The Assessment of Burden of COPD (ABC) Scale: A Reliable and Valid Questionnaire

Abstract

The newly developed Assessment of Burden of COPD (ABC) scale is a 14-item self-administered questionnaire which measures the physical, psychological, emotional and/or social burden as experienced by patients with chronic obstructive pulmonary disease (COPD). The ABC scale is part of the ABC tool that visualises the outcomes of the questionnaire. The aim of this study was to assess the reliability and construct validity of the ABC scale. This multi-centre survey study was conducted in the practices of 19 general practitioners and 9 pulmonologists throughout the Netherlands. Next to the ABC scale, patients with COPD completed the Saint George Respiratory Questionnaire (SGRQ). Reliability analyses were performed with data from 162 cases. Cronbach's alpha was 0.91 for the total scale. Test-retest reliability, measured at a two week interval (n = 137), had an intra-class correlation coefficient of 0.92. Analyses for convergent validity were performed with data from 133 cases. Discriminant and known-groups validity was analysed with data from 162 cases. The ABC scale total score had a strong correlation with the total score of the SGRQ (r = 0.72, p < 0.001) but a weak correlation with the forced expired volume in 1 second predicted (r = -0.28, p < 0.001). Subgroups with more severe disease, defined by GOLD-stage, frequency of exacerbations, activity level and depression scored statistically significantly (p < 0.05) worse on almost all domains of the ABC scale than the less severe subgroups. The ABC scale seems a valid and reliable tool with good discriminative properties.

Keywords:

• burden of disease
• integrated health status
• reliability
• validity

Acknowledgments

Note: Trial Registration: Netherlands Trial Registration NTR3788.

The ABC tool was developed under the auspices of the Lung Alliance Netherlands (Dutch: Long Alliantie Nederland; LAN) and prepared by an expert team installed by the LAN. The initiative for the development of the instrument was taken by the PICASSO foundation for COPD.

Funding was made possible by the Foundation Steunfonds Long Alliantie Nederland, and unrestricted grants provided by the health insurance companies CZ trust and Zilveren Kruis Achmea. We would like to thank Mascha Twellaar, who provided assistance in gathering the data and preparing it for analyses.

Declaration of interest statement

The authors AHMS, TCHB, DK, JCCMi’tV, and NHC declare that they have no conflicts of interest in relation to this article. GMA is an employee of Boehringer Ingelheim. TvdM developed the CCQ and reports outside the submitted work he received grants, reimbursement for travel and fees for speaking and advisory boards from AstraZeneca, GlaxoSmithKline, Boehringer Ingelheim, Novartis, Teva and MSD.

HAMK reports outside the submitted work fees paid to his institution based on his contribution, from Boehringer Ingelheim and Pfizer for advisory board participation, lectures, and per patient recruited in trials; from GlaxoSmithKline for advisory board participation and per patient recruited in trials; from Novartis for advisory board participation, lectures, and a grant for investigator initiated trial; and from Almirall and Chiesi for advisory board participation. MPMHRM reports having received a personal fee from PICASSO for COPD for participating in the working group meetings to develop the ABC-tool. Erasmus University Rotterdam received research grants and contributions for organizing meeting on cost-effectiveness modeling in COPD from Boehringer Ingelheim, GSK, Novartis, Nycomed, and Pfizer. OCPS received several unrestricted institutional grants and fees from Pfizer, Boehringer Ingelheim and AstraZeneca.

The authors alone are responsible for the content and writing of the paper.

Appendix A. The Assessment Of Burden Of COPD (ABC) Scale

Table

Appendix B. Correlations between ABC scale, the SGRQ and FEV₁% predicted

Table