Study of Correlation of Six Minute Walk Test and Spirometry Severity of Chronic Obstructive Pulmonary Disease (COPD)

Abstract

Background: Chronic obstructive pulmonary disease (COPD) is associated with progressive airflow limitation and reduced exercise capacity. The six-minute walk test (6MWT) provides a simple assessment of functional status and may complement spirometry in evaluating disease severity.

Materials and Methods: This prospective cross-sectional study included 100 patients with spirometry-confirmed COPD attending the Department of Respiratory Medicine, K.D. Medical College and Research Centre, Mathura, between April 2024 and October 2025. Spirometric parameters (FEV₁, FVC, FEV₁/FVC ratio, and MVV) and 6MWD were recorded. Correlation analysis was performed using Pearson's or Spearman's correlation coefficients, with p<0.05 considered statistically significant.

Results: The mean FEV₁ was 52.6 ± 18.4% predicted, and 64% of patients had moderate-to-severe COPD. Mean 6MWD decreased progressively from 415 ± 42 m in mild COPD to 240 ± 48 m in very severe COPD (p<0.001). A strong positive correlation was observed between 6MWD and FEV₁ (r=0.78, p<0.001), while moderate positive correlations were found with FVC, FEV₁/FVC ratio, and MVV. Exercise-induced oxygen desaturation and heart rate increased significantly with worsening disease severity. FEV₁ was the strongest independent predictor of 6MWD.

Conclusion: Six-minute walk distance correlates significantly with spirometric impairment and declines with increasing COPD severity. The 6MWT is a simple and reliable adjunct to spirometry for assessing functional capacity and disease severity in patients with COPD.