Squat-to-stand test in functional assessment of stable chronic obstructive pulmonary disease patients

Background: Assessment of functional status is vital for proper therapy and rehabilitation programs in chronic obstructive pulmonary disease (COPD) patients. Traditionally, 6 min walk test (6MWT) has been used but it by itself may not reflect the total functional status in these patients as it poorly correlates to the disease severity. A sit-to-stand test (STST) has been proposed as a better alternative to 6MWT but to test their ability to stand from the squatting position, i.e., a squat-to-stand test (SqTST) will be more appropriate in rural patients. Material and Methods: All patients, diagnosed to have stable COPD, after exclusion of asthma and other respiratory or nonrespiratory diseases were evaluated by applying 6MWT, STST, and SqTST in them. Data so obtained were statistically analyzed. Results: Ninety patients and twenty healthy controls were studied. Sixteen, 24, 23, and 27 of the patients were classed as COPD risk category A, B, C, and D, respectively. The mean post bronchodilator forced expiratory volume in 1 st second (PB FEV1) and body mass index (BMI) were significantly lower in category D as compared to the rest. The cutoff values for 6MWT, STST, and SqTST were derived as 184M, 11, and 07, respectively. 6MWT correlates poorly to disease severity ( P = 0.109) but there was a strong correlation between disease severity and SqTST and STST ( P = 0.000). Conclusion: SqTST is a feasible and effective tool to assess functional status of COPD patients residing in rural areas. BMI is an important surrogate marker of the functional status in these patients.