Functional Assessment of Stable Chronic Obstructive Pulmonary Disease Patients Using Squat-to-stand Test

Chronic obstructive pulmonary disease (COPD) is a preventable and treatable disease of airflow limitation that is not fully reversible. COPD affects the lungs and produces significant systemic consequences. In Bangladesh, the prevalence of COPD after 40 years of age is 21.24% and the general population is 4.3%. COPD leads to a sedentary life, which reduces the functional status of the individual. Functional status assessment is vital for appropriate therapy and rehabilitation programs in COPD patients. A Sit-to-stand test (STST) has been proposed as a better alternative to 6MWT, but a Squat-to-stand test (SqTST) to test their ability to stand from the squatting position will be more appropriate in rural patients. This study was conducted using a cross-sectional observational design from July 2020 and September 2021 in the Department of Respiratory Medicine at the National Institute of Diseases of the Chest and Hospital, Bangladesh. Sixty (60) diagnosed cases of COPD patients were enrolled in this study. Severities of airflow obstruction according to GOLD were categorized on the basis of post-bronchodilator FEV₁ by spirometry. SqTST was performed on all patients, and functional status was recorded. All data were collected using a preformed questionnaire. Statistical analyses of the findings were carried out using SPSS version 23.0. In this study, the majority of 21(35.0%) patients had very severe COPD, and almost half (48.3%) of the patients had abnormal SqTST. A significant relation was found between the severity of COPD with SqTST (p=0.001). Based on the receiver-operator characteristic (ROC) curve, SqTST had an area under curve 0.901. SqTST had 82.1% sensitivity, 85.7% specificity, 83.3% accuracy, 91.4% positive predictive value, and 72.0% negative predictive value to find severe COPD cases in stable COPD patients. ROC was constructed using SqTST, which gave a cut-off value <7.0, with 82.1% sensitivity and 85.7% specificity for predicting severe COPD. From this study, it may be concluded that SqTST is a clinically useful tool to assess the functional status of stable COPD patients.