Background The novel coronavirus infection is widespread in the world, resulting in more pneumoconiosis patients complicated with coronavirus disease 2019 (COVID-19).

Objective To understand the clinical characteristics and prognosis of hospitalized COVID-19 patients complicated with or without pneumoconiosis.

Methods A total of 36 COVID-19 patients admitted to the Shandong Provincial Occupational Disease Hospital from 10 December to 31 December 2022 were selected, including 21 cases in the complication group (pneumoconiosis complicated with COVID-19) and 15 cases in the COVID-19 group without pneumoconiosis. Symptoms, signs, laboratory test results(e.g. routine blood test), imaging findings, treatment plans and prognosis of the two groups were observed and compared.

Results Regarding symptoms and signs in the complication group and the COVID-19 group, the proportions of dyspnea (57.14% vs 0.00%), lung wheezing (28.57% vs 0.00%), wet rales (76.19% vs 33.30%), and fever (61.90% vs 93.33%) were significantly different (P<0.05). Compared with the COVID-19 group, the level of D-dimer in the complication group was significantly increased 2.340 (1.0, 6.5) mg·L⁻¹ vs 0.250 (0.2, 0.4) mg·L⁻¹ (P<0.01), the serum sodium level was decreased (138.10±2.68) mmol·L⁻¹ vs (140.47±2.27) mmol·L⁻¹ (P<0.05). In terms of drug treatment and prognosis, there were statistically significant differences in the proportion of antiviral drugs (19.00% vs 80.00%), glucocorticoids (38.10% vs 80.00%), and anticoagulants (28.60% vs 0.00%) between the complication group and the COVID-19 group (P<0.05). Compared with the COVID-19 group, the cure rate of the complication group (90.50% vs 100.00%) showed no statistical difference. However, there were 2 deaths in the complication group.

Conclusion Patients with pneumoconiosis complicated with COVID-19 have less fever and more dyspnea, wheezing, and wet rales. The increase of plasma D-dimer is a potential predictor in patients with pneumoconiosis complicated with COVID-19.