Physiological Cost Index of Walking among Non Smokers, Smokers and Smokers with Chronic Obstructive Pulmonary DiseaseAn Observational Study

Abstract

Introduction: Most of the Chronic Obstructive Pulmonary Disease (COPD) patients are smokers and their disease progresses with increasing age. The energy cost of walking has strong association with aging and cigarette smoking. Its implication in COPD remains unclear. Aim: To evaluate the Physiological Cost Index (PCI) of walking among non smokers, smokers and smokers with COPD and to find its association with age and duration of cigarette smoking. Materials and Methods: The cross-sectional study was carried out in the Department of Physical medicine and Rehabilitation (PMR) at Rajah Muthiah Medical College and Hospital, Annamalai University at Chidambaram, Tamil Nadu, India, from November 2019 to February 2020. The PCI was carried out in 77 males, aged between 50-75 years with body mass index between 18.5-24.9 kg/m2 . There were 24 smokers with COPD, 27 were smokers and 26 were non smokers. The evaluation of six minute walk distance, resting, and post walk heart rate was applied in MacGregor's equation to estimate the PCI. Results: The mean PCI of smokers with COPD was 0.67±0.3 which was significantly (p-value=0.001) higher than those of smokers (0.22±0.07) and non smokers (0.14±0.04). The smokers and non smokers had no significant variation in PCI (p-value=0.122). Age had no association with PCI (p-value=0.213) whereas the duration of smoking years was found to have significant association (p=0.014). Conclusion: The PCI was found to be significantly higher in smokers with COPD and a significant association was established with years of smoking rather than age.