Association between six-minute walk tests with lung diffusion capacity for carbon monoxide in chronic respiratory disease: A cross-sectional study

Abstract

Introduction and Aim: Interstitial lung disease (ILD) is a heterogeneous disorder that share common clinical, radiographic, and physiological features. Most patients with ILD usually experience an exertion – induced dyspnea as first symptom. A noticeable change in oxygen saturation was noticed in ILD patients while exercise. The study objective was to ascertain the functional parameter that correlates best with ILD by comparing age, sex, and smoking history with different ILD pattern. Materials and Methods: A proforma (including Six Minute Walk Test and Pulmonary Function Test with lung diffusion capacity) for one-year period (September 2014 - November 2015) was taken for the 40 included participants. The study includes patients with Interstitial Lung diseases diagnosed by clinical, radiological and spirometric parameters. The study tests the sensitivity and the specificity of six-minute walk test versus lung carbon monoxide diffusing ability. Results: A total of 40 participants were included (19 were males and 21 were females). 12 were smokers and 28 were non-smokers. 20 patients belonged to Usual Interstitial Pneumonia (UIP) pattern, 14 were Non-Specific Interstitial Pneumonia (NSIP) and 6 were others. The mean±SD spirometric parameters were FEV1/FVC=101.71±16.752, FVC=55.29±17.322, FEV1=57.66 ± 20.246. Conclusion: There was no statistical significance between age, gender, smoking and ILD patterns. Spirometer and diffusion capacity indices co-relate best with NSIP pattern of ILD in our study. In a resource limited setting, clinical and radiological assessment of ILD with six-minute walking distance and spirometry should or need not be supplemented by DLCO for severity assessment.