The Association of Field Test Outcomes with Peak Oxygen Uptake in Patients with Cystic Fibrosis: A Systematic Review

The purpose of the study was to evaluate the association of field test outcomes with peak oxygen uptake (VO₂peak) in patients with cystic fibrosis (CF) and to describe the main prediction equations available. Data searches were performed in five databases (Pubmed, Embase, LILACs, Scopus and Web of Science) and also in the reference lists of articles included. The following inclusion criteria were used: studies including individuals with CF, presenting both a field test and a cardiopulmonary exercise testing (CPET), and describing a predictive equation or coefficient of correlation/determination. Case studies, abstracts, letters of reply, editorials and duplicate publications were excluded. The methodological quality analysis was performed using the JBI Critical Appraisal Checklist for Analytical Cross-Sectional Studies scale. Protocol registration number: CRD42020148363. Ten studies were eligible. Five equations were found to predict VO₂peak. Equations derived from the shuttle tests (ST) showed strong correlations with VO₂peak (r = 0.79 to 0.95). The six-minute walk test (6MWT) showed moderate associations with VO₂peak in participants with moderate disease severity (r = 0.53 to 0.65). Furthermore, patients with lower maximum heart rate on the three-minute step test tended to have a higher percent predicted VO₂peak (r = -0.40), and the one-minute sit-to-stand test demonstrated moderate correlations between VO₂peak and the number of repetitions (r = 0.52 to 0.66). In conclusion, field test outcomes correlate with oxygen consumption assessed through CPET, although only the ST seems to be valid as a predictor of VO₂peak in patients with CF.