Discriminant Validity of a Single Clinical Question for the Screening of Inactivity in Individuals Living with COPD

Abstract

Introduction Quantifying physical activity in chronic obstructive pulmonary disease (COPD) with questionnaires and activity monitors in clinical practice is challenging. The aim of the present study was to analyse the discriminant validity of a single clinical question for the screening of inactive individuals living with COPD. Methods A multicentre study was carried out in stable COPD individuals both in primary and tertiary care. Patients wore the Dynaport accelerometer for 8 days and then answered 5 physical activity questions developed for the study, referring to the week in which their physical activity was monitored. Receiver operating characteristic (ROC) curve analysis with physical activity level (PAL) as the gold standard reference was used to determine the best cut-off point for each of the 5 clinical physical activity questions tested. Results A total of 86 COPD participants were analysed (males 68.6%; mean (SD) age 66.6 (8.5) years; FEV 1 50.9 (17.3)% predicted; mean of 7305 (3906) steps/day). Forty-two (48.8%) participants were considered physically inactive (PAL ≤1.69). Answers to 4 out of 5 questions significantly differed in active vs inactive patients. The Kappa index and ROC curves showed that the answer to the question “On average, how many minutes per day do you walk briskly?” had the best discriminative capacity for inactivity, with an area under the curve (AUC) (95% Confidence interval (CI)) of 0.73 (0.63–0.84) and 30 min/day was identified as the best cut-off value (sensitivity (95% CI): 0.75 (0.60–0.87); specificity: 0.76 (0.61–0.88)). Conclusion The present results indicate that self-reported brisk walk time lower than 30 min/day may be a valid tool for the screening of inactivity in individuals living with COPD in routine care, if more detailed physical activity measures are not feasible.

Motivation and Confidence about Physical Activity in Chronic Obstructive Pulmonary Disease Patients: Health Benefits Matter to Patients

“…The MIDIMAR study (daily minutes of walking, the acronym in Spanish of “MInutos DIarios de MARrcha,” as a useful measure of PA in patients with COPD), was a prospective, observational, multicentric study, the main objective of which was to identify and validate a single question that could be used for the screening of inactive COPD patients [12]. As a secondary objective, we assessed and described the different motivation, confidence, and social environment factors related to PA in COPD patients.…”

“…The methodology of the study has been published previously [12]. Briefly, we included consecutive patients older than 40 years with stable COPD from 10 Spanish centers to ensure geographical representation and a wide range of disease severity.…”