The MCID for outcome measures was based on published data.

RESULTS

787 outpatients with COPD (68.1±10.5 years old; 49.6% males) were included. Patients who completed PR (n=449, 57.1%) were significantly older with less severe airflow obstruction, lower anxiety and depression scores, less dyspnoea and better HRQoL. Only baseline CAT score (OR=0.925; 95% CI 0.879 to 0.974; p=0.003) was retained in multivariate analysis. Patients with the lowest baseline walking distance were most likely to achieve the MCID for exercise capacity. No baseline variable could independently predict achievement of an MCID in HRQoL.

CONCLUSIONS

Patients with better HRQoL are more likely to complete PR while worse baseline exercise performance makes the achievement of a positive MCID in exercise capacity more likely. However, no baseline parameter could predict who would benefit the most in terms of HRQoL.

Clinical COPD Questionnaire in patients with chronic respiratory disease

BACKGROUND AND OBJECTIVE

The Clinical Chronic Obstructive Pulmonary Disease (COPD) Questionnaire (CCQ) is an easy to complete, health-related quality of life questionnaire which has been well-validated in COPD. The responsiveness of the CCQ in chronic respiratory disease patients other than COPD has not been previously described. The study aims were to determine if the CCQ in chronic respiratory disease correlates with other health related quality of life questionnaires, to assess the responsiveness of the CCQ to pulmonary rehabilitation and to determine the minimum important difference.

METHODS

The CCQ, COPD Assessment Test (CAT), the Chronic Respiratory Questionnaire (CRQ) and St George's Respiratory Questionnaire (SGRQ) were measured in 138 chronic respiratory disease patients completing pulmonary rehabilitation. Change in CCQ with pulmonary rehabilitation was correlated with change in the other questionnaires. The minimum important difference of the CCQ was calculated using distribution and anchor-based approaches.

RESULTS

The CCQ, CAT, CRQ and SGRQ improved significantly with rehabilitation with effect sizes of -0.43, -0.26, 0.62, -0.37. Change in CCQ correlated significantly with CAT, CRQ and SGRQ (r = 0.53, -0.64, 0.30, all P < 0.0001). The minimum important difference was -0.42 at the population level and -0.4 at the individual level.

CONCLUSIONS

The CCQ is responsive to pulmonary rehabilitation in chronic respiratory disease patients, with an MID estimated at -0.4 at the individual level.

The COPD assessment test: a systematic review

The COPD assessment test (CAT) is a self-administered questionnaire that measures health-related quality of life. We aimed to systematically evaluate the literature for reliability, validity, responsiveness and minimum clinically important difference (MCID) of the CAT. Multiple databases were searched for studies analysing the psychometric properties of the CAT in adults with chronic obstructive pulmonary disease. Two reviewers independently screened, selected and extracted data, and assessed methodological quality of relevant studies using the COSMIN checklist. From 792 records identified, 36 studies were included. The number of participants ranged from 45 to 6469, mean age from 56 to 73 years, and mean forced expiratory volume in 1 s from 39% to 98% predicted. Internal consistency (reliability) was 0.85-0.98, and test-retest reliability was 0.80-0.96. Convergent and longitudinal validity using Pearson's correlation coefficient were: SGRQ-C 0.69-0.82 and 0.63, CCQ 0.68-0.78 and 0.60, and mMRC 0.29-0.61 and 0.20, respectively. Scores differed with GOLD stages, exacerbation and mMRC grades. Mean scores decreased with pulmonary rehabilitation (2.2-3 units) and increased at exacerbation onset (4.7 units). Only one study with adequate methodology reported an MCID of 2 units and 3.3-3.8 units using the anchor-based approach and distribution-based approach, respectively. Most studies had fair methodological quality. We conclude that the studies support the reliability and validity of the CAT and that the tool is responsive to interventions, although the MCID remains debatable.

COPD assessment test: a simple tool to evaluate disease severity and response to treatment

The COPD assessment test (CAT) is a short questionnaire designed to assess the impairment in health status of COPD patients. We aimed to determine the change of the CAT in COPD patients after 1 year of treatment and test the association between the score and clinical and lung function variables. Methods A cohort of 111 newly diagnosed COPD patients in primary care was evaluated at baseline and one year after the implementation of the recommended treatment according to the Global Initiative for the management of COPD (GOLD). Results Most of the patients (82%) were diagnosed with mild to moderate airflow limitation (mean FEV1 72 ± 21.5% predicted) and the CAT score increased in proportion with the GOLD stage of severity. The CAT significantly correlated with the number of exacerbations, visits to general practitioners and days of hospitalization both at the beginning and at 1 year follow-up. A strong negative correlation between the CAT score and FEV1 predicted was also observed. The CAT was responsive to the application of treatment with a significant improvement in the mean score (95% confidence interval) following 12 months of treatment by -2.4 (-2.9, -1.9) despite the small decline in lung function indices. The number of exacerbations in the preceding year and FEV1 were independent predictors of the CAT score in the general linear model. Conclusion The CAT questionnaire may serve as a simple, measurable tool complementary to spirometry in the assessment of severity and of response to treatment in unselected COPD patients in primary care.

Minimum clinically important difference for the COPD Assessment Test: a prospective analysis

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.

The Clinical COPD Questionnaire: response to pulmonary rehabilitation and minimal clinically important difference

BACKGROUND

The Clinical COPD Questionnaire (CCQ) is a simple 10-item, health-related quality of life questionnaire (HRQoL) with good psychometric properties. However, little data exists regarding the responsiveness of the CCQ to pulmonary rehabilitation (PR) or the minimal clinically important difference (MCID). The study aims were to assess the responsiveness of the CCQ to PR, to compare the responsiveness of the CCQ to other HRQoL questionnaires and to provide estimates for the MCID.

METHODS

The CCQ, St George's Respiratory Questionnaire (SGRQ), Chronic Respiratory Questionnaire (CRQ) and COPD Assessment Test (CAT) were measured in 261 patients with COPD before and after outpatient PR. Pre to post PR changes and Cohen's effect size were calculated. Changes in CCQ were compared with changes in other HRQoL questionnaires. Using an anchor-based approach and receiver operating characteristic (ROC) curves, the CCQ change cutoffs that identified patients achieving the known MCID for other health status questionnaires with PR were identified.

RESULTS

The CCQ, SGRQ, CRQ and CAT all significantly improved with PR with an effect size of -0.39, -0.33, 0.62 and -0.25, respectively. CCQ change correlated significantly with change in SGRQ, CRQ and CAT (r=0.48, -0.56, 0.54, respectively; all p<0.001). ROC curves consistently identified a CCQ change cutoff of -0.4 as the best discriminating value to identify the MCID for the SGRQ, CRQ and CAT (area under curve: 0.71, 0.75 and 0.77, respectively; all p<0.001).

CONCLUSIONS

The CCQ is responsive to PR with an estimated clinically important improvement of -0.4 points. The CCQ is a practical alternative to more time-consuming measures of HRQoL.