Validation of the Spanish Activity Questionnaire in COPD (SAQ-COPD) in Patients with Chronic Obstructive Pulmonary Disease

Abstract

Purpose

The Spanish Activity Questionnaire in COPD (SAQ-COPD) is a short, simple physical activity (PA) measurement instrument for patients with chronic obstructive pulmonary disease (COPD). In this study, we analyzed its validity and sensitivity to change.

Methods

Prospective scale validation study. An accelerometer (DynaPort MoveMonitor^®) and the Yale Physical Activity Survey (YPAS) were used as reference standards. The analyses examined the criterion validity (Spearman correlations), internal consistency (Cronbach’s alpha), factorial structure, test-retest reliability (intraclass correlation coefficient, ICC), sensitivity to change and receiver operating characteristic (ROC) curve to classify patients with low PA.

Results

A total of 300 patients diagnosed with COPD were analyzed (73% males, mean age 66 ± 8 years, 40.3% with severe airflow limitation). Cronbach’s alpha was 0.60 and Spearman's correlations with accelerometer measurements of PA [number of steps, metabolic equivalents (MET), physical activity level (PAL)] and YPAS ranged from 0.37 to 0.53 (all p < 0.001). ICC was 0.69 (95% CI 0.61–0.74) and the area under the ROC curve to identify low PA was 0.65 (95% confidence interval: 0.58–0.73). Significant variations in SAQ-COPD scores were found between groups defined by YPAS for change.

Conclusion

The SAQ-COPD questionnaire is a valid instrument for classifying PA in patients with COPD. Correlations with other instruments provide criterion validity and also demonstrate good sensitivity to change.

Keywords:

• physical activity
• chronic obstructive pulmonary disease
• SAQ-COPD
• validity
• reliability

Acknowledgments

The authors are very grateful to all participating patients for making the validation study of the SAQ-COPD questionnaire possible. Medical writing support was provided by Isabel Caballero from Dynamic S.L.U. (Evidenze Clinical Research), funded by AstraZeneca Farmacéutica Spain, S.A.

Author Contributions

All authors made a significant contribution to the work reported, whether that is in the conception, study design, execution, acquisition of data, analysis and interpretation, or in all these areas; took part in drafting, revising or critically review the article; gave final approval of the version to be published; have agreed on the journal to which the article has been submitted; and all agree to be accountable for all aspects of the work.

Disclosure

JJ Soler-Cataluña reports receiving funding from GSK, consulting fees from Chiesi, GSK, and Bial, lecture fees from Bial, Chiesi, GSK, Meranini, Boehringer, and AstraZeneca, and attendance at meetings from Chiesi, Boehringer Novartis, and Menarini. L Puente Maestu reports financial support for educational activities from GSK, Chiesi, and lecture fees from Esteve, Novartis, Boehringer, and Sanofi, research grants from Grifols, honoraria for advisory board participation, and committed support in the form of a Menarini grant. M Román Rodríguez reports grants from Astra Zeneca, during the conduct of the study; grants or personal fees from Astra Zeneca, GSK, Boehringer Ingelheim, Cipla, Teva, and Menarini, outside the submitted work. C Esteban, J Gea, R Bernabeu Mora, J Ancochea and E. Pleguezuelos Cobo declare that they have no conflicts of interest. F García-Río reports funding for his institution from GSK, Menarini, Chiesi, lecture fees from Novartis, Chiesi, Esteve, Gebro Pharma, Teva, and fees for advisory board participation from AstraZeneca, Pfizer, Rovi, GSK and Boehringer.

Additional information

Funding

This study was funded by AstraZeneca Farmacéutica Spain, S.A.