The Prognostic Role of Ventilatory Inefficiency and Exercise Capacity in Idiopathic Pulmonary Fibrosis

Abstract

BACKGROUND: Idiopathic pulmonary fibrosis (IPF) is a chronic, progressive, and fatal interstitial lung disease associated with poor prognosis and limited effective treatment options. Reliable predictors of outcome in daily clinical practice are needed to determine high-risk patients for urgent lung transplantation referral. This study aimed to identify practical prognostic predictors of mortality using cardiopulmonary exercise testing (CPET) in IPF subjects. METHODS: Thirty-four subjects with IPF (22 men and 12 women), median age 68 (range 50 -81) y were prospectively studied. At baseline, all subjects were assessed with CPET and were followed up for 40 months from baseline. Receiver operating characteristic curve analysis was conducted to determine cut-off points of CPET variables for mortality, Cox regression analysis for survival using a log-rank test, and hazard ratio for death using a Wald test. RESULTS: Peak work rate <62 watts (P ‫؍‬ .005), peak V O 2 <13.8 mL/kg/min (P ‫؍‬ .031), tidal volume reserve <0.48 L/breath (P ‫؍‬ .010), minute ventilation to carbon dioxide (V E )/V CO 2 ) ratio at the anaerobic threshold >34 (P ‫؍‬ .02), and V E )/V O 2 nadir >34 (P ‫؍‬ .002) were detected as cut-off points associated with mortality. Non-survivor subjects were characterized by higher dyspnea levels, the presence of pulmonary hypertension assessed by echocardiography, pronounced inefficient ventilatory pattern, lower exercise capacity, and more severe desaturation during physical exertion. By the end of the study, 11 subjects (7 women and 4 men) died. Overall mean survival was 60%, 33.7 months (95% CI 30.2-37.2). CONCLUSIONS: This study provides simple, practical, and novel cut-off points for CPET as predictors of prognosis to identify high-risk IPF subjects. Impairment in exercise capacity and abnormal ventilatory responses during CPET were associated with poorer survival in IPF subjects. The findings suggest considering the use of CPET for IPF risk stratification and prediction of prognosis. (ClinicalTrials.gov registration NCT01499745.) Key words: cardiopulmonary exercise testing, survival, prognostic predictors, ventilatory response, exercise intolerance. [Respir Care 2016;61(8):1100 -1109.

Exertional dyspnoea in interstitial lung diseases: the clinical utility of cardiopulmonary exercise testing

“…A prospective observational study evaluating 25 IPF patients, observed for a period of 9-64 months, showed that V′E/V′CO 2 slope and V′O 2 peak rate per kg had the strongest correlation with survival [77]. Impairment in exercise capacity and abnormal ventilatory responses during CPET were confirmed to be associated with poorer survival in a study recently performed in 34 IPF subjects who were followed-up for 40 months [78]. A multicentre retrospective study to predict 3-year mortality was completed on 63 adult patients with IPF who underwent CPET with blood gas analysis [79].…”

Comparison of CPI and GAP models in patients with idiopathic pulmonary fibrosis: a nationwide cohort study

“…As mentioned previously, predictive models of IPF prognosis rely on numerous clinical factors, physiologic parameters, radiologic features, biomarkers, and pathologic findings 5–11,17,18 . Most models developed to date are complex.…”

Physical Activity and Exertional Desaturation Are Associated with Mortality in Idiopathic Pulmonary Fibrosis

“…Thirty-eight IPF subjects treated in the Pulmonary Institute were screened for eligibility, and 34 subjects volunteered and were recruited for participation in the study based on 10% expected dropouts reported in a previous ILD training study [17]. We have previously reported that at 30-months and at 40-months follow-up, group allocation did not affect survival in this group of subjects; however, the sample size was underpowered to detect such changes [18,19]. Demographic characteristics were obtained from all subjects and evaluation for dyspnea by the modified Medical Research Council (mMRC) scale was made [20,21].…”