Diferentes aspectos na avaliação da capacidade funcional em pacientes com fibrose pulmonar idiopática.

Abstract

Idiopathic pulmonary fibrosis is an interstitial lung disease of unknown etiology which progresses with progressive dyspnea and functional loss. This disease is limited to the lungs and occurs mainly in men over 60 years of age. The evolution of idiopathic pulmonary fibrosis can be unpredictable and may including periods of acute deterioration, defined as exacerbation, representing a rapid progression of the disease and the main cause of hospitalization and death of these patients. In addition, these patients often have decreased functional capacity, which can be assessed both by cardiopulmonary testing - which requires substantial human and material resources, as well as by field tests. The aim of this thesis was: 1) to evaluate the concurrent criterion validity of the six-minute walk test, the incremental shuttle walk test and the Glittre-Activity Daily Life (ADL) test regarding cardiopulmonary exercise testing in patients with idiopathic pulmonary fibrosis; 2) to determine cut-off points of the six-minute walk test, the incremental shuttle walk test and the Glittre-ADL test to differentiate patients with idiopathic pulmonary fibrosis from healthy individuals; 3) to assess the construct convergent validity of the Glittre-ADL test in patients with IPF regarding six-minute walk test and incremental shuttle walk test and 4) to evaluate the concurrent validity of the Human Activity Profile questionnaire to estimate peak oxygen consumption in patients with idiopathic pulmonary fibrosis. Patients with idiopathic pulmonary fibrosis between ages 50-80 were included without supplemental oxygen therapy, without other respiratory and/or cardiac disease associated with idiopathic pulmonary fibrosis, as well as neurological and/or orthopedic diseases which could limit the performance of the tests. In addition, healthy subjects matched for age and sex with patients were included. In addition, healthy subjects matched for age and sex to patients with idiopathic pulmonary fibrosis. Participants who could not understand or perform any of the tests were excluded. The study was approved by the UFMG Ethics Committee (number 2.527.692) - presented in annex A - and all participants signed an informed consent form - presented in appendices A and B. Anthropometric, clinical (except diffusing capacity for carbon monoxide data which were extracted from medical records - only for the group of patients) and spirometric data were collected and all participants performed the three tests. Thus, the six- minute walk test, the incremental shuttle walk test and the Glittre-ADL test. The form for recording data collection is presented in appendix C. In addition, patients with idiopathic pulmonary fibrosis underwent the cardiopulmonary exercise testing, an exam to assess diffusing capacity for carbon monoxide and answered the Human Activity Profile questionnaire - presented in annex B, the Saint George’s Respiratory questionnaire - presented in annex C, Hospital Anxiety and Depression Scale - presented in annex D and Leicester cough questionnaire - presented in annex E. Data distribution was assessed using the Shapiro-Wilk test. Regressions were conducted to assess concurrent validity (manuscript 1), ROC curve was performed to determine cut-off points (manuscript 2), correlations assessed functional status (manuscript 3), and intraclass coefficient correlation was used to assess validity (manuscript 4). It was considered an alpha of 5%. The six-minute walk test, the incremental shuttle walk test and the Glittre-ADL test were considered valid tests compared to cardiopulmonary exercise testing (R2= 0.64, p< 0.001; R2= 0.56, p<0.001 and R2= 0.47, p= 0.001; respectively). The six-minute walk test cut-off point was 580 meters (area under the curve = 0.86, sensibility = 0.79%, specificity = 81%; p< 0.001); the Glittre-ADL test was 2 minutes 50 seconds (area under the curve = 0.83, sensibility = 79%, specificity = 75%; p= 0.001) while the incremental shuttle walk test was not able to differentiate patients with idiopathic pulmonary fibrosis from healthy subjects (area under the curve = 0.66; p= 0.105). Regarding to convergent validity, the Glittre-ADL test showed a strong negative correlation with the six-minute walk test and a moderate negative correlation with the incremental shuttle walk test (r= -0.70 and -0.69; p< 0.01, respectively). Moderate negative correlations were observed between the time spent on the Glittre-ADL test (TGlittre) and lung function parameters (p≤0.01). Moderate positive correlations were observed between TGlittre and the impact domain and total scores of the St. George’s Respiratory Questionnaire (p<0.05). No significant correlations were observed for Leicester Cough Questionnaire (p>0.05). Significant differences were observed between the peak oxygen consumption estimated by the Human Activity Profile questionnaire and the peak oxygen consumption obtained by the cardiopulmonary exercise testing (20.59 ± 3.66 ml.kg.min-1 versus 16.50 ± 3.63 ml.kg.min-1; p= 0.023). The intraclass correlation coefficient found (intraclass correlation coefficient = 0.46; p= 0.010) it can be affirmed that there is significant association of weak magnitude, however it is not possible to consider the human activity profile questionnaire as a valid instrument to estimate peak oxygen consumption in patients with idiopathic pulmonary fibrosis.