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Sedentary Behavior in Patients With COPD Detected Using Novel Questionnaire


This new questionnaire could help physicians more easily detect sedentary behaviors among patients with chronic obstructive pulmonary disease (COPD), which standard questionnaires have had difficulty identifying.

A newly developed test, the Shortness of Breath in Daily Activities Questionnaire (SOBDA-Q), has the potential to accurately identify patients with chronic obstructive pulmonary disease (COPD) who are sedentary, according to a study published in the Journal of Clinical Medicine.

According to the researchers, shortness of breath (SOB) on exertion is a symptom that accompanies exercise intolerance and reduces physical activity in patients with COPD. Consequently, sedentary behavior is more prevalent in patients with COPD and can be a predictor of their mortality.

However, identifying this symptom in patients with COPD is difficult when using a standard questionnaire because they would tend to avoid the discomfort of feeling SOB on exertion and thus underreport their symptoms. As a result, the researchers created a new questionnaire better suited for spotting this behavior.

“We devised the [SOBDA-Q], which can detect detailed situations in which patients with COPD experience SOB in their daily lives,” the authors wrote. “Therefore, we hypothesized that the SOBDA-Q could be a useful tool for detecting sedentary behavior in patients with COPD.”

The researchers explained that the SOBDA-Q comprised “22 items organized into 6 domains of daily living (morning, dietary, indoor activity, recreation, and night-time activity).” The SOBDA-Q’s score was set using a scale with a minimum of 1 point and a maximum of 6 points; 1 point equated to a patient with COPD not performing the action because they feel short of breath and 6 points equated to them performing the activity without adjusting for shortness of breath. The researchers then calculated the average score for every domain. For activities that were not originally performed, researchers said they defined them as “no evaluation” and did not factor them into the average.

To test the accuracy of the SOBDA-Q, the researchers recruited 17 healthy patients and 47 patients with COPD treated at Yamaguchi University Hospital in Ube, Japan, between January 2017 and November 2020. The researchers defined healthy patients as those with no respiratory, cardiovascular, or musculoskeletal diseases interfering with their daily lives. On the other hand, patients with COPD were diagnosed per the Global Initiative for Chronic Obstructive Lung Disease (GOLD) guidelines and treated accordingly. The authors said those with COPD “were stable and had no exacerbations for at least 3 months before the study.”

The researchers had each participant wear an activity monitor with a triaxial acceleration sensor on their waist that recorded their physical activity continuously for 2 weeks. They collected values from weekdays without rain to obtain typical physical activity data.

“We measured their metabolic equivalent (MET) values and calculated the physical activity level (PAL) by multiplying the activity METs by the duration of the activity in hours (MET × h/day),” the authors wrote.

They added that they considered patients with PAL less than 1.5 METs per hour as those with sedentary behavior. For their patient-reported outcome measures, the researchers used the modified Medical Research Council (mMRC) dyspnea scale, COPD assessment test (CAT), and SOBDA-Q.

The researchers discovered that their study population was made up of 17 healthy patients, 32 nonsedentary patients with COPD, and 15 sedentary patients with COPD. Out of all patients with COPD, 43 were classified as GOLD stages 1 and 2 (91.5%). The researchers noted that patients with COPD were more likely to be male and older and have severe airflow limitation compared with healthy patients. Patients with COPD also had a higher CAT score, mMRC grade, and smoking status.

Sedentary patients with COPD performed activities requiring at least 2 METs for about half as long as nonsedentary patients with COPD per day, at 93.8 minutes vs 208.5 minutes (P < .0001). For activities requiring at least 3 or at least 4 METs, sedentary patients spent about a quarter of the time per day compared with their nonsedentary counterparts (both P < .0001).

Overall, the researchers found that CAT and all domains of the SOBDA-Q in all patients are significantly correlated with PAL. They determined that the dietary domain (eg, eating; meal preparation, cooking, and cleanup) had the highest specificity and the outdoor activity domain (eg, gardening, washing the car) had the highest sensitivity for detecting sedentary COPD. There were no sedentary patients with COPD who tested negative in both of these domains.

The authors used receiver operating characteristics (ROC) analysis to determine that the SOBDA-Q combination for predicting sedentary COPD had an area under the curve (AUC) of 0.829, a sensitivity of 1.00, and a specificity of 0.55. In comparison, the mMRC had an AUC of 0.641, a sensitivity of 0.67, and a specificity of 0.59, and the CAT had an AUC of 0.686, a sensitivity of 0.40, and a specificity of 0.92.

“We demonstrate that the newly devised SOBDA-Q significantly correlates with PAL,” the authors wrote. “Moreover, the combination of dietary- and outdoor activity–related SOB can accurately identify patients with sedentary COPD.”

The authors identified several limitations to the study that prevent the generalizability of results, including its small sample size and ratio of male to female participants. The authors explained that some studies reported that sex correlates to differences in breathlessness and other COPD symptoms that could have impacted the results. They added that the small sample size prevented multivariate analysis.

Another limitation was that the researchers only compared the SOBDA-Q as a questionnaire to the mMRC and CAT, meaning they could not further examine its differences from other questionnaires. Additionally, the researchers did not investigate the effect of SOBDA-Q in combination with CAT or mMRC.

“Further studies will be conducted to increase the sample size and examine the usefulness of combining the SOBDA-Q with other questionnaires,” the authors wrote.


Yamaji Y, Hirano T, Ogawa H, et al. Utility of the shortness of breath in daily activities questionnaire (SOBDA-Q) to detect sedentary behavior in patients with chronic obstructive pulmonary disease (COPD). J Clin Med. 2023;12:4105. doi.org:10.3390/jcm12124105

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