Comparison of Six-Minute Walk Test and Lung Function Test (Fev1%, Fvc%) in Patients with Interstitial Lung Disease and Connective Tissue Disorder

Abstract

Background:

Interstitial lung disease (ILD) associated with connective tissue disorders (CTD) represents a significant cause of morbidity and mortality due to progressive fibrosis and impaired gas exchange. While pulmonary function tests (PFTs) assess static lung mechanics, the six-minute walk test (6MWT) provides a practical measure of functional exercise capacity and exertional oxygen desaturation. An integrated evaluation of these parameters is essential for comprehensive assessment of CTD-ILD. This study aimed to evaluate and correlate the six-minute walk test (6MWT) with lung function parameters (FEV₁%, FVC%) in patients with ILD secondary to connective tissue disorders.

Materials and Methods:

This cross-sectional observational study was conducted in the Department of Respiratory Medicine at Sree BalajiMedical College and Hospital, Chennai, over a period of 18 months. A total of 30 patients aged 18–65 years with CTD-associated ILD (rheumatoid arthritis, systemic lupus erythematosus, systemic sclerosis, and Sjögren’ssyndrome) were included. All patients underwent clinical evaluation, autoantibody profiling, HRCT chest imaging, spirometry, and 6MWT as per standard guidelines. Data were analyzed using SPSS version 20, with p < 0.05 considered statistically significant.

Results:

The majority of patients were females (63.3%) and belonged to the 51–60 years age group. Rheumatoid arthritis was the most common underlying CTD (40%). Spirometry revealed a predominant restrictive pattern with mean FVC of 61.3 ± 12.8% and FEV₁ of 67.4 ± 13.2%. The mean six-minute walk distance (6MWD) was 362.8 ± 88.2 meters, with significant exertional desaturation (mean drop in SpO₂ of 4.7%). A statistically significant positive correlation was observed between 6MWD and FVC% (r = +0.56, p = 0.001) and FEV₁% (r = +0.48, p = 0.006). Increasing age and disease duration showed negative correlations with 6MWD. Multivariate analysis identified FVC% and post-test SpO₂ as significant positive predictors, while age and disease duration were negative predictors of functional capacity.

Conclusion:

The six-minute walk test is a valuable and practical tool for assessing functional impairment in CTD-associated ILD. It correlates significantly with lung function parameters, particularly FVC%, and provides additional insight into exercise limitation and gas exchange abnormalities. Combining spirometry with 6MWT enhances clinical evaluation and may aid in better disease monitoring and prognostication.