Pulmonary functions test in asymptomatic rheumatoid lung disease patients: a hospital-based study

Abstract

Abstract Background As a common extra-articular symptom of rheumatoid arthritis (RA), pulmonary involvement affects 20–67% of patients and accounts for 10–20% of RA-related deaths. This study aimed to assess the impact of RA on pulmonary function tests (PFTs) in Sudanese RA patients attending the rheumatology clinics of the Omdurman Military Hospital. Methods This was an analytical, cross-sectional, hospital-based study of 32 RA patients who met the 2010 Rheumatoid Arthritis Classification Criteria of the American College of Rheumatology (RA ACR/EULAR) and who were nonsmokers and free of known respiratory or chronic diseases. Pulmonary function parameters (PFTs), including forced vital capacity (FVC), forced expiratory volume in 1 s (FEV1), the FEV1/FVC ratio, and the peak expiratory flow rate (PEFR), were measured for each participant using a digital spirometer. A control group of Sudanese subjects of similar age, sex, and height was matched, and the results were compared with normal reference values. Results A high prevalence of lung function abnormalities (93.8%) was observed in RA patients, and 6.2% of them had normal PFT parameters. Restrictive lung disease was recorded in 78.1% of the patients, and obstructive lung disease was observed in 15.7% of the patients. All measured PFT parameters in the RA patients were significantly lower than the published reference normal values for Sudanese subjects, except for the FEV1/FVC ratio. The mean values of FEV1, FVC, the FEV1/FVC ratio, and the PRFR in RA patients were 1.8 ± 0.3 L/min, 2.1 ± 0.4 L/min, 87.1 ± 12.2%, and 223.6 ± 86.2 L/min, respectively, compared to 2.4 ± 0.1 L/min, 2.7 ± 0.1 L/min, 90.81 ± 2.6%, and 345.4 ± 16.2 L/min, respectively, in the control group (P values of 0.001, 0.001, 0.299, and 0.001, respectively). There was no statistically significant correlation between PFT results and disease duration, age, or BMI. Conclusions Regardless of the duration of RA, restrictive lung abnormalities are frequent in asymptomatic RA patients. The PFT can serve as an indicator of RA. Spirometry has been advised as a baseline examination and for follow-up and to promote the early detection and management of pulmonary involvement in RA patients.