Original Article
The Short-Form Chronic Respiratory Disease Questionnaire was a Valid, Reliable, and Responsive Quality-of-Life Instrument in Acute Exacerbations of Chronic Obstructive Pulmonary Disease

https://doi.org/10.1016/j.jclinepi.2007.07.003Get rights and content

Abstract

Objective

To assess the psychometric properties of the short-form chronic respiratory disease questionnaire (SF-CRQ) as a quality-of-life (QOL) instrument in chronic obstructive pulmonary disease (COPD) exacerbations.

Study Design and Setting

In a prospective multicenter cohort study, consecutive emergency department (ED) patients with COPD exacerbation were interviewed using the SF-CRQ and other instruments. Baseline information was collected in the ED and from follow-up data 2 weeks later. The results of the SF-CRQ were compared with the results of the other instruments and clinical variables by correlation and factor analyses.

Results

Of the 301 enrolled patients, 80% reported improvements across each of the domains of the SF-CRQ over the 2-week post-ED period. Overall median changes for the dyspnea, fatigue, emotional function, and mastery domains were 2, 1, 1, and 1.5, respectively (P < 0.001 for each domain). Correlation and factor analyses support their convergent/divergent validity and construct validity. The reliability for the change score of the SF-CRQ was high (Cronbach's α coefficient, 0.82). Overall minimal clinically important difference for improvement in the SF-CRQ was 1.01 (95% confidence interval, 0.72–1.31).

Conclusion

SF-CRQ is a valid, reliable, and responsive instrument for the assessment of short-term QOL change in patients with COPD exacerbations.

Introduction

The use of health-related quality-of-life (QOL) measures in chronic obstructive pulmonary disease (COPD) research has achieved widespread acceptance. Although several instruments have been developed to assess QOL in patients with COPD [1], these instruments were designed and validated for use in COPD patients during chronic management, rather than for use in patients with COPD exacerbation.

COPD exacerbations account for approximately 1.5 million emergency department (ED) visits in the United States each year [2]. COPD patients with frequent exacerbations have worse QOL and a more rapid decline in health status over 1–3 years [3], [4], [5]. Little is known, however, about the impact of acute exacerbation on short-term change in QOL in these patients. We are aware of only one study that has examined this issue using the chronic respiratory disease questionnaire (CRQ) [6]. CRQ is a COPD-specific QOL measure, consisting of 20 items divided into four domains (dyspnea, fatigue, emotional function, and mastery) [7]. In the original CRQ, patients are asked to personalize the dyspnea domain by choosing five frequently performed activities of daily living (e.g., walking on the flat; trying to sleep; doing the housework; and others), which are then rated according to a seven-point Likert scale ranging from 1 (“Extremely short of breath”) to 7 (“Not at all short of breath”). Although enhancing the validity of the CRQ, this aspect of the original CRQ added to the time required to use the tool and made comparisons between patients somewhat problematic. In addition, reducing the number of items in the CRQ will enhance efficiency in COPD patients where respondent burden is already high. A previous retrospective simulation study showed that reducing to two items per domain would maintain responsiveness and reliability of the CRQ, with a trade-off of reduced validity [8].

Based on these considerations, we developed a standardized eight-item short-form CRQ (SF-CRQ) in which the activities of “Walking on the flat” and “Sleeping” were chosen to assess the dyspnea domain. By minimizing respondent burden, we felt the SF-CRQ might serve as a simpler and more practical QOL instrument than the original CRQ in acute care settings. This study assessed the validity, reliability, and responsiveness of this novel QOL measure among patients presenting to the ED with COPD exacerbations.

Section snippets

Study design

This observational study combined data from two identical prospective cohort studies performed during 2000–2001 as part of the Multicenter Airway Research Collaboration, a division of the Emergency Medicine Network (EMNet, www.emnet-usa.org). The institutional review boards at each of the 29 participating hospitals approved the study, and informed consent was obtained from all participants.

Study setting and population

Details of design and data collection have been previously published [9]. In brief, using a standard

Results

During the study period, 584 patients presented to the ED with physician-diagnosed acute exacerbation of COPD (mixed asthma-COPD or COPD only). Of the 584 patients, 397 (68%) consented to the ED interview. Reasons for not having an ED interview included refusal of an ED interview by the patient, patients were missed by investigators, or others (e.g., imminent endotracheal intubation or altered sensorium). Among the 397 patients who consented to an ED interview, 349 (88%) underwent a follow-up

Discussion

This study has demonstrated that the SF-CRQ is a valid, reliable, and responsive instrument for the assessment of short-term QOL change in patients experiencing COPD exacerbations and correlates very well with patient's global ratings of sense of well being. In addition, the SF-CRQ is practical, simple, and easy to administer in these ED patients. The mean completion time for the original CRQ was reported to be 20 minutes, not including the time required for scoring [1], whereas the SF-CRQ took

Limitations

This study has some potential limitations. First, ideally, we should have performed measures of test-retest reliability in the patients with acute exacerbations. However, the presumption of the reliability study, “identical exacerbations” at two points in time, is very unlikely to hold. Performing measures of test-retest reliability in patients with stable COPD would be more feasible but would not be of direct interest to our intended study population, that is, patients with acute

Conclusions

In summary, this study has demonstrated that SF-CRQ is a valid, reliable, and responsive instrument for the assessment of short-term QOL change in patients with a COPD exacerbation. The SF-CRQ is practical, simple, and easy to administer and therefore is appropriate in studies on COPD patients where respondent burden is already high. It is possible that the validated SF-CRQ will encourage greater clinical use of COPD-specific QOL measure in studies on COPD exacerbations. This instrument may

Acknowledgments

The authors thank the EMNet investigators for their ongoing dedication to public health research, with an emphasis on the treatment and prevention of respiratory/allergy emergencies. We are indebted to E. Francis Cook, ScD, for his critical review on an early version of this manuscript.

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  • Cited by (0)

    The study was supported by an unrestricted grant from Boehringer Ingelheim (Ridgefield, CT). Dr. Hodder has received financial support (research grants, consulting, lectures) from AstraZeneca (Mississauga, ON), Boehringer Ingelheim (Montreal, PQ), and GlaxoSmithKline (Mississauga, ON). Dr. Rowe is supported by the Government of Canada through the 21st Century Research Chairs Program and has received financial support (research grants, consulting, lectures) from AstraZeneca (Mississauga, ON), Boehringer Ingelheim (Montreal, PQ), GlaxoSmithKline (Mississauga, ON), and Abbott Pharmaceuticals (Montreal, PQ). Dr. Camargo has received financial support (research grants, consulting, lectures) from AstraZeneca (Wilmington, DE), Boehringer Ingelheim (Ridgefield, CT), GlaxoSmithKline (Research Triangle Park, NC), Novartis (East Hanover, NJ), and Schering Plough (Kenilworth, NJ).

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