EXERCISE TESTING AND PROGNOSIS IN ADULT CYSTIC-FIBROSIS

Background - The assessment of prognosis is an important issue in cyst ic fibrosis. The prognostic value of exercise testing in comparison wi th other predictors of mortality was examined. Methods - Ninety two ad ult patients with cystic fibrosis performed progressive maximal exerci se tests and outcome was assessed at five years. The results of exerci se testing were examined along with spirometric values, age, sex, body mass index (BMI), and sputum culture. Results - Twenty two subjects d ied during the five year follow up period and 67 survived. Five subjec ts received a lung transplant and were excluded from the analysis. The re were significant differences between those who survived and those w ho died: mean(SE) forced expiratory volume in one second (FEV(1)) 68.9 (2.7) versus 39.7 (3.5)% predicted, BMI 19.0 (0.3) versus 17.1 (0.4) kg/m(2), peak oxygen uptake (Vo(2) peak) 66.6 (2.2) versus 53.7 (3.7)% predicted, peak work rate (Wpeak) 89.4 (3.8) versus 71.2 (5.5)% predi cted, peak minute ventilation (VEpeak) 51.3 (2.0) versus 43.3 (3.1) 1/ min, and ventilatory equivalent for oxygen (VE/Vo(2)) 32.4 (0.6) versu s 38.7 (1.7). Age, sex, oxygen saturation and Burkholderia cepacia col onisation were not found to be significant predictors of mortality. Wh en significant independent factors were entered into a multivariate lo gistic regression model only FEV(1) was found to be a significant corr elate of mortality. A cutoff for FEV(1) of 55% predicted gave the best combination of specificity and sensitivity with 54% of those below th is value dying within five years and 96% of those above it surviving. Conclusions - The results of maximal exercise testing are correlated w ith survival but they are not better than the FEV, as prognostic indic ators.