Correlation of spirometry findings and post-six-minute walk test oxygen desaturation in chronic simple silicosis patients with age, duration of silica exposure, smoking pack years, occupation and mean pulmonary artery pressure

Silicosis is associated with preventable but irreversible lung damage. Early quantifiable assessment of silicosis workers would promote early interventional steps to reduce health deterioration. The objectives of this study were to correlate spirometry findings and post-six-minute walk test oxygen desaturation (post-6MWT OD) in chronic simple silicosis with age, duration of silica exposure (DSE), smoking pack years (SPY), occupation, and mean pulmonary artery pressure. Based on occupational exposure to silica and radiologic confirmation of chronic simple silicosis, 104 patients (all males) were enrolled and grouped based on SPY (nil, 1-10, 11-20, and >20) and occupation (drillers and dressers). They were further investigated with spirometry, post-6MWT OD, and transthoracic echocardiography (TTE), and findings were statistically analyzed. Abnormal spirometry findings were seen in 62.5% of total cases (65/104), with the highest percentage in the >20 SPY group (84%; 21/25) and drillers (68.3%; 28/41). The post-6MWT OD was seen in 50.96% of cases (53/104) with the highest percentage in the >20 SPY group (56%; 14/25) and drillers (63.4%; 26/41). Normal and restrictive patterns were predominant among <20 SPY groups, while obstructive and mixed patterns were prevalent in the >20 SPY group. Normal, obstructive, and restrictive patterns were predominant among dressers, while mixed patterns were in drillers. Mean age and mean DSE were higher for >20 SPY group and dressers; obstructive and mixed patterns; and patients with post-6MWT OD. Pulmonary hypertension was significantly associated with the presence of abnormal spirometry patterns (69.3%; 45/65) and post-6MWT OD (79.3%; 42/53). Mean forced expiratory volume in one second (FEV1)/forced vital capacity (FVC) was significantly lower for the >20 SPY group. Mean FEV1 had an inverse relation with SPY, and mean FVC was lower for drillers than dressers. Spirometry, post-6MWT OD, and TTE assessment give a complete overview of the cardiopulmonary exercise capacity of chronic silicosis patients and facilitate early interventions with special consideration for workers involved in machine-based mining activity.