A Study of Pulmonary Function Tests in Patients with Rheumatoid Arthritis and its Association with Disease Activity.

Unlabelled: Rheumatoid arthritis is a chronic inflammatory disease of unknown etiology marked by a symmetrical peripheral polyarthritis. Because it is a systemic disease RA may result in a variety of extra articular manifestations, Pulmonary involvement is a well known extra-articular manifestation of RA which can have myriad presentations and might be the second cause of death after infection. Pulmonary function test(PFTs) are widely used to provide objective measure of lung function for detecting and quantifying impairment of pulmonary function in patients with cardiopulmonary diseases. Although lung disease secondary to pulmonary infection and/or drug toxicity are frequent complications, lung disease directly associated with the underlying RA is more common. Lung involvement in RA carries a worse prognosis. The early recognition of changes in PFT may be used as early marker of pulmonary involvement and help in limiting the mortality and morbidity caused by the disease. Hence need for the study.

Material: Descriptive cross sectional study conducted on 100 cases.

Inclusion Criteria: Patients Aged 18-60 years diagnosed with RA according to American college of Rheumatology-European league against rheumatism classification criteria.

Exclusion Criteria: Known smokers, Presence of prior pulmonary disease, Known case of other Collagen vascular diseases and History of pulmonary infection in the last 3 months. Disease activity assessed by both DAS28 and CDAI score.

Observation: Mean age of cases was 43.57 years with 21% males and 79% females. 96% cases had normal FEV1/ FVC ratio with mean DAS28 of 5.12±0.8 and 4% cases had mild obstruction with mean DAS28 in mild restriction being 6.2±0.588. There was statistically significant difference in DAS28 in cases having mild restriction compared to normal cases (P-value=0.0066). Here, we also found that as severity of restrictive pattern increases there was no significant effect on DAS score (P-value=0.3221). But duration of disease and duration of methotrexate use increases as severity of restrictive pattern increases (P-value <0.0001).

Conclusion: we conclude from our study that there was predominant prevalence of restrictive pattern of PFT in the patients with RA, pulmonary involvement had significant association with duration of disease and duration of methotrexate use, on the contrary disease activity does not have much influence on pulmonary involvement in the diseased individual. Hence PFT alone can't be used as lone modality for early detection of pulmonary involvement in rheumatoid arthritis, additional implementation of DLCO along with spirometry can be tried to assess early involvement of respiratory membrane.