Cardiovascular complications in patients with interstitial lung disease and their correlation with 6-minute walk test and spirometry: A single-center study

A composite score based on cardiovascular parameters can predict the mortality risk of patients with newly diagnosed interstitial lung disease: A prospective observational study

BACKGROUND

It is crucial to identify factors that can predict the risk of mortality in patients newly diagnosed with interstitial lung disease (ILD). This study sought to develop and assess a composite scoring system for mortality prediction among ILD patients based on cardiovascular parameters, which were previously reported as predictors of survival.

METHODS

We prospectively enrolled patients with newly diagnosed ILD and monitored their survival status for 24 months. Surviving and deceased patients were compared regarding their baseline characteristics including clinical, pulmonary, and cardiovascular parameters. A system of composite scores was established based on significant cardiovascular parameters and the Gender-Age-Physiology (GAP) score. Receiver operating characteristic curves were generated to identify their optimal cut-off values. Univariate as well as multiple multivariate regression models were built to investigate the mortality prediction of different individual and combined parameters.

RESULTS

Ninety-six patients newly diagnosed with ILD underwent cardiovascular evaluation. In univariate analysis, three cardiovascular parameters were identified as significant predictors of mortality risk in ILD patients, either individually or as a combination of composite scores: tricuspid regurgitation velocity > 3.1 m/s; N-terminal pro-B-type natriuretic peptide level > 300 pg/ml and computed tomography pulmonary artery/ascending aorta diameter ratio > 0.9. In multivariate analysis, a composite score of those parameters [hazard ratio (HR) = 2.37 (confidence interval [CI]:1.06-5.33); p = 0.037; Score 1] and GAP score [HR = 1.62 (CI: 1.11-2.36); p = 0.012] were the most significant predictors for mortality among ILD patients. Combination of Score 1 and GAP score (Score 2) can increase the accuracy of survival predictions (area under the curve 0.83; p < 0.001).

CONCLUSIONS

A composite score based on cardiovascular parameters and the GAP score can be used to predict the risk of mortality of patients with ILD. Such a score achieved better diagnostic accuracy than the GAP score alone. Nevertheless, further larger-scale randomized controlled trials are required for evaluation of the newly proposed score and confirmation of our results.

Assessment of the feasibility of 1-min sit-to-stand test in evaluating functional exercise capacity in interstitial lung disease patients

Six-min walk test (6MWT) is widely used exercise test for the evaluation of interstitial lung disease (ILD). However, the long test duration and need for long and flat surface hinder its routine use. One-min sit-to-stand test (1-STST) is devoid of such limitations, but has been scarcely evaluated. The study was conducted to evaluate the performance of 1-STST by correlating it with 6MWT in ILD patients. Stable ILD patients were prospectively enrolled. After initial spirometry, all patients performed 6MWT and 1-STST following the standard recommendations. Exercise capacity and physiological parameters (heart rate, pulse oxygen saturation, blood pressure and dyspnea [modified Borg scale]) including peripheral oxygen saturation (SpO2) were correlated after the tests using Pearson correlation, Intraclass correlation coefficient (ICC) and kappa (κ) coefficient. The results showed that the mean age of the patients (n=60) was 58.8±11.5 years (male:female=1:1). Repetitions after 1-STST showed significant correlation with 6MWT (r=0.48; P<0.001). Changes in the physiological variables were similar (P>0.05) with good consistency (ICC=0.68-0.95) between 6MWT and 1-STST. Both lowest SpO2 and difference in SpO2 also showed good agreement (ICC=0.86; 95% confidence interval [CI], 0.77-0.92 and ICC=0.68; 95% CI, 0.47-0.81 respectively) and significant correlation (r=0.76 and r=0.52, respectively). 1-STST and 6MWT were consistent in identifying patients having oxygen desaturation ≥4% (κ=0.56; 96% CI, 0.30-0.82). The results demonstrated that the performance of 1-STST was consistent with 6MWT in terms of exercise capacity and change in physiological parameters. 1-STST can be a valid alternative to 6MWT in the assessment of ILD patients, especially in peripheral health centers.