Six-minute walk test among silicosis patients: Its correlation with abnormal radiographic findings on chest radiograph and high resolution computed tomography scan

Objectives Silicosis is one of the oldest chronic lung diseases that leads to relentless fibrotic changes in the lungs with a resultant fall in lung functions. This study was conducted to assess exercise capacity utilizing a six-minute walk test (6-MWT) among patients detected to have “simple” and “complicated” forms of silicosis. A further correlation between 6-MWT parameters and abnormal chest imaging findings was also done. Material and Methods Silicosis diagnosis among study subjects was based on the history of exposure to occupational silica dust along with suggestive radiological findings of pneumoconiosis assessed by the trained experts. Study subjects performed the 6-MWT as per standard protocol. Chest radiological and “high resolution computed tomographic” (HRCT) abnormalities were also analyzed in each subject and compared with their 6-MWT components (distance walked in meters and oxygen desaturation occurrence, if any). Results One hundred twelve study subjects (males 106 and females 6; mean age 44.05+10.84 years) constituted the final study population. The six-minute walk distance (6-MWD), fall in SpO 2 and BORG dyspnea scale in patients with grade “0” on chest X-ray was 362.79 ± 34.2 meter, 1.28 ± 0.91% and 0.96 ± 0.59, respectively and these parameters gradually converted with increasing International Labour Organization silicosis grading with 94.21 ± 29.4 meter, 7.11 ± 1.61% and 4.50 ± 0.93, respectively in grade “C.” A gradual change in 6-MWT parameters was also evident when compared with HRCT scan grading abnormalities. Conclusion Results of this study shows abnormally reduced lung function parameters among subjects with silicosis and it also correlates with degree of the profusion of nodules seen radiologically both on chest radiograph and HRCT.